Author name code: gopalswamy ADS astronomy entries on 2022-09-14 author:"Gopalswamy, Nat" ------------------------------------------------------------------------ Title: Effect of the Heliospheric State on CME Evolution Authors: Dagnew, Fithanegest Kassa; Gopalswamy, Nat; Tessema, Solomon Belay; Akiyama, Sachiko; Yashiro, Seiji Bibcode: 2022ApJ...936..122D Altcode: The culmination of solar cycle 24 by the end of 2019 has created the opportunity to compare the differing properties of coronal mass ejections (CMEs) between two whole solar cycles: solar cycle 23 (SC 23) and solar cycle 24 (SC 24). We report on the width evolution of limb CMEs in SCs 23 and 24 in order to test the suggestion by Gopalswamy et al. that CME flux ropes attain pressure balance at larger heliocentric distances in SC 24. We measure CME width as a function of heliocentric distance for a significantly large number of limb CMEs (~1000) and determine the distances where the CMEs reach constant width in each cycle. We introduced a new parameter, the transition height (hc) of a CME, defined as the critical heliocentric distance beyond which the CME width stabilizes to a quasi-constant value. Cycle and phase-to-phase comparisons are based on this new parameter. We find that the average value of hc in SC 24 is 62% higher than that in SC 23. SC 24 CMEs attain their peak width at larger distances from the Sun than SC 23 CMEs do. The enhanced transition height in SC 24 is new observational ratification of the anomalous expansion. The anomalous expansion of SC 24 CMEs, which is caused by the weak state of the heliosphere, accounts for the larger heliocentric distance where the pressure balance between CME flux rope and the ambient medium is attained. Title: What Is Unusual About the Third Largest Geomagnetic Storm of Solar Cycle 24? Authors: Gopalswamy, N.; Yashiro, S.; Akiyama, S.; Xie, H.; Mäkelä, P.; Fok, M. -C.; Ferradas, C. P. Bibcode: 2022JGRA..12730404G Altcode: 2022arXiv220711630G We report on the solar and interplanetary (IP) causes of the third largest geomagnetic storm (26 August 2018) in solar cycle 24. The underlying coronal mass ejection (CME) originating from a quiescent filament region becomes a 440 km/s magnetic cloud (MC) at 1 au after ∼5 days. The prolonged CME acceleration (for ∼24 hr) coincides with the time profiles of the post-eruption arcade intensity and reconnected flux. Chen et al. (2019, https://doi.org/10.3847/1538-4357/ab3f36) obtain a lower speed since they assumed that the CME does not accelerate after ∼12 hr. The presence of multiple coronal holes near the filament channel and the high-speed wind from them seem to have the combined effect of producing complex rotation in the corona and IP medium resulting in a high-inclination MC. The Dst time profile in the main phase steepens significantly (rapid increase in storm intensity) coincident with the density increase (prominence material) in the second half of the MC. Simulations using the Comprehensive Inner Magnetosphere-Ionosphere model show that a higher ring current energy results from larger dynamic pressure (density) in MCs. Furthermore, the Dst index is highly correlated with the main-phase time integral of the ring current injection that includes density, consistent with the simulations. A complex temporal structure develops in the storm main phase if the underlying MC has a complex density structure during intervals of southward IP magnetic field. We conclude that the high intensity of the storm results from the prolonged CME acceleration, complex rotation of the CME flux rope, and the high density in the 1-au MC. Title: Effect of the Heliospheric State on CME Evolution Authors: Kassa Dagnew, Fithanegest; Gopalswamy, Nat; Belay Tessema, Solomon; Akiyama, Sachiko; Yashiro, Seiji Bibcode: 2022arXiv220803536K Altcode: The culmination of solar cycle 24 by the end of 2019 has created the opportunity to compare the differing properties of coronal mass ejections (CMEs) between two whole solar cycles: Solar cycle 23 (SC 23) and Solar cycle 24 (SC 24). We report on the width evolution of limb CMEs in SC 23 and 24 in order to test the suggestion by Gopalswamy et al. (2015a) that CME flux ropes attain pressure balance at larger heliocentric distances in SC 24. We measure CME width as a function of heliocentric distance for a significantly large number of limb CMEs (~1000) and determine the distances where the CMEs reach constant width in each cycle. We introduced a new parameter: the transition height (hc) of a CME defined as the critical heliocentric distance beyond which the CME width stabilizes to a quasi-constant value. Cycle and phase-to-phase comparisons are based on this new parameter. We find that the average value of hc in SC 24 is 62% higher than in SC 23. SC 24 CMEs attain their peak width at larger distances from the Sun as compared to SC 23 CMEs. The enhanced transition height in SC 24 is new observational ratification of the anomalous expansion. The anomalous expansion of SC 24 CMEs which is caused by the weak state of the heliosphere, accounts for the larger heliocentric distance where the pressure balance between CME flux rope and the ambient medium is attained. Title: Capacity Building Workshop on Coronal and Interplanetary Shocks in Kodaikanal Authors: D'Amicis, Raffaella; Kathiravan, C.; Chellasamy Edwin, Ebenezer; Gopalswamy, Nat Bibcode: 2022cosp...44.3079D Altcode: Space-based white-light coronagraph observations, radio spectral and imaging observations from space and ground are powerful tools to study and characterize interplanetary shocks driven by coronal mass ejections (CMEs). To encourage the scientific use of a wealth of data accumulated at the CDAW Data Center at NASA Goddard Space Flight Center including space missions (SOHO, GOES, SDO, STEREO, ACE), images of type II radio bursts from the Gauribidanur Radioheliograph (GRAPH), ground based radio data from the e-CALLISTO network and the Radio Solar Telescope Network around the globe, a two-week COSPAR Capacity Building Workshop was held in Kodaikanal, India, in 2020. This workshop was intended for scientists and students in developing countries (with particular reference to people from India, Pakistan, Africa, Malaysia, Indonesia, and Sri Lanka) where the e-CALLISTO instruments are deployed to perform joint studies using their data in conjunction with space data to investigate geoeffective solar transient phenomena. The workshop consisted of a series of introductory lectures on the Sun, Solar Corona, Interplanetary medium, Solar Eruptions, Shocks, and Solar Radio Bursts and also on Python software for data analysis. Several projects were undertaken by teams consisting of lecturers and students. In this presentation, we report about this successful workshop. Title: Halo coronal mass ejections, solar energetic particles, and sustained gamma-ray emission Authors: Gopalswamy, Nat; Xie, Hong; Makela, Pertti; Yashiro, Seiji; Akiyama, Sachiko Bibcode: 2022cosp...44.1167G Altcode: Halo coronal mass ejections (CMEs) are fast and wide and hence are very energetic. CMEs that produce space weather events such as intense geomagnetic storms and large solar energetic particle (SEP) events have high proportion of halo CMEs. One CME population has 100 percent halos: the CMEs associated with sustained gamma-ray emission (SGRE) from the Sun that last for at least 3 hours. CMEs associated with SGRE are ultrafast (average speed ~2000 km/s), very similar to CMEs that produce ground level enhancement (GLE) events. The SGRE - halo CME connection supports the idea that high-energy protons accelerated at the CME shock precipitate back to the solar surface, interact with ambient protons, and produce pion decay continuum observed as SGRE. In order to further clarify the relationship, we start with all ultrafast halo CMEs (sky-plane speed at least 1800 km/s) observed in solar cycles 24 that had simultaneous gamma-ray observations from the Sun. We identified 20 such CMEs that have an average sky-plane speed of ~2142 km/s, fourteen of which were frontsided. The soft X-ray flare sizes ranged from M3.7 to X8.2. We determined the CME kinematics using the graduated cylindrical shell model applied to SOHO and STEREO coronagraph data. The three-dimensional speed from the graduated cylindrical shell (GCS) model peaks at ≥2000 km/s (average 2698 km/s). The initial acceleration of the CMEs is >1 km s-2 (average 3.5 km s-2). These speeds and accelerations are typical of GLE events, indicating strong shocks close to the Sun accelerating highest energy particles. When we examined the Fermi Large Area Telescope (Fermi/LAT) >100 MeV gamma-ray data, we found that all but one of the 14 frontsided halo CMEs are associated with an SGRE event. The lone halo without SGRE had a Fermi/LAT data gap, so we cannot rule out the possibility of SGRE association. Among the 6 backside halo CMEs, one was associated with an SGRE, which is the famous 2014 September 1 event originating about 40 degrees behind the limb. Two events had backside location similar to that of the 2014 September 1 event, but the flux rope orientation is north-south indicating a smaller longitudinal extent of the source region, so no SGRE is observed on the frontside. The remaining three events were too far behind the limb. We present additional information on the properties of the SEP events and interplanetary type II radio bursts that further support the CME-SGRE connection. Title: Flux Rope from Eruption Data (FRED) method applied to Earth-directed CMEs from solar cycles 23 and 24 Authors: Gopalswamy, Nat; Xie, Hong; Makela, Pertti; Yashiro, Seiji; Akiyama, Sachiko Bibcode: 2022cosp...44.2427G Altcode: Only a fraction of an active region magnetic flux participates in a typical eruption. The total reconnected flux within the eruption area underlying post eruption arcades (PEAs) represents this fraction. The "flux rope from eruption data" or FRED refers to a technique that defines a coronal mass ejection (CME) flux rope based on the total reconnected flux during the eruption and geometric modeling of the white-light CMEs. One of the key features of FRED is that we know the axial magnetic field strength of the flux rope in the corona. If the flux rope expands self similarly, one can obtain its magnetic field components at any location in the heliosphere. This technique was applied previously to Earth-arriving CMEs of solar cycle 23 with encouraging results. Now that solar cycle 24 is complete, we apply the FRED technique to cycle 24 events and compare the results with those obtained for cycle 23. Title: Modeling the East-West Asymmetry of Energetic Particle Fluence in Large Solar Energetic Particle Events Using the iPATH Model Authors: Ding, Zheyi; Li, Gang; Ebert, Robert W.; Dayeh, Maher A.; Fe-Dueñas, Adolfo Santa; Desai, Mihir; Xie, Hong; Gopalswamy, N.; Bruno, A. Bibcode: 2022JGRA..12730343D Altcode: It has been noted that in large solar energetic particle (SEP) events, the peak intensities show an East-West asymmetry with respect to the source flare locations. Using the 2D improved Particle Acceleration and Transport in the Heliosphere (iPATH) model, we investigate the origin of this longitudinal trend. We consider multiple cases with different solar wind speeds and eruption speeds of the coronal mass ejections (CMEs) and fit the longitudinal distributions of time-averaged fluence by symmetric/asymmetric Gaussian functions with three time intervals of 8, 24 and 48 hr after the flare onset time respectively. The simulation results are compared with a statistical study of three-spacecraft events. We suggest that the East-West asymmetry of SEP fluence and peak intensity can be primarily caused the combined effect of an extended shock acceleration process and the evolution of magnetic field connection to the shock front. Our simulations show that the solar wind speed and the CME speed are important factors determining the East-West fluence asymmetry. Title: Interhemispheric Asymmetries in Ionospheric Electron Density Responses During Geomagnetic Storms: A Study Using Space-Based and Ground-Based GNSS and AMPERE Observations Authors: Swarnalingam, N.; Wu, D. L.; Gopalswamy, N. Bibcode: 2022JGRA..12730247S Altcode: We utilize Total Electron Content (TEC) measurements and electron density (Ne) retrieval profiles from Global Navigation Satellite System (GNSS) receivers onboard multiple Low Earth Orbit (LEO) satellites to characterize large-scale ionosphere-thermosphere system responses during geomagnetic storms. We also analyze TEC measurements from GNSS receivers in a worldwide ground-based network. Measurements from four storms during June and July 2012 (boreal summer months), December 2015 (austral summer month), and March 2015 (equinoctial month) are analyzed to study global ionospheric responses and the interhemispheric asymmetry of these responses. We find that the space-based and ground-based TECs and their responses are consistent in all four geomagnetic storms. The global 3D view from GNSS-Radio Occultation (RO) Ne observations captures enhancements and the uplifting of Ne structures at high latitudes during the initial and main phases. Subsequently, Ne depletion occurs at high latitudes and starts progressing into midlatitude and low latitude as the storm reaches its recovery phase. A clear time lag is evident in the storm-induced Ne perturbations at high latitudes between the summer and winter hemispheres. The interhemispheric asymmetry in TEC and Ne appears to be consistent with the magnitudes of the Active Magnetosphere and Planetary Electrodynamics Response Experiment (AMPERE) high latitude integrated field-aligned currents (FACs), which are 3-4 MA higher in the summer hemisphere than in the winter hemisphere during these storms. The ionospheric TEC and Ne responses combined with the AMPERE-observed FACs indicate that summer preconditioning in the ionosphere-thermosphere system plays a key role in the interhemispheric asymmetric storm responses. Title: The Relation between Type III Radio Storms and CIR Energetic Particles Authors: Gopalswamy, Nat; Mäkelä, Pertti; Yashiro, Seiji; Akiyama, Sachiko; Xie, Hong Bibcode: 2022arXiv220515852G Altcode: We report on a study that compares energetic particle fluxes in corotating interaction regions (CIRs) associated with type III radio storm with those in nonstorm CIRs. In a case study, we compare the CIR particle events on 2010October 21 and 2005 November 2. The two events have similar solar and solar wind circumstances, except that the former is associated with a type III radio storm and has a higher CIR particle flux and fluence. We also perform a statistical study, which shows that the proton and electron fluences are higher in the storm associated CIRs by factor of about 6 and 8, respectively than those in the storm-free CIRs. Title: Can Type III Radio Storms be a Source of Seed Particles to Shock Acceleration? Authors: Gopalswamy, Nat; Akiyama, Sachiko; Mäkelä, Pertti; Yashiro, Seiji; Xie, Hong Bibcode: 2022arXiv220515233G Altcode: An intense type III radio storm has been disrupted by a fast halo coronal mass ejection (CME) on 2000 April 4. The CME is also associated with a large solar energetic particle (SEP) event. The storm recovers after about10 hrs. We identified another CME that occurs on 2003 November 11 with similar CME properties but there is no type III storm in progress. The 2003 November 11 CME is also not associated with an SEP event above the background (less than 2 pfu), whereas the one with type III storm has an intense SEP event (about 56 pfu). One of the factors affecting the intensity of SEP events is the presence of seed particles that are accelerated by CME-driven shocks. We suggest that the type III storm source, which accelerates electrons to produce the storm, also accelerates ions that serve as seed particles to the CME shock. Title: Study of the Mass-loss Rate from the Sun Authors: Michalek, Grzegorz; Gopalswamy, Nat; Yashiro, Seiji Bibcode: 2022ApJ...930...74M Altcode: We investigate the temporal evolution of the yearly total mass-loss rate (YTMLR) from the Sun through coronal mass ejections (CMEs) over solar cycles 23 and 24. The mass determination of CMEs can be subject to significant uncertainty. To minimize this problem, we have used extensive statistical analysis. For this purpose, we employed data included in the Coordinated Data Analysis Workshop (CDAW) catalog. We estimated the contributions to mass loss from the Sun from different subsamples of CMEs (selected on the basis of their masses, angular widths, and position angles). The temporal variations of the YTMLR were compared to those of the sunspot number (SSN), X-ray flare flux, and the Disturbance Storm Time (Dst) index. We show that the CME mass included in the CDAW catalog reflects with high accuracy the actual mass-loss rate from the Sun through CMEs. Additionally, it is shown that the CME mass distribution in the log-lin representation reflects the Gaussian distribution very well. This means that the CMEs included in the CDAW catalog form one coherent population of ejections that have been correctly identified. Unlike the CME occurrence rate, it turns out that the YTMLR is a very good indicator of solar activity (e.g., SSN) and space weather (e.g., Dst index) consequences. These results are very important, since the YTMLR, unlike the mass loss through solar wind, significantly depends on solar cycles. Title: Modern Faraday Rotation Studies to Probe the Solar Wind Authors: Kooi, Jason E.; Wexler, David B.; Jensen, Elizabeth A.; Kenny, Megan N.; Nieves-Chinchilla, Teresa; Wilson, Lynn B., III; Wood, Brian E.; Jian, Lan K.; Fung, Shing F.; Pevtsov, Alexei; Gopalswamy, Nat; Manchester, Ward B. Bibcode: 2022FrASS...941866K Altcode: For decades, observations of Faraday rotation have provided unique insights into the plasma density and magnetic field structure of the solar wind. Faraday rotation (FR) is the rotation of the plane of polarization when linearly polarized radiation propagates through a magnetized plasma, such as the solar corona, coronal mass ejection (CME), or stream interaction region. FR measurements are very versatile: they provide a deeper understanding of the large-scale coronal magnetic field over a range of heliocentric distances (especially ≈1.5 to 20 R⊙) not typically accessible to in situ spacecraft observations; detection of small-timescale variations in FR can provide information on magnetic field fluctuations and magnetohydrodynamic wave activity; and measurement of differential FR can be used to detect electric currents. FR depends on the integrated product of the plasma density and the magnetic field component along the line of sight to the observer; historically, models have been used to distinguish between their contributions to FR. In the last two decades, though, new methods have been developed to complement FR observations with independent measurements of the plasma density based on the choice of background radio source: calculation of the dispersion measure (pulsars), measurement of Thomson scattering brightness (radio galaxies), and application of radio ranging and apparent-Doppler tracking (spacecraft). New methods and new technology now make it possible for FR observations of solar wind structures to return not only the magnitude of the magnetic field, but also the full vector orientation. In the case of a CME, discerning the internal magnetic flux rope structure is critical for space weather applications. Title: Periodic Oscillations in LASCO Coronal Mass Ejection Speeds: Space Seismology Authors: Michalek, Grzegorz; Gopalswamy, Nat; Yashiro, Seiji Bibcode: 2022ApJ...927L..16M Altcode: Coronal mass ejections (CMEs) are energetic eruptions of organized magnetic structures from the Sun. Therefore, the reconnection of the magnetic field during ejection can excite periodic speed oscillations of CMEs. A previous study showed that speed oscillations are frequently associated with CME propagation. The Solar and Heliospheric Observatory mission's white-light coronagraphs have observed about 30,000 CMEs from 1996 January to the end of 2019 December. This period of time covers two solar cycles (23 and 24). In the present study, the basic attributes of speed oscillations during this period of time were analyzed. We showed that the oscillation parameters (period and amplitude) significantly depend not only on the phase of a given solar cycle but also on the intensity of individual cycles as well. This reveals that the basic attributes of speed oscillation are closely related to the physical conditions prevailing inside the CMEs as well as in the interplanetary medium in which they propagate. Using this approximation, we estimated that, on average, the CME internal magnetic field varies from 18 up to 25 mG between minimum and maximum solar activity. The obtained results show that a detailed analysis of speed oscillations can be a very efficient tool for studying not only the physical properties of the ejections themselves but also the condition of the interplanetary medium in which they expand. This creates completely new perspectives for studying the physical parameters of CMEs shortly after their eruption in the Sun's environment (space seismology). Title: Eruption of the EUV Hot Channel from the Solar Limb and Associated Moving Type IV Radio Burst Authors: Vemareddy, P.; Démoulin, P.; Sasikumar Raja, K.; Zhang, J.; Gopalswamy, N.; Vasantharaju, N. Bibcode: 2022ApJ...927..108V Altcode: 2022arXiv220106899V Using the observations from the Solar Dynamics Observatory, we study an eruption of a hot-channel flux rope (FR) near the solar limb on 2015 February 9. The pre-eruptive structure is visible mainly in EUV 131 Å images, with two highly sheared loop structures. They undergo a slow rising motion and then reconnect to form an eruptive hot channel, as in the tether-cutting reconnection model. The J-shaped flare ribbons trace the footpoint of the FR that is identified as the hot channel. Initially, the hot channel is observed to rise slowly at 40 km s-1, followed by an exponential rise from 22:55 UT at a coronal height of 87 ± 2 Mm. Following the onset of the eruption at 23:00 UT, the flare reconnection then adds to the acceleration process of the coronal mass ejection (CME) within 3 R ⊙. Later on, the CME continues to accelerate at 8 m s-2 during its propagation period. Further, the eruption also launched type II radio bursts, which were followed by type III and type IVm radio bursts. The start and end times of the type IVm burst correspond to the CME's core height of 1.5 and 6.1 R ⊙, respectively. Also, the spectral index is negative, suggesting that nonthermal electrons are trapped in the closed loop structure. Accompanied by this type IVm burst, this event is unique in the sense that the flare ribbons are very clearly observed together with the erupting hot channel, which strongly suggests that the hooked parts of the J-shaped flare ribbons outline the boundary of the erupting FR. Title: VizieR Online Data Catalog: Solar coronal mass ejections with SOHO/LASCO (Dagnew+, 2020) Authors: Dagnew, F. K.; Gopalswamy, N.; Tessema, S. B.; Akiyama, S.; Yashiro, S.; Tesfu, T. Y. Bibcode: 2022yCat..19030118D Altcode: We used data (Gopalswamy+, 2010SunGe...5....7G) from the catalog that compiles all halo coronal mass ejections (HCMEs) manually identified from the Solar and Heliospheric Observatory Large Angle and Spectrometric Coronagraph Experiment (SOHO/LASCO) images within the C2 and C3 field of view (FOV).

(1 data file). Title: Solar activity and space weather Authors: Gopalswamy, Nat; Mäkelä, Pertti; Yashiro, Seiji; Akiyama, Sachiko; Xie, Hong Bibcode: 2022JPhCS2214a2021G Altcode: 2022arXiv220102724G After providing an overview of solar activity as measured by the sunspot number (SSN) and space weather events during solar cycles (SCs) 21-24, we focus on the weak solar activity in SC 24. The weak solar activity reduces the number of energetic eruptions from the Sun and hence the number of space weather events. The speeds of coronal mass ejections (CMEs), interplanetary (IP) shocks, and the background solar wind all declined in SC 24. One of the main heliospheric consequences of weak solar activity is the reduced total (magnetic + gas) pressure, magnetic field strength, and Alfvén speed. There are three groups of phenomena that decline to different degrees in SC 24 relative to the corresponding ones in SC 23: (i) those that decline more than SSN does, (ii) those that decline like SSN, and (iii) those that decline less than SSN does. The decrease in the number of severe space weather events such as high-energy solar energetic particle (SEP) events and intense geomagnetic storms is deeper than the decline in SSN. The reduction in the number of severe space weather events can be explained by the backreaction of the weak heliosphere on CMEs. CMEs expand anomalously and hence their magnetic content is diluted resulting in weaker geomagnetic storms. The reduction in the number of intense geomagnetic storms caused by corotating interaction regions is also drastic. The diminished heliospheric magnetic field in SC 24 reduces the efficiency of particle acceleration, resulting in fewer high-energy SEP events. The numbers of IP type II radio bursts, IP socks, and high-intensity energetic storm particle events closely follow the number of fast and wide CMEs (and approximately SSN) because all these phenomena are closely related to CME-driven shocks. The number of halo CMEs in SC 24 declines less than SSN does, mainly due to the weak heliospheric state. Phenomena such as IP CMEs and magnetic clouds related to frontside halos also do not decline significantly. The mild space weather is likely to continue in SC 25, whose strength has been predicted to be not too different from that of SC 24. Title: Arrival Time Estimates of Earth-Directed CME-Driven Shocks Authors: Suresh, K.; Gopalswamy, N.; Shanmugaraju, A. Bibcode: 2022SoPh..297....3S Altcode: We report on the travel times of 19 interplanetary (IP) shocks driven by Earth-directed coronal mass ejections (CMEs) that occurred from 2010 to 2017. We track the shocks ahead of CMEs using the graduated cylindrical shell (GCS) model constructed from multiple-view observations from the Solar TErrestrial RElations Observatory (STEREO) and Solar and Heliospheric Observatory (SOHO) coronagraphs. We calculate the Earthward speed of the shocks from the height-time data obtained from the GCS fit that we use as input to the Empirical Shock Arrival (ESA) model to predict the shock travel times to 1 AU. We find that the mean absolute deviation (MAD) of the predicted IP shock travel time from the observed travel time is about 6.1 hours. The prediction error ranges from −14.3 hours to +13.1 hours with a standard deviation of 7.5 hours. The MAD and RMS errors are significantly smaller than those in the previous report (Gopalswamy et al., Space Weather11, 661, 2013), which used SOHO-STEREO quadrature observations to obtain the Earthward speed of halo CMEs. The χ2-test confirms the high consistency level between predicted and observed travel times. These results suggest that the three-dimensional speeds of shocks can be derived using the GCS model outside of quadrature intervals and can be used in the determination of shock travel times. Title: Hemisphere-Asymmetric Responses of the Ionosphere to Geomagnetic Storms as Observed by GNSS and AMPERE Authors: Swarnalingam, Nimalan; Wu, Dong; Gopalswamy, Nat Bibcode: 2021AGUFMSA24B..05S Altcode: To characterize global ionosphere-thermosphere (IT) system responses during geomagnetic storms, we use electron density (Ne) and Total Electron Content (TEC) observations from space and ground for multiple storms, occurring in the boreal and austral summer months, as well as equinoctial month. The storm-induced Ne response in the summer and winter hemispheres appears to be different and asymmetric. The summer hemisphere shows a stronger response compared to the winter hemisphere. On the other hand, the response during the equinoctial month storm is more symmetric. The global 3D view from GNSS Radio Occultation (RO) Ne observation captures enhancements and uplifting of Ne structures at high latitudes during the initial and main phases. A clear time lag is evident in the storm-induced perturbation at high latitudes between the summer and winter hemispheres. Subsequently, Ne depletions occur at high latitudes. Time lag between high and mid latitudes is also evident, as the storm reaches its recovery phase. The observed hemispheric asymmetry in the ionospheric response appears to be consistent with AMPERE Field-Aligned Current (FAC) measurements. The integrated FACs in the summer hemisphere is a 4 - 5 MA higher than the winter hemisphere during these storms. Title: The Structural Connection between CME Flux Ropes near the Sun and at 1 AU Authors: Xie, Hong; Gopalswamy, Nat; Akiyama, Sachiko Bibcode: 2021AGUFMSH35B2058X Altcode: We preformed the first comprehensive statistical analysis comparing flux rope structures of coronal mass ejections (CMEs) near the Sun and at 1 AU, using SOHO and STEREO measurements for the two full solar cycles of 23 and 24. The study aims to investigate the physical connection of 102 magnetic flux ropes (FR) among solar source regions, CMEs in the extended corona, and magnetic clouds (MCs) near Earth. Our main results include: 1) We confirmed that the hemispheric helicity rule holds true for $\sim$ 87\% of our 102 events. For the thirteen events that do not follow this rule, the FR axis directions and helicity signs can be inferred from soft X-ray and EUV images and magnetogram data in the source regions (e.g., coronal arcade skews, sigmoids, and magnetic tongues). 2) Around 25\% of the 102 events have rotations $>$ 40\dg between the MC and CME--FR axial orientations. 3) For $\sim$56\% of these rotational events, the flux rope rotations occurred within the COR2 FOV, which can be predicted from the CME tilts obtained from flux rope fitting models. In addition, we found that for 89\% of the nineteen stealth CMEs under study, we can use the CNL locations and tilts to predict the flux rope helicity and its axial direction in the MCs. The above results would help to improve the prediction of the flux rope structures in situ. We discuss their implications on space weather forecasts. Title: Novel Magnetic Field and Electron Density Measurements of CMEs (within AU) with the Proposed Multiview Observatory for Solar Terrestrial Science (MOST) Mission Authors: Jensen, P. E., C. S. P., Elizabeth; Manchester, Ward; Fung, Shing; Gopalswamy, Nat; Jian, Lan; Kenny, Megan; Kooi, Jason; Lazio, Joseph; Li, Lihua; Nieves-Chinchilla, Teresa; Pevtsov, Alexei; Wexler, David; Wilson, Lynn; Wood, Brian; Bale, Stuart; Bastian, Tim Bibcode: 2021AGUFMSH33A..08J Altcode: The Multiview Observatory for Solar Terrestrial Science (MOST) mission concept will be the most advanced solar observatory to date (Gopalswamy et al, SH0001, 2021). Comprising four spacecraft, two located in the L4 and ahead of L4 position and two located in the L5 and behind of the L5 position, the four lines-of-sight (LOSs) form the basis for the unique Faraday Effect Tracker of Coronal and Heliospheric Structures (FETCH) instrument (Wexler et al, SH0019, 2021). We report on our modeling into the expected Faraday rotation (FR) caused by an Earth-directed CME crossing the MOST/FETCH radio-sensing paths using a heliospheric 3-D MHD model to obtain the necessary LOS data on electron density and magnetic field components (see example image). Specifically, we utilized simulation data of the 2005 May 13 CME (Manchester IV et al., 2014, Plasma Phys. Control. Fusion), which erupted from the north-south polarity inversion line of AR 10759 at 16:03 UT, reaching speeds around 2000 km/s in the corona. The trajectory of the CME at an acute angle to the Earth-Sun line crosses each FETCH LOS at a different time. Two LOSs are at different viewing angles with little overlap between the CME sheath and magnetic flux rope core. A blind test fitting of the Faraday rotation functions (Figures 6 and 7 in Jensen et al., 2010, Sol. Phys.) to the simulated FETCH observations reproduced the orientation of the CME for its handedness as well as its associated complementary degenerate solution. In conclusion, one of the four LOSs will be more sensitive to observing CME flux rope structure of Earthward CMEs, depending on their trajectory. We find that two of the four LOSs enable analyzing CME evolution, whereas the other two LOSs enable analyzing the average magnetic field vector in the corresponding high density regions dominating the measurements at that time. For example, the average sheath magnetic field vector can be partially measured in the plane of the ecliptic due to the angular differences between 2 LOSs. We discuss future work as this effort develops. Title: A Study on the Near-Sun Speed and Acceleration of CMEs Associated with Sustained Gamma-Ray Emission Events Observed by FERMI-LAT Authors: Makela, Pertti; Gopalswamy, Nat; Xie, Hong; Akiyama, Sachiko; Yashiro, Seiji Bibcode: 2021AGUFMSH35E2118M Altcode: Sustained gamma-ray emission (SGRE) events, also called late-phase gamma-ray emission (LPGRE) events, are solar eruptive events that produce long-lasting >100 MeV gamma-ray flux. Enhanced gamma-ray emission can extend several hours after the impulsive phase of the associated solar flare. SGRE events have been detected since 1980s, but the highly sensitive Large Area Telescope (LAT) on the FERMI spacecraft has observed SGREs more frequently since 2010. The >100 MeV gamma-ray emission is generated by >300 MeV protons via neutral pion production and decay. Flare-related processes or shock waves driven by coronal mass ejections (CMEs) have been suggested as possible acceleration mechanisms of the >300 MeV protons. Previous studies have shown that SGRE events are associated with fast and wide halo CMEs. We describe in detail the near-Sun speed and acceleration of SGRE-event-associated CMEs and compare them with other CME populations without SGRE events. Fast acceleration suggests early shock formation with high speeds that are typical of ground level enhancement events and SGRE events indicating acceleration of high-energy particles. The height-time profiles are obtained by fitting 3D flux rope and shock wave models to the EUV and white-light images of the CME. Title: FETCH Concept: Investigating Quiescent and Transient Magnetic Structures in the Inner Heliosphere using Faraday Rotation of Spacecraft Radio Signals Authors: Wexler, David; Jensen, Elizabeth; Gopalswamy, Nat; Wilson, Lynn; Fung, Shing; Nieves-Chinchilla, Teresa; Jian, Lan; Bastian, Tim; Pevtsov, Alexei; Manchester, Ward; Kenny, Megan; Lazio, Joseph; Wood, Brian; Kooi, Jason Bibcode: 2021AGUFMSH31A..05W Altcode: The Faraday Effect Tracker of Coronal and Heliospheric structures (FETCH) is a new instrument concept being developed to probe coronal and interplanetary magnetic field structures in the ambient solar wind, corotating interaction regions and coronal mass ejections (CMEs) as they evolve in the inner heliosphere. FETCH is one of the instruments that constitute the Multiview Observatory for Solar Terrestrial (MOST) science mission. FETCH will measure Faraday rotation (FR) of linearly polarized spacecraft radio signals transmitted along four lines of sight provided by the four MOST spacecraft: two large spacecraft deployed at Sun-Earth Lagrange points 4 and 5 and two smaller spacecraft, one ahead of L4 and the other behind L5. FETCH will transmit and receive at selected radio frequencies in the 1-100 MHz range for lines of sight with solar impact parameters < 0.5 AU. FR yields the line-of-sight (LOS) integrated product of electron number density and LOS-projected magnetic field strengths. The FR measurements will be obtained from the Stokes polarization parameters while additional plasma parameters, such as electron column density, will be extracted from other signal diagnostics. The multifrequency FR data and four lines-of-sight will be used to constrain the magnetic field topology and dynamics of interplanetary plasma structures upstream from Earth. Unique to this FR experiment, the FETCH transmitter-receiver instrumentation is positioned such that the entire sensing path remains in interplanetary space, thus avoiding the complications of trans-ionospheric FR observations. The FETCH key science objectives include: (1) characterizing CME magnetic field structure and flux rope orientation, (2) tracking CME propagation and shock signatures, (3) understanding the magnetic field features of corotating interaction regions in the extended corona and inner heliosphere, and (4) determination of large-scale MHD wave organization in regions of developed ambient solar wind and its evolution during perturbed flows. The MOST mission will build upon the achievements of the Solar Heliospheric Observatory (SOHO) and the Solar Terrestrial Relations Observatory (STEREO) missions during the last couple of decades. FETCH will help fill the long-standing measurement gap of magnetic field data in the inner heliosphere. Title: The Multiview Observatory for Solar Terrestrial Science (MOST) Authors: Gopalswamy, Nat; Kucera, Therese; Leake, James; MacDowall, Robert; Wilson, Lynn; Kanekal, Shrikanth; Shih, Albert; Christe, Steven; Gong, Qian; Viall, Nicholeen; Tadikonda, Sivakumar; Fung, Shing; Yashiro, Seiji; Makela, Pertti; Golub, Leon; DeLuca, Edward; Reeves, Katharine; Seaton, Daniel; Savage, Sabrina; Winebarger, Amy; DeForest, Craig; Desai, Mihir; Bastian, Tim; Lazio, Joseph; Jensen, P. E., C. S. P., Elizabeth; Manchester, Ward; Wood, Brian; Kooi, Jason; Wexler, David; Bale, Stuart; Krucker, Sam; Hurlburt, Neal; DeRosa, Marc; Pevtsov, Alexei; Tripathy, Sushanta; Jain, Kiran; Gosain, Sanjay; Petrie, Gordon; Kholikov, Shukirjon; Zhao, Junwei; Scherrer, Philip; Woods, Thomas; Chamberlin, Philip; Kenny, Megan Bibcode: 2021AGUFMSH12A..07G Altcode: The Multiview Observatory for Solar Terrestrial Science (MOST) is a comprehensive mission concept targeting the magnetic coupling between the solar interior and the heliosphere. The wide-ranging imagery and time series data from MOST will help understand the solar drivers and the heliospheric responses as a system, discerning and tracking 3D magnetic field structures, both transient and quiescent in the inner heliosphere. MOST will have seven remote-sensing and three in-situ instruments: (1) Magnetic and Doppler Imager (MaDI) to investigate surface and subsurface magnetism by exploiting the combination of helioseismic and magnetic-field measurements in the photosphere; (2) Inner Coronal Imager in EUV (ICIE) to study large-scale structures such as active regions, coronal holes and eruptive structures by capturing the magnetic connection between the photosphere and the corona to about 3 solar radii; (3) Hard X-ray Imager (HXI) to image the non-thermal flare structure; (4) White-light Coronagraph (WCOR) to seamlessly study transient and quiescent large-scale coronal structures extending from the ICIE field of view (FOV); (5) Faraday Effect Tracker of Coronal and Heliospheric structures (FETCH), a novel radio package to determine the magnetic field structure and plasma column density, and their evolution within 0.5 au; (6) Heliospheric Imager with Polarization (HIP) to track solar features beyond the WCOR FOV, study their impact on Earth, and provide important context for FETCH; (7) Radio and Plasma Wave instrument (M/WAVES) to study electron beams and shocks propagating into the heliosphere via passive radio emission; (8) Solar High-energy Ion Velocity Analyzer (SHIVA) to determine spectra of electrons, and ions from H to Fe at multiple spatial locations and use energetic particles as tracers of magnetic connectivity; (9) Solar Wind Magnetometer (MAG) to characterize magnetic structures at 1 au; (10) Solar Wind Plasma Instrument (SWPI) to characterize plasma structures at 1 au. MOST will have two large spacecraft with identical payloads deployed at L4 and L5 and two smaller spacecraft ahead of L4 and behind L5 to carry additional FETCH elements. MOST will build upon SOHO and STEREO achievements to expand the multiview observational approach into the first half of the 21st Century. Title: Earth-affecting solar transients: a review of progresses in solar cycle 24 Authors: Zhang, Jie; Temmer, Manuela; Gopalswamy, Nat; Malandraki, Olga; Nitta, Nariaki V.; Patsourakos, Spiros; Shen, Fang; Vršnak, Bojan; Wang, Yuming; Webb, David; Desai, Mihir I.; Dissauer, Karin; Dresing, Nina; Dumbović, Mateja; Feng, Xueshang; Heinemann, Stephan G.; Laurenza, Monica; Lugaz, Noé; Zhuang, Bin Bibcode: 2021PEPS....8...56Z Altcode: 2020arXiv201206116Z This review article summarizes the advancement in the studies of Earth-affecting solar transients in the last decade that encompasses most of solar cycle 24. It is a part of the effort of the International Study of Earth-affecting Solar Transients (ISEST) project, sponsored by the SCOSTEP/VarSITI program (2014-2018). The Sun-Earth is an integrated physical system in which the space environment of the Earth sustains continuous influence from mass, magnetic field, and radiation energy output of the Sun in varying timescales from minutes to millennium. This article addresses short timescale events, from minutes to days that directly cause transient disturbances in the Earth's space environment and generate intense adverse effects on advanced technological systems of human society. Such transient events largely fall into the following four types: (1) solar flares, (2) coronal mass ejections (CMEs) including their interplanetary counterparts ICMEs, (3) solar energetic particle (SEP) events, and (4) stream interaction regions (SIRs) including corotating interaction regions (CIRs). In the last decade, the unprecedented multi-viewpoint observations of the Sun from space, enabled by STEREO Ahead/Behind spacecraft in combination with a suite of observatories along the Sun-Earth lines, have provided much more accurate and global measurements of the size, speed, propagation direction, and morphology of CMEs in both 3D and over a large volume in the heliosphere. Many CMEs, fast ones, in particular, can be clearly characterized as a two-front (shock front plus ejecta front) and three-part (bright ejecta front, dark cavity, and bright core) structure. Drag-based kinematic models of CMEs are developed to interpret CME propagation in the heliosphere and are applied to predict their arrival times at 1 AU in an efficient manner. Several advanced MHD models have been developed to simulate realistic CME events from the initiation on the Sun until their arrival at 1 AU. Much progress has been made on detailed kinematic and dynamic behaviors of CMEs, including non-radial motion, rotation and deformation of CMEs, CME-CME interaction, and stealth CMEs and problematic ICMEs. The knowledge about SEPs has also been significantly improved. An outlook of how to address critical issues related to Earth-affecting solar transients concludes this article. Title: High latitude coronal mass ejections during the solar maximum 24 Authors: Yashiro, Seiji; Gopalswamy, Nat; Akiyama, Sachiko Bibcode: 2021AGUFMSH35B2052Y Altcode: We examined high latitude CMEs using a catalog of prominence eruptions (PEs) detected automatically in the SDO/AIA 304 Å Images (https://cdaw.gsfc.nasa.gov/CME_list/autope/). The source locations are listed in the prominence catalog, so we could exclude the low-latitude CMEs but appeared in the high latitude due to the projection effects. There are 115 high latitude PEs (Latitude>= 60 degree), but we could identify 60 CMEs only. The CME association rate is similar to the that of prominence eruptions observed by microwave (Gopalswamy et al. 2003, ApJ, 586, 562). Yashiro et al. (2020, JASTP, 205, 105324) reported that the high-latitude PE speed decreased with decreasing average polar magnetic field strength, but we could not find such a clear relationship in the CME speed. The speed of high latitude CMEs are typically 400 km/s, but the CME speeds were occasionally high (e.g., ~700 km/s) when the prominence became jet-like CMEs. Because of the difference of the CME widths, the CME speed is not enough parameter to describe the CME kinematics. On the other hand, we found that the kinetic energy of the high latitude CMEs decreased with decreasing average magnetic field strength. Weaker field strengths indicate smaller amount of energy available to power the eruptions. Title: Spotless days and geomagnetic index as the predictors of solar cycle 25 Authors: Burud, Dipali S.; Jain, Rajmal; Awasthi, Arun K.; Chaudhari, Sneha; Tripathy, Sushanta C.; Gopalswamy, Nat; Chamadia, Pramod; Kaushik, Subhash C.; Vhatkar, Rajiv Bibcode: 2021RAA....21..215B Altcode: 2021arXiv210511448B We study the sunspot activity in relation to spotless days (SLDs) during the descending phase of solar cycles 11-24 to predict the amplitude of sunspot cycle 25. For this purpose, in addition to SLD, we also consider the geomagnetic activity (aa index) during the descending phase of a given cycle. A very strong correlation of the SLD (0.68) and aa index (0.86) during the descending phase of a given cycle with the maximum amplitude of next solar cycle has been estimated. The empirical relationship led us to deduce the amplitude of cycle 25 to be 99.13± 14.97 and 104.23± 17.35 using SLD and aa index, respectively as predictors. Both the predictors provide comparable amplitude for solar cycle 25 and reveal that solar cycle 25 will be weaker than cycle 24. Further, we predict that the maximum of cycle 25 is likely to occur between February and March 2024. While the aa index has been utilized extensively in the past, this work establishes SLDs as another potential candidate for predicting the characteristics of the next cycle. Title: The Structural Connection between Coronal Mass Ejection Flux Ropes near the Sun and at 1 au Authors: Xie, H.; Gopalswamy, N.; Akiyama, S. Bibcode: 2021ApJ...922...64X Altcode: We have performed the first comprehensive statistical analysis comparing flux rope (FR) structures of coronal mass ejections (CMEs) near the Sun and at 1 au, using Solar and Heliospheric Observatory and Solar Terrestrial Relations Observatory measurements for the two full solar cycles 23 and 24. This study aims to investigate the physical connection of 102 magnetic FRs among solar source regions, CMEs in the extended corona, and magnetic clouds (MCs) near Earth. Our main results are as follows: (1) We confirmed that the hemispheric-helicity rule holds true for ~87% of our 102 events. For the 13 events that do not follow this rule, the FR axis directions and helicity signs can be inferred from soft X-ray and extreme ultraviolet images and magnetogram data in the source regions (e.g., coronal arcade skews, Fe XII stalks, sigmoids, and magnetic tongues). (2) Around 25% of the 102 events have rotations >40° between the MC and CME-FR axial orientations. (3) For ~56% of these rotational events, the FR rotations occurred within the COR2 field of view, which can be predicted from the CME tilts obtained from FR fitting models. In addition, we found that for 89% of the 19 stealth CMEs under study, we were able to use coronal neutral line locations and tilts to predict the FR helicity and its axial direction in the MCs. The above results should help improve the prediction of FR structures in situ. We discuss their implications on space weather forecasts. Title: Total Solar Irradiance Variability on the Evolutionary Timescale and its Impact on the Earth's Mean Surface Temperature Authors: Shukure, N. T.; Tessema, S. B.; Gopalswamy, N. Bibcode: 2021ApJ...917...86S Altcode: 2021arXiv210603657S The Sun is the primary source of energy for the Earth. The small changes in total solar irradiance (TSI) can affect our climate on the longer timescale. In the evolutionary timescale, the TSI varies by a large amount and hence its influence on the Earth's mean surface temperature (Ts) also increases significantly. We develop a mass loss dependent analytical model of TSI in the evolutionary timescale and evaluated its influence on the Ts. We determined the numerical solution of TSI for the next 8.23 Gyr to be used as an input to evaluate the Ts which formulated based on a zero-dimensional energy balance model. We used the present-day albedo and bulk atmospheric emissivity of the Earth and Mars as initial and final boundary conditions, respectively. We found that the TSI increases by 10% in 1.42 Gyr, by 40% in about 3.4 Gyr, and by 120% in about 5.229 Gyr from now, while the Ts shows an insignificant change in 1.644 Gyr and increases to 298.86 K in about 3.4 Gyr. The Ts attains the peak value of 2319.2 K as the Sun evolves to the red giant and emits the enormous TSI of 7.93 × 106 W m-2 in 7.676 Gys. At this temperature Earth likely evolves to be a liquid planet. In our finding, the absorbed and emitted flux equally increases and approaches the surface flux in the main sequence, and they are nearly equal beyond the main sequence, while the flux absorbed by the cloud shows the opposite trend. Title: Particle Acceleration and Transport at the Sun Inferred from Fermi/LAT Observations of >100 MeV Gamma-rays Authors: Gopalswamy, Nat; Mäkelä, Pertti; Yashiro, Seiji Bibcode: 2021arXiv210811286G Altcode: The sustained gamma-ray emission (SGRE) events from the Sun are associated with an ultrafast (2000 km/s or greater) halo coronal mass ejection (CME) and a type II radio burst in the decameter-hectometric (DH) wavelengths. The SGRE duration is linearly related to the type II burst duration indicating that >300 MeV protons required for SGREs are accelerated by the same shock that accelerates tens of keV electrons that produce type II bursts. When magnetically well connected, the associated solar energetic particle (SEP) event has a hard spectrum, indicating copious acceleration of high-energy protons. In one of the SGRE events observed on 2014 January 7 by Fermi/LAT, the SEP event detected by GOES has a very soft spectrum with not many particles beyond 100 MeV. This contradicts the presence of the SGRE, implying the presence of significant number of >300 MeV protons. Furthermore, the durations of the type II burst and the SGRE agree with the known linear relationship between them (Gopalswamy et al. 2018, ApJ 868, L19). We show that the soft spectrum is due to poor magnetic connectivity of the shock nose to an Earth observer. Even though the location of the eruption (S15W11) is close to the disk center, the CME propagated non-radially making the CME flank crossing the ecliptic rather than the nose. High-energy particles are accelerated near the nose, so they do not reach GOES but they do precipitate to the vicinity of the eruption region to produce SGRE. This study provides further evidence that SGRE is caused by protons accelerated in shocks and propagating sunward to interact with the atmospheric ions. Title: The Common Origin of High-energy Protons in Solar Energetic Particle Events and Sustained Gamma-Ray Emission from the Sun Authors: Gopalswamy, N.; Yashiro, S.; Mäkelä, P.; Xie, H.; Akiyama, S. Bibcode: 2021ApJ...915...82G Altcode: 2021arXiv210501206G We report that the number of >500 MeV protons (Ng) inferred from sustained gamma-ray emission (SGRE) from the Sun is significantly correlated with that of protons propagating into space (NSEP) as solar energetic particles (SEPs). Under the shock paradigm for SGRE, shocks driven by coronal mass ejections (CMEs) accelerate high-energy protons sending them toward the Sun to produce SGRE by interacting with the atmospheric particles. Particles also escape into the space away from the Sun to be detected as SEP events. Therefore, the significant NSEP-Ng correlation (correlation coefficient 0.77) is consistent with the common shock origin for the two proton populations. Furthermore, the underlying CMEs have properties akin to those involved in ground level enhancement events indicating the presence of high-energy (up to ~GeV) particles required for SGRE. We show that the observed gamma-ray flux is an underestimate in limb events (central meridian distance >60°) because SGRE sources are partially occulted when the emission is spatially extended. With the assumption that the SEP spectrum at the shock nose is hard and that the 100 MeV particles are accelerated throughout the shock surface (half width in the range 60°-120°) we find that the latitudinal widths of SEP distributions are energy dependent with the smallest width at the highest energies. Not using the energy-dependent width results in an underestimate of NSEP in SGRE events occurring at relatively higher latitudes. Taking these two effects into account removes the apparent lack of NSEP-Ng correlation reported in previous studies. Title: The Common Origin of High-energy Protons in Solar Energetic Particle Events and Sustained Gamma-ray Emission from the Sun Authors: Gopalswamy, N.; Yashiro, S.; Makela, P.; Xie, H.; Akiyama, S. Bibcode: 2021AAS...23832208G Altcode: We report on the correlation between the number of >500 MeV protons (Ng) deduced from the Fermi/LAT >100 MeV sustained gamma-ray emission (SGRE) and the number of protons at 1 au (NSEP) estimated from PAMELA mission's solar energetic particle (SEP) measurements. The correlation is highly significant with a correlation coefficient of 0.77 and hence supports the shock origin of >300 MeV protons that interact with the solar chromosphere and resulting in pion decay observed as SGRE. The lack of correlation previously reported has been shown to be due to (i) a systematic underestimate of Ng in events originating close to the limb owing to the spatially-extended nature of SGRE, and (ii) a systematic underestimate of NSEP in events originating at higher latitudes as a consequence of poor latitudinal connectivity. Correcting for these to effects, we find that the regression line is close to the Ng = NSEP line. The close correlation found between NSEP and Ng indicating their common origin (the CME-driven shock) is consistent with other significant correlations: (i) between the SGRE duration and the duration of the associated interplanetary type II radio burst, and (ii) between the SGRE fluence and CME speed. Title: Diffuse Interplanetary Radio Emission from a Polar Coronal Mass Ejection Authors: Gopalswamy, N.; Makela, P.; Yashiro, S.; Akiyama, S. Bibcode: 2021arXiv210501216G Altcode: We report on the first detection of nonthermal radio emission associated with a polar coronal mass ejection. We call the radio emission as diffuse interplanetary radio emission (DIRE), which occurs in the decameter-hectometric wavelengths. The radio emission originates from the shock flanks that interact with nearby streamers. Title: A Weak Fermi Gamma-ray Event Associated with a Halo CME and a Type II Radio Burst Authors: Gopalswamy, N.; Mäkelä, P.; Yashiro, S. Bibcode: 2021arXiv210501212G Altcode: We report on the 2015 June 25 sustained gamma-ray emission (SGRE) event associated with a halo coronal mass ejection and a type II radio burst in the decameter-hectometric (DH) wavelengths. The duration and ending frequency of the type II burst are linearly related to the SGRE duration as found in previous works involving intense gamma-ray events. This study confirms that the SGRE event is due to protons accelerated in the shock that produced the DH type II burst. Title: Investigating width distribution of slow and fast CMEs in solar cycles 23 and 24 Authors: Pant, V.; Majumdar, S.; Patel, R.; Chauhan, A.; Banerjee, D.; Gopalswamy, N. Bibcode: 2021FrASS...8...73P Altcode: 2021arXiv210412850P Coronal Mass Ejections (CMEs) are highly dynamic events originating in the solar atmosphere, that show a wide range of kinematic properties and are the major drivers of the space weather. The angular width of the CMEs is a crucial parameter in the study of their kinematics. The fact that whether slow and fast CMEs (as based on their relative speed to the average solar wind speed) are associated with different processes at the location of their ejection is still debatable. Thus, in this study, we investigate their angular width to understand the differences between the slow and fast CMEs. We study the width distribution of slow and fast CMEs and find that they follow different power law distributions, with a power law indices ($\alpha$) of -1.1 and -3.7 for fast and slow CMEs respectively. To reduce the projection effects, we further restrict our analysis to only limb events as derived from manual catalog and we find similar results. We then associate the slow and fast CMEs to their source regions, and classified the sources as Active Regions (ARs) and Prominence Eruptions (PEs). We find that slow and fast CMEs coming from ARs and PEs, also follow different power laws in their width distributions. This clearly hints towards a possibility that different mechanisms might be involved in the width expansion of slow and fast CMEs coming from different sources.These results are also crucial from the space weather perspective since the width of the CME is an important factor in that aspect. Title: Imaging and Spectral Observations of a Type-II Radio Burst Revealing the Section of the CME-Driven Shock That Accelerates Electrons Authors: Majumdar, Satabdwa; Tadepalli, Srikar Paavan; Maity, Samriddhi Sankar; Deshpande, Ketaki; Kumari, Anshu; Patel, Ritesh; Gopalswamy, Nat Bibcode: 2021SoPh..296...62M Altcode: 2021arXiv210309536M We report on a multi-wavelength analysis of the 26 January 2014 solar eruption involving a coronal mass ejection (CME) and a Type-II radio burst, performed by combining data from various space and ground-based instruments. An increasing standoff distance with height shows the presence of a strong shock, which further manifests itself in the continuation of the metric Type-II burst into the decameter-hectometric (DH) domain. A plot of speed versus position angle (PA) shows different points on the CME leading edge traveled with different speeds. From the starting frequency of the Type-II burst and white-light data, we find that the shock signature producing the Type-II burst might be coming from the flanks of the CME. Measuring the speeds of the CME flanks, we find the southern flank to be at a higher speed than the northern flank; further the radio contours from Type-II imaging data showed that the burst source was coming from the southern flank of the CME. From the standoff distance at the CME nose, we find that the local Alfvén speed is close to the white-light shock speed, thus causing the Mach number to be small there. Also, the presence of a streamer near the southern flank appears to have provided additional favorable conditions for the generation of shock-associated radio emission. These results provide conclusive evidence that the Type-II emission could originate from the flanks of the CME, which in our study is from the southern flank of the CME. Title: On the Connection between Solar Surface Magnetic Flux and the Total Solar Irradiance Authors: Shukure, N. T.; Tessema, S. B.; Gopalswamy, N. Bibcode: 2021ApJ...907...39S Altcode: Solar surface magnetic flux evolution plays a dominant role in the variability of total solar irradiance (TSI). Different proxies of magnetic activity have been introduced to correlate solar variability and TSI. We present the daily strong flux densities (SFDs) and weak flux densities (WFDs) defined with three magnetic thresholds calculated from the Solar Dynamic Observatory/Helioseismic Magnetic Imager. TSI measurements are from the radiometers of the Variability of Solar Irradiance and Gravity Oscillations experiment on the Solar and Heliosphere Observatory, and sunspot area (SSA) is from the National Oceanic and Atmospheric Administration. We characterize the influence of the magnetic flux density variation on the TSI using the Pearson, Spearman, and percentage bend correlations and wavelet analysis between the TSI and the flux density. The Pearson's correlation shows that the TSI is negatively and strongly correlated with SFD and moderately with SSA; Spearman and 20% bend correlation shows that the TSI is moderately correlated with SFD and weakly with SSA on solar maximum, but weakly correlated on solar minimum. However, the TSI is not correlated with WFD during solar maximum and minimum. The bootstrapping tests also confirm that the influence of SFD on TSI is more significant than that of SSA. Finally, a wavelet analysis supports the idea that the SFD and TSI have a causality linkage and that the SFD dominantly influences the TSI variability on the rotational timescale. Title: INterplanetary Flux ROpe Simulator (INFROS): Predicting the magnetic-field vectors of ICMEs Authors: Srivastava, Nandita; Gopalswamy, Nat; Sarkar, Ranadeep Bibcode: 2021cosp...43E1029S Altcode: We have developed an observationally constrained analytical model, the INterplanetary Flux ROpe Simulator (INFROS), for predicting the magnetic-field vectors of interplanetary coronal mass ejections (ICMEs). The main architecture of INFROS uses the near-Sun flux rope properties obtained from the observational parameters that are evolved through the model to estimate the magnetic field vectors of ICMEs at any heliocentric distance. As a proof of concept, we present the case study of an Earth-impacting CME which occurred on 2013 April 11. The predicted magnetic field profiles of the associated ICME show good agreement with those observed by the in-situ spacecraft. We further validated INFROS model for the ICMEs detected by the radially aligned multiple spacecraft orbiting the Sun at different heliocentric distances. The in-situ observations of those ICMEs as detected in MESSENGER at ∼ 0.3 AU or VEX at ~0.7 AU and STEREO at ~1 AU , help us to constrain the INFROS model parameters in order to predict the magnetic field-vectors of the ICME at 1 AU. INFROS shows promising results in the forecasting of Bz in near real-time. It is a simple less time-consuming and computationally inexpensive compared to other models and has the potential to be implemented as a practical space-weather forecasting tool. Title: Magnetic Field Strength in and Around Coronal Flux Ropes Authors: Gopalswamy, Nat Bibcode: 2021cosp...43E1027G Altcode: It is clear from observations and modeling perspectives that all interplanetary coronal mass ejections (ICMEs) may have a flux rope structure. At the Sun, flux ropes are inferred from post eruption arcades (PEAs), which are thought to be part staying with the Sun, while the other part, viz., the flux rope is ejected into space. The total reconnected flux can be derived from the magnetic flux underlying the PEA or the swept-up flare ribbon area. The reconnected flux has important quantitative information on the magnetic content of the ejected flux rope (the poloidal flux of the flux rope). This information, when coupled with the geometrical properties of the flux rope derived from white-light coronagraph images, can be used to derive the axial field strength of the flux rope near the Sun. Under the assumption of a force-free flux rope, one can get all the components of the flux rope magnetic field, including the one that causes geomagnetic storms. Coupled with the fact that the axial magnetic field direction can be obtained from a number of techniques, we have full information on the coronal flux ropes. The internal structure of the flux rope is key to predict its geoeffectiveness. The flux rope propagates through the ambient medium and often drives a shock if super-Alfvenic. Shock-driving CMEs have an additional source of southward magnetic field that can result in geomagnetic storms. The presence of a shock near the Sun can often be inferred from type II radio bursts and white-light observations. The white-light shock structure can be used to infer the ambient magnetic field strength because the shock standoff distance and the radius of curvature of the driving flux rope are related to the shock Mach number. Since the shock speed can be measured from coronagraph observations, it is possible to derive the ambient Alfven speed and magnetic field strength. This talk illustrates the techniques to derive the flux-rope and ambient field strengths with specific examples. Title: The COSPAR Capacity Building Workshops in Solar Terrestrial Science Authors: Gopalswamy, Nat Bibcode: 2021cosp...43E2156G Altcode: The main objective of COSPAR Capacity-Building Workshops (CBWs) is to train young scientists and students from developing countries in using space data obtained by current and past missions. The training involves accessing data from various sources and processing them using free software tools available online. The COSPAR CBW activities enhance the scientific return from many space missions by addressing problems that were not originally considered by the mission teams. For solar terrestrial science, there are several data bases dealing with solar variability and its terrestrial and heliospheric impact. For example, large arrays of data have been accumulated at the CDAW Data Center of NASA's Goddard Space Flight Center from missions such as the ESA/NASA Solar and Heliospheric Observatory (SOHO) mission, NASA's Solar Terrestrial Relations Observatory (STEREO), Wind, and Advanced Composition Explorer (ACE). There are uniform and extended data sets on solar flares and coronal mass ejections that have interesting implications for magnetic energy release on the Sun and societal implications for humans. There are many data sets from ground-based observations that complement the space data and help address many problems in solar terrestrial science. This talk summarizes my experience is serving as the science lead in a couple of workshops that focused on coronal mass ejections and their relation to shocks in the inner heliosphere. Title: Space Weather Capacity Building Activities by the International Space Weather Initiative Authors: Gopalswamy, Nat Bibcode: 2021cosp...43E2435G Altcode: The International Space Weather Initiative (ISWI) is a grassroots organization involved in creating and developing space-weather-literate communities around the globe. ISWI activities include deployment of space weather instrumentation, space weather science research, and capacity building. ISWI was formed to continue the International Heliophysical Year (IHY 2007) activities focusing on the space weather aspects in the near-Earth space. Since 2013, ISWI is aligned with the permanent space weather agenda of the Science and Technology Subcommittee (STSC) formed by the United Nations Committee on Peaceful Uses of Outer Space (UNCOPUOS). The governance of ISWI involves the secretariat and a steering committee constituted by experts from the space weather community. Information on ISWI activities and space weather in general is distributed via the ISWI Newsletter issued once a month. The ISWI web site (http://iswi-secretariat.org) is a repository of documents related to ISWI activities including ISWI instrument networks, lectures from schools, workshop presentations, and the ISWI Newsletter issues. The capacity building and educational activities of ISWI are (i) running space science schools, mainly in developing countries, (ii) deployment of space weather instruments around the world, and (iii) participating in efforts by other international organizations such as COSPAR. The space science schools involve teaching all topics from the solar interior to the surface of Earth to graduate students and young scientists. These schools are run in collaboration with other international organizations such as SCOSTEP and COSPAR that have overlapping interest in capacity building. The instrument deployment is also a capacity building activity because students are involved in the deployment and operations. The data from the space weather instruments are combined with data from other sources including space missions to address space weather problems. ISWI conducts space weather workshops in collaboration with the United Nations Office of Outer Space Affairs (UNOOSA) in which ISWI instrument providers and hosts attend to present their science results. Young scientists and students are provided with travel support to attend these workshops. The lecturers of ISWI schools/workshops often visit local high schools to interact with students and science teachers to inspire the next generation scientists. Title: Properties of High-Frequency Type II Radio Bursts and Their Relation to the Associated Coronal Mass Ejections Authors: Umuhire, A. C.; Gopalswamy, N.; Uwamahoro, J.; Akiyama, S.; Yashiro, S.; Mäkelä, P. Bibcode: 2021SoPh..296...27U Altcode: Solar radio bursts are often early indicators of space weather events such as coronal mass ejections (CMEs). In this study, we determined the properties of a sample of 40 high-starting-frequency (≥ 150 MHz) type II radio bursts and the characteristics of the associated CMEs such as width, location and speed during 2010-2016. The high starting frequency implies shock formation closer to the solar surface, which has important ramifications for the analysis of particle acceleration near the Sun. We found the CME heliocentric distances at the onset time of metric type II bursts range from 1.16 to 1.90 solar radii (Rs). The study was also extended to 128 metric type II bursts to include lower-starting-frequency events for further analysis. The projected CME heights range from 1.15 to 2.85 Rs. The lower starting frequency correspond to shocks forming at larger heights. A weak correlation was found between the type-II starting frequency and CME heights, which is consistent with the density decline in the inner corona. The analysis confirmed a good correlation between the drift rate and the starting frequency of type II bursts (correlation coefficient ∼ 0.8). Taking into account the radial variation of CMEs speeds from the inner corona to the interplanetary medium, we observed the deviations from the universal drift-rate spectrum of type II bursts and confirmed the previous results relating type II bursts to CMEs. Title: The impact of CMEs on the critical frequency of F2-layer ionosphere (foF2) Authors: Seyoum, Alene; Gopalswamy, Nat; Nigussie, Melessew; Mezgebe, Nigusse Bibcode: 2021IAUS..356..400S Altcode: 2020arXiv200408278S The ionospheric critical frequency (foF2) from ionosonde measurements at geographic high, middle, and low latitudes are analyzed with the occurrence of coronal mass ejections (CMEs) in long term variability of the solar cycles. We observed trends of monthly maximum foF2 values and monthly averaged values of CME parameters such as speed, angular width, mass, and kinetic energy with respect to time. The impact of CMEs on foF2 is very high at high latitudes and low at low latitudes. The time series for monthly maximum foF2 and monthly-averaged CME speed are moderately correlated at high and middle latitudes. Title: The Balloon-Borne Investigation of Temperature and Speed of Electrons in the Corona (BITSE): Mission Description and Preliminary Results Authors: Gopalswamy, N.; Newmark, J.; Yashiro, S.; Mäkelä, P.; Reginald, N.; Thakur, N.; Gong, Q.; Kim, Y. -H.; Cho, K. -S.; Choi, S. -H.; Baek, J. -H.; Bong, S. -C.; Yang, H. -S.; Park, J. -Y.; Kim, J. -H.; Park, Y. -D.; Lee, J. -O.; Kim, R. -S.; Lim, E. -K. Bibcode: 2021SoPh..296...15G Altcode: 2020arXiv201106111G We report on the Balloon-borne Investigation of Temperature and Speed of Electrons in the corona (BITSE) mission launched recently to observe the solar corona from ≈3 Rs to 15 Rs at four wavelengths (393.5, 405.0, 398.7, and 423.4 nm). The BITSE instrument is an externally occulted single stage coronagraph developed at NASA's Goddard Space Flight Center in collaboration with the Korea Astronomy and Space Science Institute (KASI). BITSE used a polarization camera that provided polarization and total brightness images of size 1024 ×1024 pixels. The Wallops Arc Second Pointer (WASP) system developed at NASA's Wallops Flight Facility (WFF) was used for Sun pointing. The coronagraph and WASP were mounted on a gondola provided by WFF and launched from the Fort Sumner, New Mexico station of Columbia Scientific Balloon Facility (CSBF) on September 18, 2019. BITSE obtained 17,060 coronal images at a float altitude of ≈128,000 feet (≈39 km) over a period of ≈4 hrs. BITSE flight software was based on NASA's core Flight System, which was designed to help develop flight quality software. We used EVTM (Ethernet Via Telemetry) to download science data during operations; all images were stored on board using flash storage. At the end of the mission, all data were recovered and analyzed. Preliminary analysis shows that BITSE imaged the solar minimum corona with the equatorial streamers on the east and west limbs. The narrow streamers observed by BITSE are in good agreement with the geometric properties obtained by the Solar and Heliospheric Observatory (SOHO) coronagraphs in the overlapping physical domain. In spite of the small signal-to-noise ratio (≈14 ) we were able to obtain the temperature and flow speed of the western steamer. In the heliocentric distance range 4 - 7 Rs on the western streamer, we obtained a temperature of ≈1.0 ±0.3 MK and a flow speed of ≈260 km s−1 with a large uncertainty interval. Title: Comparing Solar Minimum 24/25 with Historical Solar Wind Records at 1 AU Authors: Jian, L.; Gopalswamy, N.; Luhmann, J. G.; Russell, C. T. Bibcode: 2020AGUFMSH021..04J Altcode: Following the study of previous deep solar minimum 23/24 in Jian et al. (2011), we choose a one-year interval at each solar minimum from the beginning of the acquisition of solar wind measurements in the ecliptic plane and at 1 AU, to compare the solar and solar wind parameters at the most recent solar minimum 24/25 with previous solar minima. In addition, combining the continuous solar wind measurements near 1 AU from Wind/ACE and STEREO A/B missions, we survey and characterize the large-scale solar wind structures during 1995-2019, including slow-to-fast stream interaction regions (SIRs), interplanetary coronal mass ejections (ICMEs), and interplanetary shocks. We study their solar cycle variations comprehensively, focusing on the comparison of solar cycles 23 and 24, as well as the comparison of solar minima 22/23, 23/24, and 24/25. Through the study, we describe the long-term variations of space environment for other WHPI investigations. Title: The Coronal Diagnostic Experiment (CODEX) Authors: Newmark, J. S.; Gopalswamy, N.; Kim, Y. H.; Viall, N. M.; Cho, K. S. F.; Reginald, N. L.; Bong, S. C.; Gong, Q.; Choi, S.; Strachan, L.; Yashiro, S. Bibcode: 2020AGUFMSH0280011N Altcode: Understanding solar wind sources and acceleration mechanisms is an overarching solar physics goal. Current models are highly under-constrained due to the limitations of the existing data, particularly in the ~3-10 Rs range. COronal Diagnostic EXperiment (CODEX) is designed to deliver the first global, comprehensive data sets that will impose crucial constraints and answer targeted essential questions, including: Are there signatures of hot plasma released into the solar wind from previously closed fields? What are the velocities and temperatures of the density structures that are observed so ubiquitously within streamers and coronal holes?

To provide these crucial measurements, NASA's Goddard Space Flight Center, in collaboration with the Korea Astronomy and Space Science Institute, will develop a next-generation coronagraph for the International Space Station. This imaging coronagraph uses multiple filters to obtain simultaneous measurements of electron density, temperature, and velocity within a single instrument. This will be the first time all three have been measured simultaneously for this critical field-of-view, and CODEX achieves these measurements multiple times a day. Title: Acceleration of >300 MeV particles by interplanetary shocks evidenced by sustained gamma-ray emission from the Sun Authors: Gopalswamy, N.; Makela, P.; Yashiro, S.; Akiyama, S. Bibcode: 2020AGUFMSH008..02G Altcode: No abstract at ADS Title: Intercycle and Intracycle Variation of Halo CME Rate Obtained from SOHO/LASCO Observations Authors: Dagnew, Fithanegest Kassa; Gopalswamy, Nat; Tessema, Solomon Belay; Akiyama, Sachiko; Yashiro, Seiji; Tesfu, Tesfay Yemane Bibcode: 2020ApJ...903..118D Altcode: We report on the properties of halo coronal mass ejections (HCMEs) in solar cycles 23 and 24. We compare the HCME properties between the corresponding phases (rise, maximum, and declining) in cycles 23 and 24 and compare those between the whole cycles. Despite the significant decline in the sunspot number (SSN) in cycle 24, which dropped by 46% with respect to cycle 23, the abundance of HCMEs is similar in the two cycles. The HCME rate per SSN is 44% higher in cycle 24. In the maximum phase, cycle 24 rate normalized to SSN increased by 127%, while the SSN dropped by 43%. The source longitudes of cycle 24 HCMEs are more uniformly distributed than those in cycle 23. We found that the average sky-plane speed in cycle 23 is ∼16% higher than that in cycle 24. The size distributions of the associated flares between the two cycles and the corresponding phases are similar. The average speed at a central meridian distance (CMD) ≥ 600 for cycle 23 is ∼28% higher than that of cycle 24. We discuss the unusual bump in HCME activity in the declining phase of cycle 23 as being due to exceptional active regions that produced many CMEs during 2003 October-2005 October. The differing HCME properties in the two cycles can be attributed to the anomalous expansion of cycle 24 CMEs. Considering the HCMEs in the rise, maximum, and declining phases, we find that the maximum phase shows the highest contrast between the two cycles. Title: Diffuse Interplanetary Radio Emission: Shock Emission or a Type III storm? Authors: Gopalswamy, Nat; Akiyama, Sachiko; Mäkelä, Pertti; Yashiro, Seiji Bibcode: 2020URSL....2...49G Altcode: 2020arXiv201112763G We present a clear case of a Diffuse Interplanetary Radio Emission (DIRE) event observed during 2002 March 11-12 in association with a fast coronal mass ejection (CME). In the previous event reported [1], there were two CMEs, and a detailed analysis was required to pin down the underlying CME. In the event presented here, the CME association is unambiguous, and the DIRE is found to originate from the flanks of the CME-driven shock. We also provide quantitative explanation for not observing radio emission from the shock nose. We also clarify that DIRE is not a type III storm because the latter occurs outside of solar eruptions. Title: The Energetic Particle Detector. Energetic particle instrument suite for the Solar Orbiter mission Authors: Rodríguez-Pacheco, J.; Wimmer-Schweingruber, R. F.; Mason, G. M.; Ho, G. C.; Sánchez-Prieto, S.; Prieto, M.; Martín, C.; Seifert, H.; Andrews, G. B.; Kulkarni, S. R.; Panitzsch, L.; Boden, S.; Böttcher, S. I.; Cernuda, I.; Elftmann, R.; Espinosa Lara, F.; Gómez-Herrero, R.; Terasa, C.; Almena, J.; Begley, S.; Böhm, E.; Blanco, J. J.; Boogaerts, W.; Carrasco, A.; Castillo, R.; da Silva Fariña, A.; de Manuel González, V.; Drews, C.; Dupont, A. R.; Eldrum, S.; Gordillo, C.; Gutiérrez, O.; Haggerty, D. K.; Hayes, J. R.; Heber, B.; Hill, M. E.; Jüngling, M.; Kerem, S.; Knierim, V.; Köhler, J.; Kolbe, S.; Kulemzin, A.; Lario, D.; Lees, W. J.; Liang, S.; Martínez Hellín, A.; Meziat, D.; Montalvo, A.; Nelson, K. S.; Parra, P.; Paspirgilis, R.; Ravanbakhsh, A.; Richards, M.; Rodríguez-Polo, O.; Russu, A.; Sánchez, I.; Schlemm, C. E.; Schuster, B.; Seimetz, L.; Steinhagen, J.; Tammen, J.; Tyagi, K.; Varela, T.; Yedla, M.; Yu, J.; Agueda, N.; Aran, A.; Horbury, T. S.; Klecker, B.; Klein, K. -L.; Kontar, E.; Krucker, S.; Maksimovic, M.; Malandraki, O.; Owen, C. J.; Pacheco, D.; Sanahuja, B.; Vainio, R.; Connell, J. J.; Dalla, S.; Dröge, W.; Gevin, O.; Gopalswamy, N.; Kartavykh, Y. Y.; Kudela, K.; Limousin, O.; Makela, P.; Mann, G.; Önel, H.; Posner, A.; Ryan, J. M.; Soucek, J.; Hofmeister, S.; Vilmer, N.; Walsh, A. P.; Wang, L.; Wiedenbeck, M. E.; Wirth, K.; Zong, Q. Bibcode: 2020A&A...642A...7R Altcode: After decades of observations of solar energetic particles from space-based observatories, relevant questions on particle injection, transport, and acceleration remain open. To address these scientific topics, accurate measurements of the particle properties in the inner heliosphere are needed. In this paper we describe the Energetic Particle Detector (EPD), an instrument suite that is part of the scientific payload aboard the Solar Orbiter mission. Solar Orbiter will approach the Sun as close as 0.28 au and will provide extra-ecliptic measurements beyond ∼30° heliographic latitude during the later stages of the mission. The EPD will measure electrons, protons, and heavy ions with high temporal resolution over a wide energy range, from suprathermal energies up to several hundreds of megaelectronvolts/nucleons. For this purpose, EPD is composed of four units: the SupraThermal Electrons and Protons (STEP), the Electron Proton Telescope (EPT), the Suprathermal Ion Spectrograph (SIS), and the High-Energy Telescope (HET) plus the Instrument Control Unit that serves as power and data interface with the spacecraft. The low-energy population of electrons and ions will be covered by STEP and EPT, while the high-energy range will be measured by HET. Elemental and isotopic ion composition measurements will be performed by SIS and HET, allowing full particle identification from a few kiloelectronvolts up to several hundreds of megaelectronvolts/nucleons. Angular information will be provided by the separate look directions from different sensor heads, on the ecliptic plane along the Parker spiral magnetic field both forward and backwards, and out of the ecliptic plane observing both northern and southern hemispheres. The unparalleled observations of EPD will provide key insights into long-open and crucial questions about the processes that govern energetic particles in the inner heliosphere. Title: A comparison of CME expansion speeds between solar cycles 23 and 24 Authors: Dagnew, Fithanegest K.; Gopalswamy, Nat; Tessema, Solomon B. Bibcode: 2020JPhCS1620a2003D Altcode: We report on a comparison of the expansion speeds of limb coronal mass ejections (CMEs) between solar cycles 23 and 24. We selected a large number of limb CME events associated with soft X-ray flare size greater than or equal to M1.0 from both cycles. We used data and measurement tools available at the online CME catalog (https://cdaw.gsfc.nasa.gov) that consists of the properties of all CMEs detected by the Solar and Heliospheric Observatory’s (SOHO) Large Angle and Spectrometric Coronagraph (LASCO). We found that the expansion speeds in cycle 24 are higher than those in cycle 23. We also found that the relation between radial and expansion speeds has different slopes in cycles 23 and 24. The cycle 24 slope is 45% higher than that in cycle 23. The expansion speed is also higher for a given radial speed. The difference increases with speed. For a 2000 km/s radial speed, the expansion speed in cycle 24 is ∼48% higher. These results present additional evidence for the anomalous expansion of cycle 24-CMEs, which is due to the reduced total pressure in the heliosphere. Title: Intercycle and intracycle variation of halo CME rate obtained from SOHO/LASCO observations Authors: Kassa Dagnew, Fithanegest; Gopalswamy, Nat; Belay Tessema, Solomon; Akiyama, Sachiko; Yashiro, Seiji; Yemane Tesfu, Tesfay Bibcode: 2020arXiv200906033K Altcode: We report on the properties of halo coronal mass ejections (HCMEs) in solar cycles 23 and 24. We compare the HCMEs properties between the corresponding phases (rise, maximum, and declining) in cycles 23 and 24 in addition to comparing those between the whole cycles. Despite the significant decline in the sunspot number (SSN) in cycle 24, which dropped by 46% with respect to cycle 23, the abundance of HCMEs is similar in the two cycles. The HCME rate per SSN is 44% higher in cycle 24. In the maximum phase, cycle-24 rate normalized to SSN increased by 127% while the SSN dropped by 43%. The source longitudes of cycle-24 HCMEs are more uniformly distributed than those in cycle 23. We found that the average sky-plane speed in cycle 23 is ~16% higher than that in cycle 24. The size distributions of the associated flares between the two cycles and the corresponding phases are similar. The average speed at a central meridian distance (CMD) = 600 for cycle 23 is ~28% higher than that of cycle 24. We discuss the unusual bump in HCME activity in the declining phase of cycle 23 as due to exceptional active regions that produced many CMEs during October 2003 to October 2005. The differing HCME properties in the two cycles can be attributed to the anomalous expansion of cycle-24 CMEs. Considering the HCMEs in the rise, maximum and declining phases, we find that the maximum phase shows the highest contrast between the two cycles. Title: A catalog of prominence eruptions detected automatically in the SDO/AIA 304 Å images Authors: Yashiro, S.; Gopalswamy, N.; Akiyama, S.; Mäkelä, P. A. Bibcode: 2020JASTP.20505324Y Altcode: 2020arXiv200511363Y We report on a statistical study of prominence eruptions (PEs) using a catalog of these events routinely imaged by the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory (SDO) in the 304 Å pass band. Using an algorithm developed as part of an LWS project, we have detected PEs in 304 Å synoptic images with 2-min cadence since May 2010. A catalog of these PEs is made available online (https://cdaw.gsfc.nasa.gov/CME_list/autope/). The 304 Å images are polar-transformed and divided by a background map (pixels with minimum intensity during one day) to get the ratio maps above the limb. The prominence regions are defined as pixels with a ratio ≥2. Two prominence regions with more than 50% of pixels overlapping are considered the same prominence. If the height of a prominence increases monotonically in 5 successive images, it is considered eruptive. All the PEs seen above the limb are detected by the routine, but only PEs with width ≥15° are included in the catalog to eliminate polar jets and other small-scale mass motions. The identifications are also cross-checked with the PEs identified in Nobeyama Radioheliograph images (http://solar.nro.nao.ac.jp/norh/html/prominence/). The catalog gives the date, time, central position angle, latitude, and width of the eruptive prominence. The catalog also provides links to JavaScript movies that combine SDO/AIA images with GOES soft X-ray data to identify the associated flares, and with SOHO/LASCO C2 images to identify the associated coronal mass ejections. We examined the statistical properties of the PEs and found that (1) the surges generally occur only in the active region belt while prominences are found in all latitudes, and (2) the high-latitude PE speed decreased with the decreasing of the average polar magnetic field strength of the previous cycle. Title: Effect of the Weakened Heliosphere in Solar Cycle 24 on the Properties of Coronal Mass Ejections Authors: Gopalswamy, N.; Akiyama, S.; Yashiro, S.; Michalek, G.; Xie, H.; Mäkelä, P. Bibcode: 2020JPhCS1620a2005G Altcode: 2020arXiv200708291G Solar cycle (SC) 24 has come to an end by the end of 2019, providing the opportunity to compare two full cycles to understand the manifestations of SC 24 - the smallest cycle in the Space Age that has resulted in a weak heliospheric state indicated by the reduced pressure. The backreaction of the heliospheric state is to make the coronal mass ejections (CMEs) appear physically bigger than in SC 23, but their magnetic content has been diluted resulting in a lower geoeffectiveness. The heliospheric magnetic field is also lower in SC 24, leading to the dearth of high-energy solar energetic particle (SEP) events. These space-weather events closely follow fast and wide (FW) CMEs. All but FW CMEs are higher in number in SC 24. The active region potential energy is lower in SC 24, consistent with the reduced rate of FW CMEs. The CME rate - sunspot number (SSN) correlation is high in both cycles but the rate increases faster in SC 24. We find that limb CMEs are slower in SC 24 as in the general population but wider. Limb halo CMEs also follow the same trend of slower SC-24 CMEs. However, the SC-24 CMEs become halos at a shorter distance from the Sun. Thus, slower CMEs becoming halos sooner is a clear indication of the backreaction of the weaker heliospheric state on CMEs. We can further pin down the heliospheric state as the reason for the altered CME properties because the associated flares have similar distributions in the two cycles - unaffected by the heliospheric state. Title: Interplanetary Radio Emission: A Summary of Recent Results Authors: Gopalswamy, Nat Bibcode: 2020arXiv200809222G Altcode: This paper summarizes some recent results in the low-frequency radio physics of the Sun. The spatial domain covers the space from the outer corona to the orbit of Earth. The results obtained make use of radio dynamic spectra and white-light coronagraph images and involve radio bursts associated with solar eruptions and those occurring outside solar eruptions. In particular, the connection between type II radio bursts and the sustained gamma-ray emission from the Sun is highlighted. The directivity of interplanetary type IV bursts found recently is discussed to understand the physical reason behind it. A new event showing the diffuse interplanetary radio emission (DIRE) is introduced and its properties are compared with those of regular type II bursts. The DIRE is from the flanks of a CME-driven shock propagating through nearby streamer. Finally, a new noise storm observed by two spacecraft is briefly discussed to highlight its evolution over two solar rotations including the disruption and recovery by solar eruptions. Title: The State of the Heliosphere Revealed by Limb-halo Coronal Mass Ejections in Solar Cycles 23 and 24 Authors: Gopalswamy, Nat; Akiyama, Sachiko; Yashiro, Seiji Bibcode: 2020ApJ...897L...1G Altcode: 2020arXiv200605844G We compare the properties of halo coronal mass ejections (CMEs) that originate close to the limb (within a central meridian distance range of 60°-∼90°) during solar cycles 23 and 24 to quantify the effect of the heliospheric state on CME properties. There are 44 and 38 limb halos in cycles 23 and 24, respectively. Normalized to the cycle-averaged total sunspot number, there are 42% more limb halos in cycle 24. Although the limb halos as a population are very fast (average speed ∼1464 km s-1), cycle-24 halos are slower by ∼26% than the cycle-23 halos. We introduce a new parameter, the heliocentric distance of the CME leading edge at the time a CME becomes a full halo; this height is significantly shorter in cycle 24 (by ∼20%) and has a lower cutoff at ∼6 Rs. These results show that cycle-24 CMEs become halos sooner and at a lower speed than the cycle-23 ones. On the other hand, the flare sizes are very similar in the two cycles, ruling out the possibility of eruption characteristics contributing to the differing CME properties. In summary, this study reveals the effect of the reduced total pressure in the heliosphere that allows cycle-24 CMEs to expand more and become halos sooner than in cycle 23. Our findings have important implications for the space-weather consequences of CMEs in cycle 25 (predicted to be similar to cycle 24) and for understanding the disparity in halo counts reported by automatic and manual catalogs. Title: A comparison of CME expansion speeds between solar cycles 23 and 24 Authors: Kassa Dagnew, Fithanegest; Gopalswamy, Nat; Belay Tessema, Solomon Bibcode: 2020arXiv200713204K Altcode: We report on a comparison of the expansion speeds of limb coronal mass ejections (CMEs) between solar cycles 23 and 24. We selected a large number of limb CME events associated with soft X-ray flare size greater than or equal to M1.0 from both cycles. We used data and measurement tools available at the online CME catalog (https://cdaw.gsfc.nasa.gov) that consists of the properties of all CMEs detected by the Solar and Heliospheric Observatory's (SOHO) Large Angle and Spectrometric Coronagraph (LASCO). We found that the expansion speeds in cycle 24 are higher than those in cycle 23. We also found that the relation between radial and expansion speeds has different slopes in cycles 23 and 24. The cycle 24 slope is 45% higher than that in cycle 23. The expansion speed is also higher for a given radial speed. The difference increases with speed. For a 2000 km/s radial speed, the expansion speed in cycle 24 is ~48% higher. These results present additional evidence for the anomalous expansion of cycle 24-CMEs, which is due to the reduced total pressure in the heliosphere. Title: Interplanetary shocks as a source of sustained gamma-ray emission from the Sun Authors: Gopalswamy, Nat; Mäkelä, Pertti Bibcode: 2020EGUGA..2221334G Altcode: It has recently been shown that the sustained gamma-ray emission (SGRE) from the Sun that lasts for hours beyond the impulsive phase of the associated flare is closely related to radio emission from interplanetary shocks (Gopalswamy et al. 2019, JPhCS, 1332, 012004, 2019). This relationship supports the idea that >300 MeV protons accelerated by CME-driven shocks propagate toward the Sun, collide with chromospheric protons and produce neutral pions that promptly decay into >80 MeV gamma-rays. There have been two challenges to this idea. (i) Since the location of the shock can be halfway between the Sun and Earth at the SGRE end time, it has been suggested that magnetic mirroring will not allow the high energy protons to precipitate. (ii) Lack of correlation between the number protons involved in the production of >100 MeV gamma-rays (Ng) and the number of protons (Nsep) in the associated solar energetic particle (SEP) event has been reported. In this paper, we show that the mirror ratio problem is no different from that in flare loops where electrons and protons precipitate to produce impulsive phase emissions. We also suggest that the lack of Ng - Nsep correlation is due to two reasons: (1) Nsep is underestimated in the case of eruptions happening at large ecliptic latitudes because the high-energy protons accelerated near the nose do not reach the observer. (2) In the case of limb events, the Ng is underestimated because gamma-rays from some part of the extended gamma-ray source do not reach the observer. Title: A Modified Spheromak Model Suitable for Coronal Mass Ejection Simulations Authors: Singh, Talwinder; Yalim, Mehmet S.; Pogorelov, Nikolai V.; Gopalswamy, Nat Bibcode: 2020ApJ...894...49S Altcode: 2020arXiv200210409S Coronal mass ejections (CMEs) are some of the primary drivers of extreme space weather. They are large eruptions of mass and magnetic field from the solar corona and can travel the distance between Sun and Earth in half a day to a few days. Predictions of CMEs at 1 au, in terms of both its arrival time and magnetic field configuration, are very important for predicting space weather. Magnetohydrodynamic modeling of CMEs, using flux rope-based models, is a promising tool for achieving this goal. In this study, we present one such model for CME simulations, based on spheromak magnetic field configuration. We have modified the spheromak solution to allow for independent input of poloidal and toroidal fluxes. The motivation for this is the possibility of estimating these fluxes from solar magnetograms and extreme ultraviolet data from a number of different approaches. We estimate the poloidal flux of CME using post-eruption arcades and toroidal flux from the coronal dimming. In this modified spheromak, we also have the option to control the helicity sign of flux ropes, which can be derived from the solar disk magnetograms using the magnetic tongue approach. We demonstrate the applicability of this model by simulating the 2012 July 12 CME in the solar corona. Title: Positron Processes in the Sun Authors: Gopalswamy, Nat Bibcode: 2020Atoms...8...14G Altcode: 2020arXiv200404280G Positrons play a major role in the emission of solar gamma-rays at energies from a few hundred keV to >1 GeV. Although the processes leading to positron production in the solar atmosphere are well known, the origin of the underlying energetic particles that interact with the ambient particles is poorly understood. With the aim of understanding the full gamma-ray spectrum of the Sun, I review the key emission mechanisms that contribute to the observed gamma-ray spectrum, focusing on the ones involving positrons. In particular, I review the processes involved in the 0.511 MeV positron annihilation line and the positronium continuum emissions at low energies, and the pion continuum emission at high energies in solar eruptions. It is thought that particles accelerated at the flare reconnection and at the shock driven by coronal mass ejections are responsible for the observed gamma-ray features. Based on some recent developments I suggest that energetic particles from both mechanisms may contribute to the observed gamma-ray spectrum in the impulsive phase, while the shock mechanism is responsible for the extended phase. Title: Impact of space weather on climate and habitability of terrestrial-type exoplanets Authors: Airapetian, V. S.; Barnes, R.; Cohen, O.; Collinson, G. A.; Danchi, W. C.; Dong, C. F.; Del Genio, A. D.; France, K.; Garcia-Sage, K.; Glocer, A.; Gopalswamy, N.; Grenfell, J. L.; Gronoff, G.; Güdel, M.; Herbst, K.; Henning, W. G.; Jackman, C. H.; Jin, M.; Johnstone, C. P.; Kaltenegger, L.; Kay, C. D.; Kobayashi, K.; Kuang, W.; Li, G.; Lynch, B. J.; Lüftinger, T.; Luhmann, J. G.; Maehara, H.; Mlynczak, M. G.; Notsu, Y.; Osten, R. A.; Ramirez, R. M.; Rugheimer, S.; Scheucher, M.; Schlieder, J. E.; Shibata, K.; Sousa-Silva, C.; Stamenković, V.; Strangeway, R. J.; Usmanov, A. V.; Vergados, P.; Verkhoglyadova, O. P.; Vidotto, A. A.; Voytek, M.; Way, M. J.; Zank, G. P.; Yamashiki, Y. Bibcode: 2020IJAsB..19..136A Altcode: 2019arXiv190505093A The current progress in the detection of terrestrial type exoplanets has opened a new avenue in the characterization of exoplanetary atmospheres and in the search for biosignatures of life with the upcoming ground-based and space missions. To specify the conditions favorable for the origin, development and sustainment of life as we know it in other worlds, we need to understand the nature of astrospheric, atmospheric and surface environments of exoplanets in habitable zones around G-K-M dwarfs including our young Sun. Global environment is formed by propagated disturbances from the planet-hosting stars in the form of stellar flares, coronal mass ejections, energetic particles, and winds collectively known as astrospheric space weather. Its characterization will help in understanding how an exoplanetary ecosystem interacts with its host star, as well as in the specification of the physical, chemical and biochemical conditions that can create favorable and/or detrimental conditions for planetary climate and habitability along with evolution of planetary internal dynamics over geological timescales. A key linkage of (astro) physical, chemical, and geological processes can only be understood in the framework of interdisciplinary studies with the incorporation of progress in heliophysics, astrophysics, planetary and Earth sciences. The assessment of the impacts of host stars on the climate and habitability of terrestrial (exo)planets will significantly expand the current definition of the habitable zone to the biogenic zone and provide new observational strategies for searching for signatures of life. The major goal of this paper is to describe and discuss the current status and recent progress in this interdisciplinary field and to provide a new roadmap for the future development of the emerging field of exoplanetary science and astrobiology. Title: ICME Evolution in the Inner Heliosphere Authors: Luhmann, J. G.; Gopalswamy, N.; Jian, L. K.; Lugaz, N. Bibcode: 2020SoPh..295...61L Altcode: ICMEs (interplanetary coronal mass ejections), the heliospheric counterparts of what is observed with coronagraphs at the Sun as CMEs, have been the subject of intense interest since their close association with geomagnetic storms was established in the 1980s. These major interplanetary plasma and magnetic field transients, often preceded and accompanied by solar energetic particles (SEPs), interact with planetary magnetospheres, ionospheres, and upper atmospheres in now fairly well-understood ways, although their details and context affect their overall impacts. The term ICME as it is used here refers to the complete solar-wind plasma and field disturbance, including the leading shock (if present), the compressed, deflected solar-wind plasma and the field behind the shock ("sheath"), and the coronal ejecta (the "driver") - often called a magnetic cloud. Many uncertainties remain in understanding both the relationship to what is observed at the Sun and the variety of local outcomes suggested by in-situ observations. This impacts our abilities to interpret events and to forecast effects based on solar observations. Here, we briefly consider what is known about ICMEs and their evolution en route from the Sun from the combination of available observations and interpretive models that have been developed up to now. The included references are only representative of the large body of work that has been published on this subject. Our aim is to provide the reader with an updated synthesis of research results in this still active area of heliophysics at the dawn of the Parker Solar Probe (PSP) and Solar Orbiter (SO) mission era. Title: Space, time and velocity association of successive coronal mass ejections Authors: Lara, Alejandro; Gopalswamy, Nat; Niembro, Tatiana; Pérez-Enríquez, Román; Yashiro, Seiji Bibcode: 2020A&A...635A.112L Altcode:
Aims: Our aim is to investigate the possible physical association between consecutive coronal mass ejections (CMEs).
Methods: Through a statistical study of the main characteristics of 27 761 CMEs observed by SOHO/LASCO during the past 20 years.
Results: We found the waiting time (WT) or time elapsed between two consecutive CMEs is < 5 h for 59% and < 25 h for 97% of the events, and the CME WTs follow a Pareto Type IV statistical distribution. The difference of the position-angle of a considerable population of consecutive CME pairs is less than 30°, indicating the possibility that their source locations are in the same region. The difference between the speed of trailing and leading consecutive CMEs follows a generalized Student t-distribution. The fact that the WT and the speed difference have heavy-tailed distributions along with a detrended fluctuation analysis shows that the CME process has a long-range dependence. As a consequence of the long-range dependence, we found a small but significative difference between the speed of consecutive CMEs, with the speed of the trailing CME being higher than the speed of the leading CME. The difference is largest for WTs < 2 h and tends to be zero for WTs > 10 h, and it is more evident during the ascending and descending phases of the solar cycle. We suggest that this difference may be caused by a drag force acting over CMEs closely related in space and time.
Conclusions: Our results show that the initiation and early propagation of a significant population of CMEs cannot be considered as a "pure" stochastic process; instead they have temporal, spatial, and velocity relationship. Title: Source of Energetic Protons in the 2014 September 1 Sustained Gamma-ray Emission Event Authors: Gopalswamy, N.; Mäkelä, P.; Yashiro, S.; Akiyama, S.; Xie, H.; Thakur, N. Bibcode: 2020SoPh..295...18G Altcode: 2020arXiv200103816G We report on the source of >300 MeV protons during the SOL2014-09-01 sustained gamma-ray emission (SGRE) event based on multi-wavelength data from a wide array of space- and ground-based instruments. Based on the eruption geometry we provide concrete explanation for the spatially and temporally extended γ -ray emission from the eruption. We show that the associated flux rope is of low inclination (roughly oriented in the east-west direction), which enables the associated shock to extend to the frontside. We compare the centroid of the SGRE source with the location of the flux rope's leg to infer that the high-energy protons must be precipitating between the flux rope leg and the shock front. The durations of the SOL2014-09-01 SGRE event and the type II radio burst agree with the linear relationship between these parameters obtained for other SGRE events with duration ≥3 hrs. The fluence spectrum of the SEP event is very hard, indicating the presence of high-energy (GeV) particles in this event. This is further confirmed by the presence of an energetic coronal mass ejection with a speed >2000 kms−1, similar to those in ground level enhancement (GLE) events. The type II radio burst had emission components from metric to kilometric wavelengths as in events associated with GLE events. All these factors indicate that the high-energy particles from the shock were in sufficient numbers needed for the production of γ -rays via neutral pion decay. Title: A Study of the Observational Properties of Coronal Mass Ejection Flux Ropes near the Sun Authors: Sindhuja, G.; Gopalswamy, N. Bibcode: 2020ApJ...889..104S Altcode: We present the observational properties of coronal mass ejection (CME) flux ropes (FRs) near the Sun based on a set of 35 events from solar cycle 24 (2010-2017). We derived the CME FR properties using the Flux Rope from Eruption Data technique. According to this technique, the geometrical properties are obtained from a flux-rope fit to CMEs and the magnetic properties from the reconnected flux in the source region. In addition, we use the magnetic flux in the dimming region at the eruption site. Geometric properties like radius of the FR and the aspect ratio are derived from the FR fitting. The reconnected flux exhibits a positive correlation with flare fluence in soft X-rays (SXRs), peak flare intensity in SXRs, CME speed, and kinetic energy, with correlation coefficients (cc) 0.78, 0.6, 0.48, and 0.55, respectively. We found a moderate positive correlation between magnetic flux in the core dimming regions and the toroidal flux obtained from the Lundquist solution for a force-free FR (cc = 0.43). Furthermore, we correlate the core dimming flux and CME mass (cc = 0.34). The area of the core dimming region shows a moderate correlation with the radius of the FR (cc = 0.4). Thus, we infer that greater magnetic content (poloidal and toroidal fluxes) indicates a more energetic eruption in terms of flare size, CME speed, kinetic energy, mass, and radius of the FR, suggesting important implications for space weather predictions. Title: The shock driving capability of a CME inferred from multiwavelength observations Authors: Kassa Dagnew, Fithanegest; Gopalswamy, Nat; Belay Tessema, Solomon; Umuhire, Ange Cynthia; Yashiro, Seiji; Mäkelä, Pertti; Xie, Hong Bibcode: 2020arXiv200204056K Altcode: The radial speed of a coronal mass ejection (CME) determines the shock-driving capability of a CME as indicated by the presence of a type II radio burst. Here we report on the April 18, 2014 CME that was associated with a type II radio burst in the metric and interplanetary domains. We used the radio-burst data provided by the San Vito Solar Observatory of the Radio Solar Telescope Network and data from the Wind spacecraft. The CME is a full halo in the field of view of the coronagraphs on board the Solar and Heliospheric Observatory (SOHO). The CME was also observed by the coronagraphs on board the Solar Terrestrial Relations Observatory (STEREO). We computed the CME shock and flux rope speeds based on the multi-view observations by the different coronagraphs and by EUV instruments. We determined the shock speed from metric and interplanetary radio observations and found them to be consistent with white-light observations, provided the metric type II burst and its continuation into the decameter-hectometric domain are produced at the shock flanks, where the speed is still high enough to accelerate electrons that produce the type II bursts. Interestingly, there was an interplanetary type II burst segment consistent with an origin at the shock nose suggesting that the curved shock was crossing plasma levels separated by a few solar radii. We conclude that the CME speed is high enough to produce the interplanetary Type II burst and a solar energetic particle (SEP) event. However, the speed is not high enough to produce a ground level enhancement (GLE) event, which requires the shock to form at a height of ~1.5 Rs. Title: An Observationally Constrained Analytical Model for Predicting the Magnetic Field Vectors of Interplanetary Coronal Mass Ejections at 1 au Authors: Sarkar, Ranadeep; Gopalswamy, Nat; Srivastava, Nandita Bibcode: 2020ApJ...888..121S Altcode: 2019arXiv191203494S We report on an observationally constrained analytical model, the INterplanetary Flux ROpe Simulator (INFROS), for predicting the magnetic field vectors of coronal mass ejections (CMEs) in the interplanetary medium. The main architecture of INFROS involves using the near-Sun flux rope properties obtained from the observational parameters that are evolved through the model in order to estimate the magnetic field vectors of interplanetary CMEs (ICMEs) at any heliocentric distance. We have formulated a new approach in INFROS to incorporate the expanding nature and the time-varying axial magnetic field strength of the flux rope during its passage over the spacecraft. As a proof of concept, we present the case study of an Earth-impacting CME which occurred on 2013 April 11. Using the near-Sun properties of the CME flux rope, we have estimated the magnetic vectors of the ICME as intersected by the spacecraft at 1 au. The predicted magnetic field profiles of the ICME show good agreement with those observed by the in situ spacecraft. Importantly, the maximum strength (10.5 ± 2.5 nT) of the southward component of the magnetic field (Bz) obtained from the model prediction is in agreement with the observed value (11 nT). Although our model does not include the prediction of the ICME plasma parameters, as a first-order approximation, it shows promising results in forecasting of Bz in near real time, which is critical for predicting the severity of the associated geomagnetic storms. This could prove to be a simple space-weather forecasting tool compared to the time-consuming and computationally expensive MHD models. Title: On the properties of solar energetic particle events associated with metric type II radio bursts Authors: Mäkelä, Pertti; Gopalswamy, Nat; Xie, Hong; Akiyama, Sachiko; Yashiro, Seiji; Thakur, Neeharika Bibcode: 2020arXiv200110506M Altcode: Metric type II solar radio bursts and solar energetic particles (SEPs) are both associated with shock fronts driven by coronal mass ejections (CMEs) in the solar corona. Recent studies of ground level enhancements (GLEs), regular large solar energetic particle (SEP) events and filament eruption (FE) associated large SEP events have shown that SEP events are organized by spectral index of proton fluence spectra and by the average starting frequencies of the associated type II radio bursts. Both these results indicate a hierarchical relationship between CME kinematics and SEP event properties. In this study, we expand the investigations to fluence spectra and the longitudinal extent of metric type II associated SEP events including low-intensity SEP events. We utilize SEP measurements of particle instruments on the Solar and Heliospheric Observatory (SOHO) and Solar Terrestrial Relations Observatory (STEREO) spacecraft together with radio bursts observations by ground-based radio observatories during solar cycle 24. Our results show that low-intensity SEP events follow the hierarchy of spectral index or the hierarchy of the starting frequency of type II radio bursts. We also find indications of a trend between the onset frequency of metric type II bursts and the estimated longitudinal extent of the SEP events although the scatter of data points is quite large. These two results strongly support the idea of SEP acceleration by shocks. Stronger shocks develop closer to the Sun. Title: The Shock-Driving Capability of a CME Inferred from Multiwavelength Observations Authors: Dagnew, F.; Gopalswamy, N.; Tessema, S.; Umuhire, A.; Yashiro, S.; Mäkelä, P.; Xie, H. Bibcode: 2019SunGe..14..105D Altcode: 2019SunGe..14...105 The radial speed of a coronal mass ejection (CME) determines the shock-driving capability of a CME as indicated by the presence of a type II radio burst. Here we report on the April 18, 2014 CME that was associated with a type II radio burst in the metric and interplanetary domains. We used the radio-burst data provided by the San Vito Solar Observatory of the Radio Solar Telescope Network and data from the Wind spacecraft. The CME is a full halo in the field of view of the coronagraphs on board the Solar and Heliospheric Observatory (SOHO). The CME was also observed by the coronagraphs on board the Solar Terrestrial Relations Observatory (STEREO). We computed the CME shock and flux rope speeds based on the multi-view observations by the different coronagraphs and by EUV instruments. We determined the shock speed from metric and interplanetary radio observations and found them to be consistent with white-light observations, provided the metric type II burst and its continuation into the decameter-hectometric domain are produced at the shock flanks, where the speed is still high enough to accelerate electrons that produce the type II bursts. Interestingly, there was an interplanetary type II burst segment consistent with an origin at the shock nose suggesting that the curved shock was crossing plasma levels separated by a few solar radii. We conclude that the CME speed is high enough to produce the interplanetary Type II burst and a solar energetic particle (SEP) event. However, the speed is not high enough to produce a ground level enhancement (GLE) event, which requires the shock to form at a height of ~1.5 Rs. Title: Low Frequency Radio Bursts Observed by the Wind Spacecraft and their Contribution to the Understanding of Coronal Mass Ejections Authors: Gopalswamy, N.; Makela, P.; Yashiro, S. Bibcode: 2019AGUFMSH43C3379G Altcode: At frequencies below the ionospheric cutoff, only three types of solar radio bursts caused by nonthermal electrons are observed: type II, type III, and type IV bursts. A quarter century of radio observations from the Radio and Plasma Wave (WAVES) experiment and white light observations from the Large Angle and Spectrometric Coronagraph (LASCO) have contributed enormously to our understanding of solar eruptions and their heliospheric consequences. In particular, type II bursts provide information on shocks driven by coronal mass ejections (CMEs), including the locations of particle acceleration along the shock surface and their ability to identify shocks accelerating solar energetic particle (SEP) events. The ending frequencies of type II bursts have become an important indicator of the heliocentric distance over which shocks remain as efficient particle accelerators evidenced by high-energy SEP events and sustained gamma-ray emission (SGRE) events. This paper highlights some major results regarding CMEs and low-frequency radio bursts and summarize some outstanding problems that are being investigated. Title: Solar Sources of Coronal Mass Ejections Authors: Akiyama, S.; Gopalswamy, N.; Yashiro, S.; Michalek, G. Bibcode: 2019AGUFMSH11D3389A Altcode: Coronal Mass Ejections (CMEs) are one of the important phenomena in space weather research. The SOHO/LASCO CME catalog has listed more than 29,000 CMEs since January 1996 and is extensively used in the community. The catalog provides the basic CME properties, e.g., speed, angular width, mass, and kinetic energy. However the CME source information is not included since it is difficult to examine the source of all CMEs listed in the CME catalog. Here we describe two special CME lists that include CME source information: (i) a list of wide CMEs whose angular width is ≥ 60⁰, and (ii) list of CMEs associated with ≥ C3.0 flares. To determine the source location, we use all available eruptive signatures near the surface, such as solar flares, filament eruptions, EUV waves, and coronal dimmings. The X-ray flare class and the flare start/peak times are also listed if available. We have assigned six confidence levels to the source identification: 0 - no source was identified, 5 - source was identified without doubt. We were able to identify the source locations of 6,870 wide CMEs out of 8,420 that occurred during 1996 to 2018. We found that 48% of wide CMEs originated from the active regions and 52% were from the quiet Sun. Solar flares and CMEs are closely related but there is no one-to-one correspondence. During 1996 to 2018, there are 7,658 ≥ C3 flares. From these, we find that ~90% of X-class, 50% of M-class, and 20% of C3-C9 class flares were associated with CMEs. Statistical relationship between the flares and the CMEs will be presented. Title: On the Shock Source of Sustained Gamma-Ray Emission from the Sun Authors: Gopalswamy, N.; Mäkelä, P.; Yashiro, S.; Lara, A.; Akiyama, S.; Xie, H. Bibcode: 2019JPhCS1332a2004G Altcode: 2019arXiv190713318G It has recently been shown that the spatially and temporally extended γ-ray emission in solar eruptions are caused by >300 MeV protons precipitating on the Sun from shocks driven by coronal mass ejections (CMEs). The γ-rays result from the decay of neutral pions produced in the proton-proton interaction when the >300 MeV protons collide with those in the chromosphere. The evidence comes from the close correlation between the durations of the sustained gamma-ray emission (SGRE) and the associated interplanetary (IP) type II radio bursts. In this paper, we provide further evidence that support the idea that protons accelerated in IP shocks driven by CMEs propagate toward the Sun, precipitate in the chromosphere to produce the observed SGRE. We present the statistical properties of the SGRE events and the associated CMEs, flares, and type II radio bursts. It is found that the SGRE CMEs are similar to those associated with ground level enhancement events. The CME speed is well correlated with the SGRE fluence. High CME speed is an important requirement for the occurrence of SGRE, while the flare size is not. Based on these results, we present a schematic model illustrating the spatially and temporally extended nature of SGRE related to the CME flux rope-shock structure. Title: Statistical Survey of Coronal Mass Ejections and Interplanetary Type II Bursts Authors: Krupar, V.; Magdalenić, J.; Eastwood, J. P.; Gopalswamy, N.; Kruparova, O.; Szabo, A.; Němec, F. Bibcode: 2019ApJ...882...92K Altcode: Coronal mass ejections (CMEs) are responsible for most severe space weather events, such as solar energetic particle events and geomagnetic storms at Earth. Type II radio bursts are slow drifting emissions produced by beams of suprathermal electrons accelerated at CME-driven shock waves propagating through the corona and interplanetary medium. Here, we report a statistical study of 153 interplanetary type II radio bursts observed by the two STEREO spacecraft between 2008 March and 2014 August. The shock associated radio emission was compared with CME parameters included in the Heliospheric Cataloguing, Analysis and Techniques Service catalog. We found that faster CMEs are statistically more likely to be associated with the interplanetary type II radio bursts. We correlate frequency drifts of interplanetary type II bursts with white-light observations to localize radio sources with respect to CMEs. Our results suggest that interplanetary type II bursts are more likely to have a source region situated closer to CME flanks than CME leading edge regions. Title: Are Solar Energetic Particle Events and Type II Bursts Associated with Fast and Narrow Coronal Mass Ejections? Authors: Kahler, S. W.; Ling, A. G.; Gopalswamy, N. Bibcode: 2019SoPh..294..134K Altcode: Gradual solar energetic (E >10 MeV) particle (SEP) events and metric through kilometric wavelength type II radio bursts are usually associated with shocks driven by fast (V ≥900 kms−1) and wide (W ≥60∘) coronal mass ejections (FW CMEs). This criterion was established empirically by several studies from solar cycle 23. The characteristic Alfvén speed in the corona, which ranges over 500 - 1500 km s−1 at heights ≥2 Ro, provides the minimum V requirement for a CME to drive a shock, but the general absence of SEP events or type II bursts with fast and narrow (W <60∘) CMEs has not been explained. We review and confirm the earlier studies with a more comprehensive comparison of SEP events and type II bursts with fast and narrow (FN) CMEs. We offer an explanation for the lack of SEP event and type II burst associations with FN CMEs in terms of recent heuristic arguments and modeling that show that the response of a magnetized plasma to the propagation of a CME depends on the CME geometry as well as on its speed. A clear distinction is made between a projectile that propagates through the medium to produce a bow shock, and a 3D piston that everywhere accumulates material to produce a broad shock and sheath. The bow shock is unfavorable for producing SEP events and type II bursts, but the 60∘ cut-off is not explained. Title: Statistical Study on Multispacecraft Widespread Solar Energetic Particle Events During Solar Cycle 24 Authors: Xie, H.; St. Cyr, O. C.; Mäkelä, P.; Gopalswamy, N. Bibcode: 2019JGRA..124.6384X Altcode: We conduct a statistical study on the large three-spacecraft widespread solar energetic particle (SEP) events. Longitudinal distributions of the peak intensities, onset delays, and relation between the SEP intensity, coronal mass ejection (CME) shock speed, width, and the kinetic energy of the CME have been investigated. We apply a Gaussian fit to obtain the SEP intensity I0 and distribution width σ and a forward-modeling fit to determine the true shock speed and true CME width. We found a good correlation between σ and connection angle to the flare site and I0 and the kinetic energy of the CME. By including the true shock speed and true CME widths, we reduce root-mean-square errors on the predicted SEP intensity by ∼41% for protons compared to Richardson et al.'s (2014, https://doi.org/10.1007/s11207-014-0524-8) prediction. The improved correlation between the CME kinetic energy and SEP intensity provides strong evidence for the CME-shock acceleration theory of SEPs. In addition, we found that electron and proton release time delays (DTs) relative to Type II radio bursts increase with connection angles. The average electron (proton) DT is ∼14 (32) min for strongly anisotropic events and ∼2.5 (4.4) hr for weakly anisotropic events. Poor magnetic connectivity and large scattering effects are two main reasons to cause large delays. Title: Direct Estimates of the Solar Coronal Magnetic Field Using Contemporaneous Extreme-ultraviolet, Radio, and White-light Observations Authors: Kumari, Anshu; Ramesh, R.; Kathiravan, C.; Wang, T. J.; Gopalswamy, N. Bibcode: 2019ApJ...881...24K Altcode: 2019arXiv190709721K We report a solar coronal split-band type II radio burst that was observed on 2016 March 16 with the Gauribidanur Radio Spectro-Polarimeter in the frequency range ≈90-50 MHz, and the Gauribidanur RadioheliograPH at two discrete frequencies, viz. 80 and 53.3 MHz. Observations around the same epoch in extreme ultraviolet (EUV) and white light show that the above burst was associated with a flux-rope structure and a coronal mass ejection (CME), respectively. The combined height-time plot generated using EUV, radio, and white-light data suggests that the different observed features (i.e., the flux rope, type II burst, and the CME) are all closely associated. We constructed an empirical model for the coronal electron density distribution (N e (r), where r is the heliocentric distance) from the above set of observations themselves and used it to estimate the coronal magnetic field strength (B) over the range of r values in which the respective events were observed. The B values are consistent with each other. They vary as B(r) = 2.61 × r -2.21 G in the range r ≈ 1.1-2.2R ⊙. As far as we know, similar direct estimates of B in the near-Sun corona without assuming a model for N e (r), and by combining cotemporal set of observations in two different regions (radio and white-light) of the electromagnetic spectrum, have rarely been reported. Further, the present work is a novel attempt where the characteristics of a propagating EUV flux-rope structure, considered to be the signature of a CME close to the Sun, have been used to estimate B(r) in the corresponding distance range. Title: On the Coronal Mass Ejection Detection Rate during Solar Cycles 23 and 24 Authors: Michalek, Grzegorz; Gopalswamy, Nat; Yashiro, Seiji Bibcode: 2019ApJ...880...51M Altcode: The Solar and Heliospheric Observatory (SOHO) mission’s white light coronagraphs have observed more than 25,000 coronal mass ejections (CMEs) from 1996 January to the end of 2015 July. This period of time covers almost two solar cycles (23 and 24). The basic attributes of CMEs, reported in the SOHO/Large Angle and Spectrometric Coronagraph (LASCO) catalog, during these solar cycles were statistically analyzed. The question of the CME detection rate and its connection to the solar cycles was considered in detail. Based on the properties and detection rate, CMEs can be divided into two categories: regular and specific events. The regular events are pronounced and follow the pattern of sunspot number. On the other hand, the special events are poorer and more correlated with the general conditions of heliosphere and corona. Nevertheless, both groups of CMEs are the result of the same physical phenomenon, viz. release of magnetic energy from closed field regions. It was demonstrated that the enhanced CME rate, since the solar cycle 23 polar-field reversal, is due to a significant decrease of total (magnetic and plasma) heliospheric pressure as well as the changed magnetic pattern of solar corona. CMEs expel free magnetic energy and helicity from the Sun; therefore, they are related to complex solar magnetic field structure. It is also worth emphasizing that the CMEs listed in the SOHO/LASCO catalog are real ejections (not false identification). Their detection rate reflects the global evolution of the magnetic field on the Sun, and not only changes in the magnetic structures associated with sunspots. Title: Global Energetics of Solar Flares. VII. Aerodynamic Drag in Coronal Mass Ejections Authors: Aschwanden, Markus J.; Gopalswamy, Nat Bibcode: 2019ApJ...877..149A Altcode: 2019arXiv190605804A The free energy that is dissipated in a magnetic reconnection process of a solar flare, generally accompanied by a coronal mass ejection (CME), has been considered as the ultimate energy source of the global energy budget of solar flares in previous statistical studies. Here we explore the effects of the aerodynamic drag force on CMEs, which supplies additional energy from the slow solar wind to a CME event, besides the magnetic energy supply. For this purpose, we fit the analytical aerodynamic drag model of Cargill and Vršnak et al. to the height-time profiles r(t) of LASCO/SOHO data in 14,316 CME events observed during the first 8 yr (2010-2017) of the Solar Dynamics Observatory era (ensuring EUV coverage with AIA). Our main findings are (1) a mean solar wind speed of w = 472 ± 414 km s-1, (2) a maximum drag-accelerated CME energy of E drag ≲ 2 × 1032 erg, (3) a maximum flare-accelerated CME energy of E flare ≲ 1.5 × 1033 erg, (4) the ratio of the summed kinetic energies of all flare-accelerated CMEs to the drag-accelerated CMEs amounts to a factor of 4, (5) the inclusion of the drag force slightly lowers the overall energy budget of CME kinetic energies in flares from ≈7% to ≈4%, and (6) the arrival times of CMEs at Earth can be predicted with an accuracy of ≈23%. Title: Reconstructing Extreme Space Weather From Planet Hosting Stars Authors: Airapetian, Vladimir; Adibekyan, V.; Ansdell, M.; Alexander, D.; Barklay, T.; Bastian, T.; Boro Saikia, S.; Cohen, O.; Cuntz, M.; Danchi, W.; Davenport, J.; DeNolfo, G.; DeVore, R.; Dong, C. F.; Drake, J. J.; France, K.; Fraschetti, F.; Herbst, K.; Garcia-Sage, K.; Gillon, M.; Glocer, A.; Grenfell, J. L.; Gronoff, G.; Gopalswamy, N.; Guedel, M.; Hartnett, H.; Harutyunyan, H.; Hinkel, N. R.; Jensen, A. G.; Jin, M.; Johnstone, C.; Kahler, S.; Kalas, P.; Kane, S. R.; Kay, C.; Kitiashvili, I. N.; Kochukhov, O.; Kondrashov, D.; Lazio, J.; Leake, J.; Li, G.; Linsky, J.; Lueftinger, T.; Lynch, B.; Lyra, W.; Mandell, A. M.; Mandt, K. E.; Maehara, H.; Miesch, M. S.; Mickaelian, A. M.; Mouschou, S.; Notsu, Y.; Ofman, L.; Oman, L. D.; Osten, R. A.; Oran, R.; Petre, R.; Ramirez, R. M.; Rau, G.; Redfield, S.; Réville, V.; Rugheimer, S.; Scheucher, M.; Schlieder, J. E.; Shibata, K.; Schnittman, J. D.; Soderblom, David; Strugarek, A.; Turner, J. D.; Usmanov, A.; Van Der Holst, B.; Vidotto, A.; Vourlidas, A.; Way, M. J.; Wolk, Scott J.; Zank, G. P.; Zarka, P.; Kopparapu, R.; Babakhanova, S.; Pevtsov, A. A.; Lee, Y.; Henning, W.; Colón, K. D.; Wolf, E. T. Bibcode: 2019BAAS...51c.564A Altcode: 2019astro2020T.564A; 2019arXiv190306853A The goal of this white paper is to identify and describe promising key research goals to aid the theoretical characterization and observational detection of ionizing radiation from quiescent and flaring upper atmospheres of planet hosts as well as properties of stellar coronal mass ejections (CMEs) and stellar energetic particle (SEP) events. Title: Obituary: Mukul R. Kundu (1930-2010) Authors: Gopalswamy, Nat Bibcode: 2019BAAS...51b0314G Altcode: Renowned solar physicist and radio astronomer Mukul Ranjan Kundu died on 17 June 2010 near College Park, Maryland, from complications after an automobile accident that occurred when he was returning home from work. A recipient of the American Astronomical Society's 2007 George Ellery Hale Prize, Mukul spent his entire career studying the radiophysics of the Sun. His work significantly advanced the understanding of the interactions between accelerated electrons and the magnetized solar corona and of the myriad nonthermal radio phenomena that resulted. Title: Explicit IMF By-Effect Maximizes at Subauroral Latitudes (Dedicated to the Memory of Eigil Friis-Christensen) Authors: Holappa, L.; Gopalswamy, N.; Mursula, K. Bibcode: 2019JGRA..124.2854H Altcode: 2019arXiv190404568H The most important parameter in the coupling between solar wind and geomagnetic activity is the Bz-component of the interplanetary magnetic field (IMF). However, recent studies have shown that IMF By is an additional, independent driver of geomagnetic activity. We use here local geomagnetic indices from a large network of magnetic stations to study how IMF By affects geomagnetic activity at different latitudes for all solar wind and, separately, during coronal mass ejections. We show that geomagnetic activity, for all solar wind, is 20% stronger for By > 0 than for By < 0 at subauroral latitudes of about 60° corrected geomagnetic latitude. During coronal mass ejections, the By-effect is larger, about 40%, at slightly lower latitudes of about 57° (corrected geomagnetic) latitude. These results highlight the importance of the IMF By-component for space weather at different latitudes and must be taken into account in space weather modeling. Title: Simulating Solar Coronal Mass Ejections Constrained by Observations of Their Speed and Poloidal Flux Authors: Singh, T.; Yalim, M. S.; Pogorelov, N. V.; Gopalswamy, N. Bibcode: 2019ApJ...875L..17S Altcode: 2019arXiv190400140S We demonstrate how the parameters of a Gibson-Low flux-rope-based coronal mass ejection (CME) can be constrained using remote observations. Our Multi-Scale Fluid-Kinetic Simulation Suite has been used to simulate the propagation of a CME in a data-driven solar corona background computed using the photospheric magnetogram data. We constrain the CME model parameters using the observations of such key CME properties as its speed, orientation, and poloidal flux. The speed and orientation are estimated using multi-viewpoint white-light coronagraph images. The reconnected magnetic flux in the area covered by the post-eruption arcade is used to estimate the poloidal flux in the CME flux rope. We simulate the partial halo CME on 2011 March 7 to demonstrate the efficiency of our approach. This CME erupted with the speed of 812 km s-1 and its poloidal flux, as estimated from source active region data, was 4.9 × 1021 Mx. Using our approach, we were able to simulate this CME with the speed 840 km s-1 and the poloidal flux of 5.1 × 1021 Mx, in remarkable agreement with the observations. Title: On the Properties of Solar Energetic Particle Events Associated with Metric Type II Radio Bursts Authors: Mäkelä, P.; Gopalswamy, N.; Xie, H.; Akiyama, S.; Yashiro, S.; Thakur, N. Bibcode: 2019SunGe..14..123M Altcode: 2019SunGe..14...123 Metric type II solar radio bursts and solar energetic particles (SEPs) are both associated with shock fronts driven by coronal mass ejections (CMEs) in the solar corona. Recent studies of ground level enhancements (GLEs), regular large solar energetic particle (SEP) events and filament eruption (FE) associated large SEP events have shown that SEP events are organized by spectral index of proton fluence spectra and by the average starting frequencies of the associated type II radio bursts. Both these results indicate a hierarchical relationship between CME kinematics and SEP event properties. In this study, we expand the investigations to fluence spectra and the longitudinal extent of metric type II associated SEP events including low-intensity SEP events. We utilize SEP measurements of particle instruments on the Solar and Heliospheric Observatory (SOHO) and Solar Terrestrial Relations Observatory (STEREO) spacecraft together with radio bursts observations by ground-based radio observatories during solar cycle 24. Our results show that low-intensity SEP events follow the hierarchy of spectral index or the hierarchy of the starting frequency of type II radio bursts. We also find indications of a trend between the onset frequency of metric type II bursts and the estimated longitudinal extent of the SEP events although the scatter of data points is quite large. These two results strongly support the idea of SEP acceleration by shocks. Stronger shocks develop closer to the Sun. Title: A Catalog of Type II radio bursts observed by Wind/WAVES and their Statistical Properties Authors: Gopalswamy, N.; Mäkelä, P.; Yashiro, S. Bibcode: 2019SunGe..14..111G Altcode: 2019arXiv191207370G; 2019SunGe..14...111 Solar type II radio bursts are the signature of particle acceleration by shock waves in the solar corona and interplanetary medium. The shocks originate in solar eruptions involving coronal mass ejections (CMEs) moving at super-Alfvenic speeds. Type II bursts occur at frequencies ranging from hundreds of MHz to tens of kHz, which correspond to plasma frequencies prevailing in the inner heliosphere from the base of the solar corona to the vicinity of Earth. Type II radio bursts occurring at frequencies below the ionospheric cutoff are of particular importance, because they are due to very energetic CMEs that can disturb a large volume of the heliosphere. The underlying shocks accelerate not only electrons that produce the type II bursts, but also protons and heavy ions that have serious implications for space weather. The type II radio burst catalog (https://cdaw.gsfc.nasa.gov/CME_list/radio/waves_type2.html) presented here provides detailed information on the bursts observed by the Radio and Plasma Wave Experiment (WAVES) on board the Wind Spacecraft. The catalog is enhanced by compiling the associated flares, CMEs, and solar energetic particle (SEP) events including their basic properties. We also present the statistical properties of the radio bursts and the associated phenomena, including solar-cycle variation of the occurrence rate of the type II bursts. Title: Evidence for Shock Source of Solar Sustained Gamma-ray Emission: Fermi, Wind, and SOHO Observations Authors: Gopalswamy, N.; Mäkelä, Pertti; Yashiro, Seiji; Lara Sanchez, Alejandro; Xie, Hong; Akiyama, Sachiko; MacDowall, Robert J. Bibcode: 2019AAS...23340106G Altcode: Fermi Large Area Telescope (Fermi/LAT) observations have shown that sustained gamma-ray emission (SGRE) from the Sun is rather common. Such events are now called sustained gamma ray emission (SGRE) events. Some SGRE events last for almost a day. SGRE is thought to be pion continuum resulting from the impact of >300 MeV protons impacting the solar chromosphere. Two sources of the high-energy protons have been discussed in the literature: (i) continued acceleration/trapping of protons in large-scale magnetic structures in the associated solar eruption and (ii) precipitation of sunward propagating protons accelerated in CME-driven shocks. One of the best observational signatures of CME shocks is the interplanetary type II radio emission due to nonthermal electrons accelerated in the shock front. Shocks start accelerating particles very close to the Sun and often continue to do so far into the IP medium resulting in kilohertz radio emission. We examined the type II burst properties such as the duration and ending frequencies and compared them with the SGRE durations. The SGRE duration has a significant linear relationship with the duration and ending frequency of type II bursts. This result strongly supports the idea that protons accelerated at the shock front travel back to the Sun to precipitate and produce SGRE. The protons must be traveling along field lines threading the shock front and lying at the periphery of the CME flux rope. Initial estimates show that the shocks at a distance of several tens of solar radii when the SGRE and type II bursts end. The required >300 MeV proton events are not observed at Earth in most of the events. This can be explained by the fact that SEP events need magnetic connectivity to the observer, whereas type II bursts and SGRE are electromagnetic emissions and hence do not have the connectivity requirement. Title: Interplanetary Type II Radio Bursts from Wind/WAVES and Sustained Gamma-Ray Emission from Fermi/LAT: Evidence for Shock Source Authors: Gopalswamy, Nat; Mäkelä, Pertti; Yashiro, Seiji; Lara, Alejandro; Xie, Hong; Akiyama, Sachiko; MacDowall, Robert J. Bibcode: 2018ApJ...868L..19G Altcode: We present quantitative evidence that interplanetary type II radio bursts and sustained gamma-ray emission (SGRE) events from the Sun are closely related. Out of about 30 SGRE events reported in Share et al. we consider 13 events that had a duration exceeding ∼5 hr to exclude any flare-impulsive phase gamma-rays. The SGRE duration also has a linear relation with the ending frequency of the bursts. The synchronism between the ending times of SGRE and the type II emission strongly supports the idea that the same shock accelerates electrons to produce type II bursts and protons (>300 MeV) that propagate from the shock to the solar surface to produce SGRE via pion decay. The acceleration of high-energy particles is confirmed by the associated solar energetic particle (SEP) events detected at Earth and/or at the Solar Terrestrial Relations Observatory spacecraft. Furthermore, the presence of >300 MeV protons is corroborated by the fact that the underlying coronal mass ejections (CMEs) had properties identical to those associated with ground-level enhancement events: they had speeds of >2000 km s-1 and all were full-halo CMEs. Many SEP events did not have detectable flux at Earth in the >300 MeV energy channels, presumably because of poor magnetic connectivity. Title: Coronal flux ropes and their interplanetary counterparts Authors: Gopalswamy, N.; Akiyama, S.; Yashiro, S.; Xie, H. Bibcode: 2018JASTP.180...35G Altcode: 2017arXiv170508912G We report on a study comparing coronal flux ropes inferred from eruption data with their interplanetary counterparts constructed from in situ data. The eruption data include the source-region magnetic field, post-eruption arcades, and coronal mass ejections (CMEs). Flux ropes were fit to the interplanetary CMEs (ICMEs) considered for the 2011 and 2012 Coordinated Data Analysis Workshops (CDAWs). We computed the total reconnected flux involved in each of the associated solar eruptions and found it to be closely related to flare properties, CME kinematics, and ICME properties. By fitting flux ropes to the white-light coronagraph data, we obtained the geometric properties of the flux ropes and added magnetic properties derived from the reconnected flux. We found that the CME magnetic field in the corona is significantly higher than the ambient magnetic field at a given heliocentric distance. The radial dependence of the flux-rope magnetic field strength is faster than that of the ambient magnetic field. The magnetic field strength of the coronal flux ropes is also correlated with that in interplanetary flux ropes constructed from in situ data, and with the observed peak magnetic field strength in ICMEs. The physical reason for the observed correlation between the peak field strength in ICMEs is the higher magnetic field content in faster coronal flux ropes and ultimately the higher reconnected flux in the eruption region. The magnetic flux ropes constructed from the eruption data and coronagraph observations provide a realistic input that can be used by various models to predict the magnetic properties of ICMEs at Earth and other destination in the heliosphere. Title: Very narrow coronal mass ejections producing solar energetic particles Authors: Bronarska, K.; Wheatland, M. S.; Gopalswamy, N.; Michalek, G. Bibcode: 2018A&A...619A..34B Altcode:
Aims: Our main aim is to study the relationship between low-energy solar particles (energies below 1 MeV) and very narrow coronal mass ejections ("jets" with angular width ≤ 20°).
Methods: For this purpose, we considered 125 very narrow coronal mass ejections (CMEs) from 1999 to 2003 that are potentially associated with low-energy solar particles (LESPs). These events were chosen on the basis of their source location. We studied only very narrow CMEs at the western limb, which are expected to have good magnetic connectivity with Earth.
Results: We found 24 very narrow CMEs associated with energetic particles such as ions (protons and 3He), electrons, or both. We show that arrival times at Earth of energetic particles are consistent with onset times of the respective CMEs, and that in the same time intervals, there are no other potential sources of energetic particles. We also demonstrate statistical differences for the angular width distributions using the Kolmogorov-Smirnov test for angular widths for these 24 events. We consider a coherent sample of jets (mostly originating from boundaries of coronal holes) to identify properties of events that produce solar energetic particles (velocities, widths, and position angles). Our study presents a new approach and result: very narrow CMEs can generate low-energy particles in the vicinity of Earth without other activity on the Sun. The results could be very useful for space weather forecasting. Title: Sun-to-earth propagation of the 2015 June 21 coronal mass ejection revealed by optical, EUV, and radio observations Authors: Gopalswamy, N.; Mäkelä, P.; Akiyama, S.; Yashiro, S.; Xie, H.; Thakur, N. Bibcode: 2018JASTP.179..225G Altcode: 2018arXiv180710979G We investigate the propagation of the 2015 June 21 CME-driven shock as revealed by the type II bursts at metric and longer wavelengths and coronagraph observations. The CME was associated with the second largest geomagnetic storm of solar cycle 24 and a large solar energetic particle (SEP) event. The eruption consisted of two M-class flares, with the first one being confined, with no metric or interplanetary radio bursts. However, there was intense microwave burst, indicating accelerated particles injected toward the Sun. The second flare was eruptive that resulted in a halo CME. The CME was deflected primarily by an equatorial coronal hole that resulted in the modification of the intensity profile of the associated SEP event and the duration of the CME at Earth. The interplanetary type II burst was particularly intense and was visible from the corona all the way to the vicinity of the Wind spacecraft with fundamental-harmonic structure. We computed the shock speed using the type II drift rates at various heliocentric distances and obtained information on the evolution of the shock that matched coronagraph observations near the Sun and in-situ observations near Earth. The depth of the geomagnetic storm is consistent with the 1-AU speed of the CME and the magnitude of the southward component. Title: Direction-finding Analysis of the 2012 July 6 Type II Solar Radio Burst at Low Frequencies Authors: Mäkelä, Pertti; Gopalswamy, Nat; Akiyama, Sachiko Bibcode: 2018ApJ...867...40M Altcode: The 2012 July 6 X1.1 flare at S13W59 and a halo coronal mass ejection (CME) with a space speed of ∼1900 km s-1 were associated with type III and type II radio bursts. The metric-to-decametric type II radio burst extended down to ∼5 MHz. Simultaneously, a slowly drifting feature with a harmonic structure was observed by Wind and Solar Terrestrial Relations Observatory radio receivers around and below 1 MHz, above the strong type III radio burst at lower frequencies. The radio direction-finding analysis of this lower-frequency interplanetary (IP) type II radio burst indicates that the radio source was located near the nose and possibly toward the southern flank of the CME-driven shock. These results provide an independent confirmation of the previous suggestions that when the metric and IP type II bursts are overlapping, the lower-frequency IP type II radio burst originates near the shock nose, whereas the source of the higher-frequency metric type II burst is closer to the Sun in the shock flank region. These results further support the idea that the coronal and IP type II bursts are produced by the same CME-driven shock. Title: Fermi, Wind, and SOHO Observations of Sustained Gamma-Ray Emission from the Sun Authors: Gopalswamy, N.; Makela, P.; Yashiro, S.; Lara, A.; Xie, H.; Akiyama, S.; MacDowall, R. J. Bibcode: 2018arXiv181008958G Altcode: We report on the linear relationship between the durations of two types of electromagnetic emissions associated with shocks driven by coronal mass ejections: sustained gamma-ray emission (SGRE) and interplanetary type II radio bursts. The relationship implies that shocks accelerate about 10 keV electrons (for type II bursts) and greater than 300 MeV protons (for SGRE) roughly over the same duration. The SGRE events are from the Large Area Telescope (LAT) on board the Fermi satellite, while the type II bursts are from the Radio and Plasma Wave Experiment (WAVES) on board the Wind spacecraft. Here we consider five SGRE events that were not included in a previous study of events with longer duration (greater than 5 hours). The five events are selected by relaxing the minimum duration to 3 hours. We found that some SGRE events had a tail that seems to last until the end of the associated type II burst. We pay special attention to the 2011 June 2 SGRE event that did not have a large solar energetic particle event at Earth or at the STEREO spacecraft that was well connected to the eruption. We suggest that the preceding CME acted as a magnetic barrier that mirrored protons back to Sun. Title: Properties of DH Type II Radio Bursts and Their Space Weather Implications Authors: Gopalswamy, N.; Mäkelä, P. Bibcode: 2018arXiv181011173G Altcode: We report on the properties of type II radio bursts observed by the Radio and Plasma Wave Experiment (WAVES) on board the Wind spacecraft over the past two solar cycles. We confirm that the associated coronal mass ejections (CMEs) are fast and wide, more than half the CMEs being halos. About half of the type II bursts extend down to 0.5 MHz, corresponding to a heliocentric distance of tens of solar radii. The DH type II bursts are mostly confined to the active region belt and their occurrence rate follows the solar activity cycle. Type II burst occurring on the western hemisphere of the Sun and extending to lower frequencies are good indicators of a solar energetic particle event. Title: The Effects of Uncertainty in Initial CME Input Parameters on Deflection, Rotation, Bz, and Arrival Time Predictions Authors: Kay, C.; Gopalswamy, N. Bibcode: 2018JGRA..123.7220K Altcode: Understanding the effects of coronal mass ejections (CMEs) requires knowing if and when they will impact and their properties upon impact. Of particular importance is the strength of a CME's southward magnetic field component (Bz). Kay et al. (2013, https://doi:10.1088/0004-637X/775/1/5, 2015, https://doi:10.1088/948 0004-637X/805/2/168) have shown that the simplified analytic model Forecasting a CME's Altered Trajectory (ForeCAT) can reproduce the deflection and rotation of CMEs. Kay, Gopalswamy, Reinard, and Opher (2017, https://doi.org/10.3847/1538-4357/835/2/117) introduced ForeCAT In situ Data Observer, which uses ForeCAT results to simulate magnetic field profiles. ForeCAT In situ Data Observer reproduces the in situ observations on roughly hourly time scales, suggesting that these models could be extremely useful for predictions of Bz. However, as with all models, both models are sensitive to their input parameters, which may not be precisely known for predictions. We explore this sensitivity using ensembles having small changes in the initial latitude, longitude, and orientation of the erupting CME. We explore the effects of different background magnetic field models and find that the changes in deflection and rotation resulting from the uncertainty in the initial parameters tend to exceed the changes from different magnetic backgrounds. The range in the in situ profiles tends to scale with the range in the deflection and rotation. We also consider a simple arrival time model using ForeCAT results and find an average absolute error of only 3 hr. We show that an uncertainty in the CME position of 8.1° ± 6.9° leads to variations of 6 hr in the arrival time. This measure depends strongly on the location of impact within the CME with the arrival time changing less for impacts near the nose. Title: Long-term solar activity studies using microwave imaging observations and prediction for cycle 25 Authors: Gopalswamy, N.; Mäkelä, P.; Yashiro, S.; Akiyama, S. Bibcode: 2018JASTP.176...26G Altcode: 2018arXiv180402544G We use microwave imaging observations from the Nobeyama Radioheliograph at 17 GHz for long-term studies of solar activity. In particular, we use the polar and low-latitude brightness temperatures as proxies to the polar and active-region magnetic fields, respectively. We also use the locations of prominence eruptions as a proxy to the filament locations to study their time variation. We show that the polar microwave brightness temperature is highly correlated with the polar magnetic field strength and the fast solar wind speed. We also show that the polar microwave brightness in one solar cycle is correlated with the low latitude brightness with a lag of about half a solar cycle. We use this correlation to predict the strength of the solar cycle 25: the smoothed sunspot numbers in the southern and northern hemispheres can be predicted as 89 and 59, respectively. These values indicate that cycle 25 will not be too different from cycle 24 in its strength. We also combined the rush-to-the-pole data from Nobeyama prominences with historical data going back to 1860 to study the north-south asymmetry of sign reversal at solar poles. We find that the reversal asymmetry has a quasi-periodicity of 3-5 cycles. Title: A small satellite mission for solar coronagraphy Authors: Gopalswamy, N.; Gong, Qian Bibcode: 2018SPIE10769E..0XG Altcode: We present on a concept study of the Goddard Miniature Coronagraph (GMC) mission for measuring the plasma flow in the solar corona in the form of solar wind and coronal mass ejections (CMEs). These mass flows can dramatically alter the near-Earth space environment to hazardous conditions posing danger to human technology in space. The primary science objective of the mission is to measure the properties of CMEs, coronal structures, and the solar wind near the Sun. The miniaturization of the coronagraph involves using a single-stage optics and a polarization camera, both of which reduce the size of the coronagraph. GMC will be accommodated in a small satellite that can be built with cubesat material to minimize cost. The development of the Dellingr mission at NASA/GSFC has provided expertise and a clear pathway to build the GMC mission. The hardware and software used for the Dellingr mission are technically sound, so the GMC mission can be fully defined. Software, pointing, control and communications systems developed for GSFC CubeSats can be readily adapted to cut costs. We present orbit options such as an ISS orbit or a Sun synchronous dawndusk polar orbit with the aim of maximizing solar observations. Title: Dependence of Coronal Mass Ejection Properties on Their Solar Source Active Region Characteristics and Associated Flare Reconnection Flux Authors: Pal, Sanchita; Nandy, Dibyendu; Srivastava, Nandita; Gopalswamy, Nat; Panda, Suman Bibcode: 2018ApJ...865....4P Altcode: 2018arXiv180804144P The near-Sun kinematics of coronal mass ejections (CMEs) determine the severity and arrival time of associated geomagnetic storms. We investigate the relationship between the deprojected speed and kinetic energy of CMEs and magnetic measures of their solar sources, reconnection flux of associated eruptive events, and intrinsic flux-rope characteristics. Our data covers the period 2010-2014 in solar cycle 24. Using vector magnetograms of source active regions, we estimate the size and nonpotentiality. We compute the total magnetic reconnection flux at the source regions of CMEs using the post-eruption arcade method. By forward modeling the CMEs, we find their deprojected geometric parameters and constrain their kinematics and magnetic properties. Based on an analysis of this database, we report that the correlation between CME speed and their source active region size and global nonpotentiality is weak, but not negligible. We find the near-Sun velocity and kinetic energy of CMEs to be well correlated with the associated magnetic reconnection flux. We establish a statistically significant empirical relationship between the CME speed and reconnection flux that may be utilized for prediction purposes. Furthermore, we find CME kinematics to be related with the axial magnetic field intensity and relative magnetic helicity of their intrinsic flux ropes. The amount of coronal magnetic helicity shed by CMEs is found to be well correlated with their near-Sun speeds. The kinetic energy of CMEs is well correlated with their intrinsic magnetic energy density. Our results constrain processes related to the origin and propagation of CMEs and may lead to better empirical forecasting of their arrival and geoeffectiveness. Title: Extreme Kinematics of the 2017 September 10 Solar Eruption and the Spectral Characteristics of the Associated Energetic Particles Authors: Gopalswamy, N.; Yashiro, S.; Mäkelä, P.; Xie, H.; Akiyama, S.; Monstein, C. Bibcode: 2018ApJ...863L..39G Altcode: 2018arXiv180709906G We report on the 2017 September 10 ground-level enhancement (GLE) event associated with a coronal mass ejection whose initial acceleration (∼9.1 km s-2) and initial speed (∼4300 km s-1) were among the highest observed in the Solar and Heliospheric Observatory era. The GLE event was of low intensity (∼4.4% above background) and softer-than-average fluence spectrum. We suggest that poor connectivity (longitudinal and latitudinal) of the source to Earth compounded by the weaker ambient magnetic field contributed to these GLE properties. Events with similar high initial speed either lacked GLE association or had softer fluence spectra. The shock-formation height inferred from the metric type II burst was ∼1.4 Rs, consistent with other GLE events. The shock height at solar particle release (SPR) was ∼4.4 ± 0.38 Rs, consistent with the parabolic relationship between the shock height at SPR and source longitude. At SPR, the eastern flank of the shock was observed in EUV projected on the disk near the longitudes magnetically connected to Earth: W60 to W45. Title: A New Technique to Provide Realistic Input to CME Forecasting Models Authors: Gopalswamy, Nat; Akiyama, Sachiko; Yashiro, Seiji; Xie, Hong Bibcode: 2018IAUS..335..258G Altcode: 2017arXiv170903160G We report on a technique to construct a flux rope (FR) from eruption data at the Sun. The technique involves line-of-sight magnetic fields, post-eruption arcades in the corona, and white-light coronal mass ejections (CMEs) so that the FR geometric and magnetic properties can be fully defined in addition to the kinematic properties. We refer to this FR as FRED (Flux Rope from Eruption Data). We illustrate the FRED construction using the 2012 July 12 eruption and compare the coronal and interplanetary properties of the FR. The results indicate that the FRED input should help make realistic predictions of the components of the FR magnetic field in the heliosphere. Title: Globally Coordinated Space Weather Education and Outreach Initiative Authors: Chulaki, Anna; Glover, Alexi; Nandi, Dibyendu; Gopalswamy, Nat; Di Pippo, Simonetta Bibcode: 2018cosp...42E.656C Altcode: The poster will summarize outcome from thePSW.5-Panel 2: Capacity building in space weather: Globally coordinated space weather education and outreach initiativesWe will provide summaries of ongoing international educational activities in space weather and discuss needs and opportunities for global coordination in space weather awareness, education and outreach.

What aspects of space weather education/outreach require special attention?

What type of novel education initiatives should we undertake?

Do we need a framework for coordinating international space weather educational initiatives?

What should be the role of COSPAR PSW in space weather education? Title: Relationship between SEP peak intensity and shock speed, CME width and acceleration; no Authors: Xie, Hong; St. Cyr, O. C.; Makela, P.; Gopalswamy, N. Bibcode: 2018shin.confE.112X Altcode: We study the large solar energetic particle (SEP) events that were detected by GOES in the >10 MeV energy channel during December 2006 to January 2016. Data used in this study includes the Solar Electron Proton Telescope (SEPT) and High Energy Telescopes (HET) on STEREO A and B, the Electron, Proton, and Alpha Monitor (EPAM) on ACE, and the Energetic and Relativistic Nuclei and Electron instrument (ERNE) on SOHO. From multi-spacecraft observations we obtained the peak intensity I0 at the center of the Gausssian function using the Gausssian fit. We then study the relationship between electron and proton peak intensity and shock speed and CME width. We found that the correlation between electron and proton peak intensity and shock speed can be improved by taking into account the effects of CME width and SEP connection angle. We also found that SEP onset and peak delays relative to type III onset are closely related to the CME accelerations at the main and residual acceleration phases. The implication for the SEP forecast of our obtained results will be discussed. Title: The Effects of Uncertainty on Deflection, Rotation, Bz and Arrival Time Predictions Authors: Kay, Christina; Gopalswamy, Nat Bibcode: 2018shin.confE.195K Altcode: Understanding the effects of coronal mass ejections (CMEs) requires knowing not only if and when they will impact, but also their properties upon impact. Of particular importance is the strength of a CME's southward magnetic field component (Bz). Kay et al. (2013, 2015) have shown that the simplified analytic model ForeCAT can be used to reproduce the deflection and rotation of CMEs. Kay et al. (2017) introduced FIDO, which uses the position and orientation from ForeCAT to simulate magnetic field profiles. FIDO reproduces the in situ observations on roughly hourly time scales, suggesting that the combination of ForeCAT and FIDO could be extremely useful for predictions of Bz. However, as with all models, both ForeCAT and FIDO are sensitive to their input parameters, which may not be precisely known for actual predictions. We explore the sensitivity of both models using ensembles with small changes in the initial latitude, longitude, and orientation of the erupting CME. Additionally, thus far ForeCAT has only been run using a Potential Field Source Surface (PFSS) magnetic background driven by a synoptic map. We explore the effects of different magnetic backgrounds - the Schatten Current Sheet model and synchronic maps. We find that the changes in deflection and rotation resulting from the uncertainty in the initial parameters tend to exceed the changes from different magnetic backgrounds. The range in the in situ profiles tends to scale with the range in the deflection and rotation. We also consider the effects of these changes in a simple arrival time model and show that accurate arrival times can only be achieved if the CME position and orientation are precisely known. Title: Unusual Polar Conditions of the Sun during Solar Cycle 24 and its Iplications for Cycle 25 Authors: Gopalswamy, Nat; Masuda, Satoshi; Yashiro, Seiji; Akiyama, Sachiko; Shibasaki, Kiyoto Bibcode: 2018cosp...42E1250G Altcode: Polar field strength in one solar cycle is known to indicate the strength (e.g., Sunspot number) and phase of the next cycle. In particular the polar field strength (or its proxies such as the polar coronal hole area and microwave polar brightness) during the minimum phase of a given cycle seem to be well correlated with the maximum sunspot number of the next cycle. Polar prominence eruptions and coronal mass ejections have also been found to be indicators of low polar field; their cessation signals the time of polarity reversal. While these indicators are present in the current cycle, significant differences are found regarding the phase lag between the two hemispheres and the duration of polar eruptions. We use data from the Nobeyama Radioheliograph, the Solar Dynamics Observatory, SOLIS, and Wilcox Solar Observatory to highlight these differences. We find that the north polar region of the Sun has near-zero field strength for more than three years. This is unusually long and caused by surges of both polarities heading toward the north pole that prevent the buildup of the polar field. This seems to be due to anti-Hale active regions that appeared around the 2012 peak sunspot activity in the northern hemisphere. The unusual condition is consistent with (i) the continued high-latitude prominence eruption, (ii) the extended period of high tilt angle of the heliospheric current sheet, (iii) the weak microwave polar brightness, and (iv) the lack of north polar coronal hole. On the other hand, the south polar field has started building up and the coronal hole has appeared in early 2015 because of large active regions of the correct tilt in the southern hemisphere during the 2014 peak of sunspot activity. The extended period of near-zero field in the north polar region should result in very weak and delayed sunspot activity in the northern hemisphere in cycle 25. On the other hand the south polar field has already increased significantly, suggesting that the activity in the southern hemisphere should start early; the amplitude will depend on how the south polar fields will evolve in the declining phase of cycle 24. Title: Towards a global space weather community hub and a network of International Space Weather Action Teams (ISWAT) aiming to advance space weather capabilities and to facilitate Global Space Weather Roadmap updates Authors: Kuznetsova, Maria; Glover, Alexi; Gopalswamy, Nat; Di Pippo, Simonetta Bibcode: 2018cosp...42E1899K Altcode: Panel 3: COSPAR space weather action teams: A bottom-up component of global coordination in space weather.14:00-17:30, Thursday, 19 July, Room: SR 29 (HH) - Santa Clara Chairs: Masha Kuznetsova (NASA, USA), Hermann Opgenoorth (Swedish Institute of Space Physics, Sweden)One of the key challenges identified in the COSPAR-ILWS space weather roadmap [Schrijver et al., 2015] is a transformation into an effectively functioning, information-sharing, global space weather community. To address this challenge and to demonstrate the critical value of a global coordination the COSPAR Panel on Space Weather will coordinate an active network of topical scientific action teams (a.k.a., International Space Weather Action Teams). Action teams will address space weather roadmap recommendations, provide a bottom-up push for coordination and innovation, serve as a channel for a global community voice, assess progress in various areas of space weather, and propose regular updates for guiding documents. Moderators of ISWAT clusters (action teams grouped by space environment domains and/or impacts) and organizers of PSW.1-4 events will present their outlook on the ISWAT concept, plans for topical action teams activities for the next two years, approaches to Roadmap updates, and invite community input and active participation.14:00 - 14:10 Introduction of the ISWAT concept. 14:10 - 14:40 Updates from PSW.1-4 (5-7 min)14:40 - 15:30: ISWAT moderators presentations, Q&A (5-7 min)16:00 - 17:30: Panel discussion, Q&A, community feedback Panelists: Jon Linker (Predictive Science Inc., USA)Manuela Temmer (University of Gratz, Austria)Mario Bisi (RAL SFTC, UK)Robert Wimmer-Schweingruber (University of Kiel, Germany)Hermann Opgenoorth (Swedish Institute of Space Physics, Sweden)Ian Mann (University of Alberta, Canada)Sean Bruinsma (CNES, France)Anna Belehaki (NOA, Greece)Alexi Glover (ESA)Daniel Heynderickx (DH Consultancy, Belgium)Norbert Jakowski (DLR, Germany)Manuel Grande (Aberystwyth University, UK) Title: Accurate prediction and testing of CME arrival and properties from Sun to Earth Authors: Cairns, Iver; Van der Holst, Bart; Lobzin, Vasili; Schmidt, Joachim; Neudegg, Dave; Gopalswamy, Nat; Parkinson, Murray; Steward, Graham; Kelly, Andrew Bibcode: 2018cosp...42E.492C Altcode: Most major space weather events are due to fast CMEs and their shocks interacting with Earth's magnetosphere. Accurate prediction of CME arrival, propagation, and properties is thus vital for prediction of space weather at Earth as well as elsewhere in the solar system. In particular, it is important to accurately predict the CME velocity, shape, and evolution as functions of position and time, as well as the flow velocity and magnetic field vector in the coronal and solar wind plasma, downstream of the CME shock, and inside the CME. We report the results of simulating 4 separate CMEs from the Sun to 1 AU with the Space Weather Modelling Framework (SWMF; 2015 and 2016 versions). The simulations are set up carefully using Wilcox photospheric magnetogram data and coronagraph images and height-time data below 10 solar radii from coronagraphs. Outstanding agreement between the observations and simulations is found for the CME on 29 November 2013 that was directed primarily towards STEREO A. In particular, the CME's arrival at STEREO A, deceleration of the CME in agreement with the Gopalswamy et al. [2011] model, and the time-varying plasma and field (including B_{z}) agree extremely well. from upstream of the CME shock to within the CME. Similarly, the results of the simulations to the Earth-directed CMEs of 4, 6, and 7 September 2017 range from excellent to very good for the arrival time and for the 1-hour averaged density, radial speed, B_{z}, and magnetic field strength from the shock to well into the CME. These results provide strong evidence that we have the capability with the Space Weather Modeling Framework, when sufficiently carefully initialized, to accurately predict the properties and evolution of CMEs and the interplanetary magnetic field and plasma from the Sun to 1 AU. This suggests that we are very close to being able to accurately predict the triggers for CME-driven space weather at Earth. Title: Metric Type II Onset Frequency and the Longitudinal Extent of SEP Events Authors: Makela, Pertti; Gopalswamy, N.; Yashiro, S.; Thakur, N.; Akiyama, S.; Xie, H. Bibcode: 2018shin.confE.116M Altcode: Average starting frequencies of the type II bursts observed during ground level enhancements (GLEs), regular and filament-eruption-associated solar energetic particle (SEP) events have distinct, but overlapping, distributions (Gopalswamy et al. 2017, J. Phys. Conf. Ser., Proc. 16th AIAC). Based on these results, we studied a possible dependence between the onset frequency of metric type II radio bursts and the longitudinal spread of the >25 MeV SEP events from the list of Richardson et al. (2014, Sol. Phys. 289) covering the first seven years of the STEREO mission. We have used radio data available online, mainly from the Radio Solar Telescope Network (RSTN) and e-CALLISTO international network of solar radio spectrometers, to estimate the type II onset frequencies. We find a linear trend between the extent of the SEP events and the onset frequency of the metric type II bursts, but the scatter of data points is quite large, and correlations are modest. Title: Observational Signatures of CME Structure near the Sun Authors: Gopalswamy, Nat Bibcode: 2018shin.confE.204G Altcode: Coronagraphic observations tell us about the electron density distribution in the CME structure. The famous three-part structure is determined by the dense prominence core surrounded by a magnetic structure that appears less dense (void) and forms a bright front by pushing against the ambient medium. Super-Alfvenic CMEs have another overlying structure, the shock sheath that became clear in SOHO/LASCO observations, and is now routinely observed in STEREO images. The basic magnetic structure underlying CMEs observed in the solar wind has been determined to be a flux rope, which is identified with the void structure in coronagraphic images. When an eruption happens, what is left behind on the Sun is the post-eruption arcade (PEA), which is formed over the neutral line from which the prominence erupted as part of the CME. The PEA properties provide important clues to the understanding of the flux rope structure of CMEs. Coronal dimming is another key signature, which helps understand the geometry of the flux rope with respect to the PEA and the direction of axial magnetic flux rope: PEA and the flux rope are formed due to the same reconnection process. Forward modeling CMEs observed in coronagraphic images provides the geometrical properties of flux ropes, while the reconnected flux in the eruption provides their magnetic properties. The flux rope from eruption data (FRED) represents the culmination of the CME research over the past half a century. Title: Panel Discussion: Capacity building in space weather: Globally coordinated space weather education and outreach initiatives Authors: Gopalswamy, Nat Bibcode: 2018cosp...42E1249G Altcode: Panel 2: Capacity building in space weather: Globally coordinated space weather education and outreach initiatives12:20-13:00, Thursday, 19 July, Room: SR 29 (HH) -Santa Clara Convener: Dibyendu Nandi (CESSI / IISER Kolkata, India)Chair: Nat Gopalswamy (NASA, USA)This panel discussion will bring together diverse organizations involved in space weather education and outreach activities, provide brief summaries of ongoing activities and discuss opportunities for new initiatives of the COSPAR Space Weather Panel towards global coordination in space weather awareness, education and outreach. 12:20 - 12:40: Opening Statements (5 min)12:40 - 13:00: Q&A, Discussion PanelPanelists: Simonetta Di Pippo (UNOOSA), Anna Chulaki (CCMC, USA), Alexi Glover (ESA, COSPAR's Panel on Capacity Building)Suggested questions to panelists:What aspects of space weather education/outreach require special attention? What type of novel education initiatives should we undertake?Do we need a framework for coordinating international space weather educational initiatives?What should be the role of COSPAR PSW in space weather education? The scientific committee on solar terrestrial physics (SCOSTEP) is an interdisciplinary body of the International Council for Science (ICSU) collaborating with five scientific unions unions (IAMAS, IAU, IUGG/IAGA, IUPAP, URSI) and three interdisciplinary bodies (COSPAR, SCAR, and WDS). SCOSTEP is actively involved in the science, capacity building, and public outreach activities related to solar terrestrial physics. By design, space weather is a significant part of solar terrestrial physics dealing with the short-term variability of the Sun and how it affects Earth's space environment. The space weather activities of SCOSTEP are conducted via the scientific programs such as the current VarSITI (variability of the Sun and Its Terrestrial Impact). Of particular interest for space weather is the ISEST (International Study of Earth-affecting Solar Transients) project directly deals with the two sources of space weather at Earth, viz., coronal mass ejections and high speed solar wind and their consequences (geomagnetic storms and solar energetic particle events). As part of this project, daily alerts are issued whenever a space-weather causing feature such as a filament or a coronal hole appears near the disk center of the Sun. SCOSTEP also collaborates with COSPAR, URSI, and the International Space Weather Initiative (ISWI) to run Space Science Schools for PhD students and young postdocs. These capacity building activities enhances space weather literacy among researchers in developing countries. SCOSTEP also runs a visiting scholar program that provides short-term (1-3 months) training in solar terrestrial relationship in advanced laboratories for students from developing counties. Title: The COSPAR Capacity Building Workshop at Mekelle University in Ethiopia Authors: Gopalswamy, Nat Bibcode: 2018cosp...42E1251G Altcode: This talk summarizes the experience in organizing the COSPAR Capacity-Building Workshop "Coronal and Interplanetary Shocks: Analysis of Data from SOHO, Wind, and e-CALLISTO" in Mekelle University, Ethiopia. The main objective of the COSPAR Capacity-Building Workshops is to encourage the scientific use of space data by scientists in developing countries. In particular, in view of the large number of extensive archives of data from past and current space missions, and the ready access to these and the associated analysis software via the internet, the typical workshop aims to provide a highly practical training in the use of one or more of these, based on current missions. In line with this objective, a two-week workshop introduces data analysis of space-based white-light coronagraph observations and radio spectral observations from space and ground to study shocks driven by coronal mass ejections. In particular, the wealth of data accumulated at the CDAW Data Center at NASA Goddard Space Flight Center from the ESA/NASA Solar and Heliospheric Observatory (SOHO) mission, NASA's Solar Terrestrial Relations Observatory (STEREO), NASA's Wind and Advanced Composition Explorer (ACE) missions are used. In addition, ground based radio data from the e-CALLISTO network and the Radio Solar Telescope Network (RSTN) around the globe are used for the study. Context information from NOAA's GOES mission and NASA's Solar Dynamics Observatory (SDO) missions are also used. This workshop enables scientists and students in developing countries where the e- CALLISTO instruments are deployed to use their data in conjunction with space data to study Earth- affecting solar transient phenomena. Title: Solar Energetic Particle Events Associated with Prominence Eruptions: A Case Study Authors: Thakur, Neeharika; Gopalswamy, N.; Akiyama, S.; Mäkelä, P.; Yashiro, S.; Xie, H.; Cohen, C. Bibcode: 2018shin.confE.229T Altcode: We investigated the characteristics the 2015 June 18 large solar energetic particle (SEP) event (GOES >10 MeV particle flux was >10 particles/(cm^2 s sr)) associated with a prominence eruption from the Sun. Recent work (Gopalswamy et al. 2015 ApJ 806, 8) reported on a set of large SEP events associated with filament eruption (FE) events occurring outside of active regions. The FE-associated SEPs are produced by coronal mass ejections (CMEs) that are accelerating and forming a shock at large distances from the Sun. Such SEPs exhibit a soft energy spectrum with the spectral index >4 in the 10-100 MeV range. The 2015 June 18 eruption was associated with an M1.3 flare and a prominence eruption from the west limb observed by SDO. The associated CME was fast (speed 1714 km/s), and it was accelerating in the LASCO field of view (acceleration 27.7 m/s^2). The CME did not produce a metric type II radio burst but it was associated with an interplanetary (IP) type II radio burst, implying that a strong shock formed in the interplanetary medium. We present our initial findings of this case study of prominence-associated SEPs. Title: Why was the Fluence Spectrum of the 2017 September 10 GLE So Soft? Authors: Gopalswamy, Nat; Makela, P.; Yashiro, S.; Xie, H.; Akiyama, S. Bibcode: 2018shin.confE.110G Altcode: The 2017 September 10 solar energetic particle (SEP) event with ground level enhancement (GLE) from NOAA AR 12673 was the fourth largest event in solar cycle 23 in terms of the >10 MeV intensity (1490 pfu). In spite of the ultra-high initial speed of 3100 km/s and an initial acceleration of 9.4 km s-2, the GLE was rather weak with an intensity of only 4.4% above background, much smaller than that of the 2012 May 17 GLE (18.6%) and only slightly higher than the sub-GLE event of 2014 January 6 (2.5%). The 10-100 MeV fluence spectrum (fitted to a power law) was the third softest among the GLEs of cycles 23 and 24 combined (Gopalswamy et al. 2016, ApJ 833, 216). The fluence spectral index was 3.17±.06, indicating it is softer than the 2012 May 17 GLE (2.48±0.12) and the sub-GLE of 2014 January 6 (2.54±0.11). The two GLEs with spectra softer than that of the 2017 September 10 event are the ones on 1998 August 24 (3.79±0.12) and 2003 November 2 (3.50±0.12). We show that poor latitudinal connectivity was the primary reason for the soft spectrum in these events: the ecliptic distance was larger than the average value (±13?, Gopalswamy et al. ApJ 765, L30) for GLE events. If the GeV particles are accelerated near the shock nose, a larger ecliptic distance would not be favorable for these particles to reach Earth. In the 2017 September 17 event, the flank connected to Earth was 20?.3 away from the nose. Since the nose speed of the shock was >3000 km/s, the flank speed was still large (>2800 km/s), so GeV particles were still produced at the flanks. The lower energy particles are accelerated over a much larger area of the shock resulting in a soft spectrum. Title: Sun-to-Earth simulation of the July 12, 2012 geo-effective CME with EUHFORIA+OpenGGCM Authors: Scolini, Camilla; Verbeke, Christine; Chané, Emmanuel; Zuccarello, Francesco; Poedts, Stefaan; Rodriguez, Luciano; Pomoell, Jens; Cramer, William D.; Raeder, Joachim; Gopalswamy, Nat Bibcode: 2018tess.conf10903S Altcode: In this work we perform a Sun-to-Earth comprehensive analysis of the July 12, 2012 CME with the aim of testing the space weather predictive capabilities of the newly developed EUHFORIA heliospheric model integrated with a flux rope model. In order to achieve this goal, we make use of a model chain approach by using EUHFORIA outputs at Earth as input parameters for the OpenGGCM magnetospheric model.

We first reconstruct the CME kinematic parameters by means of single- and multi- spacecraft reconstruction methods based on coronagraphic and heliospheric CME observations. The magnetic field-related parameters of the flux-rope are estimated based on imaging observations of the photospheric and low coronal source region of the eruption. We then simulate the event with EUHFORIA, using both a cone and a flux-rope CME model in order to compare the effect of the different CME kinematical and magnetic input parameters on simulation results at L1. We compare simulations outputs with in-situ observations of the Interplanetary CME and we use them as input for the OpenGGCM model, so to investigate the magnetospheric response to ICME-driven solar wind perturbations modelled with EUHFORIA. We study the ICME-driven geomagnetic storm focusing on the predicted geomagnetic activity and compare it with actual data records. Finally, we discuss the forecasting capabilities of such kind of approach and its future improvements. Title: Interplanetary type II radio bursts: STEREO observations and Monte Carlo Simulations Authors: Krupar, Vratislav; Eastwood, Jonathan P.; Magdalenic, Jasmina; Gopalswamy, Nat; Kruparova, Oksana; Szabo, Adam Bibcode: 2018EGUGA..20.9950K Altcode: Coronal mass ejections (CMEs) are responsible for most severe space weather events such as solar energetic particle events and geomagnetic storms at Earth. Type II radio bursts are slow drifting emissions produced by beams of suprathermal electrons accelerated at CME-driven MHD shock waves propagating through the corona and interplanetary medium. Here, we report a statistical study of 153 interplanetary type II radio bursts observed by the two STEREO spacecraft between March 2008 and August 2014. The shock associated radio emission was compared with CMEs from the HELCATS (Heliospheric Cataloguing, Analysis and Techniques Service) catalogue. We found that fast CMEs are statistically more likely to be associated with the interplanetary type II radio bursts. We have correlated frequency drifts with white-light observations in order to localize radio sources with a respect to a CME geometry. Our results suggest that interplanetary type II bursts are more likely to have a source region situated close to CME flanks than close to the CME nose. Finally, we performed Monte Carlo simulations to study a role of propagation on a visibility of interplanetary type II radio bursts. Title: Sun-to-Earth simulations of geo-effective Coronal Mass Ejections with EUHFORIA: a heliospheric-magnetospheric model chain approach Authors: Scolini, Camilla; Verbeke, Christine; Poedts, Stefaan; Rodriguez, Luciano; Mierla, Marilena; Pomoell, Jens; Cramer, William; Raeder, Jimmy; Gopalswamy, Nat Bibcode: 2018EGUGA..20.6441S Altcode: In this work we perform a Sun-to-Earth comprehensive analysis of the July 12, 2012 CME with the aim of testing the space weather predictive capabilities of the newly developed EUHFORIA heliospheric model integrated with a flux rope model. In order to achieve this goal, we make use of a model chain approach by using EUHFORIA outputs at Earth as input parameters for the OpenGGCM magnetospheric model. We first reconstruct the CME kinematic parameters by means of single- and multi- spacecraft reconstruction methods based on coronagraphic and heliospheric CME observations. The magnetic field-related parameters of the flux-rope are estimated based on imaging observations of the photospheric and low coronal source region of the eruption. We then simulate the event with EUHFORIA, using both a cone and a flux-rope CME model in order to compare the effect of the different CME kinematical and magnetic input parameters on simulation results at L1. We compare simulations outputs with in-situ observations of the Interplanetary CME and we use them as input for the OpenGGCM model, so to investigate the magnetospheric response to ICME-driven solar wind perturbations modelled with EUHFORIA. We study the ICME-driven geomagnetic storm focusing on the predicted geomagnetic activity and compare it with actual data records. Finally, we discuss the forecasting capabilities of such kind of approach and its future improvements. Title: Coronal mass ejections as a new indicator of the active Sun Authors: Gopalswamy, Nat Bibcode: 2018IAUS..340...95G Altcode: 2018arXiv180411112G Coronal mass ejections (CMEs) have become one of the key indicators of solar activity, especially in terms of the consequences of the transient events in the heliosphere. Although CMEs are closely related to the sunspot number (SSN), they are also related to other closed magnetic regions on the Sun such as quiescent filament regions. This makes CMEs a better indicator of solar activity. While sunspots mainly represent the toroidal component of solar magnetism, quiescent filaments (and hence CMEs associated with them) connect the toroidal and poloidal components via the rush-to-the-pole (RTTP) phenomenon. Taking the end of RTTP in each hemisphere as an indicator of solar polarity reversal, it is shown that the north-south reversal asymmetry has a quasi-periodicity of 3-5 solar cycles. Focusing on the geospace consequences of CMEs, it is shown that the maximum CME speeds averaged over Carrington rotation period show good correlation with geomagnetic activity indices such as Dst and aa. Title: Physical Conditions in the Solar Corona Derived from the Total Solar Eclipse Observations obtained on 2017 August 21 Using a Polarization Camera Authors: Gopalswamy, N.; Yashiro, Seiji; Reginald, Nelson; Thakur, Neeharika; Thompson, Barbara J.; Gong, Qian Bibcode: 2018AAS...23122008G Altcode: We present preliminary results obtained by observing the solar corona during the 2017 August 21 total solar eclipse using a polarization camera mounted on an eight-inch Schmidt-Cassegrain telescope. The observations were made from Madras Oregon during 17:19 to 17:21 UT. Total and polarized brightness images were obtained at four wavelengths (385, 398.5, 410, and 423 nm). The polarization camera had a polarization mask mounted on a 2048x2048 pixel CCD with a pixel size of 7.4 microns. The resulting images had a size of 975x975 pixels because four neighboring pixels were summed to yield the polarization and total brightness images. The ratio of 410 and 385 nm images is a measure of the coronal temperature, while that at 423 and 398.5 nm images is a measure of the coronal flow speed. We compared the temperature map from the eclipse observations with that obtained from the Solar Dynamics Observatory’s Atmospheric Imaging Assembly images at six EUV wavelengths, yielding consistent temperature information of the corona. Title: A Study of the Interplanetary Signatures of Earth-Arriving CMEs Authors: Akiyama, S.; Yashiro, S.; Gopalswamy, N.; Xie, H.; Makela, P. A.; Kay, C. Bibcode: 2017AGUFMSH51E..06A Altcode: We studied interplanetary (IP) signatures associated with coronal mass ejections (CMEs) that are likely to reach Earth. In order to find Earth- arriving CMEs, we started with disk-center CMEs originating within 30 degrees from the central meridian and the equator. Using the side-view images from the STEREO mission, we excluded CMEs that faded out before reaching the Earth orbit, or were captured by other CMEs, or erupted away from the ecliptic plane. We found 61 Earth- arriving CMEs during 2009/10/01 - 2012/07/31 (inclusive). Though all events were observed to reach Earth in the STEREO/HI2 field of view, only 34 out of 61 events (56%) were associated with magnetic cloud (MC) or ejecta (EJ) observed by ACE or Wind. We compared the CME characteristics associated with 9 MCs, 25 EJs, and 27 no- clear- signature (NCS) events to find out what might cause the difference in the IP signatures. To avoid projection effects, we used coronagraph images obtained by the STEREO mission. The average speed (width) of CMEs associated with MCs, EJs, and NCSs are 484 km/s (104°), 663 km/s (135°), and 595 km/s (144°), respectively. CMEs associated with MCs tend to be less energetic than other types in our dataset. We also checked the coronal holes (CHs) near the CME source to examine the effect of the CME deflection. In the case of MCs and EJs, only 22% (2/9) and 28% (7/25) events have CHs near the source, while 48% (13/27) NCS events have nearby CHs. We discuss what factors near the Sun cause the observed differences at Earth. Title: Sun-to-Earth simulations of geo-effective Coronal Mass Ejections with EUHFORIA: a heliospheric-magnetospheric model chain approach Authors: Scolini, C.; Verbeke, C.; Gopalswamy, N.; Wijsen, N.; Poedts, S.; Mierla, M.; Rodriguez, L.; Pomoell, J.; Cramer, W. D.; Raeder, J. Bibcode: 2017AGUFMSH31A2716S Altcode: Coronal Mass Ejections (CMEs) and their interplanetary counterparts are considered to be the major space weather drivers. An accurate modelling of their onset and propagation up to 1 AU represents a key issue for more reliable space weather forecasts, and predictions about their actual geo-effectiveness can only be performed by coupling global heliospheric models to 3D models describing the terrestrial environment, e.g. magnetospheric and ionospheric codes in the first place. In this work we perform a Sun-to-Earth comprehensive analysis of the July 12, 2012 CME with the aim of testing the space weather predictive capabilities of the newly developed EUHFORIA heliospheric model integrated with the Gibson-Low (GL) flux rope model. In order to achieve this goal, we make use of a model chain approach by using EUHFORIA outputs at Earth as input parameters for the OpenGGCM magnetospheric model. We first reconstruct the CME kinematic parameters by means of single- and multi- spacecraft reconstruction methods based on coronagraphic and heliospheric CME observations. The magnetic field-related parameters of the flux rope are estimated based on imaging observations of the photospheric and low coronal source regions of the eruption. We then simulate the event with EUHFORIA, testing the effect of the different CME kinematic input parameters on simulation results at L1. We compare simulation outputs with in-situ measurements of the Interplanetary CME and we use them as input for the OpenGGCM model, so to investigate the magnetospheric response to solar perturbations. From simulation outputs we extract some global geomagnetic activity indexes and compare them with actual data records and with results obtained by the use of empirical relations. Finally, we discuss the forecasting capabilities of such kind of approach and its future improvements. Title: A Statistical Study of Interplanetary Type II Bursts: STEREO Observations Authors: Krupar, V.; Eastwood, J. P.; Magdalenic, J.; Gopalswamy, N.; Kruparova, O.; Szabo, A. Bibcode: 2017AGUFMSH41B2774K Altcode: Coronal mass ejections (CMEs) are the primary cause of the most severe and disruptive space weather events such as solar energetic particle (SEP) events and geomagnetic storms at Earth. Interplanetary type II bursts are generated via the plasma emission mechanism by energetic electrons accelerated at CME-driven shock waves and hence identify CMEs that potentially cause space weather impact. As CMEs propagate outward from the Sun, radio emissions are generated at progressively at lower frequencies corresponding to a decreasing ambient solar wind plasma density. We have performed a statistical study of 153 interplanetary type II bursts observed by the two STEREO spacecraft between March 2008 and August 2014. These events have been correlated with manually-identified CMEs contained in the Heliospheric Cataloguing, Analysis and Techniques Service (HELCATS) catalogue. Our results confirm that faster CMEs are more likely to produce interplanetary type II radio bursts. We have compared observed frequency drifts with white-light observations to estimate angular deviations of type II burst propagation directions from radial. We have found that interplanetary type II bursts preferably arise from CME flanks. Finally, we discuss a visibility of radio emissions in relation to the CME propagation direction. Title: Relationship between SEP Peak intensity and CME Acceleration, Speed and Width Authors: Xie, H.; St Cyr, O. C.; Makela, P. A.; Gopalswamy, N. Bibcode: 2017AGUFMSH33C..01X Altcode: We study the large solar energetic particle (SEP) events that were detected by GOES in the >10 MeV energy channel during December 2006 to January 2016. Data used in this study includes the Solar Electron Proton Telescope (SEPT) and High Energy Telescopes (HET) on STEREO A and B, the Electron, Proton, and Alpha Monitor (EPAM) on ACE, and the Energetic and Relativistic Nuclei and Electron instrument (ERNE) on SOHO. By choosing the smallest connection angles between SEP solar locations and magnetic foot-points of each spacecraft, we divide SEP events as SOHO SEPs or STEREO SEPs. We then compute the SEP peak intensity I0 at the center of the Gausssian using the Gausssian expression from Richardson et al. (2014) and study the relationship between SEP electron and proton peak intensity and CME acceleration, speed and width. By using I0 derived from multi-spacecraft observations we found that the correlations between SEP peak intensity and CME acceleration and speed improved. We also found that this correlation can be further improved by taking into account the effects of CME width and its solar source latitude. The implication for the SEP forecast of our obtained results will be discussed. Title: Using the Coronal Evolution to Successfully Forward Model CMEs' In Situ Magnetic Profiles Authors: Kay, C.; Gopalswamy, N. Bibcode: 2017JGRA..12211810K Altcode: 2017arXiv171003825K Predicting the effects of a coronal mass ejection (CME) impact requires knowing if impact will occur, which part of the CME impacts, and its magnetic properties. We explore the relation between CME deflections and rotations, which change the position and orientation of a CME, and the resulting magnetic profiles at 1 AU. For 45 STEREO-era, Earth-impacting CMEs, we determine the solar source of each CME, reconstruct its coronal position and orientation, and perform a ForeCAT (Forecasting a CME's Altered Trajectory) simulation of the coronal deflection and rotation. From the reconstructed and modeled CME deflections and rotations, we determine the solar cycle variation and correlations with CME properties. We assume no evolution between the outer corona and 1 AU and use the ForeCAT results to drive the ForeCAT In situ Data Observer (FIDO) in situ magnetic field model, allowing for comparisons with ACE and Wind observations. We do not attempt to reproduce the arrival time. On average FIDO reproduces the in situ magnetic field for each vector component with an error equivalent to 35% of the average total magnetic field strength when the total modeled magnetic field is scaled to match the average observed value. Random walk best fits distinguish between ForeCAT's ability to determine FIDO's input parameters and the limitations of the simple flux rope model. These best fits reduce the average error to 30%. The FIDO results are sensitive to changes of order a degree in the CME latitude, longitude, and tilt, suggesting that accurate space weather predictions require accurate measurements of a CME's position and orientation. Title: On the Onset Frequency of Metric Type II Radio Bursts and the Longitudinal Extent of the Associated SEP Events Authors: Makela, P. A.; Gopalswamy, N.; Yashiro, S.; Thakur, N.; Akiyama, S.; Xie, H. Bibcode: 2017AGUFMSH33C..04M Altcode: In a recent study Gopalswamy et al. (2017, J. Phys. Conf. Ser., Proc. 16th AIAC) found that the ground level enhancements (GLEs), regular solar energetic particle (SEP) events and filament eruption (FE) associated SEP events have distinct average starting frequencies of the associated type II bursts, although the distributions overlap. They also found that the initial acceleration of the coronal mass ejections (CMEs) associated with the three groups were distinct. Based on these earlier results emphasizing a hierarchical relationship of CME kinematics and SEP events, we studied the possible dependence between the longitudinal spread of the SEP events and the onset frequency of metric type II. The studied >25 MeV SEP events are from the list of Richardson et al. (2014, Sol. Phys. 289) covering the first seven years of the STEREO mission. However, our preliminary results show only a weak correlation between the extent of the SEP event and the onset frequency of the metric type II radio burst. Title: Prediction of CMEs and Type II Bursts from Sun to Earth Authors: Cairns, I. H.; Schmidt, J. M.; Gopalswamy, N.; van der Holst, B. Bibcode: 2017AGUFMSH31D..06C Altcode: Most major space weather events are due to fast CMEs and their shocks interacting with Earth's magnetosphere. SImilarly, type II solar radio bursts are well-known signatures of CMEs and their shocks moving through the corona and solar wind. The properties of the space weather events and the type II radio bursts depend sensitively on the CME velocity, shape, and evolution as functions of position and time, as well as on the magnetic field vector in the coronal and solar wind plasma, downstream of the CME shock, and inside the CME. We report simulations of CMEs and type II bursts from the Sun to Earth with the Space Weather Modelling Framework (2015 and 2016 versions), set up carefully using relevant data, and a kinetic radio emission theory. Excellent agreement between observations, simulations, and theory are found for the coronal (metric) type II burst of 7 September 2014 and associated CME, including the lack of radio emission in the solar wind beyond about 10 solar radii. Similarly, simulation of a CME and type II burst from the Sun to 1 AU over the period 29 November - 1 December 2013 yield excellent agreement for the radio burst from 10 MHz to 30 kHz for STEREO A and B and Wind, arrival of the CME at STEREO A within 1 hour reported time, deceleration of the CME in agreement with the Gopalswamy et al. [2011] observational analyses, and Bz rotations at STEREO A from upstream of the CME shock to within the CME. These results provide strong support for the type II theory and also that the Space WeatherModeling Framework can accurately predict the properties and evolution of CMEs and the interplanetary magnetic field and plasma from the Sun to 1 AU when sufficiently carefully initialized. Title: Reproducing the Magnetic Field of Near-Earth ICMEs Authors: Kay, C.; Gopalswamy, N. Bibcode: 2017AGUFMSH34B..03K Altcode: Understanding the magnetic profile of an ICME is critical for predicting its potential effects near Earth. Kay et al. (2017) introduced the ForeCAT In situ Data Observer (FIDO), which uses the results of a coronal CME deflection and rotation model to orient a simple Lundquist force-flux rope, which is then propagated over a synthetic spacecraft. This work showed the potential of the FIDO model for predicting ICME magnetic field on roughly hourly time scales, and that the in situ profiles are very sensitive to precise location and orientation of the ICME flux rope. We expand upon this work with a recent study of 45 STEREO-era near-Earth CMEs and consider the circular flux rope (Nieves-Chinchilla et al. 2016) in addition to the Lundquist flux rope. We quantitatively analyze the goodness-of-fit of the FIDO fits and determine the circumstances under which the FIDO model performs best. Finally, we explore the limitations of the flux rope model itself to reproduce the data, versus our ability to determine the appropriate values of its free parameters. Title: Deflection and Rotation of STEREO-Era CMEs Authors: Kay, C.; Gopalswamy, N. Bibcode: 2017AGUFMSH51E..03K Altcode: Understanding the location and orientation of CMEs is critical for predicting whether they will impact Earth, and what their magnetic orientation may be upon impact. This requires accounting for any deflection or rotation that may occur as the CME propagates away from the Sun. For 45 Earth-directed CMEs occurring between 2007 and 2014, all observed by both STEREO spacecraft, we use EUV observations to determine the precise initial location, then reconstruct the position and orientation in COR1 and COR2 using the GCS technique. Using a model for the in situ magnet field we also determine the location and orientation near 1 AU. We then simulate the deflection and rotation of these CMEs using the ForeCAT model (Kay et al. 2015). We find good agreement between the observed and simulated CME deflections and rotations. These CMEs span the end of Solar Cycle 23 to the maximum of Solar Cycle 24 allowing us to investigate the changes in CME deflection and rotation. We find that the magnitude and direction of the deflection and rotation are determined by a balance between the changes in the background magnetic field and the changes in the CME properties, such as the mass and velocity. Title: A Sun-to-Earth Analysis of Magnetic Helicity of the 2013 March 17-18 Interplanetary Coronal Mass Ejection Authors: Pal, Sanchita; Gopalswamy, Nat; Nandy, Dibyendu; Akiyama, Sachiko; Yashiro, Seiji; Makela, Pertti; Xie, Hong Bibcode: 2017ApJ...851..123P Altcode: 2017arXiv171201114P We compare the magnetic helicity in the 2013 March 17-18 interplanetary coronal mass ejection (ICME) flux rope at 1 au and in its solar counterpart. The progenitor coronal mass ejection (CME) erupted on 2013 March 15 from NOAA active region 11692 and is associated with an M1.1 flare. We derive the source region reconnection flux using the post-eruption arcade (PEA) method that uses the photospheric magnetogram and the area under the PEA. The geometrical properties of the near-Sun flux rope is obtained by forward-modeling of white-light CME observations. Combining the geometrical properties and the reconnection flux, we extract the magnetic properties of the CME flux rope. We derive the magnetic helicity of the flux rope using its magnetic and geometric properties obtained near the Sun and at 1 au. We use a constant-α force-free cylindrical flux rope model fit to the in situ observations in order to derive the magnetic and geometric information of the 1 au ICME. We find a good correspondence in both amplitude and sign of the helicity between the ICME and the CME, assuming a semi-circular (half torus) ICME flux rope with a length of π au. We find that about 83% of the total flux rope helicity at 1 au is injected by the magnetic reconnection in the low corona. We discuss the effect of assuming flux rope length in the derived value of the magnetic helicity. This study connecting the helicity of magnetic flux ropes through the Sun-Earth system has important implications for the origin of helicity in the interplanetary medium and the topology of ICME flux ropes at 1 au and hence their space weather consequences. Title: Prominence Eruption Initiated by Helical Kink Instability of an Embedded Flux Rope Authors: Vemareddy, P.; Gopalswamy, N.; Ravindra, B. Bibcode: 2017ApJ...850...38V Altcode: 2017arXiv170910035V We study the triggering mechanism of a limb-prominence eruption and the associated coronal mass ejection (CME) near AR 12342 using Solar Dynamics Observatory and Large Angle and Spectrometric Coronagraph/Solar Heliospheric Observatory observations. The prominence is seen with an embedded flux thread (FT) at one end and bifurcates from the middle to a different footpoint location. The morphological evolution of the FT is similar to that of an unstable flux rope (FR), which we regard as a prominence-embedded FR. The FR twist exceeds the critical value. In addition, the morphology of the prominence plasma in 304 Å images marks the helical nature of the magnetic skeleton, with a total of 2.96 turns along arc length. The potential field extrapolation model indicates that the critical height of the background magnetic field gradient falls within the inner corona (105 Mm), which is consistent with the extent of coronal plasma loops. These results suggest that the helical kink instability in the embedded FR caused the slow rise of the prominence to the height of the torus instability domain. Moreover, the differential emission measure analysis unveils heating of the prominence plasma to coronal temperatures during an eruption, suggesting reconnection-related heating underneath the upward rising embedded FR. The prominence starts with a slow rise motion of 10 km s-1, which is followed by fast and slow acceleration phases that have an average acceleration of 28.9 m s-2 and 2.4 m s-2 in C2 and C3 field of view, respectively. As predicted by previous numerical simulations, the observed synchronous kinematic profiles of the CME leading edge and the core support the involved FR instability in the prominence initiation. Title: Toward a Next Generation Solar Coronagraph: Development of a Compact Diagnostic Coronagraph on the ISS Authors: Cho, K. -S.; Bong, S. -C.; Choi, S.; Yang, H.; Kim, J.; Baek, J. -H.; Park, J.; Lim, E. -K.; Kim, R. -S.; Kim, S.; Kim, Y. -H.; Park, Y. -D.; Clarke, S. W.; Davila, J. M.; Gopalswamy, N.; Nakariakov, V. M.; Li, B.; Pinto, R. F. Bibcode: 2017JKAS...50..139C Altcode: The Korea Astronomy and Space Science Institute plans to develop a coronagraph in collaboration with National Aeronautics and Space Administration (NASA) and to install it on the International Space Station (ISS). The coronagraph is an externally occulted one-stage coronagraph with a field of view from 3 to 15 solar radii. The observation wavelength is approximately 400 nm, where strong Fraunhofer absorption lines from the photosphere experience thermal broadening and Doppler shift through scattering by coronal electrons. Photometric filter observations around this band enable the estimation of 2D electron temperature and electron velocity distribution in the corona. Together with a high time cadence (<12 min) of corona images used to determine the geometric and kinematic parameters of coronal mass ejections, the coronagraph will yield the spatial distribution of electron density by measuring the polarized brightness. For the purpose of technical demonstration, we intend to observe the total solar eclipse in August 2017 with the filter system and to perform a stratospheric balloon experiment in 2019 with the engineering model of the coronagraph. The coronagraph is planned to be installed on the ISS in 2021 for addressing a number of questions (e.g., coronal heating and solar wind acceleration) that are both fundamental and practically important in the physics of the solar corona and of the heliosphere. Title: Extreme Solar Eruptions and their Space Weather Consequences Authors: Gopalswamy, Nat Bibcode: 2017arXiv170903165G Altcode: Solar eruptions generally refer to coronal mass ejections (CMEs) and flares. Both are important sources of space weather. Solar flares cause sudden change in the ionization level in the ionosphere. CMEs cause solar energetic particle (SEP) events and geomagnetic storms. A flare with unusually high intensity and/or a CME with extremely high energy can be thought of examples of extreme events on the Sun. These events can also lead to extreme SEP events and/or geomagnetic storms. Ultimately, the energy that powers CMEs and flares are stored in magnetic regions on the Sun, known as active regions. Active regions with extraordinary size and magnetic field have the potential to produce extreme events. Based on current data sets, we estimate the sizes of one-in-hundred and one-in-thousand year events as an indicator of the extremeness of the events. We consider both the extremeness in the source of eruptions and in the consequences. We then compare the estimated 100-year and 1000-year sizes with the sizes of historical extreme events measured or inferred. Title: A Hierarchical Relationship between the Fluence Spectra and CME Kinematics in Large Solar Energetic Particle Events: A Radio Perspective Authors: Gopalswamy, N.; Mäkelä, P.; Yashiro, S.; Thakur, N.; Akiyama, S.; Xie, H. Bibcode: 2017JPhCS.900a2009G Altcode: 2017arXiv170700209G We report on further evidence that solar energetic particles are organized by the kinematic properties of coronal mass ejections (CMEs)[1]. In particular, we focus on the starting frequency of type II bursts, which is related to the distance from the Sun where the radio emission starts. We find that the three groups of solar energetic particle (SEP) events known to have distinct values of CME initial acceleration, also have distinct average starting frequencies of the associated type II bursts. SEP events with ground level enhancement (GLE) have the highest starting frequency (107 MHz), while those associated with filament eruption (FE) in quiescent regions have the lowest starting frequency (22 MHz); regular SEP events have intermediate starting frequency (81 MHz). Taking the onset time of type II bursts as the time of shock formation, we determine the shock formation heights measured from the Sun center. We find that the shocks form on average closest to the Sun (1.51 Rs) in GLE events, farthest from the Sun in FE SEP events (5.38 Rs), and at intermediate distances in regular SEP events (1.72 Rs). Finally, we present the results of a case study of a CME with high initial acceleration (∼3 km s-2) and a type II radio burst with high starting frequency (∼200 MHz) but associated with a minor SEP event. We find that the relation between the fluence spectral index and CME initial acceleration continues to hold even for this minor SEP event. Title: CME Velocity and Acceleration Error Estimates Using the Bootstrap Method Authors: Michalek, Grzegorz; Gopalswamy, Nat; Yashiro, Seiji Bibcode: 2017SoPh..292..114M Altcode: The bootstrap method is used to determine errors of basic attributes of coronal mass ejections (CMEs) visually identified in images obtained by the Solar and Heliospheric Observatory (SOHO) mission's Large Angle and Spectrometric Coronagraph (LASCO) instruments. The basic parameters of CMEs are stored, among others, in a database known as the SOHO/LASCO CME catalog and are widely employed for many research studies. The basic attributes of CMEs (e.g. velocity and acceleration) are obtained from manually generated height-time plots. The subjective nature of manual measurements introduces random errors that are difficult to quantify. In many studies the impact of such measurement errors is overlooked. In this study we present a new possibility to estimate measurements errors in the basic attributes of CMEs. This approach is a computer-intensive method because it requires repeating the original data analysis procedure several times using replicate datasets. This is also commonly called the bootstrap method in the literature. We show that the bootstrap approach can be used to estimate the errors of the basic attributes of CMEs having moderately large numbers of height-time measurements. The velocity errors are in the vast majority small and depend mostly on the number of height-time points measured for a particular event. In the case of acceleration, the errors are significant, and for more than half of all CMEs, they are larger than the acceleration itself. Title: Comparison of the coronal mass ejection shock acceleration of three widespread SEP events during solar cycle 24 Authors: Xie, H.; Mäkelä, P.; St. Cyr, O. C.; Gopalswamy, N. Bibcode: 2017JGRA..122.7021X Altcode: We studied three solar energetic particle (SEP) events observed on 14 August 2010, 3 November 2011, and 5 March 2013 by Solar Terrestrial Relations Observatory (STEREO) A, B, and near-Earth (L1) spacecraft with a longitudinal distribution of particles >90°. Using a forward modeling method combined with extreme ultraviolet and white-light images, we determined the angular extent of the shock, the time and location (cobpoint) of the shock intersection with the magnetic field line connecting to each spacecraft, and compute the shock speed at the cobpoint of each spacecraft. We then examine whether the observations of SEPs at each spacecraft were accelerated and injected by the spatially extended shocks or whether another mechanism such as cross-field transport is required for an alternative explanation. Our analyses results indicate that the SEPs observed at the three spacecraft on 3 November, STEREO B (STB) and L1 on 14 August, and the 5 March SEP event at STEREO A (STA) can be explained by the direct shock acceleration. This is consistent with the observed significant anisotropies, short time delays between particle release times and magnetic connection times, and sharp rises in the SEP time profiles. Cross-field diffusion is the likely cause for the 14 August SEP event observed by STA and the 5 March SEPs observed by STB and L1 spacecraft, as particle observations featured weak electron aniotropies and slow rising intensity profiles. Otherwise, the wide longitudinal spread of these SEP increases would require an existence of a circumsolar shock, which may not be a correct assumption in the corona and heliosphere. Title: New Evidence for a Coronal Mass Ejection-driven High Frequency Type II Burst near the Sun Authors: Kumari, Anshu; Ramesh, R.; Kathiravan, C.; Gopalswamy, N. Bibcode: 2017ApJ...843...10K Altcode: We report observations of the high frequency type II radio burst (≈430-30 MHz) that occurred in the solar corona on 2015 November 4. The drift rate of the burst, estimated close to the start frequency of its fundamental component (≈215 MHz), is unusually high (≈2 MHz s-1). Our analysis shows that the estimated speed of the magnetohydrodynamic shock driver of the burst varies with time. The peak speed and acceleration are very large, ≈ 2450 {km} {{{s}}}-1 and ≈ 17 {km} {{{s}}}-2, respectively. There is spatio-temporal correlation between the type II burst and the associated coronal mass ejection (CME) in the whitelight and extreme-ultraviolet images. The time profile of the shock speed and the light curve of the associated soft X-ray flare correlate well. These results indicate that in the present case, (I) the magnetohydrodynamic shock responsible for the high frequency coronal type II burst is driven by the CME and (II) the time profile of the type II burst shock speed represents the near-Sun kinematics of the CME. Title: Direction Finding Analysis of the 2012 July 6 Radio Burst Authors: Makela, Pertti; Gopalswamy, Nat; Akiyama, Sachiko Bibcode: 2017shin.confE.141M Altcode: The 2012 July 6 X1.1 flare at S13W59 and a halo CME with a space speed of 1900 km/s were associated with type III and type II radio bursts. The metric-to-decametric type II radio burst extended down to 5 MHz. Simultaneously a slowly drifting feature with a harmonic structure was observed by Wind and STEREO radio receivers around and below 1 MHz, above the strong type III radio burst at lower frequencies. The radio direction finding analysis of this interplanetary (IP) type II radio burst indicates that the radio source was located near the nose and towards the southern flank of the CME-driven shock. This results is in accordance with previous suggestions that when the metric and IP type II burst are overlapping, the IP type II radio burst originates near the shock nose, whereas the source of the metric type II burst is closer to the Sun in the shock flank region. Title: Observations and Simulations of the Sun-to-Earth Evolution of a STEREO-Era Set of Earth-Impacting CMEs and their In Situ Magnetic Field Authors: Kay, Christina; Gopalswamy, Nat Bibcode: 2017shin.confE..20K Altcode: Coronal mass ejections (CMEs) drive extreme space weather events throughout the solar system. Predicting the effects of a CME impact requires knowing not only if a CME will impact a given point, but also which part of the CME impacts, and what its magnetic properties are upon impact. We explore the relation between CME deflections and rotations, which change the position and orientation of a CME, and the resulting magnetic profiles at 1 AU. For 45 STEREO-era, Earth-impacting CMEs, we determine the region from which each CME erupts, reconstruct its coronal position and orientation, and perform a ForeCAT (Kay et al. 2015) simulation of the coronal deflection and rotation. From this large set of reconstructed and modeled CME deflections and rotations we determine variations in the behavior over the solar cycle as well as correlations with CME properties. We then couple the ForeCAT results with the FIDO in situ magnetic field model (Kay et al. 2017), allowing for comparisons with ACE and Wind observations. FIDO successfully reproduces the in situ magnetic field for all but three of the CMEs. From random walk best fits, we distinguish between ForeCAT's ability to determine FIDO's input parameters, and the limitations of using a simple flux rope model to reproduce complicated in situ structures. We find that the FIDO results are quite sensitive to changes of order a degree in the CME latitude, longitude, and tilt, suggesting that accurate space weather predictions require accurate measurements of a CME's position and orientation. Title: Deflection and Rotation of CMEs from Active Region 11158 Authors: Kay, Christina; Gopalswamy, Nat; Xie, Hong; Yashiro, Seiji Bibcode: 2017SoPh..292...78K Altcode: 2017arXiv170407694K Between 13 and 16 February 2011, a series of coronal mass ejections (CMEs) erupted from multiple polarity inversion lines within active region 11158. For seven of these CMEs we employ the graduated cylindrical shell (GCS) flux rope model to determine the CME trajectory using both Solar Terrestrial Relations Observatory (STEREO) extreme ultraviolet (EUV) and coronagraph images. We then use the model called Forecasting a CME's Altered Trajectory (ForeCAT) for nonradial CME dynamics driven by magnetic forces to simulate the deflection and rotation of the seven CMEs. We find good agreement between ForeCAT results and reconstructed CME positions and orientations. The CME deflections range in magnitude between 10∘ and 30∘. All CMEs are deflected to the north, but we find variations in the direction of the longitudinal deflection. The rotations range between 5∘ and 50∘ with both clockwise and counterclockwise rotations. Three of the CMEs begin with initial positions within 2∘ from one another. These three CMEs are all deflected primarily northward, with some minor eastward deflection, and rotate counterclockwise. Their final positions and orientations, however, differ by 20∘ and 30∘, respectively. This variation in deflection and rotation results from differences in the CME expansion and radial propagation close to the Sun, as well as from the CME mass. Ultimately, only one of these seven CMEs yielded discernible in situ signatures near Earth, although the active region faced toward Earth throughout the eruptions. We suggest that the differences in the deflection and rotation of the CMEs can explain whether each CME impacted or missed Earth. Title: Cataloguing radio emission associated with coronal mass ejections: results from the HELCATS project Authors: Eastwood, Jonathan; Krupar, Vratislav; Magdalenic, Jasmina; Bisi, Mario; Gopalswamy, Nat; Davies, Jackie; Harrison, Richard; Barnes, David Bibcode: 2017EGUGA..19.5249E Altcode: The goal of the Heliospheric Cataloguing, Analysis and Techniques Service (HELCATS) is to add value to the STEREO dataset by cataloguing the properties of coronal mass ejections and corotating interaction regions observed by STEREO. As part of this work, the complementary nature of radio measurements and white light observations has been assessed. Here we report on the cataloguing of slowly-drifting radio emission observed by STEREO WAVES in conjunction with events identified in the HELCATS manually-generated coronal mass ejection catalogue. We present preliminary statistical results derived from the catalogue, in particular the extent to which radio emission is more likely to occur in conjunction with fast coronal mass ejections. We further use the catalogue to make an initial assessment of the angular deviation between radio emission and coronal mass ejection motion, in order to determine which part of the coronal mass ejection contributes most to the radio emission. HELCATS is project 606692 of the European Union's Seventh Framework Programme. Title: Estimation of Reconnection Flux Using Post-eruption Arcades and Its Relevance to Magnetic Clouds at 1 AU Authors: Gopalswamy, N.; Yashiro, S.; Akiyama, S.; Xie, H. Bibcode: 2017SoPh..292...65G Altcode: 2017arXiv170101943G We report on a new method to compute the flare reconnection (RC) flux from post-eruption arcades (PEAs) and the underlying photospheric magnetic fields. In previous works, the RC flux has been computed using the cumulative flare ribbon area. Here we obtain the RC flux as the flux in half of the area underlying the PEA in EUV imaged after the flare maximum. We apply this method to a set of 21 eruptions that originated near the solar disk center in Solar Cycle 23. We find that the RC flux from the arcade method (ΦrA) has excellent agreement with the flux from the flare-ribbon method (ΦrR) according to ΦrA=1.24 (ΦrR) 0.99. We also find ΦrA to be correlated with the poloidal flux (ΦP) of the associated magnetic cloud at 1 AU: ΦP=1.20 (ΦrA) 0.85. This relation is nearly identical to that obtained by Qiu et al. (Astrophys. J. 659, 758, 2007) using a set of only 9 eruptions. Our result supports the idea that flare reconnection results in the formation of the flux rope and PEA as a common process. Title: A Close Connection between Flares and Coronal Mass Ejections Revealed by the Reconnected Flux in the Solar Source Region Authors: Gopalswamy, Nat; Akiyama, Sachiko; Yashiro, Seiji; Xie, Hong Bibcode: 2017EGUGA..1918101G Altcode: We report on a study of the properties of flares and coronal mass ejections (CMEs) associated with interplanetary CMEs (ICMEs) detected close to Earth. The study is based on a set of magnetic clouds (MCs) and non-cloud ejecta (EJ) originating very close to the solar disk. We computed the total reconnected flux in each of the associated solar eruptions and compared it with the CME, flare, and ICME properties. We find that the reconnection flux is closely related to the parameters describing the three phenomena. By fitting flux ropes to the coronagraph data, we show that the CME magnetic field in the corona is significantly higher than the ambient magnetic field. The radial dependence of the Flux-rope magnetic field is faster than that of the ambient magnetic field. This technique provides a simple method to predict the magnetic properties of ICMEs at various destination in the heliosphere. Title: Predicting the Magnetic Field of Earth-impacting CMEs Authors: Kay, C.; Gopalswamy, N.; Reinard, A.; Opher, M. Bibcode: 2017ApJ...835..117K Altcode: Predicting the impact of coronal mass ejections (CMEs) and the southward component of their magnetic field is one of the key goals of space weather forecasting. We present a new model, the ForeCAT In situ Data Observer (FIDO), for predicting the in situ magnetic field of CMEs. We first simulate a CME using ForeCAT, a model for CME deflection and rotation resulting from the background solar magnetic forces. Using the CME position and orientation from ForeCAT, we then determine the passage of the CME over a simulated spacecraft. We model the CME’s magnetic field using a force-free flux rope and we determine the in situ magnetic profile at the synthetic spacecraft. We show that FIDO can reproduce the general behavior of four observed CMEs. FIDO results are very sensitive to the CME’s position and orientation, and we show that the uncertainty in a CME’s position and orientation from coronagraph images corresponds to a wide range of in situ magnitudes and even polarities. This small range of positions and orientations also includes CMEs that entirely miss the satellite. We show that two derived parameters (the normalized angular distance between the CME nose and satellite position and the angular difference between the CME tilt and the position angle of the satellite with respect to the CME nose) can be used to reliably determine whether an impact or miss occurs. We find that the same criteria separate the impacts and misses for cases representing all four observed CMEs. Title: A Hierarchical Relationship between CME Properties and the Fluence Spectral Index of Large Solar Energetic Particle Events Authors: Gopalswamy, N.; Yashiro, Seiji; Thakur, Neeharika; Makela, Pertti; Xie, Hong; Akiyama, Sachiko Bibcode: 2017AAS...22932503G Altcode: We report on a hierarchical relationship found between properties of white-light coronal mass ejections (CMEs) and the fluence spectral indices of the associated Large Solar Energetic Particle (SEP) Events. We consider 74 large SEP events from the western hemisphere in solar cycles 23 and 24 by multiple spacecraft (SAMPEX, GOES, and STEREO). The associated CMEs are observed by SOHO. We find that CMEs with high initial acceleration are associated with SEP events with the hardest fluence spectra, while those with lowest initial acceleration have SEP events with the softest fluence spectra; CMEs with intermediate initial acceleration result in SEP events with moderately hard fluence spectra. Impulsive acceleration leading to high CME speeds close to the Sun results in shock formation close to the Sun, where the ambient magnetic field and density are high and the particles are energized more efficiently. Slowly accelerating CMEs drive shocks at large distances from the Sun, where the magnetic field and density have fallen off significantly, reducing the efficiency of shock acceleration. These opposite extremes are represented by ground level enhancement (GLE) events that have high speeds early on (high initial acceleration) and the SEP events associated with CMEs from quiescent filament region that have low early speeds (low initial acceleration). This finding strongly supports the idea that CME-driven shocks accelerate SEPs and the heliocentric distance where the acceleration takes place decides the hardness of the SEP fluence spectrum. Title: CME association rate of solar flares in cycles 23 and 24 Authors: Yashiro, S.; Gopalswamy, N.; Akiyama, S.; Makela, P. A.; Masuda, S. Bibcode: 2016AGUFMSH13C2320Y Altcode: We report on the solar cycle variation of coronal mass ejection (CME) association rate of solar flares in cycles 23 and 24. There were 1,442 and 707 M flares in the cycles 23 and 24, respectively. We examine the CME associations of these flares using SOHO/LASCO and STEREO/SECCHI/COR1 images. Because the CME association rate increases with the soft X-ray flare size, we examined the CME association rate for a given flare size. We found that the CME association of the M1 flares was 43% in the cycle 23 and decreased to 33% in the cycle 24. The same trend was found in the M2 (57% vs 50%) and M3-M5 flares (61% vs 55%). A supporting observation is that the average decay time of the M1 flares was 14.3 min in the cycle 23 and 12.2 min in the cycle 24, indicating a decrease of long-duration-event (LDE) flares, which are closely related to the CMEs. We also found that the fraction of CME-poor active regions (ARs) was 13% (11 out of 87 ARs) in the cycle 23 and 22% (10 out of 45 ARs) in the cycle 24. These results suggest that the performance of the CME prediction algorithms based on the cycle 23 data could be degraded in the cycle 24. Title: Statistical Analysis of Periodic Oscillations in LASCO Coronal Mass Ejection Speeds Authors: Michalek, G.; Shanmugaraju, A.; Gopalswamy, N.; Yashiro, S.; Akiyama, S. Bibcode: 2016SoPh..291.3751M Altcode: 2016SoPh..tmp..165M A large set of coronal mass ejections (CMEs, 3463) has been selected to study their periodic oscillations in speed in the Solar and Heliospheric Observatory (SOHO) mission's Large Angle and Spectrometric Coronagraph (LASCO) field of view. These events, reported in the SOHO/LASCO catalog in the period of time 1996 - 2004, were selected based on having at least 11 height-time measurements. This selection criterion allows us to construct at least ten-point speed-distance profiles and evaluate kinematic properties of CMEs with a reasonable accuracy. To identify quasi-periodic oscillations in the speed of the CMEs a sinusoidal function was fitted to speed-distance profiles and the speed-time profiles. Of the considered events 22 % revealed periodic velocity fluctuations. These speed oscillations have on average amplitude equal to 87 kms−1 and period 7.8 R⊙/241 min (in distance/time). The study shows that speed oscillations are a common phenomenon associated with CME propagation implying that all the CMEs have a similar magnetic flux-rope structure. The nature of oscillations can be explained in terms of magnetohydrodynamic (MHD) waves excited during the eruption process. More accurate detection of these modes could, in the future, enable us to characterize magnetic structures in space (space seismology). Title: Erratum: Erratum to: Dynamics of CMEs in the LASCO Field of View Authors: Michalek, G.; Gopalswamy, N.; Yashiro, S.; Bronarska, K. Bibcode: 2016SoPh..291.3869M Altcode: 2016SoPh..tmp..159M No abstract at ADS Title: The 2012 July 23 Backside Eruption: An Extreme Energetic Particle Event? Authors: Gopalswamy, N.; Yashiro, S.; Thakur, N.; Mäkelä, P.; Xie, H.; Akiyama, S. Bibcode: 2016ApJ...833..216G Altcode: 2016arXiv161005790G The backside coronal mass ejection (CME) of 2012 July 23 had a short Sun-to-Earth shock transit time (18.5 hr). The associated solar energetic particle (SEP) event had a >10 MeV proton flux peaking at ∼5000 pfu, and the energetic storm particle event was an order of magnitude larger, making it the most intense event in the space era at these energies. By a detailed analysis of the CME, shock, and SEP characteristics, we find that the July 23 event is consistent with a high-energy SEP event (accelerating particles to gigaelectronvolt energies). The times of maximum and fluence spectra in the range 10-100 MeV were very hard, similar to those of ground-level enhancement (GLE) events. We found a hierarchical relationship between the CME initial speeds and the fluence spectral indices: CMEs with low initial speeds had SEP events with the softest spectra, while those with the highest initial speeds had SEP events with the hardest spectra. CMEs attaining intermediate speeds result in moderately hard spectra. The July 23 event was in the group of hard-spectrum events. During the July 23 event, the shock speed (>2000 km s-1), the initial acceleration (∼1.70 km s-2), and the shock-formation height (∼1.5 solar radii) were all typical of GLE events. The associated type II burst had emission components from meter to kilometer wavelengths, suggesting a strong shock. These observations confirm that the 2012 July 23 event is likely to be an extreme event in terms of the energetic particles it accelerated. Title: HELCATS: Statistical results on interplanetary type II bursts observed by STEREO/Waves Authors: Krupar, V.; Eastwood, J. P.; Magdalenic, J.; Gopalswamy, N.; Bisi, M. M.; Davies, J. A.; Harrison, R. A.; Barnes, D. Bibcode: 2016AGUFMSH11C2246K Altcode: Heliospheric Cataloguing, Analysis and Techniques Service (HELCATS) is a project of the European Union's Seventh Framework Programme. The current version of the HELCATS manually-generated Coronal Mass Ejection (CME) catalogue contains more than 1,300 CMEs observed between 2007 and 2014. CMEs are sometimes associated with the so called type II bursts which are considered to be radio signatures of fast electrons accelerated at the CME-driven shock front. We present statistical results on 153 type II bursts associated with manually-identified CMEs in the HELCATS catalogue. We found that faster CMEs are more likely to produce radio emissions. By comparing frequency drifts with white-light observations we calculated angular deviations of type II burst propagation directions from radial. Our results confirm that type II bursts statistically arise from CME flanks. We also discuss the use of interplanetary radio emission in the context of space weather forecasting. Title: Comparison on the CME-shock Acceleration of Three Widespread SEPs during Solar Cycle 24 Authors: St Cyr, O. C.; Xie, H.; Pertti, M.; Gopalswamy, N. Bibcode: 2016AGUFMSH41B2534S Altcode: Using forward-modeling of three-dimensional (3D) flux rope plus oblate spheroid shock model, we analyze three solar energetic particle (SEP) events observed in three views by STEREO and SOHO spacecraft. The three SEP events occurred on August 14, 2010, November 03, 2011, and March 05, 2013. All three SEP events show widespread distribution in longitude (> 90 degree) but with different onset delays, rate of flux increase, and electron anisotropies. By fitting the 3D flux rope + shock model to white-light and EUV images from STEREO, SOHO and SDO, we are able to best determine the 3D shape of the CME shock wave. The forward-modeling technique constrained with multi-spacecraft observations allowed us to determine the locations where the shock fronts intersect the magnetic footpoints of three spacecraft (STA, B and ACE/Wind), and compute the shock speeds and expansion speeds at the intersecting points. Our fitting results show that the November 03, 2011 SEP has the fastest expansion speed among three events, which is consistent with the rapid flux rises at all three spacecraft and small onset delay between well-connected STA and poor-connected STB and ACE/Wind ( 30 min). On the other hand, the March 05, 2013 SEP has the largest shock leading-edge speed thus the largest electron intensity. However, due to its relatively weak expansion, the shock ceased expanding at 100 degree. The intensity observed by ACE/EPAM and Wind/3DP ( 140 degree away from the SEP solar source) rose very slowly with a large delay of 5 hr, which cannot be explained by the shock acceleration. For the Aug. 14, 2010 event, the SEP observed at STB and ACE/Wind are shown to be accelerated and injected by the shock and consistent with the large anisotropies observed at these two locations. The cross-field diffusion is the likely cause of the Aug. 14, 2010 SEP event observed by STA and the March 05, 2013 event observed by STB and ACE/Wind, which show almost no anisotropy. This investigation helps explore the relative importance of the various mechanisms of SEP acceleration. Title: The ForeCAT In Situ Data Observer and the Effects of Deflection and Rotation on CME Geoeffectiveness Authors: Kay, C.; Gopalswamy, N.; Reinard, A.; Opher, M.; Nieves-Chinchilla, T. Bibcode: 2016AGUFMSH13B2298K Altcode: CMEs drive the strongest space weather events at Earth and throughout the solar system. At Earth, the amount of southward magnetic field in a CME is a major component in determining the severity of an impact. We present results from ForeCAT (Forecasting a CME's Altered Trajectory, Kay et al. 2015), which predicts the deflection and rotation of CMEs based on magnetic forces determined by the background magnetic field. Understanding these deflections and rotations is essential to understanding the geoeffectiveness of CMEs as it determines whether a CME will hit Earth and the orientation of the flux rope magnetic field upon impact. Using the CME location and orientation from ForeCAT and simple flux rope models we show that we can reproduce the in situ magnetic profiles of Earth-impacting CMEs with the new ForeCAT In situ Data Observer (FIDO). We compare these results with the in situ profiles obtained assuming that no deflection or rotation occurs, and find that including these nonradial effects is essential for accurate space weather forecasting. For several observed cases we comment on how the deflection and rotation affects the southward component of the CME's magnetic field, and therefore the CME's geoeffectiveness. Title: Shock Formation, Energetic Particle Release, and Kinematics of Coronal Mass Ejections Authors: Gopalswamy, N.; Yashiro, S.; Thakur, N.; Makela, P. A.; Xie, H.; Akiyama, S. Bibcode: 2016AGUFMSH32A..06G Altcode: There are many source and environmental parameters that affect the characteristics of large solar energetic particle (SEP) events. We report on three primary characteristics that seem to determine whether a CME-driven shock can accelerate particles to very high energies. The first one is the height of shock formation, as indicated by type II radio bursts. For SEP events with GeV particles, the shocks form very close to the Sun, about half a solar radius above the solar surface. For events from filament eruptions (FEs) outside active regions, the shock forms at much larger heights - either in the outer corona or in the interplanetary medium. The second characteristic is the acceleration profile of CMEs. In high-energy particle events, the associated CMEs accelerate impulsively (initial acceleration is 2 km/s/s), ensuring strong shocks very close to the solar surface where the ambient magnetic field is high. In FE SEP events, the acceleration is typically an order of magnitude smaller, consistent with shock formation at large distances from the Sun. The third factor is the Alfven speed profile in the ambient medium. It is well known that the Alfven speed (or magnetosonic speed) in the corona increases from 300 km/s in the region where shocks typically form to several hundred km/s around 3 solar radii. After that the characteristic speed steadily declines. The behavior of the CME speed profile with respect to the Alfven speed profile essentially determines the true strength of the shock. One of the observational consequences of these three factors is the 10-100 MeV spectral index of the SEP events. We show that the high-energy SEP events and FE SEP events fall on the opposite ends of the distribution of the spectral index: 2 and >4, respectively. Title: History and development of coronal mass ejections as a key player in solar terrestrial relationship Authors: Gopalswamy, N. Bibcode: 2016GSL.....3....8G Altcode: 2016arXiv160203665G Coronal mass ejections (CMEs) are relatively a recently discovered phenomenon—in 1971, some 15 years into the Space Era. It took another two decades to realize that CMEs are the most important players in solar terrestrial relationship as the root cause of severe weather in Earth's space environment. CMEs are now counted among the major natural hazards because they cause large solar energetic particle (SEP) events and major geomagnetic storms, both of which pose danger to humans and their technology in space and ground. Geomagnetic storms discovered in the 1700s, solar flares discovered in the 1800s, and SEP events discovered in the 1900s are all now found to be closely related to CMEs via various physical processes occurring at various locations in and around CMEs, when they interact with the ambient medium. This article identifies a number of key developments that preceded the discovery of white-light CMEs suggesting that CMEs were waiting to be discovered. The last two decades witnessed an explosion of CME research following the launch of the Solar and Heliospheric Observatory mission in 1995, resulting in the establishment of a full picture of CMEs. Title: Constraining the Solar Coronal Magnetic Field Strength using Split-band Type II Radio Burst Observations Authors: Kishore, P.; Ramesh, R.; Hariharan, K.; Kathiravan, C.; Gopalswamy, N. Bibcode: 2016ApJ...832...59K Altcode: We report on low-frequency radio (85-35 MHz) spectral observations of four different type II radio bursts, which exhibited fundamental-harmonic emission and split-band structure. Each of the bursts was found to be closely associated with a whitelight coronal mass ejection (CME) close to the Sun. We estimated the coronal magnetic field strength from the split-band characteristics of the bursts, by assuming a model for the coronal electron density distribution. The choice of the model was constrained, based on the following criteria: (1) when the radio burst is observed simultaneously in the upper and lower bands of the fundamental component, the location of the plasma level corresponding to the frequency of the burst in the lower band should be consistent with the deprojected location of the leading edge (LE) of the associated CME; (2) the drift speed of the type II bursts derived from such a model should agree closely with the deprojected speed of the LE of the corresponding CMEs. With the above conditions, we find that: (1) the estimated field strengths are unique to each type II burst, and (2) the radial variation of the field strength in the different events indicate a pattern. It is steepest for the case where the heliocentric distance range over which the associated burst is observed is closest to the Sun, and vice versa. Title: Determining ICME Magnetic Field Orientation with the ForeCAT In Situ Data Observer Authors: Kay, Christina; Gopalswamy, N.; Reinard, A.; Opher, M. Bibcode: 2016usc..confE..20K Altcode: CMEs drive the strongest space weather events at Earth and throughout the solar system. At Earth, the amount of southward magnetic field in a CME is a major component in determining the severity of an impact. We present results from ForeCAT (Forecasting a CME's Altered Trajectory, Kay et al. 2015), which predicts the deflection and rotation of CMEs based on magnetic forces determined by the background magnetic field. Using HMI magnetograms to reconstruct the background magnetic field and AIA images to constrain the early evolution of CMEs, we show that we can reproduce the deflection and rotation of CMEs observed in the corona. Using this CME location and orientation from ForeCAT results and a simple force-free flux rope model we show that we can reproduce the in situ magnetic profiles of Earth-impacting CMEs. We compare these results with the in situ profiles obtained assuming that no deflection or rotation occurs, and find that including these nonradial effects is essential for accurate space weather forecasting. Title: The Complex Solar Polarity Reversal during Cycle 24 Authors: Gopalswamy, N.; Yashiro, S.; Akiyama, S. Bibcode: 2016usc..confE..37G Altcode: The polarity reversal at solar poles is an important event with important implications for solar magnetism, the polarity of interplanetary coronal mass ejections, and even cosmic ray modulation. The poles often do not reverse simultaneously. During the several recent cycles, the north pole reversed first, followed by the south. During cycle 24, this trend has been broken in that the south pole reversed first. The polarity reversal is typically marked by the cessation of high-latitude eruptive activities such coronal mass ejections and prominence eruptions. Even though polar prominences started appearing as early as 2011, the reversal in the north was completed only by the end of 2015. On the other hand the south polar region behaved as in previous cycles and reversed over a shorter time scale, about a year before the reversal in the north. By combining prominence eruption detected automatically (Nobeyama Radioheliograph and SDO), the polar microwave brightness (Nobeyama Radioheliograph), and the magnetic butterfly diagram (SDO and NSO) we show that the complexity can be attributed to the emergence of active regions that violated the Hale polarity rule and Joy's law. The extended period of near-zero field in the north polar region should result in very weak and delayed sunspot activity in the northern hemisphere in cycle 25, the southern hemispheric activity should start early; the amplitude will depend on how the south polar fields will evolve in the declining phase of cycle (24). Title: Coronal magnetic field profiles from shock-CME standoff distances Authors: Schmidt, J. M.; Cairns, Iver H.; Gopalswamy, N.; Yashiro, S. Bibcode: 2016JGRA..121.9299S Altcode: Coronagraphs observe coronal mass ejections (CMEs) and driven shocks in white light images. From these observations the shock's speed and the shock's standoff distance from the CME's leading edge can be derived. Using these quantities, theoretical relationships between the shock's Alfvénic Mach number MA and standoff distance, and empirical radial profiles for the solar wind velocity and number density, the radial magnetic field profile upstream of the shock can be calculated. These profiles cannot be measured directly. We test the accuracy of this method for estimating the radial magnetic field profile upstream of the shock by simulating a sample CME that occurred on 29 November 2013 using the three-dimensional (3-D) magnetohydrodynamic Block-Adaptive-Tree-Solarwind-Roe-Upwind-Scheme code, retrieving shock-CME standoff distances from the simulation, and comparing the estimated and simulated radial magnetic field profiles. We find good agreement between the two profiles (within ±30%) between 1.8 and 10 R⊙. Our simulations confirm that a linear relationship exists between the standoff distance and the inverse compression ratio at the shock. We also find very good agreement between the empirical and simulated radial profiles of the number density and speed of the solar wind and inner corona. Title: On the reduced geoeffectiveness of solar cycle 24: A moderate storm perspective Authors: Selvakumaran, R.; Veenadhari, B.; Akiyama, S.; Pandya, Megha; Gopalswamy, N.; Yashiro, S.; Kumar, Sandeep; Mäkelä, P.; Xie, H. Bibcode: 2016JGRA..121.8188S Altcode: The moderate and intense geomagnetic storms are identified for the first 77 months of solar cycles 23 and 24. The solar sources responsible for the moderate geomagnetic storms are indentified during the same epoch for both the cycles. Solar cycle 24 has shown nearly 80% reduction in the occurrence of intense storms whereas it is only 40% in case of moderate storms when compared to previous cycle. The solar and interplanetary characteristics of the moderate storms driven by coronal mass ejection (CME) are compared for solar cycles 23 and 24 in order to see reduction in geoeffectiveness has anything to do with the occurrence of moderate storm. Though there is reduction in the occurrence of moderate storms, the Dst distribution does not show much difference. Similarly, the solar source parameters like CME speed, mass, and width did not show any significant variation in the average values as well as the distribution. The correlation between VBz and Dst is determined, and it is found to be moderate with value of 0.68 for cycle 23 and 0.61 for cycle 24. The magnetospheric energy flux parameter epsilon (ɛ) is estimated during the main phase of all moderate storms during solar cycles 23 and 24. The energy transfer decreased in solar cycle 24 when compared to cycle 23. These results are significantly different when all geomagnetic storms are taken into consideration for both the solar cycles. Title: Source Regions of the Type II Radio Burst Observed During a CME-CME Interaction on 2013 May 22 Authors: Mäkelä, P.; Gopalswamy, N.; Reiner, M. J.; Akiyama, S.; Krupar, V. Bibcode: 2016ApJ...827..141M Altcode: 2016arXiv160606989G We report on our study of radio source regions during the type II radio burst on 2013 May 22 based on direction-finding analysis of the Wind/WAVES and STEREO/WAVES (SWAVES) radio observations at decameter-hectometric wavelengths. The type II emission showed an enhancement that coincided with the interaction of two coronal mass ejections (CMEs) launched in sequence along closely spaced trajectories. The triangulation of the SWAVES source directions posited the ecliptic projections of the radio sources near the line connecting the Sun and the STEREO-A spacecraft. The WAVES and SWAVES source directions revealed shifts in the latitude of the radio source, indicating that the spatial location of the dominant source of the type II emission varies during the CME-CME interaction. The WAVES source directions close to 1 MHz frequencies matched the location of the leading edge of the primary CME seen in the images of the LASCO/C3 coronagraph. This correspondence of spatial locations at both wavelengths confirms that the CME-CME interaction region is the source of the type II enhancement. Comparison of radio and white-light observations also showed that at lower frequencies scattering significantly affects radio wave propagation. Title: A small mission concept to the Sun-Earth Lagrangian L5 point for innovative solar, heliospheric and space weather science Authors: Lavraud, B.; Liu, Y.; Segura, K.; He, J.; Qin, G.; Temmer, M.; Vial, J. -C.; Xiong, M.; Davies, J. A.; Rouillard, A. P.; Pinto, R.; Auchère, F.; Harrison, R. A.; Eyles, C.; Gan, W.; Lamy, P.; Xia, L.; Eastwood, J. P.; Kong, L.; Wang, J.; Wimmer-Schweingruber, R. F.; Zhang, S.; Zong, Q.; Soucek, J.; An, J.; Prech, L.; Zhang, A.; Rochus, P.; Bothmer, V.; Janvier, M.; Maksimovic, M.; Escoubet, C. P.; Kilpua, E. K. J.; Tappin, J.; Vainio, R.; Poedts, S.; Dunlop, M. W.; Savani, N.; Gopalswamy, N.; Bale, S. D.; Li, G.; Howard, T.; DeForest, C.; Webb, D.; Lugaz, N.; Fuselier, S. A.; Dalmasse, K.; Tallineau, J.; Vranken, D.; Fernández, J. G. Bibcode: 2016JASTP.146..171L Altcode: We present a concept for a small mission to the Sun-Earth Lagrangian L5 point for innovative solar, heliospheric and space weather science. The proposed INvestigation of Solar-Terrestrial Activity aNd Transients (INSTANT) mission is designed to identify how solar coronal magnetic fields drive eruptions, mass transport and particle acceleration that impact the Earth and the heliosphere. INSTANT is the first mission designed to (1) obtain measurements of coronal magnetic fields from space and (2) determine coronal mass ejection (CME) kinematics with unparalleled accuracy. Thanks to innovative instrumentation at a vantage point that provides the most suitable perspective view of the Sun-Earth system, INSTANT would uniquely track the whole chain of fundamental processes driving space weather at Earth. We present the science requirements, payload and mission profile that fulfill ambitious science objectives within small mission programmatic boundary conditions. Title: The Interaction between Coronal Mass Ejections (CMEs) and Coronal Holes (CHs) during the Solar Cycle 23 and its Geomagnetic Consequences Authors: Mohamed, Amaal; Gopalswamy, Nat Bibcode: 2016cosp...41E1319M Altcode: The interactions between the two large scale phenomena, coronal holes (CHs) and coronal mass ejections (CMEs) maybe considered as one of the most important relations that having a direct impact not only on space weather but also on the relevant plasma physics. Many observations have shown that throughout their propagation from the Sun to interplanetary space, CMEs interact with the heliospheric structures (e.g., other CMEs, Corotating interaction regions (CIRs), helmet streamers, and CHs). Such interactions could enhance the southward magnetic field component, which has important implications for geomagnetic storm generation. These interactions imply also a significant energy and momentum transfer between the interacting systems where magnetic reconnection is taking place. When CHs deflect CMEs away from or towards the Sun-Earth line, the geomagnetic response of the CME is highly affected. Gopalswamy et al. [2009] have addressed the deflection of CMEs due to the existence of CHs that are in close proximity to the eruption regions. They have shown that CHs can act as magnetic barriers that constrain CMEs propagation and can significantly affect their trajectories. Here, we study the interaction between coronal holes (CHs) and coronal mass ejections (CMEs) using a resultant force exerted by all coronal holes present on the disk and is defined as the coronal hole influence parameter (CHIP). The CHIP magnitude for each CH depends on the CH area, the distance between the CH centroid and the eruption region, and the average magnetic field within the CH at the photospheric level. The CHIP direction for each CH points from the CH centroid to the eruption region. We focus on Solar Cycle 23 CMEs originating from the disk center of the Sun (central meridian distance < 15 °). We present an extensive statistical study via compiling data sets of observations of CMEs and their interplanetary counterparts; known as interplanetary CMEs (ICMEs). There are 2 subsets of ICMEs: magnetic cloud (MC) and non-magnetic cloud (non-MC) ICMEs. MCs are identified by a smooth change of the magnetic field as measured with spacecraft at 1 AU, using ACE and Wind spacecraft. It is found that the maximum phase has the largest CHIP value (2.9 G) for non-MCs. The CHIP is the largest (5.8 G) for driverless (DL) shocks, which are shocks at 1 AU with no discernible MC or non-MC. These results suggest that the behavior of non-MCs is similar to that of the DL shocks and different from that of MCs. In other words, the CHs may deflect the CMEs away from the Sun-Earth line and force them to behave like limb CMEs with DL shocks. This finding supports the idea that all CMEs may be flux ropes if viewed from an appropriate vantage point. Title: Discussion Authors: Gopalswamy, Nat Bibcode: 2016cosp...41E.721G Altcode: Discussion Title: Discussion Authors: Gopalswamy, Nat Bibcode: 2016cosp...41E.728G Altcode: Discussion Title: Discussion Authors: Gopalswamy, Nat Bibcode: 2016cosp...41E.729G Altcode: Discussion Title: Discussion Authors: Gopalswamy, Nat Bibcode: 2016cosp...41E.714G Altcode: Discussion Title: Discussion Authors: Gopalswamy, Nat Bibcode: 2016cosp...41E.723G Altcode: Discussion Title: Discussion Authors: Gopalswamy, Nat Bibcode: 2016cosp...41E.727G Altcode: Discussion Title: Discussion Authors: Gopalswamy, Nat Bibcode: 2016cosp...41E.726G Altcode: Discussion Title: Discussion Authors: Gopalswamy, Nat Bibcode: 2016cosp...41E.716G Altcode: Discussion Title: The differences between CME-rich and CME-poor Active Regions Authors: Akiyama, Sachiko; Yashiro, Seiji; Gopalswamy, Nat; Mäkelä, Pertti Bibcode: 2016shin.confE.159A Altcode: We studied the association of coronal mass ejections (CMEs) with large X-ray flares occurring in flare-productive active regions (ARs). The flare-productive ARs are defined as those which produce more than five M1-class flares during their passage from the east to west limb. A total of 1236 large X-ray flares were produced from 132 such ARs in the period 1996 to 2015. We examined the CME association rate (RCME) for each AR as an index of AR"s CME-productivity using by LASCO/SOHO and SECCHI/STEREO. It is reasonable to expect that average RCME of the flare-productive ARs is 50%, because about half of M1 class flares have CME association. However, out of the 132 ARs, 20 were CME-rich (RCME > 80%) and 21 were CME-poor (RCME < 20%). AR size and magnetic potential energy do not seem to differ significantly between CME-rich and CME-poor ARs. We did find a significant difference in the recurrence time of flares in CME-rich ARs (average = 21.6 h) and hose in CME-poor them (14.7 h). We discuss additional differences between the two types of ARs. Title: Interaction between Coronal Mass Ejections: Limited Spatial Extent Revealed by SOHO Observations Authors: Gopalswamy, Nat; Reiner, Mike J.; Makela, Pertti; Yashiro, Seiji Bibcode: 2016cosp...41E.711G Altcode: A spectacular CME interaction event was observed on 2013 May 22 by the Large Angle and Spectrometric Coronagraph (LASCO) on board the Solar and Heliospheric Observatory (SOHO) mission as confirmed by the radio signature detected by the Radio and Plasma Wave experiment (WAVES) on board the Wind spacecraft. The interaction event was also associated with an intense solar energetic particle event, typical of such events in solar cycles 23 and 24. Detailed height-time plots of the interacting CMEs at various position angles revealed a surprising result: only a limited spatial extent of the primary CME was affected by the interaction. The speed of the primary CME showed a sharp decline in the position angle range where it interacted with the preceding CME. At these position angles, the speed of the preceding CME increased. At position angles away from the interaction region, the speed of the primary CME remained roughly the same except for the usual drag deceleration. This result has important implications to theories on CME collision: treating the interacting CMEs to be rigid bodies and using the whole mass of the CMEs may not be correct. Title: Energy dependence of SEP electron and proton onset times Authors: Xie, H.; Mäkelä, P.; Gopalswamy, N.; St. Cyr, O. C. Bibcode: 2016JGRA..121.6168X Altcode: 2016arXiv160908171X We study the large solar energetic particle (SEP) events that were detected by GOES in the >10 MeV energy channel during December 2006 to March 2014. We derive and compare solar particle release (SPR) times for the 0.25-10.4 MeV electrons and 10-100 MeV protons for the 28 SEP events. In the study, the electron SPR times are derived with the time-shifting analysis (TSA) and the proton SPR times are derived using both the TSA and the velocity dispersion analysis (VDA). Electron anisotropies are computed to evaluate the amount of scattering for the events under study. Our main results include (1) near-relativistic electrons and high-energy protons are released at the same time within 8 min for most (16 of 23) SEP events. (2)There exists a good correlation between electron and proton acceleration, peak intensity, and intensity time profiles. (3) The TSA SPR times for 90.5 MeV and 57.4 MeV protons have maximum errors of 6 min and 10 min compared to the proton VDA release times, respectively, while the maximum error for 15.4 MeV protons can reach to 32 min. (4) For 7 low-intensity events of the 23, large delays occurred for 6.5 MeV electrons and 90.5 MeV protons relative to 0.5 MeV electrons. Whether these delays are due to times needed for the evolving shock to be strengthened or due to particle transport effects remains unsolved. Title: Unusual Polar Activity of the Sun in the Northern Hemisphere and Its Implications for Solar Cycle 25 Authors: Gopalswamy, Nat; Masuda, Satoshi; Yashiro, Seiji; Akiyama, Sachiko; Shibasaki, Kiyoto Bibcode: 2016cosp...41E.712G Altcode: Polar field strength in one solar cycle is known to indicate the strength (e.g., Sunspot number) and phase of the next cycle. In particular the polar field strength (or its proxies such as the polar coronal hole area and microwave polar brightness) during the minimum phase of a given cycle seem to be well correlated with the maximum sunspot number of the next cycle. Polar prominence eruptions and coronal mass ejections have also been found to be indicators of low polar field; their cessation signals the time of polarity reversal. While these indicators are present in the current cycle, significant differences are found regarding the phase lag between the two hemispheres and the duration of polar eruptions. We use data from the Nobeyama Radioheliograph, the Solar Dynamics Observatory, SOLIS, and Wilcox Solar Observatory to highlight these differences. We find that the north polar region of the Sun has near-zero field strength for more than three years. This is unusually long and caused by surges of both polarities heading toward the north pole that prevent the buildup of the polar field. This seems to be due to anti-Hale active regions that appeared around the 2012 peak sunspot activity in the northern hemisphere. The unusual condition is consistent with (i) the continued high-latitude prominence eruption, (ii) the extended period of high tilt angle of the heliospheric current sheet, (iii) the weak microwave polar brightness, and (iv) the lack of north polar coronal hole. On the other hand, the south polar field has started building up and the coronal hole has appeared in early 2015 because of large active regions of the correct tilt in the southern hemisphere during the 2014 peak of sunspot activity. The extended period of near-zero field in the north polar region should result in very weak and delayed sunspot activity in the northern hemisphere in cycle 25. On the other hand the south polar field has already increased significantly, suggesting that the activity in the southern hemisphere should start early; the amplitude will depend on how the south polar fields will evolve in the declining phase of cycle (24). Title: Deflection and Rotation of CMEs from AR 11158 Authors: Kay, Christina Danielle; Gopalswamy, N.; Xie, H.; Yashiro, S. Bibcode: 2016shin.confE..41K Altcode: Between the 13th and 16th of February 2011 a series of CMEs erupted from multiple polarity inversion lines within AR 11158. For seven of these CMEs we use the Graduated Cylindrical Shell (GCS) flux rope model to determine the CME trajectory using both STEREO EUV and coronagraph images. We then use ForeCAT, a model for nonradial CME dynamics driven by magnetic forces, to simulate the deflection and rotation of the seven CMEs. We find good agreement between the ForeCAT results and the reconstructed CME positions and orientations. The CME deflections range in magnitude between 10 and 30 degrees. All CMEs deflect to the north but we find variation in direction of the longitudinal deflection. The rotations range between 5 degrees and 50 degrees with both clockwise and counterclockwise rotation occurring. Four of the CMEs begin with initial positions within 2 degrees of one another. These four CMEs all deflect primarily northward, with some minor eastward deflection, and rotate counterclockwise. Their final positions and orientations, however, respectively differ by 20 degrees and 30 degrees. This variation in deflection and rotation results from differences in the CME expansion and radial propagation close to the Sun, as well as the CME mass. Title: Kinematics of slow and fast CMEs in soar cycle 23 and 24 Authors: Banerjee, Dipankar; Gopalswamy, Nat; Pant, Vaibhav Bibcode: 2016cosp...41E.140B Altcode: CMEs are episodic expulsion of plasma and magnetic fields from Sun into heliosphere. CMEs can be classified, based on their speeds, as slow CMEs and fast CMEs. We find that slow CMEs and fast CMEs behave differently in two cycles. While fast CMEs seem to follow the sunspot variations, slow CMEs have much flatter distribution. Thus the distribution of total CMEs is affected by slow CME populations. We find double peak behaviour in fast CMEs, since they follow the sunspot distribution, in both the cycles without any significant delay from sunspot variation. It suggests that most of the fast CMEs originates from active regions associated with sunspots. We also find double peak behaviour in slow CMEs in cycle 24 but not in cycle 23. In addition to this the number of slow CMEs are far more than in cycle 23. These findings point towards the fact that in cycle 24 slow CMEs to some extent are associated with sunspots and due to weak heliospheric field they could somehow escape easily thus giving double peak behaviour and larger distribution in cycle 24. Apart from this we also find that slow and fast CMEs follow different power laws. This may shed light on their origin as well. Title: Discussion Authors: Gopalswamy, Nat Bibcode: 2016cosp...41E.717G Altcode: Discussion Title: Discussion Authors: Gopalswamy, Nat Bibcode: 2016cosp...41E.715G Altcode: Discussion Title: Discussion Authors: Gopalswamy, Nat Bibcode: 2016cosp...41E.720G Altcode: Discussion Title: Discussion Authors: Gopalswamy, Nat Bibcode: 2016cosp...41E.722G Altcode: Discussion Title: Discussion Authors: Gopalswamy, Nat Bibcode: 2016cosp...41E.719G Altcode: Discussion Title: Discussion Authors: Gopalswamy, Nat Bibcode: 2016cosp...41E.730G Altcode: Discussion Title: Discussion Authors: Gopalswamy, Nat Bibcode: 2016cosp...41E.718G Altcode: Discussion Title: Smaller Forbush Decreases in Solar Cycle 24: Effect of the Weak CME Field Strength? Authors: Thakur, Neeharika; Gopalswamy, N.; Yashiro, S.; Akiyama, S.; Xie, H.; Mäkelä, P. Bibcode: 2016shin.confE.172T Altcode: A Forbush decrease (FD) is a sudden depression in the intensity of galactic cosmic ray (GCR) background, followed by a gradual recovery. One of the major causes of FDs is the presence of magnetic structures such as magnetic clouds (MCs) or corotating interaction regions (CIRs) that have enhanced magnetic field, which can scatter particles away reducing the observed GCR intensity. Recent work (Gopalswamy et al. 2014, GRL 41, 2673) suggests that coronal mass ejections (CMEs) are expanding anomalously in solar cycle 24 due to the reduced total pressure in the ambient medium. One of the consequences of the anomalous expansion is the reduced magnetic content of MCs, so we expect subdued FDs in cycle 24. In this paper, we present preliminary results from a survey of FDs during MC events in cycle 24 in comparison with those in cycle 23. We find that only 17% FDs in cycle 24 had an amplitude >3%, as compared to 31% in cycle 23. This result is consistent with the difference in the maximum magnetic field intensities (Bmax) of MCs in the two cycles: only 10% of MCs in cycle 24 have Bmax>20nT, compared to 22% in cycle 23, confirming that MCs of cycle 24 have weaker magnetic field content. Therefore, we suggest that weaker magnetic field intensity in the magnetic clouds of cycle 24 has led to FDs with smaller amplitudes. Title: The 2012 July 23 Backside Event: An Extreme Energetic Particle Event? Authors: Gopalswamy, Nat; Makela, Pertti; Yashiro, Seiji Bibcode: 2016shin.confE.173G Altcode: The backside coronal mass ejection (CME) of 2012 July 23 has received considerable attention because many of its characteristics place it among the historical extreme solar events. For example, the shock transit time from Sun to 1 au was 18.5 hours, similar to the two 2003 Halloween events on October 28 and 29. The CME speed well exceeded 2000 km/s as observed from three views: the STEREO-Ahead, STEREO-Behind, and SOHO. The CME erupted from S17W141 and was heading roughly towards STEREO-A. The solar energetic particle (SEP) event had a peak value of 5000 pfu in the >10 MeV channel. The energetic storm particle (ESP) event was an order of magnitude larger, placing it among the most intense events in the space era. In this paper, we examine whether the CME in this event could have accelerated particles to GeV energies. The STEREO particle detectors do not have energy channels higher than 100 MeV, so we determine the SEP spectrum in the range 10-100 MeV and compare it with that of other ground level enhancement (GLE) events. We find that the spectrum of the 2012 July 23 event is very hard (power law index 1.66), harder than that of all GLE events in cycles 23 and 24. Only the most intense GLE of cycle 23 (2005 January 20), had a 10-100 MeV spectral index of 1.66. The two GLE events of cycle 24 had spectral indices of 2.14 (2012 May 17) and 2.18 (2014 January 6). Thus we conclude that the 2012 July 23 event is likely to be an extreme event in terms of the energetic particles it accelerated. We also discuss additional characteristics of the event, which support this conclusion. Title: Discussion Authors: Gopalswamy, Nat Bibcode: 2016cosp...41E.724G Altcode: Discussion Title: Discussion Authors: Gopalswamy, Nat Bibcode: 2016cosp...41E.725G Altcode: Discussion Title: Investigation on source locations of interplanetary type II radio bursts using radio direction finding Authors: Makela, Pertti; Gopalswamy, Nat; Akiyama, Sachiko Bibcode: 2016shin.confE.167M Altcode: Source locations of interplanetary (IP) type II radio bursts can be studied by comparing radio source directions obtained using direction finding (DF) techniques with the white-light images of the associated coronal mass ejections (CMEs). Previously this method has been used to confirm that a CME-CME interaction event is the source of the concurrently observed type II enhancement. These IP type II enhancements are well suited for DF studies, because the signal-to-noise ratio of the radio emission is sufficiently high. Regular IP type II bursts are often fainter, especially so during solar cycle 24, which is characterized by a lower solar activity level and a smaller number of intense solar eruptions compared to solar cycle 23. In addition, it is known that radio wave scattering affects the DF source directions at lower frequencies. We report on our investigation on locating the radio source of regular IP type II radio bursts by comparing the DF source directions with the white-light images of the associated CMEs. Title: Detection of Nonthermal Radio Emission from a Polar coronal mass ejection Authors: Gopalswamy, Nat; Reiner, Mike J.; Makela, Pertti; Yashiro, Seiji; Akiyama, Sachiko Bibcode: 2016cosp...41E.713G Altcode: High-latitude coronal mass ejections from the polar crown region are generally of low energy and hence thought to be not responsible for driving shocks. However, the eruption of such CMEs are associated with weak post eruption arcades suggesting that particle acceleration does happen in the reconnection region beneath the erupting filaments. An unusually fast CME erupted from the southern polar crown on 1999 June 14 observed by the Large Angle and Spectrometric Coronagraph (LASCO) on board the Solar and Heliospheric Observatory (SOHO) mission. The post eruption arcade was observed by the Soft X-ray Telescope on board the Yohkoh mission and the Extreme-ultraviolet imaging Telescope (EIT) on board SOHO. A diffuse radio emission was observed below 1 MHz by the Radio and Plasma Wave experiment (WAVES) on board the Wind spacecraft. The good temporal association between the radio burst and the CME suggests that the CME must be the source of energy for the radio emission. The drift rate of the radio burst was much smaller than that of a typical interplanetary type II burst. We suggest that the radio burst is produced by a flank of the CME-driven shock passing through a streamer located close to the east limb of the Sun. Such an interaction is likely to have caused the slow drift of the burst because the shock flank passes roughly parallel to the solar surface in the flank region. The enhanced density in the streamer makes the local Alfven speed lower, making the shock sufficiently strong to accelerate a few keV electrons that lead to the radio emission. The diffuse feature also contains a series of spikes, which suggest possible escape of nonthermal electrons along open field lines. We use the radio direction finding to confirm the results. This result has important implications for particle acceleration by shock flanks, where the geometry is expected to be quasi-perpendicular. Title: Low-Frequency Radio Bursts and Space Weather Authors: Gopalswamy, Nat Bibcode: 2016arXiv160502218G Altcode: Low-frequency radio phenomena are due to the presence of nonthermal electrons in the interplanetary (IP) medium. Understanding these phenomena is important in characterizing the space environment near Earth and other destinations in the solar system. Substantial progress has been made in the past two decades, because of the continuous and uniform data sets available from space-based radio and white-light instrumentation. This paper highlights some recent results obtained on IP radio phenomena. In particular, the source of type IV radio bursts, the behavior of type III storms, shock propagation in the IP medium, and the solar-cycle variation of type II radio bursts are considered. All these phenomena are closely related to solar eruptions and active region evolution. The results presented were obtained by combining data from the Wind and SOHO missions. Title: Solar Activity Studies using Microwave Imaging Observations Authors: Gopalswamy, Nat Bibcode: 2016arXiv160502221G Altcode: We report on the status of solar cycle 24 based on polar prominence eruptions (PEs) and microwave brightness enhancement (MBE) information obtained by the Nobeyama radioheliograph. The north polar region of the Sun had near-zero field strength for more than three years (2012 to 2015) and ended only in September 2015 as indicated by the presence of polar PEs and the lack of MBE. The zero-polar-field condition in the south started only around 2013, but it ended by June 2014. Thus the asymmetry in the times of polarity reversal switched between cycle 23 and 24. The polar MBE is a good proxy for the polar magnetic field strength as indicated by the high degree of correlation between the two. The cross-correlation between the high- and low-latitude MBEs is significant for a lag of ~5.5 to 7.3 years, suggesting that the polar field of one cycle indicates the sunspot number of the next cycle in agreement with the Babcock-Leighton mechanism of solar cycles. The extended period of near-zero field in the north-polar region should result in a weak and delayed sunspot activity in the northern hemisphere in cycle 25. Title: On the Directivity of Low-Frequency Type IV Radio Bursts Authors: Gopalswamy, Nat; Akiyama, Sachiko; Mäkelä, Pertti; Yashiro, Seiji; Cairns, Iver H. Bibcode: 2016arXiv160502223G Altcode: An intense type IV radio burst was observed by the STEREO Behind (STB) spacecraft located about 144 degres behind Earth. The burst was associated with a large solar eruption that occurred on the backside of the Sun (N05E151) close to the disk center in the STB view. The eruption was also observed by the STEREO Ahead (STA) spacecraft (located at 149 degrees ahead of Earth) as an eruption close to the west limb (N05W60) in that view. The type IV burst was complete in STB observations in that the envelope reached the lowest frequency and then receded to higher frequencies. The burst was partial viewed from STA, revealing only the edge coming down to the lowest frequency. The type IV burst was not observed at all near Earth because the source was 61 degrees behind the east limb. The eruption was associated with a low-frequency type II burst observed in all three views, although it was not very intense. Solar energetic particles were also observed at both STEREOs and at SOHO, suggesting that the shock was much extended, consistent with the very high speed of the CME (about 2048 km/s). These observations suggest that the type IV emission is directed along a narrow cone above the flare site. We confirm this result statistically using the type IV bursts of solar cycle 23. Title: Minifilament Eruptions that Drive Coronal Jets in a Solar Active Region Authors: Sterling, Alphonse C.; Moore, Ronald L.; Falconer, David; Panesar, Navdeep; Akiyama, Sachiko; Yashiro, Seiji; Gopalswamy, Nat Bibcode: 2016SPD....47.0334S Altcode: Solar coronal jets are common in both coronal holes and in active regions. Recently, Sterling et al. (2015), using data from Hinode/XRT and SDO/AIA, found that coronal jets originating in polar coronal holes result from the eruption of small-scale filaments (minifilaments). The jet bright point (JBP) seen in X-rays and hotter EUV channels off to one side of the base of the jet's spire develops at the location where the minifilament erupts, consistent with the JBPs being miniature versions of typical solar flares that occur in the wake of large-scale filament eruptions. Here we consider whether active region coronal jets also result from the same minifilament-eruption mechanism, or whether they instead result from a different mechanism, such as the hitherto popular ``emerging flux'' model for jets. We present observations of an on-disk active region that produced numerous jets on 2012 June 30, using data from SDO/AIA and HMI, and from GOES/SXI. We find that several of these active region jets also originate with eruptions of miniature filaments (size scale ~20'') emanating from small-scale magnetic neutral lines of the region. This demonstrates that active region coronal jets are indeed frequently driven by minifilament eruptions. Other jets from the active region were also consistent with their drivers being minifilament eruptions, but we could not confirm this because the onsets of those jets were hidden from our view. This work was supported by funding from NASA/LWS, NASA/HGI, and Hinode. Title: Unusual Polar Conditions in Solar Cycle 24 and Their Implications for Cycle 25 Authors: Gopalswamy, Nat; Yashiro, Seiji; Akiyama, Sachiko Bibcode: 2016ApJ...823L..15G Altcode: 2016arXiv160502217G We report on the prolonged solar-maximum conditions until late 2015 at the north-polar region of the Sun indicated by the occurrence of high-latitude prominence eruptions (PEs) and microwave brightness temperature close to the quiet-Sun level. These two aspects of solar activity indicate that the polarity reversal was completed by mid-2014 in the south and late 2015 in the north. The microwave brightness in the south-polar region has increased to a level exceeding the level of the Cycle 23/24 minimum, but just started to increase in the north. The north-south asymmetry in the polarity reversal has switched from that in Cycle 23. These observations lead us to the hypothesis that the onset of Cycle 25 in the northern hemisphere is likely to be delayed with respect to that in the southern hemisphere. We find that the unusual condition in the north is a direct consequence of the arrival of poleward surges of opposite polarity from the active region belt. We also find that multiple rush-to-the-pole episodes were indicated by the PE locations that lined up at the boundary between opposite-polarity surges. The high-latitude PEs occurred in the boundary between the incumbent polar flux and the insurgent flux of opposite polarity. Title: A Study of the 2012 January 19 Complex Type II Radio Burst Using Wind, SOHO, and STEREO Observations Authors: Teklu, T. B.; Gholap, A. V.; Gopalswamy, N.; Yashiro, S.; Mäkelä, P.; Akiyama, S.; Thakur, N.; Xie, H. Bibcode: 2016arXiv160509644T Altcode: We report on a case study of the complex type II radio burst of 2012 January 19 and its association with a white light coronal mass ejection (CME). The complexity can be described as the appearance of an additional type II burst component and strong intensity variation. The dynamic spectrum shows a pair of type II bursts with fundamental harmonic structures, one confined to decameter-hectometric (DH) wavelengths and the other extending to kilometric (km) wavelengths. By comparing the speeds obtained from white-light images with that speed of the shock inferred from the drift rate, we show that the source of the short-lived DH component is near the nose. Title: Minifilament Eruptions that Drive Coronal Jets in a Solar Active Region Authors: Sterling, Alphonse C.; Moore, Ronald L.; Falconer, David A.; Panesar, Navdeep K.; Akiyama, Sachiko; Yashiro, Seiji; Gopalswamy, Nat Bibcode: 2016ApJ...821..100S Altcode: We present observations of eruptive events in an active region adjacent to an on-disk coronal hole on 2012 June 30, primarily using data from the Solar Dynamics Observatory (SDO)/Atmospheric Imaging Assembly (AIA), SDO/Helioseismic and Magnetic Imager (HMI), and STEREO-B. One eruption is of a large-scale (∼100″) filament that is typical of other eruptions, showing slow-rise onset followed by a faster-rise motion starting as flare emissions begin. It also shows an “EUV crinkle” emission pattern, resulting from magnetic reconnections between the exploding filament-carrying field and surrounding field. Many EUV jets, some of which are surges, sprays and/or X-ray jets, also occur in localized areas of the active region. We examine in detail two relatively energetic ones, accompanied by GOES M1 and C1 flares, and a weaker one without a GOES signature. All three jets resulted from small-scale (∼20″) filament eruptions consistent with a slow rise followed by a fast rise occurring with flare-like jet-bright-point brightenings. The two more-energetic jets showed crinkle patters, but the third jet did not, perhaps due to its weakness. Thus all three jets were consistent with formation via erupting minifilaments, analogous to large-scale filament eruptions and to X-ray jets in polar coronal holes. Several other energetic jets occurred in a nearby portion of the active region; while their behavior was also consistent with their source being minifilament eruptions, we could not confirm this because their onsets were hidden from our view. Magnetic flux cancelation and emergence are candidates for having triggered the minifilament eruptions. Title: CME flux rope and shock identifications and locations: Comparison of white light data, Graduated Cylindrical Shell model, and MHD simulations Authors: Schmidt, J. M.; Cairns, Iver H.; Xie, Hong; St. Cyr, O. C.; Gopalswamy, N. Bibcode: 2016JGRA..121.1886S Altcode: Coronal mass ejections (CMEs) are major transient phenomena in the solar corona that are observed with ground-based and spacecraft-based coronagraphs in white light or with in situ measurements by spacecraft. CMEs transport mass and momentum and often drive shocks. In order to derive the CME and shock trajectories with high precision, we apply the graduated cylindrical shell (GCS) model to fit a flux rope to the CME directed toward STEREO A after about 19:00 UT on 29 November 2013 and check the quality of the heliocentric distance-time evaluations by carrying out a three-dimensional magnetohydrodynamic (MHD) simulation of the same CME with the Block Adaptive Tree Solar-Wind Roe Upwind Scheme (BATS-R-US) code. Heliocentric distances of the CME and shock leading edges are determined from the simulated white light images and magnetic field strength data. We find very good agreement between the predicted and observed heliocentric distances, showing that the GCS model and the BATS-R-US simulation approach work very well and are consistent. In order to assess the validity of CME and shock identification criteria in coronagraph images, we also compute synthetic white light images of the CME and shock. We find that the outer edge of a cloud-like illuminated area in the observed and predicted images in fact coincides with the leading edge of the CME flux rope and that the outer edge of a faint illuminated band in front of the CME leading edge coincides with the CME-driven shock front. Title: Two Exceptions in the Large SEP Events of Solar Cycles 23 and 24 Authors: Thakur, N.; Gopalswamy, N.; Mäkelä, P.; Akiyama, S.; Yashiro, S.; Xie, H. Bibcode: 2016SoPh..291..513T Altcode: 2016SoPh..tmp...21T We discuss our findings from a survey of all large solar energetic particle (SEP) events of Solar Cycles 23 and 24, i.e. the SEP events where the intensity of > 10 MeV protons observed by GOES was > 10 pfu. In our previous work (Gopalswamy et al. in Geophys. Res. Lett. 41, 2673, 2014) we suggested that ground level enhancements (GLEs) in Cycles 23 and 24 also produce an intensity increase in the GOES > 700 MeV proton channel. Our survey, now extended to include all large SEP events of Cycle 23, confirms this to be true for all but two events: i) the GLE of 6 May 1998 (GLE57) for which GOES did not observe enhancement in > 700 MeV protons intensities and ii) a high-energy SEP event of 8 November 2000, for which GOES observed > 700 MeV protons but no GLE was recorded. Here we discuss these two exceptions. We compare GLE57 with other small GLEs, and the 8 November 2000 SEP event with those that showed similar intensity increases in the GOES > 700 MeV protons but produced GLEs. We find that, because GOES > 700 MeV proton intensity enhancements are typically small for small GLEs, they are difficult to discern near solar minima due to higher background. Our results also support that GLEs are generally observed when shocks of the associated coronal mass ejections (CMEs) form at heights 1.2 - 1.93 solar radii [R⊙] and when the solar particle release occurs between 2 - 6 R⊙. Our secondary findings support the view that the nose region of the CME-shock may be accelerating the first-arriving GLE particles and the observation of a GLE is also dependent on the latitudinal connectivity of the observer to the CME-shock nose. We conclude that the GOES > 700 MeV proton channel can be used as an indicator of GLEs excluding some rare exceptions, such as those discussed here. Title: Special issue "International CAWSES-II Symposium" Authors: Yamamoto, Mamoru; Shiokawa, Kazuo; Nakamura, Takuji; Gopalswamy, Nat Bibcode: 2016EP&S...68...26Y Altcode: This special issue gathered papers from the International CAWSES-II Symposium (November 18-22, 2013 at Nagoya University, Japan). Climate and Weather of the Sun-Earth System II (CAWSES-II) is an international scientific program sponsored by Scientific Committee on Solar-Terrestrial Physics (SCOSTEP) that continued from 2009 to 2013. The program was established with the aim of significantly enhancing our understanding of the space environment and its impacts on life and society. The International CAWSES-II Symposium was successful with 388 presentations; and from that, 38 papers were published in this special issue. In this preface, we briefly discuss the contents of the special issue as well as the CAWSES-II review papers published in Progress in Earth and Planetary Science (PEPS) in 2014-2015. Title: Current Polar Activity of the Sun and Its implications for Solar Cycle 25 Authors: Gopalswamy, N.; Yashiro, S.; Akiyama, S. Bibcode: 2015AGUFMSH23A2424G Altcode: Polar activity of one solar cycle is known to indicate certain characteristics of the subsequent cycle in terms of strength (e.g., Sunspot number) and phase. In particular the polar field strength (or its proxies such as the microwave polar brightness) during the minimum phase of seem to be well correlated with the maximum sunspot number of the next cycle. Polar prominence eruptions and coronal mass ejections have also been found to be important indicators of the time of polarity reversal. While these indicators are present in the current cycle, significant differences are found regarding the phase lag between the two hemispheres and the duration of polar eruptions. We use prominence eruption data from the Nobeyama Radioheliograph and the Solar Dynamics Observatory to highlight these differences. We also use the polar microwave brightness variation and discuss the implications to solar cycle 25. Title: Energy Dependence of SEP Electron and Proton Onset Times Authors: Makela, P. A.; Xie, H.; Gopalswamy, N.; St Cyr, O. C. Bibcode: 2015AGUFMSH33B2468M Altcode: We study the large solar energetic particle (SEP) events that were detected by GOES in the > 10 MeV energy channel during December 2006 to March 2014. Using multi-spacecraft observations from STEREO A, B and SOHO, we are able to determine accurately the solar particle release (SPR) time of SEP electrons and protons. We first compute connection angles (CA) between the solar events and magnetic foot-points connecting to each spacecraft. By choosing the smallest CA, we derive the electron and proton SPRs using electron fluxes from the SOHO Electron Proton and Helium Instrument (EPHIN), proton fluxes from the SOHO Energetic and Relativistic Nuclei and Electron instrument (ERNE), and from the High Energy Telescope (HET) on STEREO. It is found that: 1) the 0.25 MeV-0.7 MeV electron SPRs are ~10 min earlier than 2.64 MeV - 10.4 Mev electron SPRs; 2) the proton SPRs inferred from high-energy channels (> 50 MeV) are similar to electron SPRs; 3) the proton SPRs inferred from lower energy channel (10 - 16.9 MeV) can be either ~ 7 min earlier than or delayed from the electron SPRs for tens of minutes to hours, especially for SEPs with large pre-event background flux levels. In this study, we evaluated the effects of large scattering and high background levels on SPRs and made suggested corrections for the background effect on SPR times. We also find that for some large SEP events, the observed EPHIN electron and ERNE proton intensity profiles show a double-peak feature. The onset of the first peak corresponds well to the associated Type III and metric Type II onset and tends to be nearly scattering-free. Title: A Comparative Study of Confined and Eruptive Solar Flares using Microwave Observations Authors: Yashiro, S.; Akiyama, S.; Masuda, S.; Shimojo, M.; Asai, A.; Imada, S.; Gopalswamy, N. Bibcode: 2015AGUFMSH43B2447Y Altcode: It is well known that about 10% X-class solar flares are not associated with coronal mass ejections (CMEs). These flares are referred to as confined flares, which are not associated with mass or energetic particles leaving the Sun. However, electrons are accelerated to MeV energies as indicated by the presence of microwave emission with a turnover frequency of ~15 GHz (Gopalswamy et al. 2009, IAU Symposium 257, p. 283). In this paper, we extend the study of confined flares to lower soft X-ray flare sizes (M and above) that occurred in the time window of the Nobeyama Radioheliograph (NoRH). We also make use of the microwave spectral information from the Nobeyama Radio Polarimeters (NoRP). During 1996 - 2014, NoRH and NoRP observed 663 flares with size M1.0 or larger. Using the CME observations made by SOHO/LASCO and STEREO/SECCHI, we found 215 flares with definite CME association (eruptive flares) and 202 flares that definitely lacked CMEs (confined flares). The remaining 146 flares whose CME association is unclear are excluded from the analysis. We examined the peak brightness temperature and the spatial size obtained by NoRH. Although there is a large overlap between the two populations in these properties, we found that microwave sources with the largest spatial extent and highest brightness temperature are associated with eruptive flares. Spectral analysis using NoRP data showed a tendency that more confined flares had higher turnover frequency (≥17 GHz). We also compare the NoRH images with the photospheric magnetograms to understand the difference in the magnetic structure of the two types of flare sources. Title: CMEs during the Two Activity Peaks in Cycle 24 and their Space Weather Consequences Authors: Gopalswamy, N.; Makela, P.; Akiyama, S.; Yashiro, S.; Thakur, N. Bibcode: 2015SunGe..10..111G Altcode: 2015arXiv150904216G We report on a comparison between space weather events that occurred around the two peaks in the sunspot number (SSN) during solar cycle 24. The two SSN peaks occurred in the years 2012 and 2014. Even though SSN was larger during the second peak, we find that there were more space weather events during the first peak. The space weather events we considered are large solar energetic particle (SEP) events and major geomagnetic storms associated with coronal mass ejections (CMEs). We also considered interplanetary type II radio bursts, which are indicative of energetic CMEs driving shocks. When we compared the CME properties between the two SSN peaks, we find that more energetic CMEs occurred during the 2012 peak. In particular, we find that CMEs accompanying IP type II bursts had an average speed of 1543 km/s during the 2012 peak compared to 1201 km/s during the 2014 peak. This result is consistent with the reduction in the average speed of the general population of CMEs during the second peak. All SEP events were associated with the interplanetary type II bursts, which are better than halo CMEs as indicators of space weather. The comparison between the two peaks also revealed the discordant behavior between the CME rate and SSN was more pronounced during the second peak. None of the 14 disk-center halo CMEs was associated with a major storm in 2014. The lone major storm in 2014 was due to the intensification of the (southward) magnetic field in the associated magnetic cloud by a shock that caught up and propagated into the magnetic cloud. Title: Short-term variability of the Sun-Earth system: an overview of progress made during the CAWSES-II period Authors: Gopalswamy, Nat; Tsurutani, Bruce; Yan, Yihua Bibcode: 2015PEPS....2...13G Altcode: 2015PESS....2...13G; 2015arXiv150406332G This paper presents an overview of results obtained during the CAWSES-II period on the short-term variability of the Sun and how it affects the near-Earth space environment. CAWSES-II was planned to examine the behavior of the solar-terrestrial system as the solar activity climbed to its maximum phase in solar cycle 24. After a deep minimum following cycle 23, the Sun climbed to a very weak maximum in terms of the sunspot number in cycle 24 (MiniMax24), so many of the results presented here refer to this weak activity in comparison with cycle 23. The short-term variability that has immediate consequence to Earth and geospace manifests as solar eruptions from closed-field regions and high-speed streams from coronal holes. Both electromagnetic (flares) and mass emissions (coronal mass ejections - CMEs) are involved in solar eruptions, while coronal holes result in high-speed streams that collide with slow wind forming the so-called corotating interaction regions (CIRs). Fast CMEs affect Earth via leading shocks accelerating energetic particles and creating large geomagnetic storms. CIRs and their trailing high-speed streams (HSSs), on the other hand, are responsible for recurrent small geomagnetic storms and extended days of auroral zone activity, respectively. The latter leads to the acceleration of relativistic magnetospheric `killer' electrons. One of the major consequences of the weak solar activity is the altered physical state of the heliosphere that has serious implications for the shock-driving and storm-causing properties of CMEs. Finally, a discussion is presented on extreme space weather events prompted by the 23 July 2012 super storm event that occurred on the backside of the Sun. Many of these studies were enabled by the simultaneous availability of remote sensing and in situ observations from multiple vantage points with respect to the Sun-Earth line. Title: Influence of the Solar Wind Speed on the Propagation of Coronal Mass Ejections Authors: Yashiro, S.; Tokumaru, M.; Fujiki, K.; Iju, T.; Akiyama, S.; Makela, P. A.; Gopalswamy, N. Bibcode: 2015AGUFMSH53B2497Y Altcode: We investigate the influence of the solar wind (SW) on the propagation of a set of 191 coronal mass ejections (CMEs) near the Sun during the period 1996-2013. The CMEs were observed by LASCO on board SOHO and their source regions were identified using the CME-associated eruptive features (flares, filament eruptions, dimmings) in X-ray, EUV, microwave, and Hα observations. The SW speeds above the CME source regions were estimated from the interplanetary scintillation (IPS) observations from the Solar Terrestrial Environ Laboratory, Nagoya University. We considered only CMEs from close to the limb in order to avoid the projection effects. We also considered CMEs with at least 10 height-time measurements in order to avoid the large uncertainty in the acceleration measurements. We confirm the well-known CME-SW relationship that the CMEs propagating faster (slower) than the ambient solar wind are likely to decelerate (accelerate). The correlation between the acceleration and the difference of the CME and the SW speeds is high with a correlation coefficient of -0.74, slightly lower compared to the one for CMEs associated with interplanetary radio bursts (Gopalswamy et al. 2001, JGR, 106, 29219). There are many accelerating CMEs in our sample with a speed similar to the ambient solar wind speed. This could be due to selection effect because accelerating CMEs tend to remain visible longer than decelerating ones. We also found that CMEs originating from around the sources of the fast solar wind tend to be faster, indicating that the open magnetic fields above the CME source regions affect the CME propagation. Title: Comparison of the 26 May 2012 SEP Event with the 3 November 2011 SEP Event Authors: Makela, P. A.; Gopalswamy, N.; Thakur, N.; Xie, H. Bibcode: 2015AGUFMSH33B2465M Altcode: We compare the solar and interplanetary events associated with two large solar energetic particle (SEP) events on 26 May 2012 and 3 November 2011. Both SEP events were detected at three longitudinally widely separated locations by STEREO A and B spacecraft (more than 100 deg away from Earth) and the Wind and SOHO spacecraft near Earth. In Earth view, the November 2011 eruption occurred far behind the east limb at N09E154, whereas the May 2012 eruption occurred closer to the west limb at N15W121, suggesting that SEPs accelerated during the 2012 event might have easier access to Earth. Even though the 2012 event was more intense in the GOES >10 MeV proton channel (peak intensity 14 pfu) than the 2011 event (peak intensity 4 pfu), we find that the latter event was more intense at higher energies (> 40 MeV). Also, the initial rise at lower energies was slightly faster for the 2011 event as measured by SOHO/ERNE. In addition, the CME associated with the May 2012 event was faster with an estimated space speed of ~2029 km/s than that in the November 2011 event (1188 km/s). STEREO/EUVI images of the associated post-eruption arcades (PEAs) indicate that their orientations were different: the PEA of the May 2012 event had a high inclination (north-south), while the inclination of the PEA of the 2011 event was more moderate. Differences in the flux rope orientation may also have effect on the longitudinal extent of the SEP events. These observations suggest that the dependence of solar proton intensities on the observer's longitudinal distance from the solar source is more complex than traditionally assumed. Title: Diffuse Interplanetary Radio Emission (DIRE) Accompanying Type II Radio Bursts Authors: Teklu, T. B.; Gopalswamy, N.; Makela, P. A.; Yashiro, S.; Akiyama, S.; Xie, H. Bibcode: 2015AGUFMSH51A2441T Altcode: We report on an unusual drifting feature in the radio dynamic spectra at frequencies below 14 MHz observed by the Radio and Plasma Wave (WAVES) experiment on board the Wind spacecraft. We call this feature as "Diffuse Interplanetary Radio Emission (DIRE)". The DIRE events are generally associated with intense interplanetary type II radio bursts produced by shocks driven by coronal mass ejections (CMEs). DIREs drift like type II bursts in the dynamic spectra, but the drifting feature consist of a series of short-duration spikes (similar to a type I chain). DIREs occur at higher frequencies than the associated type II bursts, with no harmonic relationship with the type II burst. The onset of DIREs is delayed by several hours from the onset of the eruption. Comparing the radio dynamic spectra with white-light observations from the Solar and Heliospheric Observatory (SOHO) mission, we find that the CMEs are generally very energetic (fast and mostly halos). We suggest that the DIRE source is typically located at the flanks of the CME-driven shock that is still at lower heliocentric distances. Title: Type II Radio Bursts as Indicators of Space Weather Drivers Authors: Gopalswamy, N. Bibcode: 2015AGUFMSH41F..04G Altcode: Interplanetary type II radio bursts are important indicators of shock-driving coronal mass ejections (CMEs). CME-driven shocks are responsible for large solar energetic particle (SEP) events and sudden commencement/sudden impulse events recorded by ground magnetometers. The excellent overlap of the spatial domains probed by SOHO/STEREO coronagraphs with the spectral domains of Wind/WAVES and STEREO/WAVES has contributed enormously in understanding CMEs and shocks as space weather drivers. This paper is concerned with type II bursts of solar cycle 23 and 24 that had emission components down to kilometric wavelengths. CMEs associated with these bursts seem to be the best indicators of large SEP events, better than the halo CMEs. However, there are some differences between the type II bursts of the two cycles, which are explained based on the different states of the heliosphere in the two cycles. Finally, the type II burst characteristics of some recent extreme events are discussed. Title: Advancing the understanding of the Sun-Earth interaction—the Climate and Weather of the Sun-Earth System (CAWSES) II program Authors: Tsuda, Toshitaka; Shepherd, Marianna; Gopalswamy, Nat Bibcode: 2015PEPS....2...28T Altcode: 2015PESS....2...28T The Scientific Committee on Solar-Terrestrial Physics (SCOSTEP) of the International Council for Science (ICSU) implemented an international collaborative program called Climate and Weather of the Sun-Earth System (CAWSES), which was active from 2004 to 2008; this was followed by the CAWSES II program during the period of 2009-2013. The CAWSES program was aimed at improving the understanding of the coupled solar-terrestrial system, with special emphasis placed on the short-term (weather) and long-term (climate) variability of solar activities and their effects on and responses of Geospace and Earth's environment. Following the successful implementation of CAWSES, the CAWSES II program pursued four fundamental questions addressing the way in which the coupled Sun-Earth system operates over time scales ranging from minutes to millennia, namely, (1) What are the solar influences on the Earth's climate? (2) How will Geospace respond to an altered climate? (3) How does short-term solar variability affect the Geospace environment? and (4) What is the Geospace response to variable inputs from the lower atmosphere? In addition to these four major tasks, the SCOSTEP and CAWSES promoted E-science and informatics activities including the creation of scientific databases and their effective utilization in solar-terrestrial physics research. Capacity building activities were also enhanced during CAWSES II, and this represented an important contribution of SCOSTEP to the world's solar-terrestrial physics community. This introductory paper provides an overview of CAWSES II activities and serves as a preface to the dedicated review papers summarizing the achievements of the program's four task groups (TGs) and the E-science component. Title: a Roadmap to Advance Understanding of the Science of Space Weather Authors: Schrijver, K.; Kauristie, K.; Aylward, A.; De Nardin, C. M.; Gibson, S. E.; Glover, A.; Gopalswamy, N.; Grande, M.; Hapgood, M. A.; Heynderickx, D.; Jakowski, N.; Kalegaev, V. V.; Lapenta, G.; Linker, J.; Liu, S.; Mandrini, C. H.; Mann, I. R.; Nagatsuma, T.; Nandy, D.; Obara, T.; O'Brien, T. P., III; Onsager, T. G.; Opgenoorth, H. J.; Terkildsen, M. B.; Valladares, C. E.; Vilmer, N. Bibcode: 2015AGUFMSH12A..01S Altcode: There is a growing appreciation that the environmental conditions that we call space weather impact the technological infrastructure that powers the coupled economies around the world. With that comes the need to better shield society against space weather by improving forecasts, environmental specifications, and infrastructure design. A COSPAR/ILWS team recently completed a roadmap that identifies the scientific focus areas and research infrastructure that are needed to significantly advance our understanding of space weather of all intensities and of its implications and costs for society. This presentation provides a summary of the highest-priority recommendations from that roadmap. Title: Low-Frequency Type II Radio Detections and Coronagraph Data to Describe and Forecast the Propagation of 71 CMEs/Shocks Authors: St Cyr, O. C.; Cremades, H.; Iglesias, F. A.; Xie, H.; Kaiser, M. L.; Gopalswamy, N. Bibcode: 2015AGUFMSH21B2401S Altcode: Motivated by improving predictions of arrival times at Earth of shocks driven by coronal mass ejections (CMEs), we have analyzed 71 Earth-directed events in different stages of their propagation. The study is primarily based on approximated locations of interplanetary (IP) shocks derived from Type-II radio emissions detected by the Wind/WAVES experiment during 1997-2007. Distance-time diagrams resulting from the combination of white-light corona, IP Type-II radio, and in situ data lead to the formulation of descriptive profiles of each CME's journey toward Earth. Furthermore, two different methods to track and predict the location of CME-driven IP shocks are presented. The linear method, solely based on Wind/WAVES data, arises after key modifications to a pre-existing technique that linearly projects the drifting low-frequency Type-II emissions to 1 AU. This upgraded method improves forecasts of shock arrival time by almost 50%. The second predictive method is proposed on the basis of information derived from the descriptive profiles, and relies on a single CME height-time point and on low-frequency Type-II radio emissions to obtain an approximate value of the shock arrival time at Earth. In addition, we discuss results on CME-radio emission associations, characteristics of IP propagation, and the relative success of the forecasting methods. Title: Requirements for an Operational Coronagraph Authors: Howard, R.; Vourlidas, A.; Harrison, R. A.; Bisi, M. M.; Plunkett, S. P.; Socker, D. G.; Eyles, C. J.; Webb, D. F.; DeForest, C. E.; Davies, J. A.; Howard, T. A.; de Koning, C. A.; Gopalswamy, N.; Davila, J. M.; Tappin, J.; Jackson, B. V. Bibcode: 2015AGUFMSH14A..02H Altcode: Coronal mass ejections (CMEs) have been shown to be the major driver of the non-recurrent space weather events and geomagnetic storms. The utility of continuously monitoring such events has been very effectively demonstrated by the LASCO experiment on the SOHO mission. However SOHO is aging, having been launched 20 years ago on Dec 2, 1995. The STEREO mission, in which two spacecraft in orbits about the sun are drifting away from earth, has shown the utility of multiple viewpoints off the sun-earth line. Up to now the monitoring of CMES has been performed by scientific instruments such as LASCO and SECCHI with capabilities beyond those required to record the parameters that are needed to forecast the impact at earth. However, there is great interest within the US NOAA and the UK Met Office to launch operational coronagraphs to L1 and L5. An ad-hoc group was formed to define the requirements of the L5 coronagraph. In this paper we present some requirements that must be met by operational coronagraphs. The Office of Naval Research is gratefully acknowledged. Title: Properties and geoeffectiveness of magnetic clouds during solar cycles 23 and 24 Authors: Gopalswamy, N.; Yashiro, S.; Xie, H.; Akiyama, S.; Mäkelä, P. Bibcode: 2015JGRA..120.9221G Altcode: 2015arXiv151000906G We report on a study that compares the properties of magnetic clouds (MCs) during the first 73 months of solar cycles 23 and 24 in order to understand the weak geomagnetic activity in cycle 24. We find that the number of MCs did not decline in cycle 24, although the average sunspot number is known to have declined by ~40%. Despite the large number of MCs, their geoeffectiveness in cycle 24 was very low. The average Dst index in the sheath and cloud portions in cycle 24 was -33 nT and -23 nT, compared to -66 nT and -55 nT, respectively, in cycle 23. One of the key outcomes of this investigation is that the reduction in the strength of geomagnetic storms as measured by the Dst index is a direct consequence of the reduction in the factor VBz (the product of the MC speed and the out-of-the-ecliptic component of the MC magnetic field). The reduction in MC-to-ambient total pressure in cycle 24 is compensated for by the reduction in the mean MC speed, resulting in the constancy of the dimensionless expansion rate at 1 AU. However, the MC size in cycle 24 was significantly smaller, which can be traced to the anomalous expansion of coronal mass ejections near the Sun reported by Gopalswamy et al. (2014a). One of the consequences of the anomalous expansion seems to be the larger heliocentric distance where the pressure balance between the CME flux ropes and the ambient medium occurs in cycle 24. Title: High-energy solar particle events in cycle 24 Authors: Gopalswamy, N.; Mäkelä, P.; Yashiro, S.; Xie, H.; Akiyama, S.; Thakur, N. Bibcode: 2015JPhCS.642a2012G Altcode: 2015arXiv150706162G The Sun is already in the declining phase of cycle 24, but the paucity of high-energy solar energetic particle (SEP) events continues with only two ground level enhancement (GLE) events as of March 31, 2015. In an attempt to understand this, we considered all the large SEP events of cycle 24 that occurred until the end of 2014. We compared the properties of the associated CMEs with those in cycle 23. We found that the CME speeds in the sky plane were similar, but almost all those cycle-24 CMEs were halos. A significant fraction of (16%) of the frontside SEP events were associated with eruptive prominence events. CMEs associated with filament eruption events accelerate slowly and attain peak speeds beyond the typical GLE release heights. When we considered only western hemispheric events that had good connectivity to the CME nose, there were only 8 events that could be considered as GLE candidates. One turned out to be the first GLE event of cycle 24 (2012 May 17). In two events, the CMEs were very fast (>2000 km/s) but they were launched into a tenuous medium (high Alfven speed). In the remaining five events, the speeds were well below the typical GLE CME speed (∼2000 km/s). Furthermore, the CMEs attained their peak speeds beyond the typical heights where GLE particles are released. We conclude that several factors contribute to the low rate of high-energy SEP events in cycle 24: (i) reduced efficiency of shock acceleration (weak heliospheric magnetic field), (ii) poor latitudinal and longitudinal connectivity), and (iii) variation in local ambient conditions (e.g., high Alfven speed). Title: Low-Frequency Type-II Radio Detections and Coronagraph Data Employed to Describe and Forecast the Propagation of 71 CMEs/Shocks Authors: Cremades, H.; Iglesias, F. A.; St. Cyr, O. C.; Xie, H.; Kaiser, M. L.; Gopalswamy, N. Bibcode: 2015SoPh..290.2455C Altcode: 2015arXiv150501730C; 2015SoPh..tmp..136C Motivated by improving predictions of arrival times at Earth of shocks driven by coronal mass ejections (CMEs), we have analyzed 71 Earth-directed events in different stages of their propagation. The study is primarily based on approximated locations of interplanetary (IP) shocks derived from Type-II radio emissions detected by the Wind/WAVES experiment during 1997 - 2007. Distance-time diagrams resulting from the combination of white-light corona, IP Type-II radio, and in-situ data lead to the formulation of descriptive profiles of each CME's journey toward Earth. Furthermore, two different methods for tracking and predicting the location of CME-driven IP shocks are presented. The linear method, solely based on Wind/WAVES data, arises after key modifications to a pre-existing technique that linearly projects the drifting low-frequency Type-II emissions to 1 AU. This upgraded method improves forecasts of shock-arrival times by almost 50 %. The second predictive method is proposed on the basis of information derived from the descriptive profiles and relies on a single CME height-time point and on low-frequency Type-II radio emissions to obtain an approximate value of the shock arrival time at Earth. In addition, we discuss results on CME-radio emission associations, characteristics of IP propagation, and the relative success of the forecasting methods. Title: The Mild Space Weather in Solar Cycle 24 Authors: Gopalswamy, Nat; Akiyama, Sachiko; Yashiro, Seiji; Xie, Hong; Makela, Pertti; Michalek, Grzegorz Bibcode: 2015arXiv150801603G Altcode: The space weather is extremely mild during solar cycle 24: the number of major geomagnetic storms and high-energy solar energetic particle events are at the lowest since the dawn of the space age. Solar wind measurements at 1 AU using Wind and ACE instruments have shown that there is a significant drop in the density, magnetic field, total pressure, and Alfven speed in the inner heliosphere as a result of the low solar activity. The drop in large space weather events is disproportionately high because the number of energetic coronal mass ejections that cause these events has not decreased significantly. For example, the rate of halo CMEs, which is a good indicator of energetic CMEs, is similar to that in cycle 23, even though the sunspot number has declined by about 40%. The mild space weather seems to be a consequence of the anomalous expansion of CMEs due to the low ambient pressure in the heliosphere. The anomalous expansion results in the dilution of the magnetic contents of CMEs, so the geomagnetic storms are generally weak. CME driven shocks propagating through the weak heliospheric field are less efficient in accelerating energetic particles, so the particles do not attain high energies. Finally, we would like to point out that extreme events such as the 2012 July 23 CMEs that occurred on the backside of the Sun and did not affect Earth except for a small proton event. Title: Kinematic and Energetic Properties of the 2012 March 12 Polar Coronal Mass Ejection Authors: Gopalswamy, N.; Yashiro, S.; Akiyama, S. Bibcode: 2015ApJ...809..106G Altcode: 2015arXiv150704057G We report on the energetics of the 2012 March 12 polar coronal mass ejection (CME) originating from a southern latitude of ∼60°. The polar CME is similar to low-latitude (LL) CMEs in almost all respects: three-part morphology; post-eruption arcade (PEA), CME, and filament kinematics; CME mass and kinetic energy; and the relative thermal energy content of the PEA. From polarized brightness images, we estimate the CME mass, which is close to the average mass of LL CMEs. The CME kinetic energy (3.3 × 1030 erg) is also typical of the general population of CMEs. From photospheric magnetograms, we estimate the free energy (1.8 × 1031 erg) in the polar crown source region, which we find is sufficient to power the CME and the PEA. About 19% of the free energy went into the CME kinetic energy. We compute the thermal energy content of the PEA (2.3 × 1029 erg) and find it to be a small fraction (6.8%) of the CME kinetic energy. This fraction is remarkably similar to that in active region CMEs associated with major flares. We also show that the 2012 March 12 is one among scores of polar CMEs observed during the maximum phase of cycle 24. The cycle 24 polar crown prominence eruptions have the same rate of association with CMEs as those from LLs. This investigation supports the view that all CMEs are magnetically propelled from closed field regions, irrespective of their location on the Sun (polar crown filament regions, quiescent filament regions, or active regions). Title: GOES: An Indicator for GLEs? Authors: Thakur, Neeharika; Gopalswamy, N.; Mäkelä, P.; Akiyama, S.; Yashiro, S.; Xie, H. Bibcode: 2015shin.confE.149T Altcode: We surveyed all large solar energetic particle (SEP) events (intensity at least 10 pfu in the >10 MeV GOES channel) in solar cycles 23 and 24 to confirm the suggestion that ground level enhancements (GLEs) produce an intensity increase in the GOES >700 MeV proton channel (Gopalswamy et al. 2014). The survey confirms this in all but two large SEP events: (1) the GLE of 6 May 1998 (GLE57) did not have GOES >700 MeV protons and (2) the 8 November 2000 SEP event had GOES >700 MeV protons but no GLE was recorded. We compare GLE57 with other similar GLEs, and the 8 November 2000 SEP event with those that showed similar intensity increases in the GOES >700 MeV protons but produced GLEs. We find that because GOES >700 MeV proton intensity enhancements are typically small for small GLEs; they are difficult to discern near solar minima due to higher background. Our results are consistent with previous findings that GLEs are generally observed when CME-driven shocks form at heights 1.2-1.9 solar radii (Rs) (GLE release occurs when the CMEs are at 2-6 Rs). Our study also supports the view that the nose region of the CME-shock may be accelerating GeV particles, but may not be detected due to poor latitudinal connectivity of the observer to the shock nose. We conclude that GOES >700 MeV proton channel can be used as an indicator for GLEs with some rare exceptions. Use of GOES as a GLE indicator becomes especially important because the observation of small GLEs may be missed by sparsely located neutron monitors. Title: Observational Aspects of Particle Acceleration Resulting in GLEs Authors: Gopalswamy, Nat Bibcode: 2015shin.confE.146G Altcode: Ground Level Enhancement (GLE) events in cycle 24 have been extremely rare: only 2 events have been reported as of June 4, 2015, even though solar activity is already in the declining phase. In an attempt to understand this, we examined all the large SEP events of cycle 24 that occurred until the end of 2014. We compared the properties of the SEP-associated CMEs with those in cycle 23. We found that the CME speeds in the sky plane are similar, but almost all the cycle-24 CMEs were halos. A significant fraction of (13%) of the frontside SEP events were associated with eruptive prominence events. CMEs associated with filament eruption events accelerate slowly and attain peak speeds beyond the typical GLE release heights. When we considered only western hemispheric SEP events that had good latitudinal connectivity to the CME nose, there were only 8 candidate GLE events. One turned out to be the first GLE event of cycle 24 (17 May 2012). In two events, the CMEs were very fast (>2000 km/s) but they were launched into a tenuous medium (high Alfven speed). In the remaining five events, the speeds were well below the average CME speed ( 2000 km/s) in GLE events. Furthermore, the CMEs attained their peak speeds beyond the typical heights where GLE particles are released. We conclude that there are several factors that seem to be responsible for the very low rate of high-energy SEP events in cycle 24: (i) reduced efficiency of shock acceleration (weak heliospheric magnetic field), (ii) large-ecliptic distance to solar sources of major eruptions (poor latitudinal connectivity), and (iii) variation in local ambient conditions (e.g., high Alfven speed). Title: Hierarchical relationship of DH and mDH type II bursts using the kinematic properties of the associated CMEs Authors: Teklu, Tsega Berhane; Gopalswamy, N.; Mäkelä, P.; Yashiro, S.; Akiyama, S.; Xie, H.; Thakur, N. Bibcode: 2015shin.confE..51T Altcode: Using type II radio bursts from WIND WAVES and the associated CMEs from SOHO LASCO, Gopalswamy et al., (2005) found a hierarchical relationship between the wavelength range of the type II bursts and CME kinetic energy. Under 'DH Type II bursts' they had included mDH, DH and DHkm bursts. (DH: Decameter-hectometric; m: metric; km: kilometric). In this work, we consider the pure DH and mDH subsets separately. We find that mDH have slightly larger average speed, larger halo fraction, and larger non-halo width. Despite these consistent relationships, DH CMEs have slightly larger association rate with SEPs than mDH CMEs. The DH CMEs in Gopalswamy et al. (2005) have a higher average speed because they include DH km CMEs, which are more energetic. The SEP association rate of DH and mDH type II bursts are much smaller than that of mkm type II bursts. The SEP sources are generally located in the western hemisphere because of magnetic connectivity requirement. Title: Filament Eruptions Outside of Active Regions as Sources of Large Solar Energetic Particle Events Authors: Kahler, S.; Gopalswamy, N.; Makela, P.; Akiyama, S.; Yashiro, S.; Xie, H.; Thakur, N. Bibcode: 2015ICRC...34...48K Altcode: 2015PoS...236...48K No abstract at ADS Title: Solar energetic particle association of fast and wide coronal mass ejections Authors: Yashiro, Seiji; Gopalswamy, N.; Akiyama, S.; Mäkelä, P.; Xie, H. Bibcode: 2015shin.confE..47Y Altcode: The occurrence of solar energetic particle (SEP) events in association with fast (speed ∼900 km/s) and wide (width ∼) coronal mass ejections (FW CMEs) was investigated. Source regions of the FW CMEs were identified using SOHO/EIT, STEREO/EUVI, and SDO/AIA images. Using STEREO EUV observations, we are able to determine the source locations of CMEs that occurred behind the limb with a high degree of accuracy. The >10 MeV proton flux at Earth was examined using GOES/SEM. The >10 MeV proton flux at the STEREO spacecraft was estimated using STEREO/HET, which detects energetic protons in 11 energy channels in the range 13.6 to 100 MeV. By fitting a power law to the STEREO data, we extrapolated the proton flux to the 10 - 150 MeV range as an estimate of the >10 MeV proton flux. We examined the SEP associations of 196 FW CMEs that occurred during 2006 December to 2014 September and found that (1) the SEP association rate peaked at the W61°, (2) the magnetically well-connected longitudes range from W20°-W93°, (3) the SEP association rate distribution is skewed: the eastern wing of the rate distribution drops slowly compared to the western wing, (4) all >1700 km/s CMEs originating from the well-connected longitude are associated with the SEP events. We examined the preconditioning by preceding CMEs and found that all but one huge SEP event (∼1000 pfu) are preconditioned. Title: Energy Dependence of SEP Electron and Proton Onset Times Authors: Xie, Hong; Makela, P.; Gopalswamy, N.; St. Cyr, O. C. Bibcode: 2015shin.confE..46X Altcode: We study large solar energetic particle (SEP) events with > 10 MeV proton flux observed by GOES during solar cycle 24. Using multi-spacecraft observations from STEREO A, B and SOHO, we are able to determine accurately the solar particle release (SPR) time of SEP electrons and protons. We first compute connection angles (CA) between the solar events and magnetic foot-points connecting to each spacecraft. By choosing the smallest CA, we derive the electron and proton SPRs using electron fluxes from the SOHO Electron Proton and Helium Instrument (EPHIN), proton fluxes from the SOHO Energetic and Relativistic Nuclei and Electron instrument (ERNE), and from the High Energy Telescope (HET) on STEREO. We find that the proton SPRs inferred from high-energy channels (> 50 MeV) are similar to electron SPRs; the proton SPRs inferred from lower energy channel (5.12 - 16.9 MeV) can be delayed from the electron SPRs from tens of minutes to hours, especially for SEPs with large pre-event flux levels, suggesting that lower-energy protons might be trapped for a long time or suffer more scattering than higher-energy protons. We also find that for some large SEP events, the observed EPHIN electron and ERNE proton intensity profiles show a double-peak feature. The onset of the first peak corresponds well to the associated Type III and metric Type II onset. Title: Earth-arrival of Coronal Mass Ejections originating from close to the Solar Disk Center Authors: Akiyama, Sachiko; Yashiro, S.; Gopalswamy, N.; Mäkelä, P.; Xie, H. Bibcode: 2015shin.confE..97A Altcode: Not all coronal mass ejections (CMEs) that originate from close to the solar disk center arrive at Earth due to various reasons. In order to find the fraction of CMEs that do reach Earth, we investigated a set of wide CMEs (width ∼ 60 degrees) originating from close to the disk center (Central Meridian Distance < 30 degrees). Seventy such CMEs were identified in 2011 using SOHO and STEREO coronagraphs and heliospheric imagers. The solar sources of these CMEs were confirmed to be close to the disk center using images from the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory (SDO). We found that only about a third of the disk-center CMEs arrived at Earth. We examined the possible reasons for the non-arrival of the remaining CMEs and found that 1) 31% of CMEs faded out before reaching Earth, 2) 27% were captured by following faster CMEs, and 3) 7% of CMEs left the ecliptic plane. The faded-out CMEs became invisible in STEREO/COR1 (32%), COR2 (32%), or HI1 (36%) fields of view. We also investigated the geoeffectiveness of the Earth-arriving CMEs and found that only 17% (4/22) of them produced at least a moderate geomagnetic storm (Dst index < -50 nT). The Dst index of the largest geomagnetic storms in our data set was -72 nT. In 2011 there were 3 intense geomagnetic storms (Dst Index < -100 nT), but all of them were produced by non-disk center CMEs and hence they are not in our sample. We also found that the Earth-arriving CMEs are faster than the fading-out CMEs ( 700 km/s vs. 300 km/s) from COR1 to COR2 FOVs. We conclude that only a tiny fraction of wide CMEs originating from the disk center are geoeffective (4/70 or 6%). In the future work, we are planning to expand study period to increase the sample size. Title: White-light and radio observations of CME interaction during the 2013 May 22 solar energetic particle event Authors: Mäkelä, Pertti; Gopalswamy, N.; Yashiro, S.; Xie, H.; Reiner, M. J. Bibcode: 2015shin.confE..96M Altcode: On 2013 May 22, the SOHO/LASCO coronagraph observed two coronal mass ejections (CMEs) in close sequence at 08:48 UT and 13:25 UT originating from the same NOAA AR11745 located at N15W70. The CMEs were associated with a large increase of proton flux with a peak intensity of 1660 protons cm^-2 sr^-1 s^-1 in the GOES >10 MeV integral channel. During the event, the following, faster CME with a sky-plane speed of 1466 km/s overtook and interacted with the preceding, slower CME with a sky-plane speed of 687 km/s. The LASCO white-light images clearly revealed that during the interaction the preceding CME accelerated while the following CME decelerated. The CME interaction also caused an enhancement of type II radio emission detected at the decameter-hectometric wavelengths by radio instruments on the Wind and STEREO spacecraft. The source location of the type II enhancement estimated by direction finding technique confirmed that the radio emission was coming from the interaction region. The drift rate of the type II radio burst was also seen to be different after the merger of the CMEs. Title: Estimating the Height of CMEs Associated with a Major SEP Event at the Onset of the Metric Type II Radio Burst during Solar Cycles 23 and 24 Authors: Mäkelä, P.; Gopalswamy, N.; Akiyama, S.; Xie, H.; Yashiro, S. Bibcode: 2015ApJ...806...13M Altcode: We studied the coronal mass ejection (CME) height at the onset of 59 metric type II radio bursts associated with major solar energetic particle (SEP) events, excluding ground level enhancements (GLEs), during solar cycles 23 and 24. We calculated CME heights using a simple flare-onset method used by Gopalswamy et al. to estimate CME heights at the metric type II onset for cycle 23 GLEs. We found the mean CME height for non-GLE events (1.72 R⊙) to be ∼12% greater than that (1.53 R⊙) for cycle 23 GLEs. The difference could be caused by more impulsive acceleration of the GLE-associated CMEs. For cycle 24 non-GLE events, we compared the CME heights obtained using the flare-onset method and the three-dimensional spherical-shock fitting method and found the correlation to be good (CC = 0.68). We found the mean CME height for cycle 23 non-GLE events (1.79 R⊙) to be greater than that for cycle 24 non-GLE events (1.58 R⊙), but statistical tests do not definitely reject the possibility of coincidence. We suggest that the lower formation height of the shocks during cycle 24 indicates a change in the Alfvén speed profile because solar magnetic fields are weaker and plasma density levels are closer to the surface than usual during cycle 24. We also found that complex type III bursts showing diminution of type III emission in the 7-14 MHz frequency range are more likely associated with events with a CME height at the type II onset above 2 R⊙, supporting suggestions that the CME/shock structure causes the feature. Title: Understanding space weather to shield society: A global road map for 2015-2025 commissioned by COSPAR and ILWS Authors: Schrijver, Carolus J.; Kauristie, Kirsti; Aylward, Alan D.; Denardini, Clezio M.; Gibson, Sarah E.; Glover, Alexi; Gopalswamy, Nat; Grande, Manuel; Hapgood, Mike; Heynderickx, Daniel; Jakowski, Norbert; Kalegaev, Vladimir V.; Lapenta, Giovanni; Linker, Jon A.; Liu, Siqing; Mandrini, Cristina H.; Mann, Ian R.; Nagatsuma, Tsutomu; Nandy, Dibyendu; Obara, Takahiro; Paul O'Brien, T.; Onsager, Terrance; Opgenoorth, Hermann J.; Terkildsen, Michael; Valladares, Cesar E.; Vilmer, Nicole Bibcode: 2015AdSpR..55.2745S Altcode: 2015arXiv150306135S There is a growing appreciation that the environmental conditions that we call space weather impact the technological infrastructure that powers the coupled economies around the world. With that comes the need to better shield society against space weather by improving forecasts, environmental specifications, and infrastructure design. We recognize that much progress has been made and continues to be made with a powerful suite of research observatories on the ground and in space, forming the basis of a Sun-Earth system observatory. But the domain of space weather is vast - extending from deep within the Sun to far outside the planetary orbits - and the physics complex - including couplings between various types of physical processes that link scales and domains from the microscopic to large parts of the solar system. Consequently, advanced understanding of space weather requires a coordinated international approach to effectively provide awareness of the processes within the Sun-Earth system through observation-driven models. This roadmap prioritizes the scientific focus areas and research infrastructure that are needed to significantly advance our understanding of space weather of all intensities and of its implications for society. Advancement of the existing system observatory through the addition of small to moderate state-of-the-art capabilities designed to fill observational gaps will enable significant advances. Such a strategy requires urgent action: key instrumentation needs to be sustained, and action needs to be taken before core capabilities are lost in the aging ensemble. We recommend advances through priority focus (1) on observation-based modeling throughout the Sun-Earth system, (2) on forecasts more than 12 h ahead of the magnetic structure of incoming coronal mass ejections, (3) on understanding the geospace response to variable solar-wind stresses that lead to intense geomagnetically-induced currents and ionospheric and radiation storms, and (4) on developing a comprehensive specification of space climate, including the characterization of extreme space storms to guide resilient and robust engineering of technological infrastructures. The roadmap clusters its implementation recommendations by formulating three action pathways, and outlines needed instrumentation and research programs and infrastructure for each of these. An executive summary provides an overview of all recommendations. Title: Large Solar Energetic Particle Events Associated with Filament Eruptions Outside of Active Regions Authors: Gopalswamy, N.; Mäkelä, P.; Akiyama, S.; Yashiro, S.; Xie, H.; Thakur, N.; Kahler, S. W. Bibcode: 2015ApJ...806....8G Altcode: 2015arXiv150400709G We report on four large filament eruptions (FEs) from solar cycles 23 and 24 that were associated with large solar energetic particle (SEP) events and interplanetary type II radio bursts. The post-eruption arcades corresponded mostly to C-class soft X-ray enhancements, but an M1.0 flare was associated with one event. However, the associated coronal mass ejections (CMEs) were fast (speeds ∼ 1000 km s-1) and appeared as halo CMEs in the coronagraph field of view. The interplanetary type II radio bursts occurred over a wide wavelength range, indicating the existence of strong shocks throughout the inner heliosphere. No metric type II bursts were present in three events, indicating that the shocks formed beyond 2-3 Rs. In one case, there was a metric type II burst with low starting frequency, indicating a shock formation height of ∼2 Rs. The FE-associated SEP events did have softer spectra (spectral index >4) in the 10-100 MeV range, but there were other low-intensity SEP events with spectral indices ≥4. Some of these events are likely FE-SEP events, but were not classified as such in the literature because they occurred close to active regions. Some were definitely associated with large active region flares, but the shock formation height was large. We definitely find a diminished role for flares and complex type III burst durations in these large SEP events. Fast CMEs and shock formation at larger distances from the Sun seem to be the primary characteristics of the FE-associated SEP events. Title: The Peculiar Behavior of Halo Coronal Mass Ejections in Solar Cycle 24 Authors: Gopalswamy, N.; Xie, H.; Akiyama, S.; Mäkelä, P.; Yashiro, S.; Michalek, G. Bibcode: 2015ApJ...804L..23G Altcode: 2015arXiv150401797G We report on the remarkable finding that the halo coronal mass ejections (CMEs) in cycle 24 are more abundant than in cycle 23, although the sunspot number in cycle 24 has dropped by ∼40%. We also find that the distribution of halo-CME source locations is different in cycle 24: the longitude distribution of halos is much flatter with the number of halos originating at a central meridian distance ≥slant 60{}^\circ twice as large as that in cycle 23. On the other hand, the average speed and associated soft X-ray flare size are the same in both cycles, suggesting that the ambient medium into which the CMEs are ejected is significantly different. We suggest that both the higher abundance and larger central meridian longitudes of halo CMEs can be explained as a consequence of the diminished total pressure in the heliosphere in cycle 24. The reduced total pressure allows CMEs to expand more than usual making them appear as halos. Title: Geometrical Relationship Between Interplanetary Flux Ropes and Their Solar Sources Authors: Marubashi, K.; Akiyama, S.; Yashiro, S.; Gopalswamy, N.; Cho, K. -S.; Park, Y. -D. Bibcode: 2015SoPh..290.1371M Altcode: 2015SoPh..tmp...46M We investigated the physical connection between interplanetary flux ropes (IFRs) near Earth and coronal mass ejections (CMEs) by comparing the magnetic field structures of IFRs and CME source regions. The analysis is based on the list of 54 pairs of ICMEs (interplanetary coronal mass ejections) and CMEs that are taken to be the most probable solar source events. We first attempted to identify the flux rope structure in each of the 54 ICMEs by fitting models with a cylinder and torus magnetic field geometry, both with a force-free field structure. This analysis determined the possible geometries of the identified flux ropes. Then we compared the flux rope geometries with the magnetic field structure of the solar source regions. We obtained the following results: (1) Flux rope structures are seen in 51 ICMEs out of the 54. The result implies that all ICMEs have an intrinsic flux rope structure, if the three exceptional cases are attributed to unfavorable observation conditions. (2) It is possible to find flux rope geometries with the main axis orientation close to the orientation of the magnetic polarity inversion line (PIL) in the solar source regions, the differences being less than 25°. (3) The helicity sign of an IFR is strongly controlled by the location of the solar source: flux ropes with positive (negative) helicity are associated with sources in the southern (northern) hemisphere (six exceptions were found). (4) Over two-thirds of the sources in the northern hemisphere are concentrated along PILs with orientations of 45° ± 30° (measured clockwise from the east), and over two-thirds in the southern hemisphere along PILs with orientations of 135° ± 30°, both corresponding to the Hale boundaries. These results strongly support the idea that a flux rope with the main axis parallel to the PIL erupts in a CME and that the erupted flux rope propagates through the interplanetary space with its orientation maintained and is observed as an IFR. Title: Dynamics of CMEs in the LASCO Field of View Authors: Michalek, G.; Gopalswamy, N.; Yashiro, S.; Bronarska, K. Bibcode: 2015SoPh..290..903M Altcode: 2015SoPh..tmp...20M A large set (16 000) of coronal mass ejections (CMEs) observed during 1996 - 2011 was selected to study their dynamics in the LASCO field of view (LFOV). These events were selected based on the criterion that at least three height-time measurements were available for each CME. The height-time measurements included in the SOHO/LASCO catalog were used to determine velocities and accelerations of the respective CMEs at successive distances from the Sun. Next, these parameters were sorted into 30 subsamples depending on the distance from the Sun at which they were determined. The mean velocities and accelerations calculated for the successive distance-dependent subsamples of CMEs were used to study their dynamics. We demonstrate that CMEs in the LFOV manifest three distinct phases of propagation: (i) The propelling Lorentz force dominates the dynamics of CMEs in the inner (C2 LASCO) FOV, (ii) a stable propagation occurs as a result of the balance between the propelling and drag forces, (iii) the drag force dominates at the outer edge of the LFOV. When we considered different categories of CME separately, we found different acceleration-distance profiles for different categories. Title: The Dynamics of Eruptive Prominences Authors: Gopalswamy, Nat Bibcode: 2015ASSL..415..381G Altcode: 2014arXiv1407.2594G This chapter discusses the dynamical properties of eruptive prominences in relation to coronal mass ejections (CMEs). The fact that eruptive prominences are a part of CMEs is emphasized in terms of their physical association and kinematics. The continued propagation of prominence material into the heliosphere is illustrated using in-situ observations. The solar-cycle variation of eruptive prominence locations is discussed with a particular emphasis on the rush-to-the-pole (RTTP) phenomenon. One of the consequences of the RTTP phenomenon is polar CMEs, which are shown to be similar to the low-latitude CMEs. This similarity is important because it provides important clues to the mechanism by which CMEs erupt. The nonradial motion of CMEs is discussed, including the deflection by coronal holes that have important space weather consequences. Finally, the implications of the presented observations for CME modeling are outlined. Title: Instant: An Innovative L5 Small Mission Concept for Coordinated Science with Solar Orbiter and Solar Probe Plus Authors: Lavraud, B.; Liu, Y. D.; Harrison, R. A.; Liu, W.; Auchere, F.; Gan, W.; Lamy, P. L.; Xia, L.; Eastwood, J. P.; Wimmer-Schweingruber, R. F.; Zong, Q.; Rochus, P.; Maksimovic, M.; Temmer, M.; Escoubet, C. P.; Kilpua, E.; Rouillard, A. P.; Davies, J. A.; Vial, J. C.; Gopalswamy, N.; Bale, S. D.; Li, G.; Howard, T. A.; DeForest, C. E. Bibcode: 2014AGUFMSH21B4109L Altcode: We will present both the science objectives and related instrumentation of a small solar and heliospheric mission concept, INSTANT: INvestigation of Solar-Terrestrial Activity aNd Transients. It will be submitted as an opportunity to the upcoming ESA-China S-class mission call later this year. This concept was conceived to allow innovative measurements and unprecedented, early determination of key properties of Earthbound CMEs from the L5 vantage point. Innovative measurements will include magnetic field determination in the corona thanks to Hanle measurement in Lyman-α and polarized heliospheric imaging for accurate determination of CME trajectories. With complementary in situ measurements, it will uniquely permit solar storm science, solar storm surveillance, and synergy with Solar Orbiter and Solar Probe Plus (the ESA-China S2 mission launch is planned in 2021). Title: The Relation Between Large-Scale Coronal Propagating Fronts and Type II Radio Bursts Authors: Nitta, Nariaki V.; Liu, Wei; Gopalswamy, Nat; Yashiro, Seiji Bibcode: 2014SoPh..289.4589N Altcode: 2014arXiv1409.4754N Large-scale, wave-like disturbances in extreme-ultraviolet (EUV) and type II radio bursts are often associated with coronal mass ejections (CMEs). Both phenomena may signify shock waves driven by CMEs. Taking EUV full-disk images at an unprecedented cadence, the Atmospheric Imaging Assembly (AIA) onboard the Solar Dynamics Observatory has observed the so-called EIT waves or large-scale coronal propagating fronts (LCPFs) from their early evolution, which coincides with the period when most metric type II bursts occur. This article discusses the relation of LCPFs as captured by AIA with metric type II bursts. We show examples of type II bursts without a clear LCPF and fast LCPFs without a type II burst. Part of the disconnect between the two phenomena may be due to the difficulty in identifying them objectively. Furthermore, it is possible that the individual LCPFs and type II bursts may reflect different physical processes and external factors. In particular, the type II bursts that start at low frequencies and high altitudes tend to accompany an extended arc-shaped feature, which probably represents the 3D structure of the CME and the shock wave around it, and not just its near-surface track, which has usually been identified with EIT waves. This feature expands and propagates toward and beyond the limb. These events may be characterized by stretching of field lines in the radial direction and may be distinct from other LCPFs, which may be explained in terms of sudden lateral expansion of the coronal volume. Neither LCPFs nor type II bursts by themselves serve as necessary conditions for coronal shock waves, but these phenomena may provide useful information on the early evolution of the shock waves in 3D when both are clearly identified in eruptive events. Title: Vision for the Future of Lws TR&T Authors: Schwadron, N.; Mannucci, A. J.; Antiochos, S. K.; Bhattacharjee, A.; Gombosi, T. I.; Gopalswamy, N.; Kamalabadi, F.; Linker, J.; Pilewskie, P.; Pulkkinen, A. A.; Spence, H. E.; Tobiska, W. K.; Weimer, D. R.; Withers, P.; Bisi, M. M.; Kuznetsova, M. M.; Miller, K. L.; Moretto, T.; Onsager, T. G.; Roussev, I. I.; Viereck, R. A. Bibcode: 2014AGUFMSH33B..02S Altcode: The Living With a Star (LWS) program addresses acute societal needs for understanding the effects of space weather and developing scientific knowledge to support predictive capabilities. Our society's heavy reliance on technologies affected by the space environment, an enormous number of airline customers, interest in space tourism, and the developing plans for long-duration human exploration space missions are clear examples that demonstrate urgent needs for space weather models and detailed understanding of space weather effects and risks. Since its inception, the LWS program has provided a vehicle to innovate new mechanisms for conducting research, building highly effective interdisciplinary teams, and ultimately in developing the scientific understanding needed to transition research tools into operational models that support the predictive needs of our increasingly space-reliant society. The advances needed require broad-based observations that cannot be obtained by large missions alone. The Decadal Survey (HDS, 2012) outlines the nation's needs for scientific development that will build the foundation for tomorrow's space weather services. Addressing these goals, LWS must develop flexible pathways to space utilizing smaller, more diverse and rapid development of observational platforms. Expanding utilization of ground-based assets and shared launches will also significantly enhance opportunities to fulfill the growing LWS data needs. Partnerships between NASA divisions, national/international agencies, and with industry will be essential for leveraging resources to address increasing societal demand for space weather advances. Strengthened connections to user communities will enhance the quality and impact of deliverables from LWS programs. Thus, we outline the developing vision for the future of LWS, stressing the need for deeper scientific understanding to improve forecasting capabilities, for more diverse data resources, and for project deliverables that address the growing needs of user communities. Title: Association Rate of Major Sep Events As a Function of CME Speed and Source Longitude Authors: Yashiro, S.; Gopalswamy, N.; Akiyama, S.; Makela, P. A.; Xie, H. Bibcode: 2014AGUFMSH43A4186Y Altcode: We report on the fraction of fast and wide coronal mass ejections (FW CMEs; speed>900 km/s; width>60°) that produce solar energetic particle (SEP) events. Source regions of the FW CMEs were identified using SOHO/EIT, STEREO/EUVI, and SDO/AIA. Using STEREO EUV observations, we are able to determine the source locations behind the west limb with a high degree of accuracy. The >10 MeV proton flux at Earth was examined using GOES/SEM. The >10 MeV proton flux at the STEREO spacecraft was estimated using STEREO/HET, which detects energetic protons in 11 channels from 13.6 to 100 MeV. We extrapolated the proton flux in the 10 - 150 MeV range with a power-law fit and derived the corresponding >10 MeV proton flux. For each FW CME, we have three proton flux values for three different relative source longitudes with respect to the observer. The SEP association rate is determined by dividing the number of SEP-producing CMEs by the total number of events in each 20° bin of the relative source longitude. We found that the SEP association rate peaked at the W60°-W80° bin and the magnetically well-connected longitudes range from W20°-W100°. We also found that the rate distribution is skewed: the eastern wing of the rate distribution drops slowly compared to the western wing. This indicates that the eastern CMEs (longitude < 0°) have a better chance to reach the magnetic field line connected to Earth than the far-behind-the-west-limb (longitude > 120°) CMEs. Title: Estimation of Reconnection Flux using Post-eruption Arcades and Prediction of Bz at Earth Authors: Gopalswamy, N.; Xie, H.; Yashiro, S.; Akiyama, S. Bibcode: 2014AGUFMSH21C4139G Altcode: Coronal mass ejections (CMEs) and flares share the same eruption process as has been confirmed from various aspects of the two phenomena. In particular, the post-eruption arcade and the CME flux rope are formed out of the same reconnection process. It is customary to compute the flare reconnection flux from the flare-ribbon area and photospheric/chromosphericmagnetic field strength. Here we report on a new method to compute the reconnection flux from post-eruption arcades (PEAs). Instead of counting the ribbon pixels in a series of images, we simply measure the area under PEAs after the flare maximum and the underlying photospheric magnetic field. The reconnection flux is then half of the product of these two quantities. We illustrate this method using specific examples and show that the ribbon and arcade methods yield very similar results. We show that this method provides a simple means of predicting the 1-AU flux rope magnetic field (including Bz) from measurements made near the Sun. Title: Factors Affecting the Occurrence of Large Solar Energetic Particle Events Authors: Gopalswamy, N.; Yashiro, S.; Akiyama, S.; Xie, H.; Makela, P. A.; Thakur, N. Bibcode: 2014AGUFMSH41D..07G Altcode: In order to understand the paucity of high-energy solar energetic particle (SEP) events in solar cycle 24, we examined all major eruptions (soft X-ray flare size ≥M5.0) on the front side of the Sun during the period from December 1, 2008 to January 31, 2014. There were 59 such eruptions that were associated with CMEs. When a flux rope was fitted to the white-light CMEs observed by SOHO and STEREO it was found that the CME sources were on the disk only for 55 eruptions. There were 16 large SEP events (proton intensity ≥10 pfu in the >10 MeV channel) detected by GOES and 4 by STEREO-B in association with these eruptions. When the CMEs were grouped according to their speeds (<1500 km/s and ≥ 1500 km/s) it was found that only three of the <1500 km/s CMEs (or 11%) were associated with large SEP events compared to 17 or (61%) of the ≥ 1500 km/s CMEs. This result confirms the importance of CME speed for SEP association. In fact there were ten other large SEP events with flare size <M5.0, but associated with fast CMEs, suggesting that the flare size does not determine SEP association. In order to narrow down the properties of CMEs that produce GLE events, we divided the SEP-associated CMEs into a different speed range: ≥2000 km/s and 1500-1999 km/s. We also required that the CMEs originated from the longitudinal range of W20 to W90 (traditional GLE longitudes). There were sixteen such events, 6 with speed in the range 1500-1999 km/s and 10 with ≥2000 km/s. When we further applied the criterion that the latitudinal distance of the CME sources from the ecliptic must be within ±13o (Gopalswamy et al. 2013 ApJL 765, L30), we found that there were only four CMEs that met this criterion. One of the four was the GLE event of 2012 May 17 whose CME speed was only slightly less than 2000 km/s. The 2011 August 9 CME was ejected into a tenuous medium, which means the shock was likely weak due to higher ambient Alfven speed, even though the CME speed was well above 2000 km/s. The speed of the 2011 June 7 CME (1680 km/s) was well below the typical speed of GLE CMEs. The last one, the 2013 May 22 event was an interacting CME event, but the speed of the primary CME was only 1880 km/s. Thus we conclude that the CME speed, the ecliptic distance of the CME source, and the ambient conditions are all important in deciding whether an SEP event would have GLE particles. Work supported by NASA's Living with a Star Program. Title: High Energy Particle Events in Solar Cycles 23 and 24 Authors: Thakur, N.; Gopalswamy, N.; Makela, P. A.; Yashiro, S.; Akiyama, S.; Xie, H. Bibcode: 2014AGUFMSH43A4190T Altcode: We present a study of high-energy solar energetic particle (SEP) events in solar cycles 23 and 24 using GOES data. We selected large SEP events, which showed intensity enhancements in the >500 MeV and >700 MeV GOES energy channels. A study of cycle 24 and the first half of cycle 23 ground level enhancements (GLEs) by Gopalswamy et al. 2014 showed that typically, SEP events with intensity enhancement at >700 MeV have been associated with GLEs. We have extended the survey to cover the whole cycle 23. Our preliminary survey confirms this to be true for all except for three cases. There were two GLEs (1998/05/06 and 2006/12/06) for which a clear increase in >700 MeV protons was not observed by GOES. There was one high energy SEP event (2000/11/08), for which GOES observed >700 MeV protons but no GLE was produced. Here we compare all the high-energy particle events from cycles 23 and 24 with GLEs. We also compare energy spectra of all high-energy SEP events with those that produced GLEs. Work supported by NASA's Living with a Star Program. Ref.: Gopalswamy et al. 2014, GRL, 41, 2673 Title: Major solar eruptions and high-energy particle events during solar cycle 24 Authors: Gopalswamy, Nat; Xie, Hong; Akiyama, Sachiko; Mäkelä, Pertti A.; Yashiro, Seiji Bibcode: 2014EP&S...66..104G Altcode: 2014arXiv1408.3617G We report on a study of all major solar eruptions that occurred on the frontside of the Sun during the rise to peak phase of cycle 24 (first 62 months) in order to understand the key factors affecting the occurrence of large solar energetic particle events (SEPs) and ground level enhancement (GLE) events. The eruptions involve major flares with soft X-ray peak flux ≥ 5.0 x10-5 Wm-2 (i.e., flare size ≥ M5.0) and accompanying coronal mass ejections (CMEs). The selection criterion was based on the fact that the only front-side GLE in cycle 24 (GLE 71) had a flare size of M5.1. Only approximately 37% of the major eruptions from the western hemisphere resulted in large SEP events. Almost the same number of large SEP events was produced in weaker eruptions (flare size < M5.0), suggesting that the soft X-ray flare is not a good indicator of SEP or GLE events. On the other hand, the CME speed is a good indicator of SEP and GLE events because it is consistently high supporting the shock acceleration mechanism. We found the CME speed, magnetic connectivity to Earth (in longitude and latitude), and ambient conditions as the main factors that contribute to the lack of high-energy particle events during cycle 24. Several eruptions poorly connected to Earth (eastern-hemisphere or behind-the-west-limb events) resulted in very large SEP events detected by the Solar Terrestrial Relations Observatory (STEREO) spacecraft. Some very fast CMEs, likely to have accelerated particles to GeV energies, did not result in a GLE event because of poor latitudinal connectivity. The stringent latitudinal requirement suggests that the highest-energy particles are likely accelerated in the nose part of shocks, while the lower energy particles are accelerated at all parts. There were also well-connected fast CMEs, which did not seem to have accelerated high-energy particles due to possible unfavorable ambient conditions (high Alfven speed, overall reduction in acceleration efficiency in cycle 24). Title: Strategic Science to Address Current and Future Space Weather Needs Authors: Mannucci, A. J.; Schwadron, N.; Antiochos, S. K.; Bhattacharjee, A.; Bisi, M. M.; Gopalswamy, N.; Kamalabadi, F.; Pulkkinen, A. A.; Tobiska, W. K.; Weimer, D. R.; Withers, P. Bibcode: 2014AGUFMSM24A..09M Altcode: NASA's Living With a Star (LWS) program has contributed a wealth of scientific knowledge that is relevant to space weather and user needs. A targeted approach to science questions has resulted in leveraging new scientific knowledge to improve not only our understanding of the Heliophysics domain, but also to develop predictive capabilities in key areas of LWS science. This fascinating interplay between science and applications promises to benefit both domains. Scientists providing feedback to the LWS program are now discussing an evolution of the targeted approach that explicitly considers how new science improves, or enables, predictive capability directly. Long-term program goals are termed "Strategic Science Areas" (SSAs) that address predictive capabilities in six specific areas: geomagnetically induced currents, satellite drag, solar energetic particles, ionospheric total electron content, radio frequency scintillation induced by the ionosphere, and the radiation environment. SSAs are organized around user needs and the impacts of space weather on society. Scientists involved in the LWS program identify targeted areas of research that reference (or bear upon) societal needs. Such targeted science leads to new discoveries and is one of the valid forms of exploration. In this talk we describe the benefits of targeted science, and how addressing societal impacts in an appropriate way maintains the strong science focus of LWS, while also leading to its broader impacts. Title: Homologous flare-CME events and their metric type II radio burst association Authors: Yashiro, S.; Gopalswamy, N.; Mäkelä, P.; Akiyama, S.; Uddin, W.; Srivastava, A. K.; Joshi, N. C.; Chandra, R.; Manoharan, P. K.; Mahalakshmi, K.; Dwivedi, V. C.; Jain, R.; Awasthi, A. K.; Nitta, N. V.; Aschwanden, M. J.; Choudhary, D. P. Bibcode: 2014AdSpR..54.1941Y Altcode: Active region NOAA 11158 produced many flares during its disk passage. At least two of these flares can be considered as homologous: the C6.6 flare at 06:51 UT and C9.4 flare at 12:41 UT on February 14, 2011. Both flares occurred at the same location (eastern edge of the active region) and have a similar decay of the GOES soft X-ray light curve. The associated coronal mass ejections (CMEs) were slow (334 and 337 km/s) and of similar apparent widths (43° and 44°), but they had different radio signatures. The second event was associated with a metric type II burst while the first one was not. The COR1 coronagraphs on board the STEREO spacecraft clearly show that the second CME propagated into the preceding CME that occurred 50 min before. These observations suggest that CME-CME interaction might be a key process in exciting the type II radio emission by slow CMEs. Title: An Estimate of the Coronal Magnetic Field near a Solar Coronal Mass Ejection from Low-frequency Radio Observations Authors: Hariharan, K.; Ramesh, R.; Kishore, P.; Kathiravan, C.; Gopalswamy, N. Bibcode: 2014ApJ...795...14H Altcode: We report ground-based, low-frequency (<100 MHz) radio imaging, spectral, and polarimeter observations of the type II radio burst associated with the solar coronal mass ejection (CME) that occurred on 2013 May 2. The spectral observations indicate that the burst has fundamental (F) and harmonic (H) emission components with split-band and herringbone structures. The imaging observations at 80 MHz indicate that the H component of the burst was located close to leading edge of the CME at a radial distance of r ≈ 2 R ⊙ in the solar atmosphere. The polarimeter observations of the type II burst, also at 80 MHz, indicate that the peak degree of circular polarization (dcp) corresponding to the emission generated in the corona ahead of and behind the associated MHD shock front are ≈0.05 ± 0.02 and ≈0.1 ± 0.01, respectively. We calculated the magnetic field B in the above two coronal regions by adopting the empirical relationship between the dcp and B for the harmonic plasma emission and the values are ≈(0.7-1.4) ± 0.2 G and ≈(1.4-2.8) ± 0.1 G, respectively. Title: Coronal Mass Ejections and Non-recurrent Forbush Decreases Authors: Belov, A.; Abunin, A.; Abunina, M.; Eroshenko, E.; Oleneva, V.; Yanke, V.; Papaioannou, A.; Mavromichalaki, H.; Gopalswamy, N.; Yashiro, S. Bibcode: 2014SoPh..289.3949B Altcode: 2014SoPh..tmp...73B Coronal mass ejections (CMEs) and their interplanetary counterparts (interplanetary coronal mass ejections, ICMEs) are responsible for large solar energetic particle events and severe geomagnetic storms. They can modulate the intensity of Galactic cosmic rays, resulting in non-recurrent Forbush decreases (FDs). We investigate the connection between CME manifestations and FDs. We used specially processed data from the worldwide neutron monitor network to pinpoint the characteristics of the recorded FDs together with CME-related data from the detailed online catalog based upon the Solar and Heliospheric Observatory (SOHO)/Large Angle and Spectrometric Coronagraph (LASCO) data. We report on the correlations of the FD magnitude to the CME initial speed, the ICME transit speed, and the maximum solar wind speed. Comparisons between the features of CMEs (mass, width, velocity) and the characteristics of FDs are also discussed. FD features for halo, partial halo, and non-halo CMEs are presented and discussed. Title: Ground Level Enhancement in the 2014 January 6 Solar Energetic Particle Event Authors: Thakur, N.; Gopalswamy, N.; Xie, H.; Mäkelä, P.; Yashiro, S.; Akiyama, S.; Davila, J. M. Bibcode: 2014ApJ...790L..13T Altcode: 2014arXiv1406.7172T We present a study of the 2014 January 6 solar energetic particle event which produced a small ground level enhancement (GLE), making it the second GLE of this unusual solar cycle 24. This event was primarily observed by the South Pole neutron monitors (increase of ~2.5%) while a few other neutron monitors recorded smaller increases. The associated coronal mass ejection (CME) originated behind the western limb and had a speed of 1960 km s-1. The height of the CME at the start of the associated metric type II radio burst, which indicates the formation of a strong shock, was measured to be 1.61 Rs using a direct image from STEREO-A/EUVI. The CME height at the time of the GLE particle release (determined using the South Pole neutron monitor data) was directly measured as 2.96 Rs based on STEREO-A/COR1 white-light observations. These CME heights are consistent with those obtained for GLE71, the only other GLE of the current cycle, as well as cycle-23 GLEs derived using back-extrapolation. GLE72 is of special interest because it is one of only two GLEs of cycle 24, one of two behind-the-limb GLEs, and one of the two smallest GLEs of cycles 23 and 24. Title: ISEST Program: International Stud of Earth-affecting Solar Transients Authors: Zhang, Jie; Temmer, Manuela; Gopalswamy, Nat Bibcode: 2014shin.confE...7Z Altcode: A new international program: International Study of Earth-affecting Solar Transients (IEST), is introduced. This program is one of the four scientific elements supported by the VarSITI (Variability of the Sun and Its Terrestrial Impact) project, a five-year long international-cross-discipline-collaboration project from 2014-2018, sponsored by the SCOSTEP (Scientific Committee of Solar-Terrestrial Physics). The aim of ISEST is to understand the origin, propagation and evolution of solar transients, including CMEs, CIRs and SEPs, through the space between the Sun and the Earth, and improve the prediction capability for space weather. Particular emphasis will be placed on the weak solar activity prevailing in Solar Cycle 24 (MiniMax24). The ISEST program consists of six working groups, encompassing data analysis, theoretical interpretation, numerical modeling, B-south challenge, event campaign study, and long-term MiniMax24 campaign studies. It is anticipated that the ISEST will create a comprehensive online database of Earth-affecting solar transients contributed by both observers and modelers. By the end of the program It is expected that the space weather prediction using solar observations will be improved significantly. Title: An Investigation of the Interplanetary Type II Radio Bursts Observed on 2012 January 19 Authors: Teklu, Tsega Berhane; Gopalswamy, N.; Mäkelä, P.; Yashiro, S.; Akiyama, S.; Xie, H. Bibcode: 2014shin.confE.155T Altcode: We report on the analysis of the 2012 January 19 type II radio bursts observed by the Wind/WAVES experiment. The type II radio burst had two components. The first was a short-lived burst in decameter-hectometric (DH) while the second was long lived extending to kilometric (km) wavelengths. The short-lived type II burst had a high drift rate (- 5.4 kHz/s) while the long-lived one had a regular drift rate (- 2.7 kHz/s). The type II burst was associated with a halo CME observed by SOHO/LASCO moving with a speed of 1120 km/s. The presence of two type II bursts seems to be due to the interaction of the halo CME with a proceeding CME, as indicated by SOHO and STEREO coronagrpahic images. Analysis of the scale heights based on coronal density variations confirms the interaction. We establish the connection between CME height and the frequency of the type II bursts. The CME was also associated with solar energetic particles, consistent with the strong shock. The Earth arrival of the CME-driven shock was also observed by Wind/TNR and SoHO/CELIAS Proton Monitor. Title: Understanding the Longitudinal Extent and Timing of SEP Onsets: The November 3 2011 Event Authors: Xie, Hong; St. Cyr, C.; Gopalswamy, N. Bibcode: 2014shin.confE..86X Altcode: We study a multi-spacecraft solar energetic particle (SEP) event, which occurred on November 3 2011. The CME associated with the SEP event was observed as a behind the east-limb event (N06E152) by SOHO/LASCO. The CME was observed to be at W102 and E50 in STEREO-A and B views, respectively. This SEP event had a remarkable prompt particle increase at all three spacecraft despite their wide separation. Using a forward-fitting technique with an oblate spheroid model, we study the evolution of the CME shock and EUV wave in the low corona. Observations from STEREO and SOHO (white light), and SDO (EUV) were used to constraint the 3D shock shape and the EUV imprints on the solar surface. The combination of a full 3D model and multi-wavelength observational constraints allowed us to determine the radial and expansion speeds of the CME-shock and EUV wave in a consistent way. We were also able to determine the timing and the locations where the shock front intersects the magnetic footpoints connected to each spacecraft. The Parker-spiral theory with the average solar-wind speed measured in situ was used to estimate the location of magnetic field lines connecting the Sun to each spacecraft. The SEP onset time was determined by carrying out a velocity-dispersion analysis on the particles arriving at each spacecraft. By comparing the SEP onset delay with the time taken for the shock to expand to the longitudes of the connecting magnetic field lines, we confirmed that the wide spread SEP event was in fact a result of the expanding shock and the EUV wave for this case. Title: Estimating the Height of CMEs at the Onset of Metric Type II Bursts Authors: Makela, Pertti; Gopalswamy, Nat Bibcode: 2014shin.confE.103M Altcode: The onset of type II radio bursts indicates the moment when a shock front ahead of a coronal mass ejection (CME) forms and starts to accelerate electrons in the solar corona. Therefore, the onset of metric type II bursts, which can be observed remotely by radio instruments, provides us the first indication of the CME-driven shock front propagating in the solar corona. Several methods have been suggested to estimate the height of the associated CME. Here we estimate the CME height by assuming that CMEs with an initial height of 1.25 Rs accelerate from rest to final speed (the measured linear speed of the CME) during a period starting at the flare onset time and ending at the flare peak time, after which they propagate with a final speed. Using this method Gopalswamy et al. (2012) found the CME height at metric type II burst onset with mean and median values of 1.53 Rs and 1.47 Rs, respectively for the cycle 23 ground level enhancement (GLE) events. We have expanded this study to include all major non-GLE solar energetic particle (SEP) events. We find that the average and median height of non-GLE CMEs at the onset of the metric type II bursts to be 1.73 Rs and 1.61 Rs, respectively. For cycle 23 (cycle 24) CMEs the average height is 1.78 Rs (1.59 Rs) and the median height 1.61 Rs (1.45 Rs), respectively. Because Alfven speed is proportional to magnetic field, weaker solar magnetic fields during cycle 24 result in lower Alfven speeds on average and hence shocks could form earlier, if we assume that CME speed distributions are similar in cycle 23 and cycle 24. Title: Are Polar-crown Coronal Mass Ejections Similar to the Low-latitude Counterparts? Authors: Gopalswamy, N.; Yashiro, Seiji; Akiyama, Sachiko Bibcode: 2014AAS...22430306G Altcode: Coronal mass ejections (CMEs) from the polar-crown filament region originate above 60-degree latitude during solar activity maxima. Polar-crown CMEs originate from bipolar magnetic regions, whereas both bipolar and multipolar regions produce CMEs at low latitudes. If polar CMEs are similar to the low-latitude ones, then a single eruption mechanism can apply to all CMEs, the common element being the magnetic free energy. We examine several polar-crown CMEs to determine their three-part morphology, acceleration profile including the height of peak acceleration, CME-flare relationship, and energetics. We found that these properties are similar to those of low-latitude CMEs. We use illustrative examples from the Solar Dynamics Observatory images to show quantitatively that the polar-crown CMEs are very similar to their low-latitude counterparts. Even though the post eruption arcades are weak, we show that the peak thermal energy of these arcades is a few percent of the CME kinetic energy, similar to what is observed in large eruptive events. These observations suggest that a bipolar configuration is sufficient for the production of CMEs. Title: Latitudinal Connectivity of Ground Level Enhancement Events Authors: Gopalswamy, N.; Mäkelä, P. Bibcode: 2014ASPC..484...63G Altcode: 2013arXiv1310.8506G We examined the source regions and coronal environment of the historical ground level enhancement (GLE) events in search of evidence for non-radial motion of the associated coronal mass ejection (CME). For the 13 GLE events that had source latitudes >30° we found evidence for possible non-radial CME motion due to deflection by large-scale magnetic structures in nearby coronal holes, streamers, or pseudo streamers. Polar coronal holes are the main source of deflection in the rise and declining phases of solar cycles. In the maximum phase, deflection by large-scale streamers or pseudo streamers overlying high-latitude filaments seems to be important. The B0 angle reduced the ecliptic distance of some GLE source regions and increased in others with the net result that the average latitude of GLE events did not change significantly. The non-radial CME motion is the dominant factor that reduces the ecliptic distance of GLE source regions, thereby improving the latitudinal connectivity to Earth. We further infer that the GLE particles must be accelerated at the nose part of the CME-driven shocks, where the shock is likely to be quasi-parallel. Title: Anomalous expansion of coronal mass ejections during solar cycle 24 and its space weather implications Authors: Gopalswamy, Nat; Akiyama, Sachiko; Yashiro, Seiji; Xie, Hong; Mäkelä, Pertti; Michalek, Grzegorz Bibcode: 2014GeoRL..41.2673G Altcode: 2014arXiv1404.0252G The familiar correlation between the speed and angular width of coronal mass ejections (CMEs) is also found in solar cycle 24, but the regression line has a larger slope: for a given CME speed, cycle 24 CMEs are significantly wider than those in cycle 23. The slope change indicates a significant change in the physical state of the heliosphere, due to the weak solar activity. The total pressure in the heliosphere (magnetic + plasma) is reduced by ~40%, which leads to the anomalous expansion of CMEs explaining the increased slope. The excess CME expansion contributes to the diminished effectiveness of CMEs in producing magnetic storms during cycle 24, both because the magnetic content of the CMEs is diluted and also because of the weaker ambient fields. The reduced magnetic field in the heliosphere may contribute to the lack of solar energetic particles accelerated to very high energies during this cycle. Title: Do Solar Coronal Holes Affect the Properties of Solar Energetic Particle Events? Authors: Kahler, S. W.; Arge, C. N.; Akiyama, S.; Gopalswamy, N. Bibcode: 2014SoPh..289..657K Altcode: The intensities and timescales of gradual solar energetic particle (SEP) events at 1 AU may depend not only on the characteristics of shocks driven by coronal mass ejections (CMEs), but also on large-scale coronal and interplanetary structures. It has long been suspected that the presence of coronal holes (CHs) near the CMEs or near the 1-AU magnetic footpoints may be an important factor in SEP events. We used a group of 41 E≈ 20 MeV SEP events with origins near the solar central meridian to search for such effects. First we investigated whether the presence of a CH directly between the sources of the CME and of the magnetic connection at 1 AU is an important factor. Then we searched for variations of the SEP events among different solar wind (SW) stream types: slow, fast, and transient. Finally, we considered the separations between CME sources and CH footpoint connections from 1 AU determined from four-day forecast maps based on Mount Wilson Observatory and the National Solar Observatory synoptic magnetic-field maps and the Wang-Sheeley-Arge model of SW propagation. The observed in-situ magnetic-field polarities and SW speeds at SEP event onsets tested the forecast accuracies employed to select the best SEP/CH connection events for that analysis. Within our limited sample and the three analytical treatments, we found no statistical evidence for an effect of CHs on SEP event peak intensities, onset times, or rise times. The only exception is a possible enhancement of SEP peak intensities in magnetic clouds. Title: Multiwavelength diagnostics of the precursor and main phases of an M1.8 flare on 2011 April 22 Authors: Awasthi, A. K.; Jain, R.; Gadhiya, P. D.; Aschwanden, M. J.; Uddin, W.; Srivastava, A. K.; Chandra, R.; Gopalswamy, N.; Nitta, N. V.; Yashiro, S.; Manoharan, P. K.; Choudhary, D. P.; Joshi, N. C.; Dwivedi, V. C.; Mahalakshmi, K. Bibcode: 2014MNRAS.437.2249A Altcode: 2013arXiv1310.6029A; 2013MNRAS.tmp.2720A We study the temporal, spatial and spectral evolution of the M1.8 flare, which occurred in the active region 11195 (S17E31) on 2011 April 22, and explore the underlying physical processes during the precursor phase and their relation to the main phase. The study of the source morphology using the composite images in 131 Å wavelength observed by the Solar Dynamics Observatory/Atmospheric Imaging Assembly and 6-14 keV [from the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI)] revealed a multiloop system that destabilized systematically during the precursor and main phases. In contrast, hard X-ray emission (20-50 keV) was absent during the precursor phase, appearing only from the onset of the impulsive phase in the form of foot-points of emitting loops. This study also revealed the heated loop-top prior to the loop emission, although no accompanying foot-point sources were observed during the precursor phase. We estimate the flare plasma parameters, namely temperature (T), emission measure (EM), power-law index (γ) and photon turn-over energy (ɛto), and found them to be varying in the ranges 12.4-23.4 MK, 0.0003-0.6 × 1049 cm-3, 5-9 and 14-18 keV, respectively, by forward fitting RHESSI spectral observations. The energy released in the precursor phase was thermal and constituted ≈1 per cent of the total energy released during the flare. The study of morphological evolution of the filament in conjunction with synthesized T and EM maps was carried out, which reveals (a) partial filament eruption prior to the onset of the precursor emission and (b) heated dense plasma over the polarity inversion line and in the vicinity of the slowly rising filament during the precursor phase. Based on the implications from multiwavelength observations, we propose a scheme to unify the energy release during the precursor and main phase emissions in which the precursor phase emission was originated via conduction front that resulted due to the partial filament eruption. Next, the heated leftover S-shaped filament underwent slow-rise and heating due to magnetic reconnection and finally erupted to produce emission during the impulsive and gradual phases. Title: INSTANT: INvestigation of Solar-Terrestrial Associated Natural Threats Authors: Lavraud, Benoit; Vial, Jean-Claude; Harrison, Richard; Davies, Jackie; Escoubet, C. Philippe; Zong, Qiugang; Auchere, Frederic; Liu, Ying; Bale, Stuart; Gopalswamy, Nat; Li, Gang; Maksimovic, Milan; Liu, William; Rouillard, Alexis Bibcode: 2014cosp...40E1758L Altcode: The INSTANT mission will tackle both compelling solar and heliospheric science objectives and novel space weather capabilities. This is allowed by combining innovative and state-of-the-art instrumentation at an appropriate off-Sun-Earth line location on an orbit lagging the Earth around the Sun, near the L5 Lagrangian point. It is an affordable mission that tackles major objectives of the European and Chinese communities in terms of space physics and space weather. The science objectives are: 1. What is the magnetic field magnitude and topology in the corona? 2. How does the magnetic field reconfigure itself during CME eruptions? 3. What are the sources and links between the slow and fast winds? 4. How do CMEs accelerate and interact in the interplanetary medium? The mission will further allow the following crucial space weather capabilities: 5. Three-days advance knowledge of CIR properties that reach Earth. 6. Twelve hours to 2 days advance warning of Earth-directed CMEs. 7. Thanks to Lyman-α observations, first-ever capability of determining the magnetic field magnitude and orientation of Earth-directed CMEs. The mission will be proposed in the context of the upcoming ESA-China S-class call for mission. Title: Flare - Flux Rope Relationship using Post-eruption Arcades Authors: Gopalswamy, Nat; Xie, Hong; Yashiro, Seiji; Akiyama, Sachiko Bibcode: 2014cosp...40E1047G Altcode: A close connection between the coronal mass ejections (CME) and flare in a given solar eruption has been confirmed from various aspects of the two phenomena. The relation between the reconnection flux and the poloidal flux of the associated 1-AU flux ropes is of particular importance because it can be used for space weather predictions. It is customary to compute the flare reconnection flux from the flare-ribbon area and photospheric/chromospheric magnetic field strength. Here we report on a new method to compute the reconnection flux from post-eruption arcades (PEAs). Instead of counting the ribbon pixels in a series of images, we simply measure the area under PEAs after the flare maximum and the underlying photospheric magnetic field. The reconnection flux is then half of the product of these two quantities. We illustrate this method using specific examples and show that the ribbon and arcade methods yield results, which are in good agreement. Finally, we show that this provides a simple means of predicting the 1-AU flux rope magnetic field from measurements made near the Sun. Title: Future L5 Missions for Solar Physics and Space Weather Authors: Auchere, Frederic; Gopalswamy, Nat Bibcode: 2014cosp...40E.148A Altcode: Coronal mass ejections (CMEs) and corotating interaction regions (CIR) are the sources of intense space weather in the heliosphere. Most of the current knowledge on CMEs accumulated over the past few decades has been derived from observations made from the Sun-Earth line, which is not the ideal vantage point to observe Earth-affecting CMEs (Gopalswamy et al., 2011a,b). In this paper, the advantages of remote-sensing and in-situ observations from the Sun-Earth L5 point are discussed. Locating a mission at Sun-Earth L5 has several key benefits for solar physics and space weather: (1) off the Sun-Earth line view is critical in observing Earth-arriving parts of CMEs, (2) L5 coronagraphic observations can also provide near-Sun space speed of CMEs, which is an important input to models that forecast Earth-arrival time of CMEs, (3) backside and frontside CMEs can be readily distinguished even without inner coronal imagers, (4) preceding CMEs in the path of Earth-affecting CMEs can be identified for a better estimate of the travel time, (5) CIRs reach the L5 point a few days before they arrive at Earth, and hence provide significant lead time before CIR arrival, (6) L5 observations can provide advance knowledge of CME and CIR source regions (coronal holes) rotating to Earth view, and (7) magnetograms obtained from L5 can improve the surface magnetic field distribution used as input to MHD models that predict the background solar wind. The paper also discusses L5 mission concepts that can be achieved in the near future. References Gopalswamy, N., Davila, J. M., St. Cyr, O. C., Sittler, E. C., Auchère, F., Duvall, T. L., Hoeksema, J. T., Maksimovic, M., MacDowall, R. J., Szabo, A., Collier, M. R. (2011a), Earth-Affecting Solar Causes Observatory (EASCO): A potential International Living with a Star Mission from Sun-Earth L5 JASTP 73, 658-663, DOI: 10.1016/j.jastp.2011.01.013 Gopalswamy, N., Davila, J. M., Auchère, F., Schou, J., Korendyke, C. M. Shih, A., Johnston, J. C., MacDowall, R. J., Maksimovic, M., Sittler, E., et al. (2011b), Earth-Affecting Solar Causes Observatory (EASCO): a mission at the Sun-Earth L5, Solar Physics and Space Weather Instrumentation IV. Ed. Fineschi, S. & Fennelly, J., Proceedings of the SPIE, Volume 8148, article id. 81480Z, DOI: 10.1117/12.901538 Title: Obscuration of Flare Emission by an Eruptive Prominence Authors: Gopalswamy, Nat; Yashiro, Seiji Bibcode: 2013PASJ...65S..11G Altcode: 2013arXiv1309.2046G We report on the eclipsing of microwave flare emission by an eruptive prominence from a neighboring region as observed by the Nobeyama Radioheliograph at 17 GHz. The obscuration of the flare emission appears as a dimming feature in the microwave flare light curve. We use the dimming feature to derive the temperature of the prominence and the distribution of heating along the length of the filament. We find that the prominence is heated to a temperature above the quiet Sun temperature at 17 GHz. The duration of the dimming is the time taken by the eruptive prominence in passing over the flaring region. We also find evidence for the obscuration in EUV images obtained by the Solar and Heliospheric Observatory (SOHO) mission. Title: Solar energetic particle events during the rise phases of solar cycles 23 and 24 Authors: Chandra, R.; Gopalswamy, N.; Mäkelä, P.; Xie, H.; Yashiro, S.; Akiyama, S.; Uddin, W.; Srivastava, A. K.; Joshi, N. C.; Jain, R.; Awasthi, A. K.; Manoharan, P. K.; Mahalakshmi, K.; Dwivedi, V. C.; Choudhary, D. P.; Nitta, N. V. Bibcode: 2013AdSpR..52.2102C Altcode: We present a comparative study of the properties of coronal mass ejections (CMEs) and flares associated with the solar energetic particle (SEP) events in the rising phases of solar cycles (SC) 23 (1996-1998) (22 events) and 24 (2009-2011) (20 events), which are associated with type II radio bursts. Based on the SEP intensity, we divided the events into three categories, i.e. weak (intensity < 1 pfu), minor (1 pfu < intensity < 10 pfu) and major (intensity ⩾ 10 pfu) events. We used the GOES data for the minor and major SEP events and SOHO/ERNE data for the weak SEP event. We examine the correlation of SEP intensity with flare size and CME properties. We find that most of the major SEP events are associated with halo or partial halo CMEs originating close to the sun center and western-hemisphere. The fraction of halo CMEs in SC 24 is larger than the SC 23. For the minor SEP events one event in SC23 and one event in SC24 have widths < 120° and all other events are associated with halo or partial halo CMEs as in the case of major SEP events. In case of weak SEP events, majority (more than 60%) of events are associated with CME width < 120°. For both the SC the average CMEs speeds are similar. For major SEP events, average CME speeds are higher in comparison to minor and weak events. The SEP event intensity and GOES X-ray flare size are poorly correlated. During the rise phase of solar cycle 23 and 24, we find north-south asymmetry in the SEP event source locations: in cycle 23 most sources are located in the south, whereas during cycle 24 most sources are located in the north. This result is consistent with the asymmetry found with sunspot area and intense flares. Title: A Study of Coronal Holes Observed by SoHO/EIT and the Nobeyama Radioheliograph Authors: Akiyama, Sachiko; Gopalswamy, Nat; Yashiro, Seiji; Mäkelä, Pertti Bibcode: 2013PASJ...65S..15A Altcode: Coronal holes (CHs) are areas of reduced emission in EUV and X-ray images that show bright patches of microwave enhancements (MEs) related to magnetic network junctions inside the CHs. A clear correlation between the CH size and the solar wind (SW) speed is well known, but we have less information about the relationship between MEs and other CH and SW properties. We studied the characteristics of 21 equatorial CHs associated with corotating interaction regions (CIRs) during 1996 to 2005. Our CHs were divided into two groups according to the intensity of the associated geomagnetic storms: Dst ≤ -100 nT (10 events) and > -100 nT (11 events). Using EUV 284 Å images obtained by SOHO/EIT and 17 GHz microwave images obtained by the Nobeyama Radioheliograph (NoRH), we found a linear correlation not only between the maximum SW speed and the area of EUV CH (r = 0.62), but also between the maximum SW speed and the area of the ME (r = 0.79). We also compared the EUV CH areas with and without an overlapping ME. The area of the CHs with an ME is better correlated with the SW speed (r = 0.71) than the area of those without an ME (r = 0.36). Therefore, the radio ME may play an important role in understanding the origin of SW. Title: Testing the empirical shock arrival model using quadrature observations Authors: Gopalswamy, N.; Mäkelä, P.; Xie, H.; Yashiro, S. Bibcode: 2013SpWea..11..661G Altcode: 2013arXiv1310.8510G The empirical shock arrival (ESA) model was developed based on quadrature data from Helios (in situ) and P-78 (remote sensing) to predict the Sun-Earth travel time of coronal mass ejections (CMEs). The ESA model requires earthward CME speed as input, which is not directly measurable from coronagraphs along the Sun-Earth line. The Solar Terrestrial Relations Observatory (STEREO) and the Solar and Heliospheric Observatory (SOHO) were in quadrature during 2010-2012, so the speeds of Earth-directed CMEs were observed with minimal projection effects. We identified a set of 20 full halo CMEs in the field of view of SOHO that were also observed in quadrature by STEREO. We used the earthward speed from STEREO measurements as input to the ESA model and compared the resulting travel times with the observed ones from L1 monitors. We find that the model predicts the CME travel time within about 7.3 h, which is similar to the predictions by the ENLIL model. We also find that CME-CME and CME-coronal hole interaction can lead to large deviations from model predictions. Title: Flux emergence, flux imbalance, magnetic free energy and solar flares Authors: Choudhary, Debi Prasad; Gosain, Sanjay; Gopalswamy, Nat; Manoharan, P. K.; Chandra, R.; Uddin, W.; Srivastava, A. K.; Yashiro, S.; Joshi, N. C.; Kayshap, P.; Dwivedi, V. C.; Mahalakshmi, K.; Elamathi, E.; Norris, Max; Awasthi, A. K.; Jain, R. Bibcode: 2013AdSpR..52.1561C Altcode: Emergence of complex magnetic flux in the solar active regions lead to several observational effects such as a change in sunspot area and flux embalance in photospheric magnetograms. The flux emergence also results in twisted magnetic field lines that add to free energy content. The magnetic field configuration of these active regions relax to near potential-field configuration after energy release through solar flares and coronal mass ejections. In this paper, we study the relation of flare productivity of active regions with their evolution of magnetic flux emergence, flux imbalance and free energy content. We use the sunspot area and number for flux emergence study as they contain most of the concentrated magnetic flux in the active region. The magnetic flux imbalance and the free energy are estimated using the HMI/SDO magnetograms and Virial theorem method. We find that the active regions that undergo large changes in sunspot area are most flare productive. The active regions become flary when the free energy content exceeds 50% of the total energy. Although, the flary active regions show magnetic flux imbalance, it is hard to predict flare activity based on this parameter alone. Title: Understanding shock dynamics in the inner heliosphere with modeling and type II radio data: A statistical study Authors: Xie, H.; St. Cyr, O. C.; Gopalswamy, N.; Odstrcil, D.; Cremades, H. Bibcode: 2013JGRA..118.4711X Altcode: We study two methods of predicting interplanetary shock location and strength in the inner heliosphere: (1) the ENLIL simulation and (2) the kilometric type II (kmTII) prediction. To evaluate differences in the performance of the first method, we apply two sets of coronal mass ejections (CME) parameters from the cone-model fitting and flux-rope (FR) model fitting as input to the ENLIL model for 16 halo CMEs. The results show that the ENLIL model using the actual CME speeds from FR-fit provided an improved shock arrival time (SAT) prediction. The mean prediction errors for the FR and cone-model inputs are 4.90±5.92 h and 5.48±6.11 h, respectively. A deviation of 100 km s-1 from the actual CME speed has resulted in a SAT error of 3.46 h on average. The simulations show that the shock dynamics in the inner heliosphere agrees with the drag-based model. The shock acceleration can be divided as two phases: a faster deceleration phase within 50 Rs and a slower deceleration phase at distances beyond 50 Rs. The linear-fit deceleration in phase 1 is about 1 order of magnitude larger than that in phase 2. When applying the kmTII method to 14 DH-km CMEs, we found that combining the kmTII method with the ENLIL outputs improved the kmTII prediction. Due to a better modeling of plasma density upstream of shocks and the kmTII location, we are able to provide a more accurate shock time-distance and speed profiles. The mean kmTII prediction error using the ENLIL model density is 6.7±6.4 h; it is 8.4±10.4 h when the average solar wind plasma density is used. Applying the ENLIL density has reduced the mean kmTII prediction error by ∼2 h and the standard deviation by 4.0 h. Especially when we applied the combined approach to two interacting events, the kmTII prediction error was drastically reduced from 29.6 h to -4.9 h in one case and 10.6 h to 4.2 h in the other. Furthermore, the results derived from the kmTII method and the ENLIL simulation, together with white-light data, provide a valuable validation of shock formation location and strength. Such information has important implications for solar energetic particle acceleration. Title: A multiwavelength study of eruptive events on January 23, 2012 associated with a major solar energetic particle event Authors: Joshi, N. C.; Uddin, W.; Srivastava, A. K.; Chandra, R.; Gopalswamy, N.; Manoharan, P. K.; Aschwanden, M. J.; Choudhary, D. P.; Jain, R.; Nitta, N. V.; Xie, H.; Yashiro, S.; Akiyama, S.; Mäkelä, P.; Kayshap, P.; Awasthi, A. K.; Dwivedi, V. C.; Mahalakshmi, K. Bibcode: 2013AdSpR..52....1J Altcode: 2013arXiv1303.1251J We use multiwavelength data from space and ground based instruments to study the solar flares and coronal mass ejections (CMEs) on January 23, 2012 that were responsible for one of the largest solar energetic particle (SEP) events of solar cycle 24. The eruptions consisting of two fast CMEs (≈1400 km s-1 and ≈2000 km s-1) and M-class flares that occurred in active region 11402 located at ≈N28 W36. The two CMEs occurred in quick successions, so they interacted very close to the Sun. The second CME caught up with the first one at a distance of ≈11-12 Rsun. The CME interaction may be responsible for the elevated SEP flux and significant changes in the intensity profile of the SEP event. The compound CME resulted in a double-dip moderate geomagnetic storm (Dst∼-73nT). The two dips are due to the southward component of the interplanetary magnetic field in the shock sheath and the ICME intervals. One possible reason for the lack of a stronger geomagnetic storm may be that the ICME delivered a glancing blow to Earth. Title: An Automatic Detection Technique for Prominence Eruptions and Surges using SDO/AIA Images Authors: Yashiro, Seiji; Gopalswamy, N.; Makela, P.; Akiyama, S.; Sterling, A. C. Bibcode: 2013SPD....44...99Y Altcode: We present an automatic technique to detect and characterize eruptive events (EEs), e.g. prominence eruptions and surges, using SDO/AIA 304 Å images. The technique works as follows. 1) The SDO 304 Å images are polar-transformed for easy handling of the outward motion of EEs and for saving computer resources. 2) The transformed images are divided by a background map, which is determined as the minimum intensity of each pixel during 24 hours. 3) The EEs are defined as a region in the ratio maps with pixels having a ratio >2. Because a stationary prominence has relatively high background, the prominence is detected only when it moves. 4) Pattern recognition is performed to separate different EEs at different locations. 5) In successive images, two EEs with more than 50% of pixels overlapping are considered to be the same EE. 6) If the height of an EE increases monotonically in 5 successive images, we consider it as a reliable eruption. The technique detects 1428 prominence eruptions and 1921 surges from 2010 May to 2012 December. The locations of PEs identified by this technique clearly indicated decayed onset of the maximum phase in the south with respect to the north. This work was supported by NASA Living with a Star TR&T programAbstract (2,250 Maximum Characters): We present an automatic technique to detect and characterize eruptive events (EEs), e.g. prominence eruptions and surges, using SDO/AIA 304 Å images. The technique works as follows. 1) The SDO 304 Å images are polar-transformed for easy handling of the outward motion of EEs and for saving computer resources. 2) The transformed images are divided by a background map, which is determined as the minimum intensity of each pixel during 24 hours. 3) The EEs are defined as a region in the ratio maps with pixels having a ratio >2. Because a stationary prominence has relatively high background, the prominence is detected only when it moves. 4) Pattern recognition is performed to separate different EEs at different locations. 5) In successive images, two EEs with more than 50% of pixels overlapping are considered to be the same EE. 6) If the height of an EE increases monotonically in 5 successive images, we consider it as a reliable eruption. The technique detects 1428 prominence eruptions and 1921 surges from 2010 May to 2012 December. The locations of PEs identified by this technique clearly indicated decayed onset of the maximum phase in the south with respect to the north. This work was supported by NASA Living with a Star TR&T program Title: Solar Sources of Wide Coronal Mass Ejections during the Ascending Phase of Cycle 24 Authors: Akiyama, Sachiko; Gopalswamy, N.; Yashiro, S.; Makela, P. Bibcode: 2013SPD....44..130A Altcode: It is well known that fast and wide CMEs are generally involved in large solar energetic particle (SEP) events and are generally important in affecting the heliosphere. We examined the solar sources of all wide CMEs (width ≥ 60°) observed by SOHO/LASCO and STEREO/SECCHI in 2011 (ascending phase of solar cycle 24) by confirming the back-sided events using STEREO data. We identified 600 wide CMEs, of which 323 (54%) and 163 (27%) were associated with active region flares and eruptive quiescent filaments, respectively. In 88 cases (15%) only EUV dimmings were observed. The remaining 26 (4%) CMEs were of unknown origin, including 7 stealth CMEs. It is significant that about 1% of all wide CMEs do not have identifiable near-surface signatures. Considering only the front side CMEs, the median X-ray intensity associated with ARs and filament regions were C3.7 and C1.6, respectively. The average speeds of AR and quiescent-filament CMEs were, 537 and 373 km/s. We conclude that some the results of the previous solar cycles can be clarified because of the availability of STEREO data.Abstract (2,250 Maximum Characters): It is well known that fast and wide CMEs are generally involved in large solar energetic particle (SEP) events and are generally important in affecting the heliosphere. We examined the solar sources of all wide CMEs (width ≥ 60°) observed by SOHO/LASCO and STEREO/SECCHI in 2011 (ascending phase of solar cycle 24) by confirming the back-sided events using STEREO data. We identified 600 wide CMEs, of which 323 (54%) and 163 (27%) were associated with active region flares and eruptive quiescent filaments, respectively. In 88 cases (15%) only EUV dimmings were observed. The remaining 26 (4%) CMEs were of unknown origin, including 7 stealth CMEs. It is significant that about 1% of all wide CMEs do not have identifiable near-surface signatures. Considering only the front side CMEs, the median X-ray intensity associated with ARs and filament regions were C3.7 and C1.6, respectively. The average speeds of AR and quiescent-filament CMEs were, 537 and 373 km/s. We conclude that some the results of the previous solar cycles can be clarified because of the availability of STEREO data. Title: On the Solar Sources of Polar-crown Coronal Mass Ejections Authors: Gopalswamy, N.; Yashiro, S.; Akiyama, S. Bibcode: 2013SPD....44...83G Altcode: Coronal mass ejections (CMEs) from the polar crown filament region originate above 60-degree latitude during solar activity maxima. Cessation of these high-latitude CMEs marks the end of the maximum phase when the solar poles reverse their polarity. The eruption mechanism of these polar CMEs is not well understood: they originate from bipolar magnetic regions in contrast to the low-latitude ones, which may occur from both bipolar and multipolar regions. One of the key questions is whether the polar CMEs are associated with flare-like brightening and if so what the nature of the CME-flare relationship is. We investigated a number of polar CMEs, which do have post-eruption arcades (PEAs) observed in soft X-ray and EUV wavelengths. We combine data from the Solar Dynamics Observatory (SDO), the Solar Terrestrial Relations Observatory (STEREO), and the Solar Heliospheric Observatory (SOHO) to examine the flare-CME relationship in the case of polar crown CMEs. In particular, we measure the initial CME acceleration and compare it with the time-derivative of the PEA intensity to demonstrate a relationship akin to Neupert effect. The CME morphology, mass, and kinematics are similar to the low-latitude CMEs. The ratio of the thermal energy content of PEAs to the CME kinetic energy is very similar to that from low-latitude CMEs. Finally, the free energy estimated from photospheric magnetograms and the area covered by the PEAs, we find that the free energy is sufficient to power the CMEs and PEAs. Thus, we conclude that the polar-crown CMEs are fundamentally similar to the low-latitude CMEs and hence may have similar eruption mechanism. Title: Connecting Near-Sun CME flux Ropes to the 1-AU Flux Ropes using the Flare-CME Relationship Authors: Gopalswamy, N.; Xie, H.; Yashiro, S.; Akiyama, S. Bibcode: 2013SPD....4430001G Altcode: Coronal mass ejections (CMEs) and solar flares are closely related in various ways because the two phenomena are different manifestations of the same energy release in closed magnetic regions on the sun. Of particular interest is the relation between flare reconnection flux at the Sun and the poloidal flux of the 1-AU flux rope associated with the flare. If a flux rope forms due to flare reconnection, then the two fluxes are almost equal. The flare reconnection flux is normally computed from the flare-ribbon area and the photospheric field strength in the ribbon area. Here we report on another technique, which makes use of the area under the post-eruption arcade (PEA). We show that the reconnection flux derived from the PEA technique agrees with the one derived from flare ribbons. We also fit a flux rope to the white-light CME observations and derive the aspect ratio of the flux rope. Assuming self-similar expansion of the flux rope, we show that the magnetic content and size of the 1-AU flux rope can be predicted from the flare magnetic field (the average photospheric field strength within half of the PEA area) and the aspect ratio of the coronal flux rope. We illustrate the method with several examples. Title: Effect of CME interactions on SEP intensity: modeling the 2012-March-07 SEP event with ENLIL Authors: Xie, Hong; Gopalswamy, N.; St. Cyr, O. C. Bibcode: 2013SPD....44..125X Altcode: We performed a case study on the effect of CME interactions on SEP intensity for the 2012-March-07 SEP event. The 2012 March 07 SEP event had the second largest intensity during solar cycle 24. The SEP/ESP peak intensities peaked at 1500/6000 pfu. The event was associated with a double X-ray flare and two CMEs in quick succession. In soft X-rays, the flares reached peak flux levels of X5.4 (00:02 UT) and X1.1, respectively, from AR1429 (N18E31). The flare peaks were at ~00:24 and ~01:14 UT, while the onset times were 00:02 UT and 01:05 UT. The associated CMEs were very fast: 2376 km/s (CME1) and 2203 km/s (CME2) and appeared < 1 hour apart. Two distinct type II radio bursts were detected in the decameter-hectometric (DH) spectrum observed by the Wind/WAVES experiment. The interaction of two CMEs was clearly seen from STEREO COR2 B movie from West limb around 01:54 UT, with enhanced signature in DH type II spectrum around the same time. The two CMEs arrived at 21.5 Rs (inner boundary of ENLIL) at 01:55 UT and 02:40 UT, respectively, with flux-rope fitted propagation directions of N17E27 and N00E17. Two ENLIL runs were performed: 1) only CME1 was inserted at 21.5Rs and 2) both CME1 and CME2 were inserted in the simulation to study the effect of CME interactions. Comparing the results of the two runs, we found that both the shock intensity and shock speed of Run2 were higher than Run1, suggesting that the CME interaction have not only enhanced shock intensity but also caused higher speed, therefore resulting in larger SEP intensity. This work was supported by NASA Living with a Star TR&T programAbstract (2,250 Maximum Characters): We performed a case study on the effect of CME interactions on SEP intensity for the 2012-March-07 SEP event. The 2012 March 07 SEP event had the second largest intensity during solar cycle 24. The SEP/ESP peak intensities peaked at 1500/6000 pfu. The event was associated with a double X-ray flare and two CMEs in quick succession. In soft X-rays, the flares reached peak flux levels of X5.4 (00:02 UT) and X1.1, respectively, from AR1429 (N18E31). The flare peaks were at ~00:24 and ~01:14 UT, while the onset times were 00:02 UT and 01:05 UT. The associated CMEs were very fast: 2376 km/s (CME1) and 2203 km/s (CME2) and appeared < 1 hour apart. Two distinct type II radio bursts were detected in the decameter-hectometric (DH) spectrum observed by the Wind/WAVES experiment. The interaction of two CMEs was clearly seen from STEREO COR2 B movie from West limb around 01:54 UT, with enhanced signature in DH type II spectrum around the same time. The two CMEs arrived at 21.5 Rs (inner boundary of ENLIL) at 01:55 UT and 02:40 UT, respectively, with flux-rope fitted propagation directions of N17E27 and N00E17. Two ENLIL runs were performed: 1) only CME1 was inserted at 21.5Rs and 2) both CME1 and CME2 were inserted in the simulation to study the effect of CME interactions. Comparing the results of the two runs, we found that both the shock intensity and shock speed of Run2 were higher than Run1, suggesting that the CME interaction have not only enhanced shock intensity but also caused higher speed, therefore resulting in larger SEP intensity. This work was supported by NASA Living with a Star TR&T program Title: Observations of CMEs and models of the eruptive corona Authors: Gopalswamy, Nat Bibcode: 2013AIPC.1539....5G Altcode: 2013arXiv1304.0087G Current theoretical ideas on the internal structure of CMEs suggest that a flux rope is central to the CME structure, which has considerable observational support both from remote-sensing and in-situ observations. The flux-rope nature is also consistent with the post-eruption arcades with high-temperature plasmas and the charge states observed within CMEs arriving at Earth. The model involving magnetic loop expansion to explain CMEs without flux ropes is not viable because it contradicts CME kinematics and flare properties near the Sun. The flux rope is fast, it drives a shock, so the global picture of CMEs becomes complete if one includes the shock sheath to the CSHKP model. Title: Height of shock formation in the solar corona inferred from observations of type II radio bursts and coronal mass ejections Authors: Gopalswamy, N.; Xie, H.; Mäkelä, P.; Yashiro, S.; Akiyama, S.; Uddin, W.; Srivastava, A. K.; Joshi, N. C.; Chandra, R.; Manoharan, P. K.; Mahalakshmi, K.; Dwivedi, V. C.; Jain, R.; Awasthi, A. K.; Nitta, N. V.; Aschwanden, M. J.; Choudhary, D. P. Bibcode: 2013AdSpR..51.1981G Altcode: 2013arXiv1301.0893G Employing coronagraphic and EUV observations close to the solar surface made by the Solar Terrestrial Relations Observatory (STEREO) mission, we determined the heliocentric distance of coronal mass ejections (CMEs) at the starting time of associated metric type II bursts. We used the wave diameter and leading edge methods and measured the CME heights for a set of 32 metric type II bursts from solar cycle 24. We minimized the projection effects by making the measurements from a view that is roughly orthogonal to the direction of the ejection. We also chose image frames close to the onset times of the type II bursts, so no extrapolation was necessary. We found that the CMEs were located in the heliocentric distance range from 1.20 to 1.93 solar radii (Rs), with mean and median values of 1.43 and 1.38 Rs, respectively. We conclusively find that the shock formation can occur at heights substantially below 1.5 Rs. In a few cases, the CME height at type II onset was close to 2 Rs. In these cases, the starting frequency of the type II bursts was very low, in the range 25-40 MHz, which confirms that the shock can also form at larger heights. The starting frequencies of metric type II bursts have a weak correlation with the measured CME/shock heights and are consistent with the rapid decline of density with height in the inner corona. Title: Observations of the Highest Energy Particles from the Sun and the Identification of their Acceleration Mechanism Authors: Gopalswamy, Nat; Xie, H.; Yashiro, S. Bibcode: 2013shin.confE.142G Altcode: The highest energy ( GeV) particles accelerated by the Sun are the Ground Level Enhancement (GLE) in solar energetic particle (SEP) events during large solar eruptions. Extensive observations of GLE-associated coronal mass ejections (CMEs) during solar cycle 23 suggest that shocks forming very close to the Sun have sufficient time to accelerate GeV particles. The first GLE event of solar cycle 24 (on May 17, 2012) is consistent with the shock acceleration mechanism because the CME was very fast ( 2000 km/s), but the associated flare was rather weak (M-class flare). Gopalswamy et al. (2013, ApJ 765, L30) showed that the unfavorable B0 angle and non-radial motion of CMEs might have rendered the shock nose poorly connected to Earth in other similar or larger eruptions during solar cycle 24. In such non-GLE events, the latitudinal distance of the source region to the ecliptic was much larger than that in cycle-23 GLE events. In one case, even though the connectivity was not an issue, the shock seemed to be rather weak probably because of a higher Alfven speed in the ambient medium. Thus, GLE events require special conditions in terms of CME kinematics, coronal environment, and the magnetic connectivity of the solar source to an Earth observer. In this work, we examined the source locations of historical GLE events and found that the apparent higher-latitude GLE events indeed have favorable B0 angle and coronal-hole deflection toward the equator. We also examined additional large eruptions of cycle 24 and confirmed the importance of connectivity to Earth. Title: Near-Sun Flux-Rope Structure of CMEs Authors: Xie, H.; Gopalswamy, N.; St. Cyr, O. C. Bibcode: 2013SoPh..284...47X Altcode: 2012arXiv1212.1409X We have used the Krall flux-rope model (Krall and St. Cyr, Astrophys. J.2006, 657, 1740) (KFR) to fit 23 magnetic cloud (MC)-CMEs and 30 non-cloud ejecta (EJ)-CMEs in the Living With a Star (LWS) Coordinated Data Analysis Workshop (CDAW) 2011 list. The KFR-fit results shows that the CMEs associated with MCs (EJs) have been deflected closer to (away from) the solar disk center (DC), likely by both the intrinsic magnetic structures inside an active region (AR) and ambient magnetic structures (e.g. nearby ARs, coronal holes, and streamers, etc.). The mean absolute propagation latitudes and longitudes of the EJ-CMEs (18∘, 11∘) were larger than those of the MC-CMEs (11∘, 6∘) by 7∘ and 5∘, respectively. Furthermore, the KFR-fit widths showed that the MC-CMEs are wider than the EJ-CMEs. The mean fitting face-on width and edge-on width of the MC-CMEs (EJ-CMEs) were 87 (85)∘ and 70 (63)∘, respectively. The deflection away from DC and narrower angular widths of the EJ-CMEs have caused the observing spacecraft to pass over only their flanks and miss the central flux-rope structures. The results of this work support the idea that all CMEs have a flux-rope structure. Title: On the Relationship Between Metric and DH Type II Bursts Authors: Makela, P.; Gopalswamy, N.; Yashiro, S.; Akiyama, S.; Xie, H. Bibcode: 2013AGUSMSH52A..01M Altcode: The metric and decameter-hectometric (DH) type II radio bursts provide an opportunity to remotely observe the formation and propagation of shocks in the solar corona and in interplanetary (IP) space. However, the radio spectral observations give only limited information on the location of the source of the type II emission, which has led to a long-held controversy over whether the metric type II bursts are due to blast waves or CME-driven shocks. For example, metric type II bursts are occasionally observed to be coincidental with DH type II bursts. In these cases it has been suggested that the DH-component could be associated with a CME-driven shock and the m-component with a blast wave or unknown source, or that the DH-component originates from the nose of the CME-driven shock and the m-component from the shock flanks. In our presentation we use coronal Alfven speed profile, CME kinematics, and type II drift rate characteristics to provide a comprehensive explanation for the observed relationship between coronal and IP type II bursts. Title: The Solar Connection of Enhanced Heavy Ion Charge States in the Interplanetary Medium: Implications for the Flux-Rope Structure of CMEs Authors: Gopalswamy, N.; Mäkelä, P.; Akiyama, S.; Xie, H.; Yashiro, S.; Reinard, A. A. Bibcode: 2013SoPh..284...17G Altcode: 2012arXiv1212.0900G We investigated a set of 54 interplanetary coronal mass ejection (ICME) events whose solar sources are very close to the disk center (within ± 15∘ from the central meridian). The ICMEs consisted of 23 magnetic-cloud (MC) events and 31 non-MC events. Our analyses suggest that the MC and non-MC ICMEs have more or less the same eruption characteristics at the Sun in terms of soft X-ray flares and CMEs. Both types have significant enhancements in ion charge states, although the non-MC structures have slightly lower levels of enhancement. The overall duration of charge-state enhancement is also considerably smaller than that in MCs as derived from solar wind plasma and magnetic signatures. We find very good correlation between the Fe and O charge-state measurements and the flare properties such as soft X-ray flare intensity and flare temperature for both MCs and non-MCs. These observations suggest that both MC and non-MC ICMEs are likely to have a flux-rope structure and the unfavorable observational geometry may be responsible for the appearance of non-MC structures at 1 AU. We do not find any evidence for an active region expansion resulting in ICMEs lacking a flux-rope structure because the mechanism of producing high charge states and the flux-rope structure at the Sun is the same for MC and non-MC events. Title: Post-Eruption Arcades and Interplanetary Coronal Mass Ejections Authors: Yashiro, S.; Gopalswamy, N.; Mäkelä, P.; Akiyama, S. Bibcode: 2013SoPh..284....5Y Altcode: We compare the temporal and spatial properties of posteruption arcades (PEAs) associated with coronal mass ejections (CMEs) at the Sun that end up as magnetic cloud (MC) and non-MC events in the solar wind. We investigate the length, width, area, tilt angle, and formation time of the PEAs associated with 22 MC and 29 non-MC events and we find no difference between the two populations. According to current ideas on the relation between flares and CMEs, the PEA is formed together with the CME flux-rope structure by magnetic reconnection. Our results indicate that at the Sun flux ropes form during CMEs in association with both MC and non-MC events; however, for non-MC events the flux-rope structure is not observed in the interplanetary space because of the geometry of the observation, i.e. the location of the spacecraft when the structure passes through it. Title: Preface Authors: Gopalswamy, N.; Nieves-Chinchilla, T.; Hidalgo, M.; Zhang, J.; Riley, P.; van Driel-Gesztelyi, L.; Mandrini, C. H. Bibcode: 2013SoPh..284....1G Altcode: 2013arXiv1304.0085G This Topical Issue of Solar Physics, devoted to the study of flux-rope structure in coronal mass ejections (CMEs), is based on two Coordinated Data Analysis Workshops (CDAWs) held in 2010 (20 - 23 September in Dan Diego, California, USA) and 2011 (September 5-9 in Alcala, Spain). The primary purpose of the CDAWs was to address the question: Do all CMEs have flux rope structure? There are 18 papers om this topical issue, including this preface. Title: Propagation Characteristics of CMEs Associated with Magnetic Clouds and Ejecta Authors: Kim, R. -S.; Gopalswamy, N.; Cho, K. -S.; Moon, Y. -J.; Yashiro, S. Bibcode: 2013SoPh..284...77K Altcode: We have investigated the characteristics of magnetic cloud (MC) and ejecta (EJ) associated coronal mass ejections (CMEs) based on the assumption that all CMEs have a flux rope structure. For this, we used 54 CMEs and their interplanetary counterparts (interplanetary CMEs: ICMEs) that constitute the list of events used by the NASA/LWS Coordinated Data Analysis Workshop (CDAW) on CME flux ropes. We considered the location, angular width, and speed as well as the direction parameter, D. The direction parameter quantifies the degree of asymmetry of the CME shape in coronagraph images, and shows how closely the CME propagation is directed to Earth. For the 54 CDAW events, we found the following properties of the CMEs: i) the average value of D for the 23 MCs (0.62) is larger than that for the 31 EJs (0.49), which indicates that the MC-associated CMEs propagate more directly toward the Earth than the EJ-associated CMEs; ii) comparison between the direction parameter and the source location shows that the majority of the MC-associated CMEs are ejected along the radial direction, while many of the EJ-associated CMEs are ejected non-radially; iii) the mean speed of MC-associated CMEs (946 km s−1) is faster than that of EJ-associated CMEs (771 km s−1). For seven very fast CMEs (≥ 1500 km s−1), all CMEs with large D (≥ 0.4) are associated with MCs and the CMEs with small D are associated with EJs. From the statistical analysis of CME parameters, we found the superiority of the direction parameter. Based on these results, we suggest that the CME trajectory essentially determines the observed ICME structure. Title: Coronal Mass Ejections and Ground Level Enhancement Events Authors: Gopalswamy, N. Bibcode: 2013AGUSMSH33B..04G Altcode: Ground level enhancement (GLE) in solar energetic particle (SEP) events represent the production of GeV particles by the Sun during large solar eruptions. Although the GLE events were first detected in 1942 and reported by Scott Forbush (1946) a few years later, the mechanism for the production of these high-energy particles is not fully understood. GLEs were attributed to solar flares from the beginning, but after the discovery of coronal mass ejections (CMEs) in 1971, the possibility of CME-driven shocks accelerating GLE particles has also gained importance. Extensive CME observations in association with GLEs became available only during solar cycle 23, enabling a fresh look at the importance of CME-driven shocks. This paper presents a summary of CME properties obtained primarily from the Solar and Heliospheric Observatory (SOHO), which are fully consistent with shock acceleration of GLE particles. During solar cycle 24, there has been only one GLE event (on May 17, 2012) as of this writing. This is the first GLE event to be fully observed by the Solar Terrestrial Relations Observatory (STEREO) mission, providing critical information on CME kinematics that helped verify the results obtained for cycle 23 GLE events. In particular, it is confirmed that (i) the shock forms very close to the solar surface (within half a solar radius) and the GLE particles are released ~10 minutes later, and (ii) GLE events require special conditions in terms of CME kinematics, coronal environment, and the magnetic connectivity of the solar source to an Earth observer. Forbush, S. E., Three Unusual Cosmic-Ray Increases Possibly Due to Charged Particles from the Sun, Physical Review, 70, 771, 1946 Title: Comparison of Helicity Signs in Interplanetary CMEs and Their Solar Source Regions Authors: Cho, K. -S.; Park, S. -H.; Marubashi, K.; Gopalswamy, N.; Akiyama, S.; Yashiro, S.; Kim, R. -S.; Lim, E. -K. Bibcode: 2013SoPh..284..105C Altcode: If all coronal mass ejections (CMEs) have flux ropes, then the CMEs should keep their helicity signs from the Sun to the Earth according to the helicity conservation principle. This study presents an attempt to answer the question from the Coordinated Data Analysis Workshop (CDAW), "Do all CMEs have flux ropes?", by using a qualitative helicity sign comparison between interplanetary CMEs (ICMEs) and their CME source regions. For this, we select 34 CME-ICME pairs whose source active regions (ARs) have continuous SOHO/MDI magnetogram data covering more than 24 hr without data gap during the passage of the ARs near the solar disk center. The helicity signs in the ARs are determined by estimation of cumulative magnetic helicity injected through the photosphere in the entire source ARs. The helicity signs in the ICMEs are estimated by applying the cylinder model developed by Marubashi (Adv. Space. Res., 26, 55, 2000) to 16 second resolution magnetic field data from the MAG instrument onboard the ACE spacecraft. It is found that 30 out of 34 events (88 %) are helicity sign-consistent events, while four events (12 %) are sign-inconsistent. Through a detailed investigation of the source ARs of the four sign-inconsistent events, we find that those events can be explained by the local helicity sign opposite to that of the entire AR helicity (28 July 2000 ICME), incorrectly reported solar source region in the CDAW list (20 May 2005 ICME), or the helicity sign of the pre-existing coronal magnetic field (13 October 2000 and 20 November 2003 ICMEs). We conclude that the helicity signs of the ICMEs are quite consistent with those of the injected helicities in the AR regions from where the CMEs erupted. Title: Coronal Hole Influence on the Observed Structure of Interplanetary CMEs Authors: Mäkelä, P.; Gopalswamy, N.; Xie, H.; Mohamed, A. A.; Akiyama, S.; Yashiro, S. Bibcode: 2013SoPh..284...59M Altcode: 2013arXiv1301.2176M We report on the coronal hole (CH) influence on the 54 magnetic cloud (MC) and non-MC associated coronal mass ejections (CMEs) selected for studies during the Coordinated Data Analysis Workshops (CDAWs) focusing on the question if all CMEs are flux ropes. All selected CMEs originated from source regions located between longitudes 15E - 15W. Xie, Gopalswamy, and St. Cyr (2013, Solar Phys., doi:10.1007/s11207-012-0209-0) found that these MC and non-MC associated CMEs are on average deflected towards and away from the Sun-Earth line, respectively. We used a CH influence parameter (CHIP) that depends on the CH area, average magnetic field strength, and distance from the CME source region to describe the influence of all on-disk CHs on the erupting CME. We found that for CHIP values larger than 2.6 G the MC and non-MC events separate into two distinct groups where MCs (non-MCs) are deflected towards (away) from the disk center. Division into two groups was also observed when the distance to the nearest CH was less than 3.2×105 km. At CHIP values less than 2.6 G or at distances of the nearest CH larger than 3.2×105 km the deflection distributions of the MC and non-MCs started to overlap, indicating diminishing CH influence. These results give support to the idea that all CMEs are flux ropes, but those observed to be non-MCs at 1 AU could be deflected away from the Sun-Earth line by nearby CHs, making their flux rope structure unobservable at 1 AU. Title: The First Ground Level Enhancement Event of Solar Cycle 24: Direct Observation of Shock Formation and Particle Release Heights Authors: Gopalswamy, N.; Xie, H.; Akiyama, S.; Yashiro, S.; Usoskin, I. G.; Davila, J. M. Bibcode: 2013ApJ...765L..30G Altcode: 2013arXiv1302.1474G We report on the 2012 May 17 ground level enhancement (GLE) event, which is the first of its kind in solar cycle 24. This is the first GLE event to be fully observed close to the surface by the Solar Terrestrial Relations Observatory (STEREO) mission. We determine the coronal mass ejection (CME) height at the start of the associated metric type II radio burst (i.e., shock formation height) as 1.38 Rs (from the Sun center). The CME height at the time of GLE particle release was directly measured from a STEREO image as 2.32 Rs, which agrees well with the estimation from CME kinematics. These heights are consistent with those obtained for cycle-23 GLEs using back-extrapolation. By contrasting the 2012 May 17 GLE with six other non-GLE eruptions from well-connected regions with similar or larger flare sizes and CME speeds, we find that the latitudinal distance from the ecliptic is rather large for the non-GLE events due to a combination of non-radial CME motion and unfavorable solar B0 angle, making the connectivity to Earth poorer. We also find that the coronal environment may play a role in deciding the shock strength. Title: A High-frequency Type II Solar Radio Burst Associated with the 2011 February 13 Coronal Mass Ejection Authors: Cho, K. -S.; Gopalswamy, N.; Kwon, R. -Y.; Kim, R. -S.; Yashiro, S. Bibcode: 2013ApJ...765..148C Altcode: We examine the relationship between the high-frequency (425 MHz) type II radio burst and the associated white-light coronal mass ejection (CME) that occurred on 2011 February 13. The radio burst had a drift rate of 2.5 MHz s-1, indicating a relatively high shock speed. From SDO/AIA observations we find that a loop-like erupting front sweeps across high-density coronal loops near the start time of the burst (17:34:17 UT). The deduced distance of shock formation (0.06 Rs) from the flare center and speed of the shock (1100 km s-1) using the measured density from SDO/AIA observations are comparable to the height (0.05 Rs, from the solar surface) and speed (700 km s-1) of the CME leading edge observed by STEREO/EUVI. We conclude that the type II burst originates even in the low corona (<59 Mm or 0.08 Rs, above the solar surface) due to the fast CME shock passing through high-density loops. Title: Extremely Impulsive Eruption associated with an X-class Flare on 2012 October 23 Authors: Gopalswamy, N.; Yashiro, S.; Akiyama, S. Bibcode: 2013enss.confE.146G Altcode: Typically about 10% X-class solar flares are confined, i.e., they are not association with mass ejection or type II bursts in the metric and longer wavelengths. Failed eruptions are known to occur occasionally, indicating the weakness of the propelling force compared to the overlying restraining forces. Here we report an event on 2012 October 23 that is closer to an eruptive event: it was associated with a metric type II burst, EUV disturbance (SDO, STEREO) and an extremely brief CME in the STEREO coronagraphic field of view. This paper presents an analysis of the event showing that the EUV disturbance is close to a blast wave, but not quite. Model fitting indicates that the speed falls faster than that of a blast wave indicating a quick shutoff of the propelling force. We also compare this event with another eruptive event on 2012 January 27 that had a similar flare magnitude, but was accompanied by a huge CME with all the usual interplanetary disturbances. Title: Implications of Mass and Energy Loss due to Coronal Mass Ejections on Magnetically Active Stars Authors: Drake, Jeremy J.; Cohen, Ofer; Yashiro, Seiji; Gopalswamy, Nat Bibcode: 2013ApJ...764..170D Altcode: 2013arXiv1302.1136D Analysis of a database of solar coronal mass ejections (CMEs) and associated flares over the period 1996-2007 finds well-behaved power-law relationships between the 1-8 Å flare X-ray fluence and CME mass and kinetic energy. We extrapolate these relationships to lower and higher flare energies to estimate the mass and energy loss due to CMEs from stellar coronae, assuming that the observed X-ray emission of the latter is dominated by flares with a frequency as a function of energy dn/dE = kE -α. For solar-like stars at saturated levels of X-ray activity, the implied losses depend fairly weakly on the assumed value of α and are very large: \dot{M}∼ 5× 10^{-10} M_⊙ yr-1 and \dot{E}∼ 0.1 L_⊙. In order to avoid such large energy requirements, either the relationships between CME mass and speed and flare energy must flatten for X-ray fluence >~ 1031 erg, or the flare-CME association must drop significantly below 1 for more energetic events. If active coronae are dominated by flares, then the total coronal energy budget is likely to be up to an order of magnitude larger than the canonical 10-3 L bol X-ray saturation threshold. This raises the question of what is the maximum energy a magnetic dynamo can extract from a star? For an energy budget of 1% of L bol, the CME mass loss rate is about 5 × 10-11 M ⊙ yr-1. Title: Multi-wavelength diagnostics of thermal and non-thermal characteristics in 22 April 2011 confined flare Authors: Awasthi, Arun K.; Jain, Rajmal; Aschwanden, Markus J.; Uddin, Wahab; Srivastava, Abhishek K.; Chandra, Ramesh; Gopalswamy, Nat; Nitta, Nariaki; Yashiro, Seiji; Manoharan, P. K.; Prasad Choudhary, Debi; Joshi, N. C.; Dwivedi, Vidya Charan; Mahalakshmi, K. Bibcode: 2013ASInC...9...71A Altcode: We study the spatial, spectral and temporal characteristics of thermal and non-thermal emission in an M1.8 flare, which occurred in NOAA AR 11195 (S17E31) on 22 April 2011. This study quantifies spatial and temporal correlation of thermal and non-thermal emissions in precursor, impulsive as well as gradual phase of energy release employing multi-wavelength observation from SDO, HESSI and SOXS missions. Based on spectral fitting analysis performed on the X-ray emission observed by RHESSI as well as SOXS missions in low energy and high energy respectively, we define that <20 keV emission corresponds to thermal and >20 keV emission to be non-thermal counterpart of the emission. Therefore, we construct X-ray images employing RHESSI observation in energy bands 6-20 and 20-100 keV over the time integration of 30s. We report co-spatial X-ray emission in various phases of emission. We also report absence of non-thermal counterpart in the X-ray emission in precursor phase however visible at the commencement of main phase. To characterize thermal and non-thermal signatures, we overlay the X-ray image contours on the Hα and EUV observations from GONG and SDO/AIA respectively. We report thermal emission in the precursor phase to be co-spatial to UV counterpart. In contrast, we report absence of emission in the EUV wavebands i.e. 1600 and 1700 Å which, in principle, correspond to temperature minimum zone and photosphere during the precursor phase. This confirms the absence of non-thermal emission as appeared in X-ray emission during the precursor phase. Further, during the impulsive as well as in gradual phase, thermal and non-thermal emissions have been found to be originated from a compact source, co-spatial in nature. Analysis of Line of sight (LOS) magnetic field observations from SDO/HMI does not reveal noticeable changes in the positive and negative fluxes as well as magnetic-field gradient during this event. In contrast, Hα emission observed by GONG has revealed the filament eruption as the trigger of flare. This suggests filament eruption to be driver of this event, consistent with the CSHKP model of solar flare. Title: STEREO and SOHO contributions to coronal mass ejection studies: Some recent results Authors: Gopalswamy, N. Bibcode: 2013ASInC..10...11G Altcode: This paper summarizes some recent results on coronal mass ejections (CMEs) obtained from the Solar Terrestrial Relations Observatory (STEREO) that relate to previous results from the Solar and Heliospheric Observatory (SOHO). Making use of the extended field of view of the STEREO instruments and the capability to view solar eruptions from vantage points away from the Sun-Earth line, this paper addresses CME morphology and the early evolution of CMEs including shock formation indicated by type II radio bursts and EUV disturbances. In situ observations from STEREO locations and Sun-Earth L1 are used to provide evidence to support the idea that all CMEs in the interplanetary medium may be flux ropes. Finally, the use of shock-flux rope morphology to determine the heliospheric magnetic field is discussed. Title: Erratum: "Behavior of Solar Cycles 23 and 24 Revealed by Microwave Observations" (2012, ApJ, 750, L42) Authors: Gopalswamy, N.; Yashiro, S.; Mäkelä, P.; Michalek, G.; Shibasaki, K.; Hathaway, D. H. Bibcode: 2013ApJ...763L..24G Altcode: No abstract at ADS Title: Homologous Flare-CME Events with and without a metric type II radio burst Authors: Yashiro, S.; Gopalswamy, N.; Makela, P. A. Bibcode: 2012AGUFMSH43A2139Y Altcode: Active region NOAA 11158 produced many flares and CMEs during its disk passage, out of which at least two can be considered as homologous. The events are the C6.6 flare at 06:51 UT and C9.4 flare at 12:41 UT on February 14, 2011. Both flares occurred at the same location (eastern edge of the active region) and have a similar decay of the GOES soft X-ray light curve. The associated CMEs were slow (319 km/s and 337 km/s) and of similar widths (63 and 64 degree), but they had different radio signature. The second event was associated with a metric type II burst while the first one was not. The COR1 coronagraphs on board the STEREO spacecraft clearly show that the second CME propagated into the aftermath a preceding CME. These observations suggest that CME-CME interaction might be a key process in exciting the type II radio emission by slow CMEs. Title: A Space Weather Mission to the Earth's 5th Lagrangian Point (L5) Authors: Howard, R. A.; Vourlidas, A.; Ko, Y.; Biesecker, D. A.; Krucker, S.; Murphy, N.; Bogdan, T. J.; St Cyr, O. C.; Davila, J. M.; Doschek, G. A.; Gopalswamy, N.; Korendyke, C. M.; Laming, J. M.; Liewer, P. C.; Lin, R. P.; Plunkett, S. P.; Socker, D. G.; Tomczyk, S.; Webb, D. F. Bibcode: 2012AGUFMSA13D..07H Altcode: The highly successful STEREO mission, launched by NASA in 2006, consisted of two spacecraft in heliocentric orbit, one leading and one trailing the Earth and each separating from Earth at the rate of about 22.5 degrees per year. Thus the two spacecraft have been probing different probe/Sun/Earth angles. The utility of having remote sensing and in-situ instrumentation away from the Sun-Earth line was well demonstrated by STEREO. Here we propose the concept of a mission at the 5th Lagrangian "point" in the Earth/Sun system, located behind Earth about 60 degrees to the East of the Sun-Earth line. Such a mission would enable many aspects affecting space weather to be well determined and thus improving the prediction of the conditions of the solar wind as it impinges on geospace. For example, Coronal Mass Ejections can tracked for a significant distance toward Earth, new active regions can be observed before they become visible to the Earth observer, the solar wind can be measured before it rotates to Earth. The advantages of such a mission will be discussed in this presentation. Title: Tracking Solar Wind Input from the Sun to the Magnetosphere: 2007-2011 Authors: St Cyr, O. C.; Mays, M. L.; Xie, H.; Gopalswamy, N. Bibcode: 2012AGUFMSH43C..02S Altcode: During 2011 we were in the fortunate circumstance of having the twin STEREO spacecraft (Kaiser et al., 2008) pass through quadrature with the Sun-Earth line. As a result, the STEREO heliospheric imagers offer the possibility to track solar wind density features (e.g., CMEs and CIRs) from the Sun-to-Earth. We have examined all instances of Dst <-30 for this five year period, and we have identified the solar wind sources of these magnetospheric disturbances using remote sensing and in situ measurements. Title: Hot Precursor Ejecta and Other Peculiarities of the 2012 May 17 Ground Level Enhancement Event Authors: Gopalswamy, N.; Xie, H.; Nitta, N. V.; Usoskin, I.; Davila, J. M. Bibcode: 2012AGUFMSH21A2180G Altcode: We report on the first Ground Level Enhancement (GLE) event of Solar Cycle 24, which occurred on May 17, 2012 from a well-connected region (NOAA AR 11476, N11W76) on the Sun. There has been a real dearth of GLE events during cycle 24: even though the Sun has reached its solar maximum phase, it has produced only this one GLE event. Over the first 4.5 years of solar cycle 23, there were 5 GLE events, which is roughly a third of all the events of that cycle. The recent GLE event was associated with a moderate flare with an X-ray size of only M5.1, well below the median flare size (X3.8) of cycle 23 GLE events. On the other hand, the associated CME was very fast (~2000 km/s), typical of GLE events. During cycle 23, the CME speeds in GLE events ranged from 1203 km/s to 3675 km/s with an average value of 2083 km/s (Gopalswamy et al., 2012). The speed of the cycle 24 GLE was measured accurately because it was a limb event in the SOHO coronagraphic field of view. The CME was also observed by the STEREO coronagraphs, which helped derive the initial acceleration as 1.5 km/s/s, which is also typical of GLE-producing CMEs. We were also able to directly determine the heliocentric distance of the CME (2.3 solar radii (Rs)) at the time of the release of GLE particles because there was a STEREO/COR1 image precisely at the time of the particle release. This result is consistent with what was obtained for the cycle 23 GLE events, including the distance of the CME at the time of metric type II burst onset (1.3 Rs), indicating shock formation very close to the Sun ( ~0.3 Rs above the solar surface). We infer that the shock had to travel an additional 1 Rs before the GLE particles were released. The CME had a precursor in the form of a hot ejecta some tens of minutes before the main eruption. The preceding ejecta is termed hot because it was observed only in the 94 A images obtained by the Solar Dynamics Observatory (SDO). The 94 A images correspond to coronal a temperature of ~6MK. The lower temperature images such as at 193 A did not show the ejecta. The hot ejecta was accelerating and attained a speed of ~70 km/s before it was blasted by the big GLE-producing CMEs. We suggest that the hot material of the precursor ejecta might have been further accelerated by the CME-driven shock resulting in the GLE event. Reference Gopalswamy, N.,Xie, H., Yashiro, S., Akiyama, S., Mäkelä, P., Usoskin, I. G., Properties of Ground Level Enhancement Events and the Associated Solar Eruptions During Solar Cycle 23, Space Science reviews, DOI: 10.1007/s11214-012-9890-4 Title: Energetic particle and other space weather events of solar cycle 24 Authors: Gopalswamy, Nat Bibcode: 2012AIPC.1500...14G Altcode: 2012arXiv1208.3951G We report on the space weather events of solar cycle 24 in comparison with those during a similar epoch in cycle 23. We find major differences in all space weather events: solar energetic particles, geomagnetic storms, and interplanetary shocks. Dearth of ground level enhancement (GLE) events and major geomagnetic storms during cycle 24 clearly standout. The space weather events seem to reflect the less frequent solar eruptions and the overall weakness of solar cycle 24. Title: Properties of Ground Level Enhancement Events and the Associated Solar Eruptions During Solar Cycle 23 Authors: Gopalswamy, N.; Xie, H.; Yashiro, S.; Akiyama, S.; Mäkelä, P.; Usoskin, I. G. Bibcode: 2012SSRv..171...23G Altcode: 2012SSRv..tmp...38G; 2012arXiv1205.0688G Solar cycle 23 witnessed the most complete set of observations of coronal mass ejections (CMEs) associated with the Ground Level Enhancement (GLE) events. We present an overview of the observed properties of the GLEs and those of the two associated phenomena, viz., flares and CMEs, both being potential sources of particle acceleration. Although we do not find a striking correlation between the GLE intensity and the parameters of flares and CMEs, the solar eruptions are very intense involving X-class flares and extreme CME speeds (average ∼2000 km/s). An M7.1 flare and a 1200 km/s CME are the weakest events in the list of 16 GLE events. Most (80 %) of the CMEs are full halos with the three non-halos having widths in the range 167 to 212 degrees. The active regions in which the GLE events originate are generally large: 1290 msh (median 1010 msh) compared to 934 msh (median: 790 msh) for SEP-producing active regions. For accurate estimation of the CME height at the time of metric type II onset and GLE particle release, we estimated the initial acceleration of the CMEs using flare and CME observations. The initial acceleration of GLE-associated CMEs is much larger (by a factor of 2) than that of ordinary CMEs (2.3 km/s2 vs. 1 km/s2). We confirmed the initial acceleration for two events for which CME measurements are available in the inner corona. The GLE particle release is delayed with respect to the onset of all electromagnetic signatures of the eruptions: type II bursts, low frequency type III bursts, soft X-ray flares and CMEs. The presence of metric type II radio bursts some 17 min (median: 16 min; range: 3 to 48 min) before the GLE onset indicates shock formation well before the particle release. The release of GLE particles occurs when the CMEs reach an average height of ∼3.09 R s (median: 3.18 R s ; range: 1.71 to 4.01 R s ) for well-connected events (source longitude in the range W20-W90). For poorly connected events, the average CME height at GLE particle release is ∼66 % larger (mean: 5.18 R s ; median: 4.61 R s ; range: 2.75-8.49 R s ). The longitudinal dependence is consistent with shock accelerations because the shocks from poorly connected events need to expand more to cross the field lines connecting to an Earth observer. On the other hand, the CME height at metric type II burst onset has no longitudinal dependence because electromagnetic signals do not require magnetic connectivity to the observer. For several events, the GLE particle release is very close to the time of first appearance of the CME in the coronagraphic field of view, so we independently confirmed the CME height at particle release. The CME height at metric type II burst onset is in the narrow range 1.29 to 1.8 R s , with mean and median values of 1.53 and 1.47 R s . The CME heights at metric type II burst onset and GLE particle release correspond to the minimum and maximum in the Alfvén speed profile. The increase in CME speed between these two heights suggests an increase in Alfvénic Mach number from 2 to 3. The CME heights at GLE particle release are in good agreement with those obtained from the velocity dispersion analysis (Reames in Astrophys. J. 693:812, 2009a; Astrophys. J. 706:844, 2009b) including the source longitude dependence. We also discuss the implications of the delay of GLE particle release with respect to complex type III bursts by ∼18 min (median: 16 in; range: 2 to 44 min) for the flare acceleration mechanism. A similar analysis is also performed on the delay of particle release relative to the hard X-ray emission. Title: Determination of the Heliospheric Radial Magnetic Field from the Standoff Distance of a CME-driven Shock Observed by the STEREO Spacecraft Authors: Poomvises, Watanachak; Gopalswamy, Nat; Yashiro, Seiji; Kwon, Ryun-Young; Olmedo, Oscar Bibcode: 2012ApJ...758..118P Altcode: We report on the determination of radial magnetic field strength in the heliocentric distance range from 6 to 120 solar radii (R ⊙) using data from Coronagraph 2 (COR2) and Heliospheric Imager I (HI1) instruments on board the Solar Terrestrial Relations Observatory spacecraft following the standoff-distance method of Gopalswamy & Yashiro. We measured the shock standoff distance of the 2008 April 5 coronal mass ejection (CME) and determined the flux-rope curvature by fitting the three-dimensional shape of the CME using the Graduated Cylindrical Shell model. The radial magnetic field strength is computed from the Alfvén speed and the density of the ambient medium. We also compare the derived magnetic field strength with in situ measurements made by the Helios spacecraft, which measured the magnetic field at the heliocentric distance range from 60 to 215 R ⊙. We found that the radial magnetic field strength decreases from 28 mG at 6 R ⊙ to 0.17 mG at 120 R ⊙. In addition, we found that the radial profile can be described by a power law. Title: Preface Authors: Gopalswamy, N.; Nitta, N. V. Bibcode: 2012SSRv..171....1G Altcode: 2012SSRv..tmp...79G No abstract at ADS Title: Deflections of Fast Coronal Mass Ejections and the Properties of Associated Solar Energetic Particle Events Authors: Kahler, S. W.; Akiyama, S.; Gopalswamy, N. Bibcode: 2012ApJ...754..100K Altcode: The onset times and peak intensities of solar energetic particle (SEP) events at Earth have long been thought to be influenced by the open magnetic fields of coronal holes (CHs). The original idea was that a CH lying between the solar SEP source region and the magnetic footpoint of the 1 AU observer would result in a delay in onset and/or a decrease in the peak intensity of that SEP event. Recently, Gopalswamy et al. showed that CHs near coronal mass ejection (CME) source regions can deflect fast CMEs from their expected trajectories in space, explaining the appearance of driverless shocks at 1 AU from CMEs ejected near solar central meridian (CM). This suggests that SEP events originating in CME-driven shocks may show variations attributable to CH deflections of the CME trajectories. Here, we use a CH magnetic force parameter to examine possible effects of CHs on the timing and intensities of 41 observed gradual E ~ 20 MeV SEP events with CME source regions within 20° of CM. We find no systematic CH effects on SEP event intensity profiles. Furthermore, we find no correlation between the CME leading-edge measured position angles and SEP event properties, suggesting that the widths of CME-driven shock sources of the SEPs are much larger than the CMEs. Independently of the SEP event properties, we do find evidence for significant CME deflections by CH fields in these events. Title: The Relationship Between the Expansion Speed and Radial Speed of CMEs Confirmed Using Quadrature Observations of the 2011 February 15 CME Authors: Gopalswamy, N.; Makela, P.; Yashiro, S.; Davila, J. M. Bibcode: 2012SunGe...7....7G Altcode: 2012arXiv1205.0744G It is difficult to measure the true speed of Earth-directed CMEs from a coronagraph along the Sun-Earth line because of the occulting disk. However, the expansion speed (the speed with which the CME appears to spread in the sky plane) can be measured by such coronagraph. In order to convert the expansion speed to radial speed (which is important for space weather applications) one can use empirical relationship between the two that assumes an average width for all CMEs. If we have the width information from quadrature observations, we can confirm the relationship between expansion and radial speeds derived by Gopalswamy et al. (2009a). The STEREO spacecraft were in qudrature with SOHO (STEREO-A ahead of Earth by 87oand STEREO-B 94obehind Earth) on 2011 February 15, when a fast Earth-directed CME occurred. The CME was observed as a halo by the Large-Angle and Spectrometric Coronagraph (LASCO) on board SOHO. The sky-plane speed was measured by SOHO/LASCO as the expansion speed, while the radial speed was measured by STEREO-A and STEREO-B. In addition, STEREO-A and STEREO-B images measured the width of the CME, which is unknown from Earth view. From the SOHO and STEREO measurements, we confirm the relationship between the expansion speed (Vexp) and radial speed (Vrad) derived previously from geometrical considerations (Gopalswamy et al. 2009a): Vrad=1/2 (1 + cot w)Vexp, where w is the half width of the CME. STEREO-B images of the CME, we found that CME had a full width of 7 6o, so w=3 8o. This gives the relation as Vrad=1.1 4 Vexp. From LASCO observations, we measured Vexp=897 km/s, so we get the radial speed as 10 2 3 km/s. Direct measurement of radial speed yields 945 km/s (STEREO-A) and 105 8 km/s (STEREO-B). These numbers are different only by 7.6 % and 3.4 % (for STEREO-A and STEREO-B, respectively) from the computed value. Title: Dependence of solar proton events on their associated activities: Coronal mass ejection parameters Authors: Park, J.; Moon, Y. -J.; Gopalswamy, N. Bibcode: 2012JGRA..117.8108P Altcode: 2012JGRA..11708108P In this study we have examined the occurrence probability of solar proton events (SPEs) and their peak fluxes depending on coronal mass ejection (CME) parameters, linear speed (V), angular width (AW), and location (L). For this we used the NOAA SPE list and their associated CME data from 1997 to 2006. We found that the probability strongly depends on CME speed and angular width as follows. The highest association (36.1%) is found for the full halo CMEs with V ≥ 1500 kms-1 but the lowest association (0.9%) is found for the partial halo CMEs with 400 kms-1 ≤ V < 1000 kms-1. The SPE occurrence probabilities are different as much as 4.9 to 23 times according to CME speed and 1.6 to 6.5 times to angular width. The probabilities depending on CME speed and location increase from the eastern region to the western region and with speed. We have also examined the relationship between CME speed and SPE flux as well as its dependence on angular width (partial halo and full halo), longitude (east, center, and west) and direction parameter (<0.4 and ≥0.4). Our results show that the relationships strongly depend on longitude as well as direction parameter. Title: Radio-loud CMEs from the disk center lacking shocks at 1 AU Authors: Gopalswamy, N.; MäKelä, P.; Akiyama, S.; Yashiro, S.; Xie, H.; MacDowall, R. J.; Kaiser, M. L. Bibcode: 2012JGRA..117.8106G Altcode: 2012arXiv1207.0021G; 2012JGRA..11708106G A coronal mass ejection (CME) associated with a type II burst and originating close to the center of the solar disk typically results in a shock at Earth in 2-3 days and hence can be used to predict shock arrival at Earth. However, a significant fraction (about 28%) of such CMEs producing type II bursts were not associated with shocks at Earth. We examined a set of 21 type II bursts observed by the Wind/WAVES experiment at decameter-hectometric (DH) wavelengths that had CME sources very close to the disk center (within a central meridian distance of 30 degrees), but did not have a shock at Earth. We find that the near-Sun speeds of these CMEs average to ∼644 km/s, only slightly higher than the average speed of CMEs associated with radio-quiet shocks. However, the fraction of halo CMEs is only ∼30%, compared to 54% for the radio-quiet shocks and 91% for all radio-loud shocks. We conclude that the disk-center radio-loud CMEs with no shocks at 1 AU are generally of lower energy and they drive shocks only close to the Sun and dissipate before arriving at Earth. There is also evidence for other possible processes that lead to the lack of shock at 1 AU: (i) overtaking CME shocks merge and one observes a single shock at Earth, and (ii) deflection by nearby coronal holes can push the shocks away from the Sun-Earth line, such that Earth misses these shocks. The probability of observing a shock at 1 AU increases rapidly above 60% when the CME speed exceeds 1000 km/s and when the type II bursts propagate to frequencies below 1 MHz. Title: On the Oscillatory and Non-oscillatory Loop Systems and Dynamical Processes during the X2.1 Solar Flare on 06 September 2011 Authors: Srivastava, Abhishek K.; Jain, Rajmal; Prasad Choudhary, Debi; Charan Dwivedi, Vidya; Aschwanden, Markus; Nitta, Nariaki; Gopalswamy, Nat; Awasthi, Arun Kumar; Chandra, Ramesh; Kayshap, Pradeep; Joshi, N. C.; Manoharan, P. K.; Norris, Max; Makela, Pertti; Mahalakshmi, K.; Elamathi, E. Bibcode: 2012cosp...39.1882S Altcode: 2012cosp.meet.1882S No abstract at ADS Title: Magnetic Flux Imbalance in Active Regions NOAA 11283 and NOAA 11302 Authors: Prasad Choudhary, Debi; Jain, Rajmal; Charan Dwivedi, Vidya; Aschwanden, Markus; Nitta, Nariaki; Gopalswamy, Nat; Awasthi, Arun Kumar; Chandra, Ramesh; Srivastava, Abhishek K.; Manoharan, P. K.; Norris, Max; Mahalakshmi, K.; Elamathi, E.; Uddin, Wahab; Yashiro, Seiji Bibcode: 2012cosp...39..334P Altcode: 2012cosp.meet..334P We investigate the magnetic flux imbalance of two active regions NOAA 11302 and NOAA 11283 during their disk passage. The active region NOAA 11302 appeared in the east limb on September 23, 2011 as beta-gamma complexity and produced 73 c-class, 27 M-class and 2 X-class flares many of which were associated with CMEs during the disk passage. The active region NOAA 11283 appeared on the east limb on September 1, 2011 as beta-gamma complexity and produced 16 c-class, 9 m-class and 2 x-class flares and CMEs. Both these active regions were of similar size but the evolution of magnetic complexity during their disk passage was very different. None of them made second disk passage. These two active regions represent two different class of activity. Among several reasons, the magnetic flux imbalance of the active regions result due to the presence of electric current with in the active regions. The high cadence full disk magnetograms obtained using the GONG and SDO-HMI instruments serve as the primary data source of this investigation. We relate the change in the magnetic flux imbalance with the flare occurrence in these two contrasting active regions. Title: Height of Shock Formation in the Solar Corona Inferred from Observations of Type II Radio Bursts and Coronal Mass Ejections Authors: Gopalswamy, Nat; Jain, Rajmal; Prasad Choudhary, Debi; Charan Dwivedi, Vidya; Aschwanden, Markus; Nitta, Nariaki; Awasthi, Arun Kumar; Srivastava, Abhishek K.; Joshi, N. C.; Manoharan, P. K.; Makela, Pertti; Mahalakshmi, K.; Elamathi, E.; Uddin, Wahab; Yashiro, Seiji; Akiyam, Sachiko Bibcode: 2012cosp...39..653G Altcode: 2012cosp.meet..653G No abstract at ADS Title: Multi-wavelength diagnostics of thermal and non-thermal sources in the 22 April 2011 flare event Authors: Awasthi, Arun Kumar; Jain, Rajmal; Prasad Choudhary, Debi; Charan Dwivedi, Vidya; Aschwanden, Markus; Nitta, Nariaki; Gopalswamy, Nat; Chandra, Ramesh; Srivastava, Abhishek K.; Kayshap, Pradeep; Joshi, N. C.; Manoharan, P. K.; Norris, Max; Mahalakshmi, K.; Elamathi, E.; Uddin, Wahab Bibcode: 2012cosp...39...75A Altcode: 2012cosp.meet...75A No abstract at ADS Title: Coronal Mass Ejections and Type II Radio Bursts from Active Region 11158 Authors: Yashiro, Seiji; Jain, Rajmal; Prasad Choudhary, Debi; Charan Dwivedi, Vidya; Aschwanden, Markus; Nitta, Nariaki; Gopalswamy, Nat; Awasthi, Arun Kumar; Chandra, Ramesh; Srivastava, Abhishek K.; Kayshap, Pradeep; Joshi, N. C.; Manoharan, P. K.; Makela, Pertti; Mahalakshmi, K.; Elam, E. Bibcode: 2012cosp...39.2205Y Altcode: 2012cosp.meet.2205Y The NOAA active region (AR) 11158 emerged at around S20E50 on 2011 February 10 as two bipoles and quickly developed into a large complex region. During 2011 February 13-17, AR 11158 produced 48 flares (>C1 level) including the first X-class flare of 15 February, 2011 in solar cycle 24. The 48 flares can be divided into four groups based on their location within the AR. We examined their associations of coronal mass ejections (CMEs) and metric type II radio bursts in order to find preferred locations of both the phenomena. We found that, out of 48 flares, 15 had associated CMEs, occurring frequently at the eastern edge of the AR. We also found that six flares were associated with type II radio bursts and all of them were associated with CMEs also. No type II was associated with the CME-less flare. This suggests that the CME association is a necessary condition for a flare to be associated with a metric type II burst. Title: The 3-D structure of CMEs as Inferred from Coronagraph Observations Authors: Gopalswamy, Nat Bibcode: 2012cosp...39..649G Altcode: 2012cosp.meet..649G Although the 3-D nature of coronal mass ejections (CMEs) has been suspected for a long time, it is only after the launch of the Solar Terrestrial Relations Observatory (STEREO) mission that it became possible to directly observe such structures. The twin instrument suite of the STEREO mission combined with the Solar and Heliospheric Observatory (SOHO) instruments helped enormously in obtaining the 3-D structure of CMEs. One of the earliest revelations is the confirmation that halo CMEs are like normal CMEs, except that they are viewed head on (or tail on) and are generally more energetic than the normal CMEs. EUV observations from STEREO and from the Solar Dynamics Observatory (SDO) also reveal the hemispheric nature of the early-phase shock-driving CMEs. STEREO coronagraphs provided broad-side views of such CMEs, so it became possible to estimate the width of the halo CMEs and hence validate CME cone models. In particular, the quadrature observations that became possible in 2010 and 2011 when the STEREO spacecraft were separated from the Sun-Earth line by about 90 degrees, revealed that CMEs are generally cone-shaped. Current theoretical ideas on the internal structure of CMEs suggest that a flux rope is central to the CME structure, which has considerable observational support. The cone model can be reconciled with the flux-rope structure with certain requirements on the thickness of the rope legs. The quadrature observations also helped us understand the relation between the radial and expansion speeds of CMEs, which were only known from empirical relations in the past. This paper highlights some key results obtained using observations from the declining phase of solar cycle 23 and the rise phase of solar cycle 24. Title: Inferences on the Behavior of Solar Cycle 24 from the Polar Coronal Hole Enhancement and the Rate of Prominence Eruptions Observed by the Nobeyama Radioheliograph Authors: Gopalswamy, Nat; Yashiro, Seiji; Akiyama, Sachiko; Shibasaki, Kiyoto Bibcode: 2012cosp...39..651G Altcode: 2012cosp.meet..651G After a prolonged minimum at the end of the solar cycle 23, solar activity picked up, but generally at low levels. One of the indicators of the level of activity is the rate of prominence eruptions (PEs) automatically detected in the images obtained by the Nobeyama Radioheliograph (NoRH). The relation between PEs and coronal mass ejections (CMEs) has a specific characteristic during solar minima: The PE latitude is generally higher than that of the associated CME nose indicating a general equatorward deflection of CMEs. The overall extent of the offset seems to be similar during the rise phases of cycle 23 and 24, but there are far fewer PEs during cycle 24. The open field lines emanating from the polar coronal hole are thought to deflect CMEs away from the polar region. It is found that the offset starts in the year 2007, roughly two years before the deepest solar minimum and continued into the rise phase of the solar cycle 24. A significant north-south asymmetry is observed in the deflection process, which can be explained by the different behavior of the north and south polar coronal holes. We also constructed NoRH microwave butterfly diagram using 17 GHz images, which reveal that the solar activity has reached the maximum phase in the north pole. This is further confirmed by the latitudes of prominence eruptions reminiscent of the maximum phase. Title: A Study of the 12 June 2010 C6.1/SF flare associated with a CME, surge and energetic particles Authors: Uddin, Wahab; Jain, Rajmal; Manoharan, P. K.; Prasad Choudhary, Debi; Charan Dwivedi, Vidya; Aschwanden, Markus; Nitta, Nariaki; Gopalswamy, Nat; Awasthi, Arun Kumar; Chandra, Ramesh; Srivastava, Abhishek K.; Kayshap, Pradeep; Joshi, N. C.; Norris, Max; Makela, Pertti; Mahalaksh, K. Bibcode: 2012cosp...39.2026U Altcode: 2012cosp.meet.2026U In this paper, we present the multiwavelength analysis of the C6.1/SF flare on 12 June 2010 from NOAA AR 11081. The flare was observed by various ground based (ARIES H-alpha; HIRAS Radio) and space borne observatories (SDO, STEREO, SOHO, GOES). The flare was accompanied by a spray/surge and a slow coronal mass ejection (CME) that propagated with a speed of ~382 km/s. The eruption was associated with a weak solar energetic particle (SEP) event. The solar source of the eruption was a rapid emerging flux region. The eruption was also associated with the three major types of radio bursts (type II, III and IV). The interesting observation is the shock production (type II burst and SEP event) by a relatively slow CME. We interpret the results in the light of existing theories. Title: Global Cooperation in the Capacity Building Activities on Sun-Earth Connection Studies Authors: Gopalswamy, Nat; Davila, Joseph; Luebken, Franz-Josef; Shepherd, Marianna; Tsuda, Toshitaka Bibcode: 2012cosp...39..650G Altcode: 2012cosp.meet..650G The importance of global cooperation in Sun-Earth connection studies can be readily seen in the formation of a number of international collaborative programs such as the Climate and Weather of the Sun Earth System (CAWSES) by SCOSTEP* and the International Space Weather Initiative (ISWI). ISWI is the continuation of the successful International Heliophysical Year (IHY) program. These programs have brought scientists together to tackle issues of solar-terrestrial phenomena. An important element of these organizations is capacity building activities, which include deployment of low-cost ground based instruments for Sun-Earth connection studies and training young people (scientists and graduate students) from developing countries to operate these instruments and become members of the international solar-terrestrial scientific community. The training also helps young people to make use of data from the vast array of space and ground based instruments currently available for Sun-Earth connection studies. This paper presents a summary of CAWSES and ISWI activities that promote space Sun-Earth connection studies via complementary approaches in international scientific collaborations, capacity building, and public outreach. *Scientific Committee on Solar Terrestrial Physics (SCOSTEP) is an Interdisciplinary Body of the International Council for Science with representations from COSPAR, IAU, IUGG/IAGA, IUPAP, IAMAS, SCAR, and URSI (http://www.yorku.ca/scostep) Title: The location of solar metric type II radio bursts with respect to the associated coronal mass ejections Authors: Ramesh, R.; Gopalswamy, Nat; Lakshmi, Anna M.; Kathiravan, C. Bibcode: 2012cosp...39.1549R Altcode: 2012cosp.meet.1549R No abstract at ADS Title: A Global View of the Energetic Solar Eruptions during 2012 January 19-27 Authors: Gopalswamy, Nat; Davila, Joseph; Kaiser, Michael; Macdowall, Robert; Cyr, Chris; Xie, Hong; Makela, Pertti; Yashiro, Seiji; Poomvises, Watanachak Bibcode: 2012cosp...39..652G Altcode: 2012cosp.meet..652G The rise phase of solar cycle was generally unremarkable and subdued in terms of large solar eruptive events that had significant heliospheric consequences. Towards the end of the rise phase, a series of three coronal mass ejections (CMEs) originated from NOAA active region 11402 that were accompanied by M or X-class flares, significant solar energetic particle events (including the largest event as of this writing), interplanetary type II radio bursts, and shocks. While the particle radiation was very intense in two events, the plasma impact on the magnetosphere was moderate. This paper provides an overview of the eruptive events, focusing on the kinematic evolution of the CMEs in relation to the interplanetary type II radio bursts and shocks. In particular we compare the drift rate variation of the interplanetary type II bursts with the speed variation of the CMEs obtained from heliospheric imaging. We make use of data from the Solar and Heliospheric Observatory (SOHO), Solar Terrestrial Relations Observatory (STEREO), Solar Dynamics Observatory (SDO), Wind, GOES, and ground based observatories for this investigation. Title: Solar Energetic Particle Events and Associated CMEs during the Rising Phases of Solar Cycle 23 and 24 - A Comparative study Authors: Chandra, Ramesh; Jain, Rajmal; Prasad Choudhary, Debi; Charan Dwivedi, Vidya; Aschwanden, Markus; Nitta, Nariaki; Gopalswamy, Nat; Awasthi, Arun Kumar; Srivastava, Abhishek K.; Kayshap, Pradeep; Joshi, N. C.; Manoharan, P. K.; Makela, Pertti; Mahalakshmi, K.; Elamathi, E.; Uddi, Wahab Bibcode: 2012cosp...39..303C Altcode: 2012cosp.meet..303C No abstract at ADS Title: Flare and CME Productivity of Active Region 11429 Authors: Yashiro, Seiji; Gopalswamy, N.; Akiyama, S.; Michalek, G.; Makela, P. Bibcode: 2012shin.confE.161Y Altcode: Active region NOAA 11429 produced 3 X- and 15 M-class flares duringMarch 2 to 13. We examined their CME association using SOHO/LASCO andSTEREO/COR1 and found that 8 flares were CME-associated and theremaining 10 were CME-less. We found that the 10 CME-less flaresoccurred successively between 19 UT on March 5 and 22 UT on March 6. Theintensities of the flares were relatively low (range: M1.0 - M2.1;median: M1.3), but the occurrence rate was very high (at 3-hourintervals on average). During this period a CME erupted from thesouthern edge of this region but the X-ray enhancement was not detectedby GOES. The CME-associated flares are relatively intense (range: M2.0 -X5.4; median M8.1), and the waiting times (intervals between successiveflares) are longer ( 36 hours on average) than those of the CME-lessflares. We present a comprehensive view of flare-CME activities of theactive region 11429 and discuss the difference of the CME-associated andCME-less flares. Title: The Location of Solar Metric Type II Radio Bursts with Respect to the Associated Coronal Mass Ejections Authors: Ramesh, R.; Lakshmi, M. Anna; Kathiravan, C.; Gopalswamy, N.; Umapathy, S. Bibcode: 2012ApJ...752..107R Altcode: Forty-one solar type II radio bursts located close to the solar limb (projected radial distance r >~ 0.8 R ⊙) were observed at 109 MHz by the radioheliograph at the Gauribidanur observatory near Bangalore during the period 1997-2007. The positions of the bursts were compared with the estimated location of the leading edge (LE) of the associated coronal mass ejections (CMEs) close to the Sun. 38/41 of the type II bursts studied were located either at or above the LE of the associated CME. In the remaining 3/41 cases, the burst was located behind the LE of the associated CME at a distance of <0.5 R ⊙. Our results suggest that nearly all the metric type II bursts are driven by the CMEs. Title: A study of cold-high density materials in ICMEs Authors: Akiyama, Sachiko; Gopalswamy, Nat; Yashiro, Seiji; Kim, Rok-Soon; Mäkelä, Pertti; Xie, Hong; Marubashi, Katsuhide Bibcode: 2012shin.confE.136A Altcode: Eruptive prominence (EP) is dynamic and is well known as the core of coronal mass ejections (CMEs) near the Sun. Reports of filament material in in-situ observations are rare, even though EPs are identified as a solar source of an interplanetary CMEs. We studied cold high-density material in 54 ICMEs (1997 - 2006), whose solar source was located within 15 degrees from the disk center. All events were part of the Living with a Star (LWS) Coordinated Data-Analysis Workshop (CDAW) known as the 'Flux Rope CDAW', which took place in 2012 and 2011. Using SXT, EIT, TRACE and Ha data, we carefully checked the solar sources to see whether EPs including filament disappearances were observed coincidently or not. We found 33 (21) CME-ICME pairs associated with (without) EPs. Then we selected cold high-density bumps within the overall interval of the ICMEs, which satisfied the following conditions: 1) There is a proton and He++ density increase for more than two hours. 2) Maximum proton temperature remains lower than the average temperature of the ICME. 3) Exclude density increases at the boundary between sheath and ICME. 4) In cases where the ICME is followed by another ICME or a corotating interaction region, exclude the density increase at the rear boundary. With these criteria, we found 20 (10) cold high-density material in ICMEs with (without) EPs. We found that the average proton and He++ density increases in ICMEs associated with EP (15.8 and 0.56 /cm^3) are larger than in ICMEs associated with non-EPs (10.7 and 0.34 /cm^3). There is no preferred location of the density increase during the ICME. Average location of increase is near the center of the ICME. Title: Behavior of Solar Cycles 23 and 24 Revealed by Microwave Observations Authors: Gopalswamy, N.; Yashiro, S.; Mäkelä, P.; Michalek, G.; Shibasaki, K.; Hathaway, D. H. Bibcode: 2012ApJ...750L..42G Altcode: 2012arXiv1204.2816G Using magnetic and microwave butterfly diagrams, we compare the behavior of solar polar regions to show that (1) the polar magnetic field and the microwave brightness temperature during solar minimum substantially diminished during the cycle 23/24 minimum compared to the 22/23 minimum. (2) The polar microwave brightness temperature (Tb) seems to be a good proxy for the underlying magnetic field strength (B). The analysis indicates a relationship, B = 0.0067Tb - 70, where B is in G and Tb in K. (3) Both the brightness temperature and the magnetic field strength show north-south asymmetry most of the time except for a short period during the maximum phase. (4) The rush-to-the-pole phenomenon observed in the prominence eruption (PE) activity seems to be complete in the northern hemisphere as of 2012 March. (5) The decline of the microwave brightness temperature in the north polar region to the quiet-Sun levels and the sustained PE activity poleward of 60oN suggest that solar maximum conditions have arrived at the northern hemisphere. The southern hemisphere continues to exhibit conditions corresponding to the rise phase of solar cycle 24. Title: Comparison between Major Confined and Eruptive Flares Authors: Gopalswamy, N.; Yashiro, S.; Mäkelä, P.; Dennis, B. R. Bibcode: 2012AAS...22042402G Altcode: Statistical studies have shown that a large fraction of major solar flares (42% M-class and 15% X-class) are not associated with coronal mass ejections (CMEs). The CME-less flares are confined flares as opposed to the eruptive flares associated with CMEs. Confined flares are certainly good particle accelerators as inferred from intense microwave, hard X-ray, and gamma-ray emissions. Note that a single acceleration mechanism operates in confined flares, whereas eruptive flares can have both flare-resident and shock accelerations (the shock acceleration is due to energetic CMEs). In this paper, we report on a statistical study of more than two dozen confined flares with soft X-ray flare size exceeding M5 in comparison with a control sample of eruptive flares with similar soft X-ray flare size. We compare the microwave and X-ray emission characteristics in the two populations; these emissions correspond to sunward energy flow. For a given X-ray flare size, the microwave flux is scattered over a wider range for the eruptive flares when compared to the confined flares. We also compare the metric and longer wavelength radio bursts between the two populations; these emissions correspond to the flow of nonthermal electrons away from the Sun. We find that almost all the confined flares lack metric radio bursts, suggesting that there is very little flow of energy into the interplanetary medium. On the other hand, there is high degree of association between eruptive flares and metric radio bursts. This suggests that in confined flares the accelerated electrons have no access to open magnetic field lines. Finally, we examined the association of EUV waves with the two flare populations. While we find EUV waves in most of the eruptive flares, there was no confined flare with EUV waves. This suggests that CMEs is a necessary condition for the generation of global waves. Title: A Comparison of Solar Energetic Particle Events with 1 AU Magnetic Field Connections to Solar Coronal Holes Authors: Kahler, Stephen W.; Arge, C. N.; Akiyama, S.; Gopalswamy, N. Bibcode: 2012AAS...22020436K Altcode: The observed properties of solar energetic particle (SEP) events are known to depend on the source locations and speeds of their associated coronal mass ejections (CMEs). However, the CME characteristics cannot account for a great deal of the variability in SEP event intensities and time scales. It has long been suspected that the presence of coronal holes (CHs) near the CMEs or near the 1 AU magnetic footpoints may be an important factor in SEP events. We use a group of E 20 MeV SEP events with origins near solar central meridian to look for possible CH effects. The CH connections from 1 AU are determined from the 4-day forecast maps based on Mount Wilson Observatory and the National Solar Observatory synoptic magnetic field maps and the Wang-Sheeley-Arge model of solar wind propagation. The observed in situ magnetic field polarities and solar wind speeds at SEP event onsets test the forecast accuracies to select the best SEP/CH connection events for analysis. The SEP event properties are then compared with the relative locations and separations of the CMEs and the 1 AU footpoints to determine whether and how the CHs may affect SEP events. Title: CME-associated Radio Bursts from Satellite Observations Authors: Gopalswamy, Nat Bibcode: 2012AAS...22030403G Altcode: Coronal mass ejections (CMEs) are closely associated with various types of radio bursts from the Sun. All radio bursts are due to nonthermal electrons, which are accelerated during the eruption of CMEs. Radio bursts at frequencies below about 15 MHz are of particular interest because they are associated with energetic CMEs that contribute to severe space weather. The low-frequency bursts need to be observed primarily from space because of the ionospheric cutoff. The main CME-related radio bursts are associated are: type III bursts due to accelerated electrons propagating along open magnetic field lines, type II bursts due to electrons accelerated in shocks, and type IV bursts due to electrons trapped in post-eruption arcades behind CMEs. This paper presents a summary of results obtained during solar cycle 23 primarily using the white-light coronagraphic observations from the Solar Heliospheric Observatory (SOHO) and the WAVES experiment on board Wind. Particular emphasis will be placed on what we can learn about particle acceleration in the coronal and interplanetary medium by analyzing the CMEs and the associated radio bursts. Title: On the Relationship Between a High-frequency Type II Solar Radio Burst and Coronal Mass Ejection on February 13, 2011 Authors: Cho, Kyung-Suk; Gopalswamy, N.; Kwon, R.; Kim, R.; Yashiro, S. Bibcode: 2012AAS...22052502C Altcode: We examine the relationship between a metric type II radio burst that started from an unusually high frequency of 425 MHz (fundamental component) and the associated white-light coronal mass ejection on 2011 February 11. The radio burst had a drift rate of 3 MHz/sec, indicating a relatively high shock speed. The question we would like to answer is whether the high frequency type II burst is generated by the CME. To avoid the ambiguity normally caused by the use of density models in the analysis of type II bursts, we measure the coronal electron density by applying automated emission measure analysis code developed by Aschwanden et al. (2011) to AIA/SDO images in 6 coronal filters. From SDO AIA observations we find that a loop-like erupting front sweeps across high density coronal loops near the start time of the burst (17:34:15 UT). The deduced height of shock formation (1.2 Rs) from the measured density is comparable to the height (1.15 Rs) of the CME observed by STEREO/EUVI. Thus we conclude that the high frequency type II burst could be generated at locations where the CME passes through the high density loops in the low corona. Title: Propagation Characteristics of CMEs Associated Magnetic Clouds and Ejecta Authors: Kim, Roksoon; Gopalswamy, N.; Cho, K.; Moon, Y.; Yashiro, S. Bibcode: 2012AAS...22052108K Altcode: We have investigated the characteristics of magnetic cloud (MC) and ejecta (EJ) associated coronal mass ejections (CMEs) based on the assumption that all CMEs have a flux rope structure. For this, we used 54 CMEs and their interplanetary counter parts (interplanetary CMEs: ICMEs) that constitute the list of events used by the NASA/LWS Coordinated Data Analysis Workshop (CDAW) on CME flux ropes. We considered the location, angular width, speed, and direction parameter, D, that quantifies the propagation direction of a CME. For the 54 CDAW events, we found several properties of the CMEs as follows: (1) the average value of D for the 23 MCs (0.62) is larger than that for the 31 EJs (0.49), which indicates that the MC-associated CMEs propagate more directly to the Earth than the EJ-associated CMEs; (2) comparison between the direction parameter and the source location shows that the majority of the MC-associated CMEs are ejected along the radial direction, while many of the EJ-associated CMEs are ejected non-radially; (3) the mean speed of MC-associated CMEs (946 km/s) is faster than that of EJ-associated CMEs (771 km/s). For seven very fast CMEs (> 1500 km/s), all CMEs with large D (> 0.4) are associated with MCs and the CMEs with small D are associated with EJs. On the basis of these results, we suggest that the CME trajectory essentially decides the observed ICME structure. Title: Factors affecting the intensity of solar energetic particle events Authors: Gopalswamy, Nat Bibcode: 2012AIPC.1436..247G Altcode: 2011arXiv1109.2933G This paper updates the influence of environmental and source factors of shocks driven by coronal mass ejections (CMEs) that are likely to influence the solar energetic particle (SEP) events. The intensity variation due to CME interaction reported in [1] is confirmed by expanding the investigation to all the large SEP events of solar cycle 23. The large SEP events are separated into two groups, one associated with CMEs running into other CMEs, and the other with CMEs running into the ambient solar wind. SEP events with CME interaction generally have a higher intensity. New possibilities such as the influence of coronal holes on the SEP intensity are also discussed. For example, the presence of a large coronal hole between a well-connected eruption and the solar disk center may render the shock poorly connected because of the interaction between the CME and the coronal hole. This point is illustrated using the 2004 December 3 SEP event delayed by about 12 hours from the onset of the associated CME. There is no other event at the Sun that can be associated with the SEP onset. This event is consistent with the possibility that the coronal hole interaction influences the connectivity of the CMEs that produce SEPs, and hence the intensity of the SEP event. Title: Erratum to: Relation Between Type II Bursts and CMEs Inferred from STEREO Observations Authors: Gopalswamy, N.; Thompson, W. T.; Davila, J. M.; Kaiser, M. L.; Yashiro, S.; Mäkelä, P.; Michalek, G.; Bougeret, J. -L.; Howard, R. A. Bibcode: 2012SoPh..277..459G Altcode: 2011SoPh..tmp..421G; 2011SoPh..tmp..425G No abstract at ADS Title: Coronal mass ejection-driven shocks and the associated sudden commencements/sudden impulses Authors: Veenadhari, B.; Selvakumaran, R.; Singh, Rajesh; Maurya, Ajeet K.; Gopalswamy, N.; Kumar, Sushil; Kikuchi, T. Bibcode: 2012JGRA..117.4210V Altcode: 2012JGRA..11704210V Interplanetary (IP) shocks are mainly responsible for the sudden compression of the magnetosphere, causing storm sudden commencement (SC) and sudden impulses (SIs) which are detected by ground-based magnetometers. On the basis of the list of 222 IP shocks compiled by Gopalswamy et al. (2010), we have investigated the dependence of SC/SIs amplitudes on the speed of the coronal mass ejections (CMEs) that drive the shocks near the Sun as well as in the interplanetary medium. We find that about 91% of the IP shocks were associated with SC/SIs. The average speed of the SC/SI-associated CMEs is 1015 km/s, which is almost a factor of 2 higher than the general CME speed. When the shocks were grouped according to their ability to produce type II radio burst in the interplanetary medium, we find that the radio-loud (RL) shocks produce a much larger SC/SI amplitude (average ∼32 nT) compared to the radio-quiet (RQ) shocks (average ∼19 nT). Clearly, RL shocks are more effective in producing SC/SIs than the RQ shocks. We also divided the IP shocks according to the type of IP counterpart of interplanetary CMEs (ICMEs): magnetic clouds (MCs) and nonmagnetic clouds. We find that the MC-associated shock speeds are better correlated with SC/SI amplitudes than those associated with non-MC ejecta. The SC/SI amplitudes are also higher for MCs than ejecta. Our results show that RL and RQ type of shocks are important parameters in producing the SC/SI amplitude. Title: Understanding shock dynamics in the inner heliosphere with modeling and Type II radio data: The 2010-04-03 event Authors: Xie, H.; Odstrcil, D.; Mays, L.; St. Cyr, O. C.; Gopalswamy, N.; Cremades, H. Bibcode: 2012JGRA..117.4105X Altcode: 2012JGRA..11704105X The 2010 April 03 solar event was studied using observations from STEREO SECCHI, SOHO LASCO, and Wind kilometric Type II data (kmTII) combined with WSA-Cone-ENLIL model simulations performed at the Community Coordinated Modeling Center (CCMC). In particular, we identified the origin of the coronal mass ejection (CME) using STEREO EUVI and SOHO EIT images. A flux-rope model was fit to the SECCHI A and B, and LASCO images to determine the CME's direction, size, and actual speed. J-maps from STEREO COR2/HI-1/HI-2 and simulations from CCMC were used to study the formation and evolution of the shock in the inner heliosphere. In addition, we also studied the time-distance profile of the shock propagation from kmTII radio burst observations. The J-maps together with in-situ data from the Wind spacecraft provided an opportunity to validate the simulation results and the kmTII prediction. Here we report on a comparison of two methods of predicting interplanetary shock arrival time: the ENLIL model and the kmTII method; and investigate whether or not using the ENLIL model density improves the kmTII prediction. We found that the ENLIL model predicted the kinematics of shock evolution well. The shock arrival times (SAT) and linear-fit shock velocities in the ENLIL model agreed well with those measurements in the J-maps along both the CME leading edge and the Sun-Earth line. The ENLIL model also reproduced most of the large scale structures of the shock propagation and gave the SAT prediction at Earth with an error of ∼1 ± 7 hours. The kmTII method predicted the SAT at Earth with an error of ∼15 hours when using n0 = 4.16 cm-3, the ENLIL model plasma density near Earth; but it improved to ∼2 hours when using n0 = 6.64 cm-3, the model density near the CME leading edge at 1 AU. Title: Comparison of Dst forecast models for intense geomagnetic storms Authors: Ji, Eun-Young; Moon, Y. -J.; Gopalswamy, N.; Lee, D. -H. Bibcode: 2012JGRA..117.3209J Altcode: 2012JGRA..11703209J We have compared six Dst forecast models using 63 intense geomagnetic storms (Dst ≤ -100 nT) that occurred from 1998 to 2006. For comparison, we estimated linear correlation coefficients and RMS errors between the observed Dst data and the predicted Dst during the geomagnetic storm period as well as the difference of the value of minimum Dst (ΔDstmin) and the difference in the absolute value of Dst minimum time (ΔtDst) between the observed and the predicted. As a result, we found that the model by Temerin and Li (2002, 2006) gives the best prediction for all parameters when all 63 events are considered. The model gives the average values: the linear correlation coefficient of 0.94, the RMS error of 14.8 nT, the ΔDstmin of 7.7 nT, and the absolute value of ΔtDst of 1.5 hour. For further comparison, we classified the storm events into two groups according to the magnitude of Dst. We found that the model of Temerin and Lee (2002, 2006) is better than the other models for the events having -100 ≤ Dst < -200 nT, and three recent models (the model of Wang et al. (2003), the model of Temerin and Li (2002, 2006), and the model of Boynton et al. (2011b)) are better than the other three models for the events having Dst ≤ -200 nT. Title: Magnetic Field Strength in the Upper Solar Corona Using White-light Shock Structures Surrounding Coronal Mass Ejections Authors: Kim, R. -S.; Gopalswamy, N.; Moon, Y. -J.; Cho, K. -S.; Yashiro, S. Bibcode: 2012ApJ...746..118K Altcode: 2011arXiv1112.0288K To measure the magnetic field strength in the solar corona, we examined 10 fast (>=1000 km s-1) limb coronal mass ejections(CMEs) that show clear shock structures in Solar and Heliospheric Observatory/Large Angle and Spectrometric Coronagraph images. By applying the piston-shock relationship to the observed CME's standoff distance and electron density compression ratio, we estimated the Mach number, Alfvén speed, and magnetic field strength in the height range 3-15 solar radii (Rs ). The main results from this study are as follows: (1) the standoff distance observed in the solar corona is consistent with those from a magnetohydrodynamic model and near-Earth observations; (2) the Mach number as a shock strength is in the range 1.49-3.43 from the standoff distance ratio, but when we use the density compression ratio, the Mach number is in the range 1.47-1.90, implying that the measured density compression ratio is likely to be underestimated owing to observational limits; (3) the Alfvén speed ranges from 259 to 982 km s-1 and the magnetic field strength is in the range 6-105 mG when the standoff distance is used; (4) if we multiply the density compression ratio by a factor of two, the Alfvén speeds and the magnetic field strengths are consistent in both methods; and (5) the magnetic field strengths derived from the shock parameters are similar to those of empirical models and previous estimates. Title: Interplanetary shocks lacking type II radio bursts. Authors: Gopalswamy, N.; Xie, H.; Makela, P.; Akiyama, S.; Yashiro, S.; Kaiser, M. L.; Howard, R. A.; Bougeret, J. -L. Bibcode: 2012yCat..17101111G Altcode: No abstract at ADS Title: Coronal Magnetic Field Measurement from EUV Images Made by the Solar Dynamics Observatory Authors: Gopalswamy, Nat; Nitta, Nariaki; Akiyama, Sachiko; Mäkelä, Pertti; Yashiro, Seiji Bibcode: 2012ApJ...744...72G Altcode: 2011arXiv1109.2925G By measuring the geometrical properties of the coronal mass ejection (CME) flux rope and the leading shock observed on 2010 June 13 by the Solar Dynamics Observatory (SDO) mission's Atmospheric Imaging Assembly we determine the Alfvén speed and the magnetic field strength in the inner corona at a heliocentric distance of ~1.4 Rs. The basic measurements are the shock standoff distance (ΔR) ahead of the CME flux rope, the radius of curvature of the flux rope (R c), and the shock speed. We first derive the Alfvénic Mach number (M) using the relationship, ΔR/R c = 0.81[(γ-1) M 2 + 2]/[(γ+1)(M 2 - 1)], where γ is the only parameter that needed to be assumed. For γ = 4/3, the Mach number declined from 3.7 to 1.5 indicating shock weakening within the field of view of the imager. The shock formation coincided with the appearance of a type II radio burst at a frequency of ~300 MHz (harmonic component), providing an independent confirmation of the shock. The shock compression ratio derived from the radio dynamic spectrum was found to be consistent with that derived from the theory of fast-mode MHD shocks. From the measured shock speed and the derived Mach number, we found the Alfvén speed to increase from ~140 km s-1 to 460 km s-1 over the distance range 1.2-1.5 Rs. By deriving the upstream plasma density from the emission frequency of the associated type II radio burst, we determined the coronal magnetic field to be in the range 1.3-1.5 G. The derived magnetic field values are consistent with other estimates in a similar distance range. This work demonstrates that the EUV imagers, in the presence of radio dynamic spectra, can be used as coronal magnetometers. Title: Relation Between the 3D-Geometry of the Coronal Wave and Associated CME During the 26 April 2008 Event Authors: Temmer, M.; Veronig, A. M.; Gopalswamy, N.; Yashiro, S. Bibcode: 2012esrs.book..115T Altcode: We study the kinematical characteristics and 3D geometry of a large-scale coronal wave that occurred in association with the 26 April 2008 flare-CME event. The wave was observed with the EUVI instruments aboard both STEREO spacecraft (STEREO-A and STEREO-B) with a mean speed of ∼ 240 km s-1. The wave is more pronounced in the eastern propagation direction, and is thus, better observable in STEREO-B images. From STEREO-B observations we derive two separate initiation centers for the wave, and their locations fit with the coronal dimming regions. Assuming a simple geometry of the wave we reconstruct its 3D nature from combined STEREO-A and STEREO-B observations. We find that the wave structure is asymmetric with an inclination toward East. The associated CME has a deprojected speed of ∼ 750±50 km s-1, and it shows a non-radial outward motion toward the East with respect to the underlying source region location. Applying the forward fitting model developed by Thernisien, Howard, and Vourlidas (Astrophys. J. 652, 763, 2006), we derive the CME flux rope position on the solar surface to be close to the dimming regions. We conclude that the expanding flanks of the CME most likely drive and shape the coronal wave. Title: The relation between coronal holes and coronal mass ejections during the rise, maximum, and declining phases of Solar Cycle 23 Authors: Mohamed, A. A.; Gopalswamy, N.; Yashiro, S.; Akiyama, S.; Mäkelä, P.; Xie, H.; Jung, H. Bibcode: 2012JGRA..117.1103M Altcode: 2012JGRA..11701103M We study the interaction between coronal holes (CHs) and coronal mass ejections (CMEs) using a resultant force exerted by all the coronal holes present on the disk and is defined as the coronal hole influence parameter (CHIP). The CHIP magnitude for each CH depends on the CH area, the distance between the CH centroid and the eruption region, and the average magnetic field within the CH at the photospheric level. The CHIP direction for each CH points from the CH centroid to the eruption region. We focus on Solar Cycle 23 CMEs originating from the disk center of the Sun (central meridian distance ≤15°) and resulting in magnetic clouds (MCs) and non-MCs in the solar wind. The CHIP is found to be the smallest during the rise phase for MCs and non-MCs. The maximum phase has the largest CHIP value (2.9 G) for non-MCs. The CHIP is the largest (5.8 G) for driverless (DL) shocks, which are shocks at 1 AU with no discernible MC or non-MC. These results suggest that the behavior of non-MCs is similar to that of the DL shocks and different from that of MCs. In other words, the CHs may deflect the CMEs away from the Sun-Earth line and force them to behave like limb CMEs with DL shocks. This finding supports the idea that all CMEs may be flux ropes if viewed from an appropriate vantage point. Title: CME Parameter Input to ENLIL: LASCO halo cone versus STEREO measurements Authors: St Cyr, O. C.; Orlove, M.; Xie, H.; Gilbert, H. R.; Odstrcil, D.; Gopalswamy, N.; Mays, M. L.; Quirk, C. A.; Henning, C. Bibcode: 2011AGUFMSH33B2046S Altcode: ENLIL is a well-known model in the solar-helio community (Odstrcil and Pizzo, 1999) and is frequently used to predict the arrival of coronal mass ejections (CMEs) at Earth based on observations from the SOHO LASCO coronagraphs. The halo CME parameters needed to drive ENLIL are the CME size, speed, and direction, and these are typically derived from fitting a "cone model" to the LASCO CME images to drive interplanetary disturbances through the inner heliosphere (Xie et al., 2004). But as seen from a single vantage point along the Sun-Earth line, it is difficult to determine these projected CME parameters unambiguously (e.g., Gopalswamy et al., 2009). Over the past few years we have been in the fortunate circumstance of having the twin STEREO spacecraft (Kaiser et al., 2008) at quadrature with the Sun-Earth line, so we can compare directly the validity of the cone model with actual measurements of the CMEs heading toward Earth. We report here on a comparison of more than twenty SOHO LASCO halo coronal mass ejections that were also observed by STEREO between 2008 and mid-2011. Title: What Controls the Magnetic Field Configuration of Interplanetary Coronal Mass Ejections ? Authors: Moon, Y.; Gopalswamy, N.; Kim, R.; Xie, H.; Yashiro, S. Bibcode: 2011AGUFMSH51A1994M Altcode: In this work we address the question of the classification of interplanetary coronal mass ejections (ICMEs): magnetic cloud (MC) or ejecta (EJ). Using 186 shock-associated ICMEs from 1997 to 2006, we have examined three possible causes : (1) magnetic complexity characterized by sunspot number, (2) CME direction characterized by CME angular distance (the angle between the CME cone axis and the sky plane), and (3) CME-CME interaction characterized by the number of halo CMEs. First, the annual fraction of MC is poorly anti-correlated (R=-0.36) with annual sunspot number. Second, more than half of the CMEs that originated near the central meridian produced EJs and the distribution of CME angular distance for 38 EJs is not much different from that for 16 MCs. Third, the annual fraction of MC is well anti-correlated (R=-0.78) with the annual number of halo CMEs. In addition, we also searched for candidate of interacting CMEs according to temporal and spatial closeness by considering all halo CMEs during the same period. As a result, we find that the annual fraction of interacting CMEs is well correlated (R=0.87) with the annual number of the halo CMEs as well as anti-correlated (R=-0.85) with the annual fraction of MCs. The contingency table between CME-CME interaction and MC occurrence also shows a good statistical result (Prediction of detection 'yes' is 0.88, and Critical Success Index is 0.62), which is better than that for the halo CME-storm relationship. Our results imply that the CME interaction is mainly responsible for their observed structure (MC or EJ) in the interplanetary medium. Title: CME Productivity of Active Regions 11158 and 11166 Authors: Yashiro, S.; Gopalswamy, N.; Akiyama, S.; Makela, P. A. Bibcode: 2011AGUFMSH13B1965Y Altcode: Active regions (ARs) 11158 and 11166 respectively produced an X-class flare on 2011 Feb 15 and March 9. The former flare was associated with a CME, but the latter one was not. We examined the CME productivity of the two active regions. AR 11158 emerged at around 3 UT on 2011 Feb 10. The first major flare from the active region was the M6.6 flare at 17:28 on Feb 13 which was associated with a CME. The CME productivity was very high on Feb 14 and 15. Out of 11 flares (>C3 level), 10 had an associated CMEs. The CME productivity suddenly dropped on Feb 18. There were 2 M- and 4 C-class flares but none of them had an associated CME. AR 11166 emerged on Feb 25 on the far side of the Sun and appeared on the east limb on March 2. One X-, four M-, and 16 upper C-class (C3-C9) flares occurred during the disk passage. The CME productivity of the AR was not low since 11 out of 20 M- and C-class flares had an associated CME. The X1.5 flare lacking an associated CME is very special in terms of the CME productivity of the AR 11166. We discuss the reason why the X flare lacked a CME. Title: Type II Radio Bursts as an Indicator of CME Location Authors: Quirk, C. A.; St Cyr, O. C.; Henning, C.; Xie, H.; Gilbert, H. R.; Orlove, M.; Gopalswamy, N.; Odstrcil, D. Bibcode: 2011AGUFMSH33B2047Q Altcode: We examined a subset of nine low-frequency radio events with type II radio bursts that drifted below 2 megahertz and were detected by the WAVES investigation on the WIND spacecraft. For each event, we identified the associated coronal mass ejection (CME) and derived the electron density using a model of solar wind plasma frequency (fp ≈ 9 * ne1/2, where fp is plasma frequency in kHz and ne is electron density in cm-3) . We also used the pb_inverter program in SolarSoft developed by Howard and Hayes to examine the electron density structure. Expanding on the Van De Hulst process of inverting polarized brightness measurements, the program inverts total brightness measurements from SOHO LASCO images to extract electron density information. From the electron density inferred from radio spectra, we derived the location of the CME using five standard electron density to height models (Leblanc, 1996; Saito, 1977; Bougeret, 1984; Alvarez, 1973; and Fainberg, 1971). Using images from the LASCO instrument on SOHO and the SECCHI instrument on STEREO, we extracted locations of the leading edge of the CME and compared the heights and velocities to those found using the frequency data. For the lowest frequency events, we also compared our results to the outputs of ENLIL, a time-dependent, three-dimensional, MHD model of the heliosphere hosted by the Community Coordinated Modeling Center (CCMC) at NASA Goddard Space Flight Center. Title: Location of Coronal and IP Type II Burst Source Regions from Radio and White-light Observations Authors: Makela, P. A.; Gopalswamy, N.; Yashiro, S. Bibcode: 2011AGUFMSH23A1947M Altcode: We present our preliminary results on the locations of source regions of the type II radio bursts in the metric (m) and dekameter-hectometric (DH) wavelength range. Type II bursts are occasionally observed to consist of two temporally overlapping lanes of metric and DH bursts. It has been suggested that the DH-component could be associated with a CME-driven shock and the m-component with a blast wave or unknown source, or that the DH-component originates from the shock nose and the m-component from the shock flanks. In our study we used time-height measurements of the associated coronal mass ejections (CMEs) to estimate speeds at various position angles (PAs) along the CME front. We also estimated plasma densities at the same PAs in the corona from inversion of polarized brightness (pB) images of SOHO/LASCO coronagraphs. These measurements suggest that both the m and DH-components can be explained reasonably well with a single CME-driven shock as their source. Title: Earth-Affecting Solar Causes Observatory (EASCO): A Heliophysics Mission at the Sun-Earth L5 Authors: Gopalswamy, N.; Easco Team Bibcode: 2011AGUFMSH22A..04G Altcode: The wealth of knowledge accumulated on coronal mass ejections over the past decade primarily comes from the SOHO and STEREO missions. Unfortunately, these missions lacked some key measurements. For example, STEREO did not have a magnetograph and SOHO did not have an in-situ magnetometer. From the Sun-Earth line, SOHO was not well-suited for observing Earth-directed CMEs because of the occulting disk. STEREO's angle with the Sun-Earth line is changing constantly, so only a limited number of Earth-directed CMEs were observed in profile. The next generation Heliophysics mission should overcome these deficiencies and observe the Sun from a vantage point different from the Sun-Earth line. The Sun-Earth Lagrange point L5 is well suited for stationing such a mission. Such a mission would provide broad-side view of Earth directed CMEs and the shocks if the CMEs are fast enough. Additionally, corotating interaction regions (CIRs), which also cause adverse space weather, first arrive at L5 and a few days later at Earth, thus providing excellent prediction opportunity based on in-situ measurements at L5. Solar sources (active regions, coronal holes) of these large-scale disturbances can be observed more than a week before they rotate to Earth View. A suite of ten instruments (seven remote-sensing in X-ray, EUV, optical, and radio wavelengths and 3 in situ for plasma, magnetic field, and energetic particles) would constitute an ideal scientific payload. Recently an L5 mission concept known as the Earth-Affecting Solar Causes Observatory (EASCO) (Gopalswamy et al., 2011) was studied at the Mission Design Laboratory (MDL) of NASA's Goddard Space Flight Center. The aim of the MDL study was to see how the scientific payload consisting of ten instruments can be accommodated in the spacecraft bus, what propulsion system can transfer the payload to the Sun-Earth L5, and what launch vehicles are appropriate. The study found that all the ten instruments can be readily accommodated and can be launched using an intermediate size vehicle such as Taurus II with enhanced faring. The study also found that a hybrid propulsion system consisting of an ion thruster (using ~55 kg of Xenon) and hydrazine (~10 kg) is adequate to position the spacecraft at L5. The transfer to L5 will take about 2 years and the science mission will last for 4 years around the next solar maximum in 2025. The mission can be readily extended for another solar cycle to get a solar-cycle worth of data on Earth-affecting CMEs and CIRs. This paper describes the EASCO mission, the scientific payload, and the results of the MDL study. Reference: Gopalswamy, N. et al., Earth-Affecting Solar Causes Observatory (EASCO): A potential International Living with a Star Mission from Sun-Earth L5, J. Atmospheric and Solar-Terrestrial Physics, 73, 658, 2011 Title: First direct observational evidence of a CME deflection by coronal hole on 15 February 2011 and a comparison with computations Authors: Mohamed, A. A.; Gopalswamy, N. Bibcode: 2011AGUFMSH23A1950M Altcode: It has been shown that coronal holes (CHs) can deflect a coronal mass ejection (CME) away or towards the Sun-Earth line depending on their relative location (Gopalswamy et al., 2009). This effect can be described using a coronal-hole influence parameter (CHIP), which depends on the CH area, the distance between the CH and the eruption region, and the magnetic field strength within the CH at the photospheric level. We have direct observation of CME deflection during the 2011February 15 CME, which was associated with an X2.2 flare (S21W21) on 01:44 UT from STEREO/COR1 and COR2 observations. The CHIP is computed for the 2011 February 15 CME to be 0.73 G with a deflection angle of 62o. We use the 193 Å AIA image from the Solar Dynamics Observatory (SDO) for CH identification and SDO/HMI for determining the magnetic field strength inside the CH. The largest CH (centroid at S59W15)) was close to the CME eruption region (S21W21). We measured the deflection angle as 38o, using STEREO/COR2 images. This deflection angle is not too different from that obtained from the coronal hole observations. Title: High Angular Resolution Imaging of Solar Radio Bursts from the Lunar Surface Authors: MacDowall, R. J.; Lazio, J.; Bale, S.; Burns, J. O.; Farrell, W. M.; Gopalswamy, N.; Jones, D. L.; Kasper, J. C.; Weiler, K. Bibcode: 2011AGUFM.P13D1738M Altcode: Locating low frequency radio observatories on the lunar surface has a number of advantages, including positional stability and a very low ionospheric radio cutoff. Here, we describe the Radio Observatory on the Lunar Surface for Solar studies (ROLSS), a concept for a low frequency, radio imaging interferometric array designed to study particle acceleration in the corona and inner heliosphere. ROLSS would be deployed during an early lunar sortie or by a robotic rover as part of an unmanned landing. The preferred site is on the lunar near side to simplify the data downlink to Earth. The prime science mission is to image type II and type III solar radio bursts with the aim of determining the sites at and mechanisms by which the radiating particles are accelerated. Secondary science goals include constraining the density of the lunar ionosphere by measuring the low radio frequency cutoff of the solar radio emissions or background galactic radio emission, measuring the flux, particle mass, and arrival direction of interplanetary and interstellar dust, and constraining the low energy electron population in astrophysical sources. Furthermore, ROLSS serves a pathfinder function for larger lunar radio arrays. Key design requirements on ROLSS include the operational frequency and angular resolution. The electron densities in the solar corona and inner heliosphere are such that the relevant emission occurs below 10 MHz, essentially unobservable from Earth's surface due to the terrestrial ionospheric cutoff. Resolving the potential sites of particle acceleration requires an instrument with an angular resolution of at least 2 deg at 10 MHz, equivalent to a linear array size of approximately one kilometer. The major components of the ROLSS array are 3 antenna arms, each of 500 m length, arranged in a Y formation, with a central electronics package (CEP) at their intersection. Each antenna arm is a linear strip of polyimide film (e.g., Kapton) on which 16 single polarization dipole antennas are located by depositing a conductor (e.g., silver). The arms also contain transmission lines for carrying the radio signals from the science antennas to the CEP. Operations would consist of data acquisition during the lunar day, with data downlinks to Earth one or more times every 24 hours. This work is supported in part by the NASA Lunar Science Institute via Cooperative Agreement NNA09DB30A with the LUNAR team. Title: From SOHO to STEREO: Understanding Propagation of Coronal Mass Ejections Authors: Gopalswamy, N. Bibcode: 2011AGUFMSH32A..08G Altcode: Direct comparison between coronal mass ejections (CMEs) from near the Sun and their solar wind counterparts became possible roughly a decade after the discovery of CMEs (Lindsay et al. 1999). This comparison revealed that fast CMEs decelerate and slow CMEs accelerate due to the interaction with the solar wind. Gopalswamy et al. (2000) quantified this interaction as an interplanetary acceleration which is useful in predicting the arrival time and speed of CMEs at 1 AU. The interplanetary acceleration is essentially due to the aerodynamic drag between the CME and the solar wind because the propelling force and the solar gravity are effective only near the Sun. Combined remote-sensing and in situ observations from SOHO and Wind/ACE have helped us estimate the influence of the solar wind on the propagation of CMEs. However, these measurements have severe limitations because the remote-sensed and in-situ observations correspond to different portions of the CME. Furthermore, the true speeds of Earth-directed CMEs cannot be measured accurately from a spacecraft located along the Sun-Earth line. There have been attempts to model the CME as a cone and get the space speed of the CME, which did improve the travel time predictions. Instruments on board the Solar Terrestrial Relations Observatory (STEREO) mission were able to provide observations of Earth-arriving CMEs without projection effects, while the same CMEs were observed at Sun-Earth L1 by Wind and ACE spacecraft. The quadrature between STEREO and L1 spacecraft presented an ideal situation to study the interplanetary evolution of CMEs and test earlier model results. The quadrature observations did improve the CME travel time predictions, but additional factors such as the unusually slow solar wind, CME cannibalism, and coronal-hole deflection need to be considered to reconcile the difference between observed and predicted travel times. This point is illustrated using the 2011 February 15 CME. References Gopalswamy, N. et al., Interplanetary acceleration of coronal mass ejections, Geophys. Res. Lett., 27, 145, 2000 Lindsay, G. et al., Relationships between coronal mass ejection speeds from coronagraph images and interplanetary characteristics of associated interplanetary coronal mass ejections, J. Geophys. Res., 104, 12515, 1999 Title: The Effects of Coronal Holes on the Time Profiles of Gradual Solar Energetic Particle Events Authors: Kahler, S. W.; Akiyama, S.; Gopalswamy, N. Bibcode: 2011AGUFMSH44A..06K Altcode: The onset times and peak intensities of solar energetic particle (SEP) events at Earth have long been thought to be influenced by the open magnetic fields of coronal holes (CHs). The basic idea is that when CHs lie between the solar SEP source region and the interplanetary magnetic field lines connecting the Earth to the Sun, there will be a delay in onset and/or a diminution in the peak intensity of the SEP event. Shen et al.(2006) found that neither CH proximity nor CH relative location produced any obvious effect on SEP peak intensities. However, Gopalswamy et al.(2009) have used SOHO/EIT CHs and a defined CH influence parameter to show that nearby CHs can deflect fast CMEs from their expected directions in space, explaining the appearance of driverless shocks at 1 AU from CMEs ejected near solar central meridian. Recent work has looked at the relation between CHs and CMEs over the rise, maximum, and declining phases of solar cycle 23. Here we use the CH locations and influence parameters to examine the effects of CHs on the timing and intensities of SEP events observed by the GOES and Wind spacecraft. We also include cases of fast CMEs that drive shocks but produce no or only weak SEP events at Earth. The goal is to use CH locations to help predict the SEP events produced by fast and wide CMEs. Title: The Radio Observatory on the Lunar Surface for Solar studies Authors: Lazio, T. Joseph W.; MacDowall, R. J.; Burns, Jack O.; Jones, D. L.; Weiler, K. W.; Demaio, L.; Cohen, A.; Paravastu Dalal, N.; Polisensky, E.; Stewart, K.; Bale, S.; Gopalswamy, N.; Kaiser, M.; Kasper, J. Bibcode: 2011AdSpR..48.1942L Altcode: The Radio Observatory on the Lunar Surface for Solar studies (ROLSS) is a concept for a near-side low radio frequency imaging interferometric array designed to study particle acceleration at the Sun and in the inner heliosphere. The prime science mission is to image the radio emission generated by Type II and III solar radio burst processes with the aim of determining the sites at and mechanisms by which the radiating particles are accelerated. Specific questions to be addressed include the following: (1) Isolating the sites of electron acceleration responsible for Type II and III solar radio bursts during coronal mass ejections (CMEs); and (2) Determining if and the mechanism(s) by which multiple, successive CMEs produce unusually efficient particle acceleration and intense radio emission. Secondary science goals include constraining the density of the lunar ionosphere by searching for a low radio frequency cutoff to solar radio emission and constraining the low energy electron population in astrophysical sources. Key design requirements on ROLSS include the operational frequency and angular resolution. The electron densities in the solar corona and inner heliosphere are such that the relevant emission occurs at frequencies below 10 MHz. Second, resolving the potential sites of particle acceleration requires an instrument with an angular resolution of at least 2°, equivalent to a linear array size of approximately 1000 m. Operations would consist of data acquisition during the lunar day, with regular data downlinks. No operations would occur during lunar night. ROLSS is envisioned as an interferometric array, because a single aperture would be impractically large. The major components of the ROLSS array are 3 antenna arms arranged in a Y shape, with a central electronics package (CEP) located at the center. The Y configuration for the antenna arms both allows for the formation of reasonably high dynamic range images on short time scales as well as relatively easy deployment. Each antenna arm is a linear strip of polyimide film (e.g., Kapton™) on which 16 science antennas are located by depositing a conductor (e.g., silver). The antenna arms can be rolled for transport, with deployment consisting of unrolling the rolls. Each science antenna is a single polarization dipole. The arms also contain transmission lines for carrying the radio signals from the science antennas to the CEP. The CEP itself houses the receivers for the science antennas, the command and data handling hardware, and, mounted externally, the downlink antenna. We have conducted two experiments relevant to the ROLSS concept. First, we deployed a proof-of-concept science antenna. Comparison of the impedance of the antenna feed points with simulations showed a high level of agreement, lending credence to the antenna concept. Second, we exposed a sample of space-qualified polyimide film, with a silver coating on one side, to temperature cycling and UV exposure designed to replicate a year on the lunar surface. No degradation of the polyimide film's material or electric properties was found. Both of these tests support the notion of using polyimide-film based antennas. The prime science mission favors an equatorial site, and a site on the limb could simplify certain aspects of the instrument design. A site on the lunar near side is sufficient for meeting the science goals. While the site should be of relatively low relief topography, the entire site does not have to be flat as the fraction of the area occupied by the antenna arms is relatively small (∼0.3%). Further, the antenna arms do not have to lay flat as deviations of ±1 m are still small relative to the observational wavelengths. Deployment could be accomplished either with astronauts, completely robotically, or via a combination of crewed and robotic means. Future work for the ROLSS concept includes more exhaustive testing of the radio frequency (RF) and environmental suitability of polyimide film-based science antennas, ultra-low power electronics in order to minimize the amount of power storage needed, batteries with a larger temperature range for both survival and operation, and rovers (robotic, crewed, or both) for deployment. The ROLSS array could also serve as the precursor to a larger array on the far side of the Moon for astrophysical and cosmological studies. Title: Understanding Shock Dynamics in the Inner Heliosphere with Modeling and Type II Radio Data: the 2010-04-03 event Authors: Xie, H.; Odstrcil, D.; Mays, M. L.; St Cyr, O. C.; Gopalswamy, N.; Cremades, H. Bibcode: 2011AGUFMSH33B2050X Altcode: The 2010 April 03 solar event was studied using observations from STEREO A and B SECCHI, SOHO LASCO, and kilometric type II data combined with the WSA-Cone-ENLIL model. In particular, we identified the origin of the coronal mass ejection (CME) using STEREO EUVI and SOHO EIT images. A flux-rope model fit to the SECCHI A and B, and LASCO images were used to determine the CME's direction, size, and actual speed. J-maps from STEREO COR2/HI-1/HI-2 and simulations from the ENLIL model were used to study the formation and evolution of the shock in the inner heliosphere. In addition, we also studied the time-distance profile of the shock propagation from kilometric type II (kmTII) radio burst observations. Here we report on a comparison of two methods of predicting interplanetary shock arrival time: the ENLIL model and the kmTII method; and investigate whether or not using the ENLIL model density improves the kmTII rediction. We found that the ENLIL model predicted the kinematics of shock evolution well. The shock arrival times (SAT) and linear fit shock velocities in the ENLIL model agreed well with those measurements in the J-maps along both the CME leading edge and the Sun-Earth line. The model also reproduced most of the large scale structures of the shock propagation and gave the SAT prediction at Earth with an error of 1.5 hours. The kmTII method predicted the SAT at Earth with an error of 8 hours when using the ENLIL model plasma density at near Earth; but it improved to 3 hours when using the model density near the CME leading edge at 1 AU. Title: Magnetic field strength in the upper solar corona using white-light shock structures surrounding coronal mass ejections Authors: Kim, R.; Gopalswamy, N.; Moon, Y.; Cho, K.; Yashiro, S. Bibcode: 2011AGUFMSH43B1955K Altcode: To measure the magnetic field strength in the solar corona, we examined 12 fast (> 1000 km s-1) limb CMEs which show clear shock-like structures in SOHO/LASCO observations. By applying piston-shock relationship to the observed CME's standoff distance and electron density compression ratio, we estimated the Mach number, Alfven speed, and magnetic field strength in the height range 3 to 15 solar radii (Rs). We found: (1) the standoff distance observed in the solar corona is consistent with those from a magnetohydrodynamic (MHD) model and near-Earth observations; (2) the Mach number as a shock strength is in the range 1.49 to 3.52 from the standoff distance data, but when we use the compression ratio, the Mach number is in the range 1.47 to 1.90, implying that the measured density compression ratio is likely to be underestimated due to observational limit; (3) the Alfven speed ranges from 259 to 982 km s-1 and the magnetic field strength is in the range 6 to 120 mG when the standoff distance is used; (4) if we multiply the density compression ratio by a factor of 2, the Alfven speeds and the magnetic field strengths are consistent in both methods; (5) the magnetic field strengths derived from the shock parameters are similar to those of empirical models and previous estimates. This is a new attempt to measure magnetic field strength in the upper corona up to 15 Rs from coronagraph observations alone. Our observations support the idea that the diffuse structures surrounding the CME front can be interpreted as shock structures. Title: Determination of the heliospheric radial magnetic field from the Standoff Distance of a CME-driven shock Observed by the STEREO spacecraft Authors: Poomvises, W.; Gopalswamy, N.; Yashiro, S. Bibcode: 2011AGUFMSH23A1948P Altcode: Recent work by Gopalswamy and Yashiro (2011) determined the radial coronal magnetic field strength from 6 to 23 solar radii (Rs) by measuring the standoff distance of a CME-driven shock observed in the coronagraphic field of view. We now extend their work to determine radial magnetic field strength in the heliocentric distance range 6 - 100 Rs using data from COR2 and HI 1 instruments onboard the STEREO spacecraft. We apply the Raytrace model (Thernisien 2006, 2009) to measure the shock standoff distance for the April 5, 2008 CME. In addition, we determine the flux rope curvature by fitting a circle to the CME. The ratio of the standoff distance to the radius of curvature is a known function of the shock Mach number and the adiabatic index. Thus we can obtain the shock Mach number, assuming the value of the adiabatic index. The Alfven velocity can then be calculated using the ambient solar wind velocity, shock velocity obtained from the height-time measurements, and the Mach number. Finally, the radial magnetic field trength is computed from the Alfven speed and the density of the ambient medium. We also compare the derived magnetic field strength with the in-situ measurements made by the Helios spacecraft, which measured the magnetic field in the distance range 60 - 215 Rs. We found that the magnetic field strength decreases from 17 mG at 6 Rs to 1 mG at 100 Rs. In addition, the radial profile can be described by a power law. Title: United Nations Basic Space Science Initiative: 2010 Status Report on the International Space Weather Initiative Authors: Gadimova, S.; Haubold, H. J.; Danov, D.; Georgieva, K.; Maeda, G.; Yumoto, K.; Davila, J. M.; Gopalswamy, N. Bibcode: 2011SunGe...6....7G Altcode: 2011arXiv1108.2247G The UNBSSI is a long-term effort for the development of astronomy and space science through regional and international cooperation in this field on a worldwide basis. A series of workshops on BSS was held from 1991 to 2004 (India 1991, Costa Rica and Colombia 1992, Nigeria 1993, Egypt 1994, Sri Lanka 1995, Germany 1996, Honduras 1997, Jordan 1999, France 2000, Mauritius 2001, Argentina 2002, and China 2004) Pursuant to resolutions of the United Nations Committee on the Peaceful Uses of Outer Space (UNCOPUOS) and its Scientific and Technical Subcommittee, since 2005, these workshops focused on the International Heliophysical Year 2007 (UAE 2005, India 2006, Japan 2007, Bulgaria 2008, Ro Korea 2009) Starting in 2010, the workshops focus on the International Space Weather Initiative (ISWI) as recommended in a three-year-work plan as part of the deliberations of UNCOPUOS (www.iswi-secretariat.org/). Workshops on the ISWI have been scheduled to be hosted by Egypt in 2010 for Western Asia, Nigeria in 2011 for Africa, and Ecuador in 2012 for Latin America and the Caribbean. Currently, fourteen IHY/ISWI instrument arrays with more than five hundred instruments are operational in ninety countries. Title: Relation Between the 3D-Geometry of the Coronal Wave and Associated CME During the 26 April 2008 Event Authors: Temmer, M.; Veronig, A. M.; Gopalswamy, N.; Yashiro, S. Bibcode: 2011SoPh..273..421T Altcode: 2011SoPh..tmp...75T; 2011arXiv1103.0196T; 2011SoPh..tmp..227T; 2011SoPh..tmp..158T We study the kinematical characteristics and 3D geometry of a large-scale coronal wave that occurred in association with the 26 April 2008 flare-CME event. The wave was observed with the EUVI instruments aboard both STEREO spacecraft (STEREO-A and STEREO-B) with a mean speed of ∼ 240 km s−1. The wave is more pronounced in the eastern propagation direction, and is thus, better observable in STEREO-B images. From STEREO-B observations we derive two separate initiation centers for the wave, and their locations fit with the coronal dimming regions. Assuming a simple geometry of the wave we reconstruct its 3D nature from combined STEREO-A and STEREO-B observations. We find that the wave structure is asymmetric with an inclination toward East. The associated CME has a deprojected speed of ∼ 750±50 km s−1, and it shows a non-radial outward motion toward the East with respect to the underlying source region location. Applying the forward fitting model developed by Thernisien, Howard, and Vourlidas (Astrophys. J. 652, 763, 2006), we derive the CME flux rope position on the solar surface to be close to the dimming regions. We conclude that the expanding flanks of the CME most likely drive and shape the coronal wave. Title: Earth-Affecting Solar Causes Observatory (EASCO): a mission at the Sun-Earth L5 Authors: Gopalswamy, Nat; Davila, Joseph M.; Auchère, Frédéric; Schou, Jesper; Korendyke, Clarence M.; Shih, Albert; Johnston, Janet C.; MacDowall, Robert J.; Maksimovic, Milan; Sittler, Edward; Szabo, Adam; Wesenberg, Richard; Vennerstrom, Suzanne; Heber, Bernd Bibcode: 2011SPIE.8148E..0ZG Altcode: 2011SPIE.8148E..30G; 2011arXiv1109.2929G Coronal mass ejections (CMEs) and corotating interaction regions (CIRs) as well as their source regions are important because of their space weather consequences. The current understanding of CMEs primarily comes from the Solar and Heliospheric Observatory (SOHO) and the Solar Terrestrial Relations Observatory (STEREO) missions, but these missions lacked some key measurements: STEREO did not have a magnetograph; SOHO did not have in-situ magnetometer. SOHO and other imagers such as the Solar Mass Ejection Imager (SMEI) located on the Sun-Earth line are also not well-suited to measure Earth-directed CMEs. The Earth-Affecting Solar Causes Observatory (EASCO) is a proposed mission to be located at the Sun-Earth L5 that overcomes these deficiencies. The mission concept was recently studied at the Mission Design Laboratory (MDL), NASA Goddard Space Flight Center, to see how the mission can be implemented. The study found that the scientific payload (seven remote-sensing and three in-situ instruments) can be readily accommodated and can be launched using an intermediate size vehicle; a hybrid propulsion system consisting of a Xenon ion thruster and hydrazine has been found to be adequate to place the payload at L5. Following a 2-year transfer time, a 4-year operation is considered around the next solar maximum in 2025. Title: Coronal magnetic field measurement using CME-driven shock observations Authors: Gopalswamy, N.; Nitta, N.; Yashiro, S.; Mäkelä, P.; Xie, H.; Akiyama, S. Bibcode: 2011sdmi.confE..22G Altcode: Collisionless shocks form ahead of coronal mass ejections (CMEs) when the CME speed exceeds the Alfven speed of the ambient plasma in the corona and interplanetary medium. The shock stands at a distance from the CME flux rope that depends on the shock Mach number, the geometry of the driver, and the adiabatic index. While the shock ahead of the CME has been observed for a long time in the in situ data, it has been identified recently near the Sun in the coronagraphic and EUV images. Unlike in situ observations, the imaging observations are two dimensional, so one can better discern the CME-shock relationship near the Sun. Gopalswamy and Yashiro (2011) demonstrated that the coronal magnetic field can be derived from the shock standoff distance measured in coronagraphic images. The method involves measuring the standoff distance, the radius of curvature of the flux rope, and assuming the value of the adiabatic index and deriving the Alfvénic Mach number. The next step is to derive the Alfvénic Mach number from the measured shock speed and an estimate of the local solar wind speed. The final step involves deriving the magnetic field from the Alfven speed by measuring the local plasma density either from coronagraphic (polarized brightness) images (Gopalswamy and Yashiro 2011) or from the band-splitting of type II radio bursts (Gopalswamy et al., 2011). In this paper, we derive the combined magnetic field profile from near the Sun to the edge of the LASCO field of view (1.5 to 30 solar radii) and compare it with the current model profiles. Title: Energetic storm particle events in coronal mass ejection-driven shocks Authors: Mäkelä, P.; Gopalswamy, N.; Akiyama, S.; Xie, H.; Yashiro, S. Bibcode: 2011JGRA..116.8101M Altcode: We investigate the variability in the occurrence of energetic storm particle (ESP) events associated with shocks driven by coronal mass ejections (CMEs). The interplanetary shocks were detected during the period from 1996 to 2006. First, we analyze the CME properties near the Sun. The CMEs with an ESP-producing shock are faster ($\langle$VCME$\rangle$ = 1088 km/s) than those driving shocks without an ESP event ($\langle$VCME$\rangle$ = 771 km/s) and have a larger fraction of halo CMEs (67% versus 38%). The Alfvénic Mach numbers of shocks with an ESP event are on average 1.6 times higher than those of shocks without. We also contrast the ESP event properties and frequency in shocks with and without a type II radio burst by dividing the shocks into radio-loud (RL) and radio-quiet (RQ) shocks, respectively. The shocks seem to be organized into a decreasing sequence by the energy content of the CMEs: RL shocks with an ESP event are driven by the most energetic CMEs, followed by RL shocks without an ESP event, then RQ shocks with and without an ESP event. The ESP events occur more often in RL shocks than in RQ shocks: 52% of RL shocks and only ∼33% of RQ shocks produced an ESP event at proton energies above 1.8 MeV; in the keV energy range the ESP frequencies are 80% and 65%, respectively. Electron ESP events were detected in 19% of RQ shocks and 39% of RL shocks. In addition, we find that (1) ESP events in RQ shocks are less intense than those in RL shocks; (2) RQ shocks with ESP events are predominately quasi-perpendicular shocks; (3) their solar sources are located slightly to the east of the central meridian; and (4) ESP event sizes show a modest positive correlation with the CME and shock speeds. The observation that RL shocks tend to produce more frequently ESP events with larger particle flux increases than RQ shocks emphasizes the importance of type II bursts in identifying solar events prone to producing high particle fluxes in the near-Earth space. However, the trend is not definitive. If there is no type II emission, an ESP event is less likely but not absent. The variability in the probability and size of ESP events most likely reflects differences in the shock formation in the low corona and changes in the properties of the shocks as they propagate through interplanetary space and the escape efficiency of accelerated particles from the shock front. Title: The Strength and Radial Profile of the Coronal Magnetic Field from the Standoff Distance of a Coronal Mass Ejection-driven Shock Authors: Gopalswamy, Nat; Yashiro, Seiji Bibcode: 2011ApJ...736L..17G Altcode: 2011arXiv1106.4832G We determine the coronal magnetic field strength in the heliocentric distance range 6-23 solar radii (Rs) by measuring the shock standoff distance and the radius of curvature of the flux rope during the 2008 March 25 coronal mass ejection imaged by white-light coronagraphs. Assuming the adiabatic index, we determine the Alfvén Mach number, and hence the Alfvén speed in the ambient medium using the measured shock speed. By measuring the upstream plasma density using polarization brightness images, we finally get the magnetic field strength upstream of the shock. The estimated magnetic field decreases from ~48 mG around 6 Rs to 8 mG at 23 Rs. The radial profile of the magnetic field can be described by a power law in agreement with other estimates at similar heliocentric distances. Title: First direct observational evidence of a CME deflection by coronal hole on 15 February 2011 and a comparison with computations Authors: Mohamed, Amaal Abd-Alla; Gopalswamy, Nat Bibcode: 2011shin.confE.127M Altcode: It has been shown that coronal holes (CHs) can deflect a coronal mass ejection (CME) away or towards the Sun-Earth line depending on their relative location (Gopalswamy et al., 2009). This effect can be described using a coronal-hole influence parameter (CHIP), which depends on the CH area, the distance between the CH and the eruption region, and the magnetic field strength within the CH at the photospheric level. We have direct observation of CME deflection during the 2011February 15 CME, which was associated with an X2.2 flare (S21W21) on 01:44 UT from STEREO/COR1 and COR2 observations. The CHIP is computed for the 2011 February 15 CME to be 0.73 G with a deflection angle of 62o. We use the 193 Å AIA image from the Solar Dynamics Observatory (SDO) for CH identification and SDO/HMI for determining the magnetic field strength inside the CH. The largest CH (centroid at S59W15)) was close to the CME eruption region (S21W21). We measured the deflection angle as 38o, using STEREO/COR2 images. This deflection angle is not too different from that obtained from the coronal hole observations. Title: Halo CMEs: Comparing Observations and Models Authors: Gilbert, Holly; St. Cyr, Matthew Orlove. C.; Xie, Hong; Mays, Leila; Gopalswamy, N.; Quirk, Cori; Henning, Christina Bibcode: 2011shin.confE..49G Altcode: Since 1996, the SOHO LASCO coronagraphs have detected 'halo' CMEs that appear to be directed toward Earth, but information about the size and speed of these events seen face-on has been limited. From a single vantage point along the Sun-Earth line, the primary limitation has been ambiguity in fitting the cone model (or other forward-modeling techniques, e.g., Thernisian et al., 2006). But in the past few years, the STEREO mission has provided a view of Earth-directed events from the side. These events offer the opportunity to compare measurements (width and speed) of halo CMEs observed by STEREO with models that derive halo CME properties. We report here results of such a comparison on a large sample of LASCO CMEs in the STEREO era Title: Effects of Refraction on Angles and Times of Arrival of Solar Radio Bursts Authors: Thejappa, G.; MacDowall, R. J.; Gopalswamy, N. Bibcode: 2011ApJ...734...16T Altcode: Solar type III and type II radio bursts suffer severe bending and group delay due to refraction while escaping from the source where the refractive index μ can be as low as ~0 to the observer where μ ~ 1. These propagation effects can manifest themselves as errors in the observed directions and times of arrival at the telescope. We describe a ray-tracing technique that can be used to estimate these errors. By applying this technique to the spherically symmetric density model derived using the data from the WIND/Waves experiment, we show that (1) the fundamental and harmonic emissions escape the solar atmosphere in narrow cones (at 625 kHz the widths of these escape cones are ~1fdg1 and ~8°, respectively), (2) the errors in the angles as well as the times of arrival increase monotonically with the angle of arrival (at 625 kHz these errors are 0fdg26 and ~17.2 s for the fundamental and ~0fdg52 and ~7.6 s for the harmonic at the maximum possible angles of arrival of ~0fdg55 and ~4°, respectively), and (3) the lower the frequencies are, the higher the errors in both the angles and times of arrival are. This implies that at 625 kHz the measured arrival angles and arrival times of the fundamental and harmonic are off by ~50% and ~13%, and ~3.4% and ~1.5%, respectively. Title: Relationship between the Expansion Speed and Radial Speed of CMEs Confirmed Using Quadrature Observations from Soho and Stereo Authors: Gopalswamy, N.; Makela, P.; Yashiro, S. Bibcode: 2011simi.conf....2G Altcode: The STEREO spacecraft were in qudrature with SOHO (STEREO-A ahead of Earth by 87o and STEREO-B 94o behind Earth) on 2011 February 15, when a fast Earth-directed CME occurred. The CME was observed as a halo by the Large-Angle and Spectrometric Coronagraph (LASCO) on board SOHO. The sky-plane speed was measured by SOHO/LASCO as the expansion speed, while the radial speed was measured by STEREO-A and STEREO-B. In addition, STEREO-A and STEREO-B images measured the width of the CME, which is unknown from Earth view. From the SOHO and STEREO measurements, we confirm the relationship between the expansion speed (Vexp) and radial speed (Vrad) derived previously from geometrical considerations (Gopalswamy et al. 2009): Vrad = Ѕ (1 + cot w) Vexp, where w is the half width of the CME. STEREO-B images of the CME, we found that CME had a full width of 75 degrees, so w = 37.5 degrees. This gives the relation as Vrad = 1.15 Vexp. From LASCO observations, we measured Vexp = 897 km/s, so we get the radial speed as 1033 km/s. Direct measurement of radial speed from STEREO gives 945 km/s (STEREO-A) and 1057 km/s (STEREO-B). These numbers are different only by 2.3% and 8.5% (for STEREO-A and STEREO-B, respectively) from the computed value. Title: A Radio Observatory on the Lunar Surface for Solar studies (ROLSS) Authors: MacDowall, R. J.; Lazio, T. J.; Bale, S. D.; Burns, J.; Farrell, W. M.; Gopalswamy, N.; Jones, D. L.; Weiler, K. W. Bibcode: 2011arXiv1105.0666M Altcode: By volume, more than 99% of the solar system has not been imaged at radio frequencies. Almost all of this space (the solar wind) can be traversed by fast electrons producing radio emissions at frequencies lower than the terrestrial ionospheric cutoff, which prevents observation from the ground. To date, radio astronomy-capable space missions consist of one or a few satellites, typically far from each other, which measure total power from the radio sources, but cannot produce images with useful angular resolution. To produce such images, we require arrays of antennas distributed over many wavelengths (hundreds of meters to kilometers) to permit aperture synthesis imaging. Such arrays could be free-flying arrays of microsatellites or antennas laid out on the lunar surface. In this white paper, we present the lunar option. If such an array were in place by 2020, it would provide context for observations during Solar Probe Plus perihelion passes. Studies of the lunar ionosphere's density and time variability are also important goals. This white paper applies to the Solar and Heliospheric Physics study panel. Title: What Controls the Classification of Interplanetary Mass Ejections Authors: Moon, Yong-Jae; Gopalswamy, N.; Kim, R.; Xie, H.; Yashiro, S. Bibcode: 2011SPD....42.2401M Altcode: 2011BAAS..43S.2401M In this paper we address a question what controls the classification of interplanetary mass ejections (ICMEs): magnetic cloud (MC) or ejecta (EJ). Using 186 shock-associated ICMEs from 1997 to 2006, we have examined three possible causes : (1) magnetic complexity with a proxy of sunspot number, (2) CME direction as a proxy of cone angle (the angle between the CME cone axis and the plane of sky), and (3) ICME-ICME interaction with a proxy of the number of halo CMEs. First, the fraction of MC is poorly anti-correlated (R=-0.36) with annual sunspot number. Second, the distribution of CME cone angle for 38 EJs is not much different from that for 16 MCs. Third, the annual fraction of magnetic cloud is well anti-correlated (R=-0.78) with the annual number of halo CMEs. To demonstrate such a relationship, we consider all halo CMEs during the same period and statistically searched the candidate of interacting ICMEs according to temporal and spatial closeness. As a result, we find that the annual fraction of interacting ICME candidates is well correlated (R=0.87) with the annual number of the halo CMEs as well as anti-correlated (R=-0.85) with the annual fraction of MCs. The contingency table between ICME-ICME interaction and MC occurrence also shows a good statistical result: Hit (110), False Alarm (53), Prediction of detection 'yes' (0.88), and Critical Success Index (0.62). Our results imply that the interaction of ICMEs is mainly responsible for their classification. Title: Magnetic Field Strength in the Upper Solar Corona Using White-light Shock Structures Surrounding Coronal Mass Ejections Authors: Kim, Roksoon; Gopalswamy, N.; Moon, Y.; Cho, K.; Yashiro, S. Bibcode: 2011SPD....42.2306K Altcode: 2011BAAS..43S.2306K To measure the magnetic field strength in the solar corona, we examined 12 fast (> 1000 km s-1) limb CMEs which show clear shock-like structures in SOHO/LASCO observations. By applying piston-shock relationship to the observed CME's standoff distance and electron density compression ratio, we estimated the Mach number, Alfven speed, and magnetic field strength in the height range 3 to 15Rs. Main results from this study are: (1) the standoff distance observed in the solar corona is consistent with those from a magnetohydrodynamic (MHD) model and near-Earth observations; (2) the Mach number as a shock strength is in the range 1.49 to 3.52 from the standoff distance data, but when we use the compression ratio, the Mach number is in the range 1.47 to 1.90, implying that the measured density compression ratio is likely to be underestimated due to projection effects; (3) the Alfven speeds range from 259 to 982 km s-1 and the magnetic field strength is in the range 0.04 to 0.35 G when the standoff distance is used; (4) if we multiply the compression ratio by a factor of 2, the Alfven speeds and the magnetic field strengths are consistent in both methods; (5) the derived magnetic field strengths in the inner corona are similar to those of empirical models but noticeably higher in the upper corona. This is a new attempt to measure magnetic field strength from coronagraph observation alone. These observations are consistent with the idea that the diffuse structures surrounding the CME front can be interpreted as shock structures. Title: Understanding Interplanetary Shock Dynamics In The Inner Heliosphere:The 2010 April 03 and August 01 Events Authors: Xie, Hong; May, L.; St Cyr, C. O.; Gopalswamy, N.; Odstrcil, D.; Cremades, H. Bibcode: 2011SPD....42.2312X Altcode: 2011BAAS..43S.2312X The 2010 April 03 and 2010 August 01 CMEs were studied using observations from STEREO A and B, and SOHO LASCO, combined with ENLIL+Cone model simulations preformed at the Community Coordinated Modelling Center (CCMC). In particular, we identified the origin of CMEs using STEREO EUVI and/or SDO images. A flux-rope model fitting to the SECCHI A and B, SOHO/LASCO images was used to determine CME directions and actual speeds. J-maps from COR2/HI-1/HI-2 and simulations from CCMC were used to study the formation and evolution of the shocks in the inner heliosphere. We compared the simulation results with the observed height-time profiles of the shock from white light and kilometric type II (KmTII) burst (Wind/WAVES) observations. The predicted shock arrival at Earth is compared with in-situ observations from ACE. It is found that that ENLIL+cone model predicts the kinematics of shock evolution well for both cases and the KmTII method is more successful when using ENLIL model plasma density. Title: The 2011 February 15 Coronal Mass Ejection: Reconciling SOHO and STEREO Observations in Quadrature Authors: Gopalswamy, N.; Yashiro, S.; Makela, P.; Kaiser, M. L. Bibcode: 2011SPD....42.2322G Altcode: 2011BAAS..43S.2322G The Large-Angle and Spectrometric Coronagraph (LASCO) on board SOHO observed a fast halo coronal mass ejection on 2011 February 15. The STEREO spacecraft were in qudrature with SOHO (STEREO-A ahead of Earth by 87 deg and STEREO-B 94 deg behind Earth), enabling CME measurement using the three spacecraft. The sky-plane speed measured by SOHO/LASCO is closely related to the expansion speed of the CME, while the radial speed was measured by STEREO-A and STEREO-B. In addition, STEREO-A and STEREO-B images measured the width of the CME, which is unknown from Earth view. From the SOHO and STEREO measurements, we confirm the relationship between the expansion speed (Vexp) and radial speed (Vrad) derived previously from geometrical considerations (Gopalswamy et al. 2009): = Vrad = ½ (1 + cot w) Vexp, where w is the half width of the CME. We can also measure the Earthward speed of the CME directly from the STEREO measurements. The travel time to Earth predicted from the Earthward speed using the Empirical Shock Arrival model is 12 hours shorter than the actual travel time obtained from in situ measurements at L1. The primary reason for this discrepancy seems to be the interaction with the two preceding CMEs that slowed down the CME in question. The CME interaction is also confirmed from the radio enhancement observed by Wind/WAVES and STEREO WAVES experiments. Title: Earth-Affecting Solar Causes Observatory (EASCO): Results of the Mission Concept Study Authors: Gopalswamy, N.; EASCO Team Bibcode: 2011SPD....42.1518G Altcode: 2011BAAS..43S.1518G Coronal mass ejections (CMEs) corotating interaction regions (CIRs) are two large-scale structures that originate from the Sun and affect the heliosphere in general and Earth in particular. While CIRs are generally detected by in-situ plasma signatures, CMEs are remote-sensed when they are still close to the Sun. The current understanding of CMEs primarily come from the SOHO and STEREO missions. In spite of the enormous progress made, there are some serious deficiencies in these missions. For example, these missions did not carry all the necessary instruments (STEREO did not have a magnetograph; SOHO did not have in-situ magnetometer). From the Sun-Earth line, SOHO was not well-suited for observing Earth-directed CMEs because of the occulting disk. STEREO's angle with the Sun-Earth line is changing constantly, so only a limited number of Earth-directed CMEs were observed in profile. In order to overcome these difficulties, we proposed a news L5 mission concept known as the Earth-Affecting Solar Causes Observatory (EASCO). The mission concept was recently studied at the Mission Design Laboratory (MDL), NASA Goddard Space Flight Center. The aim of the MDL study was to see how the scientific payload consisting of ten instruments can be accommodated in the spacecraft bus, what propulsion system can transfer the payload to the Sun-Earth L5, and what launch vehicles are appropriate. The study found that all the ten instruments can be readily accommodated and can be launched using an intermediate size vehicle such as Taurus II with enhanced faring. The study also found that a hybrid propulsion system consisting of an ion thruster (using 55 kg of Xenon) and hydrazine ( 10 kg) is adequate to place the payload at L5. The transfer will take about 2 years and the science mission will last for 4 years around the next solar maximum in 2025. Title: Comparison between Linear and Quadratic Drag Models for ICME Propagation Authors: Moon, Yong-Jae; Vrsnak, B.; Gopalswamy, N.; Yashiro, S. Bibcode: 2011SPD....42.2318M Altcode: 2011BAAS..43S.2318M In this paper, we have examined a recent issue what kinds of drag form (linear or quadratic drag) is proper for interplanetary coronal mass ejections (ICMEs). For this work, we have examined well-observed LASCO CMEs associated with DH Type II bursts satisfying the following conditions: (1) the CMEs speeds are larger than 600 km/s, (2) their longitudes are larger than 60 degrees, (3) the numbers of their LASCO data points are larger than 6, and (4) their accelerations are smaller than -1 m/s2. We find that their accelerations (Log a) in the LASCO field of view has a very good quadratic relationship with the CME relative speeds Log (Vcme-400) with the correlation coefficient of R=0.83, supporting the quadratic drag force. Another test has been made by applying two drag models to two well-observed STEREO/SECCHI events. As a result, we found that (1) while two speed profiles are well fitted by the quadratic drag model, one speed profile can not be fitted by the linear model; (2) while the physical parameters for the quadratic model are well consistent with observations, the kinematic viscosity for the linear model should be four orders larger than its observed value. From this study, we conclude that the quadratic drag model for ICME propagation should be proper than the linear drag model. Title: Halo Coronal Mass Ejections: Comparing Observations to Models Authors: Gilbert, Holly; Orlove, M.; St. Cyr, O.; Xie, H.; Mays, L. M.; Gopalswamy, N. Bibcode: 2011SPD....42.2310G Altcode: 2011BAAS..43S.2310G Since 1996, the SOHO LASCO coronagraphs have detected "halo” CMEs that appear to be directed toward Earth, but information about the size and speed of these events seen face-on has been limited. From a single vantage point along the Sun-Earth line, the primary limitation has been ambiguity in fitting the cone model (or other forward-modeling techniques, e.g., Thernisian et al., 2006). But in the past few years, the STEREO mission has provided a view of Earth-directed events from the side. These events offer the opportunity to compare measurements (width and speed) of halo CMEs observed by STEREO with models that derive halo CME properties. We report here results of such a comparison on a large sample of LASCO CMEs in the STEREO era. Title: Association of EUV Waves and Coronal Mass Ejections Authors: Yashiro, Seiji; Gopalswamy, N. Bibcode: 2011SPD....42.2317Y Altcode: 2011BAAS..43S.2317Y The association between EUV waves and coronal mass ejections (CMEs) is difficult to establish for disk flares using observations from the Sun-Earth line because of visibility issues. The other possibility is the real absence of mass motion in flares. This issue can be effectively addressed by the twin spacecraft of the Solar Terrestrial Relations Observatory (STEREO) mission. The Ahead and Behind spacecraft of the STEREO mission were located around ±90° from the Sun-Earth line from 2010 to 2012. This is the first opportunity to investigate the connection between CMEs and EUV waves with a high degree of accuracy. During January 28 - March 9, 2011, two X- and 28 M-class flares occurred. We examined their CME associations using STEREO/SECCHI and SOHO/LASCO observations, and EUV wave associations using SDO/AIA data. We found that 10 out of 30 flares were associated with clear flux-rope CMEs (FRCMEs) while 16 did not have any erupting features above the flaring regions in the coronagraph images. The remaining four flares had narrow CMEs or outflow above the flaring regions but their connection to the flares is unclear. We also found all of the FRCME-associated flares had clear EUV waves, while the flares without CMEs also lacked EUV waves. We found one-to-one correspondence between EUV waves and FRCMEs. Title: Source of Coronal and IP Type II Bursts Inferred from Radio and White-light Observations Authors: Makela, Pertti; Gopalswamy, N.; Yashiro, S. Bibcode: 2011SPD....42.2316M Altcode: 2011BAAS..43S.2316M We report on a study of the speeds of type II radio bursts in the metric (m) and dekameter-hectometric (DH) wavelength range constrained by the time-height measurements of the associated coronal mass ejections (CMEs). Dynamic spectra of type II bursts show occasionally a clear discontinuity in frequency and temporal overlap of metric and DH type II bursts. This has been interpreted to signify either (1) a different origin of the type II components, i.e., the DH-component is caused by a CME-driven shock and the m-component by a blast wave or unknown source, or (2) same source but a different location, i.e., the DH-component originates from the shock nose and the m-component from the shock flanks. Our preliminary results suggest that the single CME-driven shock scenario can match both m and DH-component of type II bursts reasonably well, assuming that true space speeds of the CMEs and shocks are utilized. Title: Cme Evolution In The Interplanetary Space Based On Stereo Observations. Authors: Poomvises, Watanachak; Gopalswamy, N.; Zhang, J. Bibcode: 2011SPD....42.2311P Altcode: 2011BAAS..43S.2311P STEREO/SECCHI observations help identify the true 3-D geometric structure of CMEs and track their true evolution in the inner heliosphere. Using STEREO observations, it is possible to obtain the true speed of CMEs, which is key in predicting the arrival time of CMEs at Earth (Gopalswamy et al. 2001). From the STEREO data, we are able to track and measure CMEs in 3-D by using Raytrace model (Thernisien et al 2006, 2009), which is free from projection effects and thus result in true CME velocities. Studied study 5 CME events, we found that the acceleration/deceleration of CMEs occur within 50 Rs from the Sun, after that the CME velocity converges to the narrow range (Poomvises et al 2010). Additionally, we found that expansion velocity of CMEs also converges to a narrow range after 50 Rs.

The observations are consistent with the theoretical flux rope model. The CME evolution can be explained by different forces that act on the CME: Lorentz force, thermal pressure force, gravity force, aero-dynamic drag force, and the magnetic drag force. The drag coefficient typically varies between 2.5 to 3.0, which is much smaller than the factor of twelve suggested by earlier studies. Moreover, the value of the polytropic index has been found to be between 1.35 to 1.60. Therefore, we have been able to narrow down the range of values for the drag coefficient and the polytropic index, which help in improve the prediction of CME travel time. Title: Earth-Affecting Solar Causes Observatory (EASCO): A potential International Living with a Star Mission from Sun-Earth L5 Authors: Gopalswamy, N.; Davila, J. M.; St. Cyr, O. C.; Sittler, E. C.; Auchère, F.; Duvall, T. L.; Hoeksema, J. T.; Maksimovic, M.; MacDowall, R. J.; Szabo, A.; Collier, M. R. Bibcode: 2011JASTP..73..658G Altcode: This paper describes the scientific rationale for an L5 mission and a partial list of key scientific instruments the mission should carry. The L5 vantage point provides an unprecedented view of the solar disturbances and their solar sources that can greatly advance the science behind space weather. A coronagraph and a heliospheric imager at L5 will be able to view CMEs broadsided, so space speed of the Earth-directed CMEs can be measured accurately and their radial structure discerned. In addition, an inner coronal imager and a magnetograph from L5 can give advance information on active regions and coronal holes that will soon rotate on to the solar disk. Radio remote sensing at low frequencies can provide information on shock-driving CMEs, the most dangerous of all CMEs. Coordinated helioseismic measurements from the Sun-Earth line and L5 provide information on the physical conditions at the base of the convection zone, where solar magnetism originates. Finally, in situ measurements at L5 can provide information on the large-scale solar wind structures (corotating interaction regions (CIRs)) heading towards Earth that potentially result in adverse space weather. Title: Coronal mass ejections and their heliospheric consequences Authors: Gopalswamy, N. Bibcode: 2011ASInC...2..241G Altcode: This paper is concerned with the properties of coronal mass ejections (CMEs) that affect the heliosphere. The special populations of CMEs that drive shocks, accelerate solar energetic particles, and produce geomagnetic storms are discussed in comparison with the general population (all CMEs of cycle 23). It is shown that the average CME speeds of the special populations are larger than that of the general population by a factor in the range 2--3. The angular width of these CMEs is also generally large because most of the CMEs were halos. The October -- November 2003 period produced a large number of energetic CMEs, two of which were of historical proportions. These extreme events are discussed in order to understand what one might expect from the Sun as the largest event, given the maximum area and magnetic field strength of the source active regions. Title: Universal Heliophysical Processes Authors: Gopalswamy, Nat Bibcode: 2011sswh.book....9G Altcode: No abstract at ADS Title: Coronal Mass Ejections and Solar Radio Emissions Authors: Gopalswamy, N. Bibcode: 2011pre7.conf..325G Altcode: Three types of low-frequency nonthermal radio bursts are associated with coronal mass ejections (CMEs): Type III bursts due to accelerated electrons propagating along open magnetic field lines, type II bursts due to electrons accelerated in shocks, and type IV bursts due to electrons trapped in post-eruption arcades behind CMEs. This paper presents a summary of results obtained during solar cycle 23 primarily using the white-light coronagraphic observations from the Solar Heliospheric Observatory (SOHO) and the WAVES experiment on board Wind. Title: Observing Solar Radio Bursts from the Lunar Surface Authors: MacDowall, R. J.; Lazio, T. J.; Bale, S. D.; Burns, J.; Gopalswamy, N.; Jones, D. L.; Kaiser, M. L.; Kasper, J. C.; Weiler, K. W. Bibcode: 2011pre7.conf..541M Altcode: Locating low frequency radio observatories on the lunar surface has a number of advantages, including fixed locations for the antennas and no terrestrial inteference on the far side of the moon. Here, we describe the Radio Observatory on the Lunar Surface for Solar studies (ROLSS), a concept for a near-side, low frequency, interferometric radio imaging array designed to study particle acceleration in the corona and inner heliosphere. ROLSS would be deployed during an early lunar sortie or by a robotic rover as part of an unmanned landing. The prime science mission is to image intense type II and type III solar radio bursts with the aim of determining the sites at and mechanisms by which the radiating particles are accelerated. Secondary science goals include constraining the density of the lunar ionosphere by searching for a low radio frequency cutoff of the solar radio emissions and detecting the low energy electron population in astrophysical sources. Furthermore, ROLSS serves as a pathfinder for larger, far-side lunar radio arrays, designed for faint sources. Title: The International Space Weather Initiative (ISWI) Authors: Davila, Joseph M.; Gopalswamy, Nat; Thompson, Barbara J.; Bogdan, Tom; Hapgood, Mike Bibcode: 2011sswh.book..375D Altcode: No abstract at ADS Title: Heliocentric Distance of Coronal Mass Ejections at the Time of Energetic Particle Release: Revisiting the Ground Level experiments and instrumentation Authors: Gopalswamy, Nat Bibcode: 2011ICRC...10..159G Altcode: 2011ICRC...32j.159G No abstract at ADS Title: Low-frequency type III radio bursts and solar energetic particle events Authors: Gopalswamy, N.; Mäkelä, P. Bibcode: 2011CEAB...35...71G Altcode: Complex type III bursts at low-frequencies (<14 MHz) are thought to indicate large solar energetic particle (SEP) events. We analysed six complex type III bursts from the same active region, one of which was not accompanied by a SEP event. This event was accompanied by a fast and wide coronal mass ejection (CME), but lacked a type II burst and an interplanetary shock. When we examined the evolution and the magnetic configuration of the active region, we did not find anything peculiar. The lowest frequency of type III emission occurred at the local plasma frequency in the vicinity of the Wind spacecraft that observed the type III, which confirms that the magnetic connectivity of the source region was good. We conclude that the lack of SEPs is due to the lack of production rather than due to poor magnetic connectivity. We also show that neither the type III burst duration nor the burst intensity was able to distinguish between SEP and non-SEP events. The lack of SEP event can be readily explained under the shock-acceleration paradigm, but not under the flare-acceleration paradigm. Title: Maximum Coronal Mass Ejection Speed as an Indicator of Solar and Geomagnetic Activities Authors: Kilcik, A.; Yurchyshyn, V. B.; Abramenko, V.; Goode, P. R.; Gopalswamy, N.; Ozguc, A.; Rozelot, J. P. Bibcode: 2011ApJ...727...44K Altcode: 2011arXiv1111.4000K We investigate the relationship between the monthly averaged maximal speeds of coronal mass ejections (CMEs), international sunspot number (ISSN), and the geomagnetic Dst and Ap indices covering the 1996-2008 time interval (solar cycle 23). Our new findings are as follows. (1) There is a noteworthy relationship between monthly averaged maximum CME speeds and sunspot numbers, Ap and Dst indices. Various peculiarities in the monthly Dst index are correlated better with the fine structures in the CME speed profile than that in the ISSN data. (2) Unlike the sunspot numbers, the CME speed index does not exhibit a double peak maximum. Instead, the CME speed profile peaks during the declining phase of solar cycle 23. Similar to the Ap index, both CME speed and the Dst indices lag behind the sunspot numbers by several months. (3) The CME number shows a double peak similar to that seen in the sunspot numbers. The CME occurrence rate remained very high even near the minimum of the solar cycle 23, when both the sunspot number and the CME average maximum speed were reaching their minimum values. (4) A well-defined peak of the Ap index between 2002 May and 2004 August was co-temporal with the excess of the mid-latitude coronal holes during solar cycle 23. The above findings suggest that the CME speed index may be a useful indicator of both solar and geomagnetic activities. It may have advantages over the sunspot numbers, because it better reflects the intensity of Earth-directed solar eruptions. Title: Understanding Interplanetary Shock Dynamics in the Inner Heliosphere with New Observations and Modeling Techniques Authors: St Cyr, O. C.; Henning, C.; Xie, H.; Odstrcil, D.; Mays, L.; Cremades, H.; Iglesias, F.; Gopalswamy, N.; Kaiser, M. L. Bibcode: 2010AGUFMSH23B1850S Altcode: This is a status report of our work predicting interplanetary shock location and strength throughout the inner heliosphere. Coronal mass ejection (CME) shocks accelerate energetic particles, and CME sheaths and ejecta are the primary cause of severe geomagnetic storms. We have evaluated an empirical prediction technique against ENLIL model runs produced at the Community Coordinated Modelling Center (CCMC). The prediction method is a technique based on the kilometric wavelength interplanetary Type II radio emissions measured by Wind/WAVES and described by Cremades, et al., 2007 (hereafter called "kmTII" technique). For a subset of Earth-directed CMEs that were also observed by SOHO LASCO, we have produced multiple ENLIL+cone model predictions of the location of the shock and compared the predicted arrival of at Earth with both the actual arrival and the kmTII prediction. We will report the preliminary results of the comparison in this poster. Title: Aspects of Coronal Mass Ejections Related to Space Weather Authors: Gopalswamy, N. Bibcode: 2010AGUFMSH52A..03G Altcode: Solar cycle 23 witnessed an unprecedented array of space- and ground-based instruments observing the violent eruptions from the Sun that had huge impact on the heliosphere. It was possible to characterize coronal mass ejections (CMEs) that cause extreme solar energetic particle events and geomagnetic storms, the two aspects that concern the space weather community. In this paper I discuss the special populations of CMEs that have significant interplanetary consequences: shock-driving CMEs identified based on their association with type II radio bursts and in-situ shocks, SEP-producing CMEs, and geoeffective CMEs (those that produce geomagnetic storms). I discuss the kinematic and solar-source properties of these populations and how they vary with the solar activity cycle. I also compare their properties with the general population of CMEs, so one can recognize when and where these events occur on the Sun. Title: Relation between CME Speed and Magnetic Helicity in Solar Source Regions Authors: Jung, H.; Gopalswamy, N.; Akiyama, S.; Yashiro, S.; Xie, H. Bibcode: 2010AGUFMSH51C1686J Altcode: Coronal mass ejections (CMEs) are thought to be powered by the free energy in the solar source regions. The magnetic helicity in the source regions is one of the indicators of this free energy. In order to see the relationship between the magnetic helicity of CME source regions and CME energy, we considered a set of 41 solar source regions (from solar cycle 23) from which CMEs erupted and ended up as magnetic clouds near Earth. Using EUV and magnetogram data from the Solar and Heliospheric Observatory (SOHO) mission, we determined the most probable linear force-free magnetic structure and its magnetic helicity for each CME source region. The magnetograms taken just prior to the CME eruption were used to compute the magnetic helicity. The CME speeds were obtained from the SOHO/LASCO CME catalog (http://cdaw.gsfc.nasa.gov). We found that the magnetic helicity is positively correlated with the speed of CMEs. This result suggests that the magnetic helicity of CME source regions maybe useful for predicting CME speed. Title: Statistical Study of Solar Activity Associated with SOHO UVCS Coronal Mass Ejections Authors: O'Neill, J. F.; St Cyr, O. C.; Mays, L.; Gopalswamy, N.; Raymond, J. C.; Ciaravella, A.; Yashiro, S.; Xie, H.; Giordano, S.; Quirk, C. Bibcode: 2010AGUFMSH23B1838O Altcode: Recently a preliminary catalogue of coronal mass ejections (CMEs) detected by the SOHO ultraviolet coronal spectrometer (UVCS) has been made available to the scientific community through the online LASCO CME catalogue (http://cdaw.gsfc.nasa.gov/). We have undertaken an initial study to identify solar activity associated with the UVCS CMEs with radio Type II events, and EUV and X-ray flares. Over 800 CMEs have been identified in UVCS data, and we have found associated activity for 185 events. In this poster we report the basic statistics as a function of time, longitude, latitude, CME speed, etc. Title: An Earth-Directed CME not Observed in LASCO Images Authors: Yashiro, S.; Gopalswamy, N.; Akiyama, S. Bibcode: 2010AGUFMSH23A1835Y Altcode: The COR1 coronagraphs on STEREO-A and -B observed an Earth-directed CME originating from N09W15 at 02:20 UT on 2010/07/09. The apparent CME speed is only 291 km/s, and the angular width is 60 degrees. The CME is somewhat slower than the average LASCO CME (average speed ~450 km/s) but not narrow. The CME was expected to be seen as a halo CME because of the geometry and large width. However, the CME could not be identified in the LASCO running difference movie because of the visibility of the white-light coronagraph. On the other hand, EUV images taken by SDO/AIA show a clear dimming to the northwest of the source region and a wave-like feature propagating to the east. Faint Earth-directed CMEs, seem to be better indicated by surface eruptive signatures such as dimming and EUV waves. We discuss how to estimate CME parameters using the EUV data alone. Title: Radio-Loud Coronal Mass Ejections without Shocks near Earth Authors: Akiyama, S.; Gopalswamy, N.; Xie, H.; Yashiro, S.; Makela, P. A.; St Cyr, O. C.; MacDowall, R. J.; Kaiser, M. L. Bibcode: 2010AGUFMSH32A..07A Altcode: Type II radio bursts are produced by low energy electrons accelerated in shocks driven by coronal mass ejections (CMEs). One can infer shocks near the Sun, in the Interplanetary medium, and near Earth depending on the wavelength range in which the type II bursts are produced. In fact, type II bursts are good indicators of CMEs that produce solar energetic particles. If the type II burst occurs from a source on the Earth-facing side of the solar disk, it is highly likely that a shock arrives at Earth in 2-3 days and hence can be used to predict shock arrival at Earth. However, a significant fraction of CMEs producing type II bursts were not associated shocks at Earth, even though the CMEs originated close to the disk center. There are several reasons for the lack of shock at 1 AU. CMEs originating at large central meridian distances (CMDs) may be driving a shock, but the shock may not be extended sufficiently to reach to the Sun-Earth line. Another possibility is CME cannibalism because of which shocks merge and one observes a single shock at Earth. Finally, the CME-driven shock may become weak and dissipate before reaching 1 AU. We examined a set of 30 type II bursts observed by the Wind/WAVES experiment that had the solar sources very close to the disk center (within a CMD of 15 degrees), but did not have shock at Earth. We find that the near-Sun speeds of the associated CMEs average to ~600 km/s, only slightly higher than the average speed of CMEs associated with radio-quiet shocks. However, the fraction of halo CMEs is only ~28%, compared to 40% for radio-quiet shocks and 72% for all radio-loud shocks. We conclude that the disk-center radio loud CMEs with no shocks at 1 AU are generally of lower energy and they drive shocks only close to the Sun. Title: The Relation between Coronal Holes and CMEs during the Rise, Maximum and Declining Phases of the Solar Cycle 23 Authors: Mohamed, A. A.; Gopalswamy, N.; Yashiro, S.; Akiyama, S.; Makela, P. A.; Xie, H.; Jung, H. Bibcode: 2010AGUFMSH23B1852M Altcode: We investigate the influence of coronal holes (CHs) on the propagation of CMEs considering both magnetic clouds (MCs) and non-magnetic clouds (non-MCs), during the three phases of the solar cycle 23. We consider events originating within a central meridian distance of 15○. The influence of the CHs is computed as a fictitious force that depends on the CH area, the distance between the CH and the eruption region, and the magnetic field within the CH at the photospheric level. We find that the influence parameter is the smallest during the rise phase of the cycle and increases during the maximum and then in the declining phases. The largest influence parameter was observed to be for non-MCs in the Maximum phase F= 2.9 G. However, the average influence parameter is only about half of what was computed for driverless shocks F= 5.8 G. The CH effect on the non-MCs is found to be larger than that for MCs during maximum phase; this may suggest that non-MCs may also have flux rope structure which is hidden from observation due to the deflection by the nearby CHs as has been suggested in the case of driverless shocks (Gopalswamy et al., 2009, JGR). reference: Gopalswamy, N., p. Makela, H. Xie, S. Akiyama, and S. Yashiro, (2009), "CME Interaction with coronal holes and their interplanetary consequences" , J. Geophys. Res., 114,A00A22 doi:10.1029/2008JA013686. Title: On the Occurrence of Energetic Storm Particle Events and Type II Radio Bursts in CME-driven Shocks Authors: Makela, P. A.; Gopalswamy, N.; Akiyama, S.; Xie, H.; Yashiro, S. Bibcode: 2010AGUFMSH23B1847M Altcode: We discuss correlations between energetic storm particle (ESP) events and type II radio emission associated with coronal mass ejection-driven shocks detected during 1996-2006. Shocks that could not be associated with any type II radio emission within metric-to-kilometric wavelength range were defined to be radio-quiet (RQ). All other shocks were defined to be radio-loud (RL). ESP events were identified from the 66 keV-50 MeV proton intensities measured by the Electron, Proton and Alpha Monitor (EPAM) instrument on the Advanced Composition Explorer (ACE) spacecraft and the Energetic and Relativistic Nuclei and Electron (ERNE) experiment on the Solar and Heliospheric Observatory (SOHO). Electron ESP events were identified in the 38-53 keV energy channel of EPAM. It is remarkable that a large fraction (32%) of RQ shocks produced a particle flux increase at energies above 1.8 MeV. On the other hand, only 52% of RL shocks produced ESP events. Electron ESP events were observed in 20% of RQ shocks and 39% of RL shocks. We also find that ESP events during RQ shocks are less intense than those associated with RL shocks. Among RQ shocks, those with an ESP event have slightly more eastern source longitudes (median longitude E07), whereas those without have more western longitudes (median longitude W03). This difference probably reflects the asymmetry in the relative size of ESP events between the eastern and western flanks of the shock. Our results indicate that type II emission is important for the occurrence of ESP events. RL shocks produce frequently ESP events, and the associated ESP events are also more intense than those observed during RQ shocks. The variability in the occurrence of ESP events and type II radio bursts is probably due to differences in the shock formation in the low corona and changes in the properties of the shocks as they propagate through interplanetary space, and the escape efficiency of accelerated particles from the shock front. Title: International Space Weather Initiative (ISWI) Authors: Gopalswamy, N.; Davila, J. M. Bibcode: 2010nspm.conf..160G Altcode: The International Space Weather Initiative (ISWI) is an international scientific program to understand the external drivers of space weather. The science and applications of space weather has been brought to prominence because of the rapid development of space based technology that is useful for all human beings. The ISWI program has its roots in the successful International Heliophysical Year (IHY) program that ran during 2007 - 2009. The primary objective of the ISWI program is to advance the science space weather by a combination of instrument deployment, analysis and interpretation of space weather data from the instruments deployed in conjunction with space data, and communicate the results to the public and students. Like the IHY, the ISWI will be a grass roots organization with key participation from national coordinators with cooperation in an international steering committee. This talk outlines the ISWI program including its organization and proposed activities. Title: Opportunities for Ionospheric Science as Part of the International Space Weather Initiative (ISWI) (Invited) Authors: Davila, J. M.; Gopalswamy, N.; Haubold, H. Bibcode: 2010AGUFMSA43C..01D Altcode: The International Heliophysical Year (IHY), which lasted for approximately two years and involved the effort of thousands of scientists from over 70 countries, ended in February 2009. The major objectives of the IHY included over 60 collaborative studies of universal physical processes in the solar system, the deployment of arrays of small instruments to observe heliophysical processes, a unique program of educational and public outreach, and the preservation of the history of the IGY. The International Space Weather Initiative (ISWI), an international effort fully supported by the United Nations, is designed to build on the momentum developed during the IHY to develop the capability to observe, understand, and predict space weather phenomena, and provide the opportunity for the deployment of new instrumentation in Africa and other regions. In this talk the basic elements of the ISWI will be discussed, and the opportunities for the deployment of new instrument will be discussed. Title: Understanding Interplanetary Shock Dynamics in the Inner Heliosphere with New Observations and Modeling Techniques: Case studies on the 2010-04-03 and 2010-08-01 events Authors: Xie, H.; Mays, L.; St Cyr, O. C.; Gopalswamy, N.; Odstrcil, D.; Cremades, H. Bibcode: 2010AGUFMSH23B1858X Altcode: The 2010 April 03 and August 01 CMEs were studied using observations from STEREO A and B, and SOHO LASCO, combined with ENLIL+Cone model simulations preformed at the Community Coordinated Modelling Center (CCMC). In particular, we identified the origin of CMEs using STEREO EUVI and/or SDO images. A flux-rope model fitting to the SECCHI A and B, SOHO/LASCO images was used to reconstruct the 3D structures of CMEs and determine their actual speeds. J-maps were obtained from COR-2/HI-1/HI-2 and simulations using ENLIL+cone model were conducted to study the formation and evolution of the CME-driven shocks in the inner heliosphere. We compared the simulation results with the observed height-time profiles of the shocks from white light and kilometric type II burst (Wind/WAVES) observations. The predicted shock arrival at Earth is compared with in-situ observations from ACE and Wind. We report the preliminary results of the study in this poster. Title: Corona Mass Ejections: a Summary of Recent Results Authors: Gopalswamy, N. Bibcode: 2010nspm.conf..108G Altcode: Corona mass ejections (CMEs) have been Recognized as the most energetic phenomenon in the heliosphere, deriving their energy from the stressed magnetic fields on the Sun. This paper highlights some of the recent results obtained on CMEs from the Solar and Heliospheric Observatory (SOHO) and the Solar Terrestrial Relations Observatory (STEREO) missions. The summary of follows the talk. SOHO observations revealed that the CME rate is almost a factor of: Two larger than previously thought and varied with the solar activity cycle in a complex way (eg, high-latitude CMEs occurred in great abundance during the solar years maximum). CMEs were found to interact with other CMEs as well as with other large-scale structures (corona holes), Resulting in deflections and additional particle acceleration. STEREO observations have confirmed the three-dimensional nature of CMEs and shocks the surrounding them. The EUV signatures (flare arcades, Corona dimming, filament Eruption, and EUV waves) associated with CMEs have become vital in the identification of sources from Which solar CMEs erupt. CMEs with speeds exceeding the characteristic speeds of the corona and the interplanetary medium drive shocks, which produce type II radio bursts. The wavelength range of type II bursts depends on the CME kinetic energy: type II bursts with emission components at all wavelengths (metric to kilometric) due to CMEs are of the highest kinetic energy. Some CMEs, as fast as 1600 km / s do not produce type II bursts, while slow CMEs (400 km / s) occasionally produce type II bursts. These observations can be explained as the variation in the ambient flow speed (solar wind) speed and the Alfvén. Not all CME-driven shocks produce type II bursts because they are either subcritical Or do not have the appropriate geometry. The same shocks that produce type II bursts also produce solar energetic particles (SEPS), Whose release near the Sun seems to be delayed with respect to the onset of type II bursts. This may indicate a subtle difference in the acceleration of the ions and ~ 10 keV electrons needed to produce type II bursts. Surprisingly, some shocks lacking type II bursts are associated with energetic storm particle events (ESPs), pointing to the importance of electron escape from the shock for producing the radio emission. CMEs slow down or accelerate in the interplanetary medium because of the drag force, which modifies the transit time of CMEs and shocks. Halo CMEs that appear to surround the occulting disk were known before the SOHO era, and occasional events. During the SOHO era, they became very prominent because of their ability to impact Earth and producing geomagnetic storms. Halo CMEs are generally more energetic than ordinary CMEs, which means they can produce north of the impact on Earth's magnetosphere. Their origin close to the center disk of the Sun ensures direct impact on the magnetosphere, although their internal magnetic structure is crucial in causing storms. The solar sources of CMEs that produce SEP events at Earth, on the other hand, are generally in the western hemisphere because of the magnetic connectivity. Thus, CMEs are very interesting from the point of view of plasma physics as well as practical implications because of their space weather impact. Title: A Catalog of Halo Coronal Mass Ejections from SOHO Authors: Gopalswamy, N.; Yashiro, S.; Michalek, G.; Xie, H.; Mäkelä, P.; Vourlidas, A.; Howard, R. A. Bibcode: 2010SunGe...5....7G Altcode: Coronal mass ejections (CMEs) that appear to surround the occulting disk of the observing coronagraph are known as halo CMEs. Halos constitute a subset of energetic CMEs that have important heliospheric consequences. Here we describe an on-line catalog that contains all the halo CMEs that were identified in the images obtained by the Solar and Heliospheric Observatory (SOHO) mission's Large Angle and Spectrometric Coronagraph (LASCO) since 1996. Until the end of 2007, some 396 halo CMEs were recorded. For each halo CME, we identify the solar source (heliographic coordinates), the soft X-ray flare importance, and the flare onset time. From the sky-plane speed measurements and the solar source information we obtain the space speed of CMEs using a cone model. In addition to the description of the catalog (http://cdaw.gsfc.nasa.gov/CME_list/HALO/halo.html), we summarize the statistical properties of the halo CMEs. We confirm that halo CMEs are twice faster than ordinary CMEs and are associated with major flares on the average. We also compared the annual rate of halo CMEs with that obtained by automatic detection methods and found that most of these methods have difficulty in identifying full halo CMEs. Title: Long-duration Low-frequency Type III Bursts and Solar Energetic Particle Events Authors: Gopalswamy, Nat; Mäkelä, Pertti Bibcode: 2010ApJ...721L..62G Altcode: We analyzed the coronal mass ejections (CMEs), flares, and type II radio bursts associated with a set of three complex, long-duration, low-frequency (<14 MHz) type III bursts from active region 10588 in 2004 April. The durations were measured at 1 and 14 MHz using data from Wind/WAVES and were well above the threshold value (>15 minutes) normally used to define these bursts. One of the three type III bursts was not associated with a type II burst, which also lacked a solar energetic particle (SEP) event at energies >25 MeV. The 1 MHz duration of the type III burst (28 minutes) for this event was near the median value of type III durations found for gradual SEP events and ground level enhancement events. Yet, there was no sign of an SEP event. On the other hand, the other two type III bursts from the same active region had similar duration but were accompanied by WAVES type II bursts; these bursts were also accompanied by SEP events detected by SOHO/ERNE. The CMEs for the three events had similar speeds, and the flares also had similar size and duration. This study suggests that the occurrence of a complex, long-duration, low-frequency type III burst is not a good indicator of an SEP event. Title: Type III Radio Burst Duration and SEP events Authors: Gopalswamy, Nat; Makela, P.; Xie, H. Bibcode: 2010shin.confE..19G Altcode: Long-duration (>15 min), low-frequency (<14 MHz) type III radio bursts have been reported to be indicative of solar energetic particle (SEP) events. We measured the durations of type III bursts associated with large SEP events of solar cycle 23. The Type III durations are distributed symmetrically at 1 MHz yielding a mean value of 34 min (median = 33 min) for the large SEP events. When the SEP events with ground level enhancement (GLE) are considered, the distribution is essentially unchanged (mean = 32 min; median = 30 min). To test the importance of type III bursts in indicating SEP events, we considered a set of six type III bursts from the same active region (AR 10588) whose durations fit the 'long duration' criterion. We analyzed the coronal mass ejections (CMEs), flares, and type II radio bursts associated with the type III bursts. The CMEs were of similar speeds and the flares are also of similar size and duration. All but one of the type III bursts was not associated with a type II burst in the metric or longer wavelength domains. The burst without type II burst also lacked a SEP event at energies >25 MeV. The 1-MHz duration of the type III burst (28 min) is near the median value of type III durations found for gradual SEP events and ground level enhancement (GLE) events. Yet, there was no sign of SEP events. On the other hand, two other type III bursts from the same active region had similar duration but accompanied by WAVES type II bursts; these bursts were also accompanied by SEP events detected by SOHO/ERNE. This study suggests that the type III burst duration may not be a good indicator of an SEP event, consistent with the statistical study of Cliver and Ling (2009, ApJ). Title: Shock-driving CMEs near the Sun, in the Interplanetary Medium, and near Earth. Authors: Gopalswamy, Nat; Xie, H.; Makela, P.; Akiyama, S.; Yashiro, S.; Kaiser, M. L.; Howard, R. A.; Bougeret, J. -L. Bibcode: 2010shin.confE.133G Altcode: The excellent correspondence between type II radio bursts and solar energetic particles (SEPs) made it clear that the same shock accelerates ions and electrons. A recent investigation involving a large number of IP shocks revealed that about 35% of IP shocks do not produce type II bursts (radio quiet) or SEPs. Comparing the RQ shocks with the radio loud (RL) ones revealed some interesting results, which will be summarized in this poster. (1) There is no evidence for blast waves. (2) Even a small fraction (20%) of RQ shocks is associated with ion enhancements at the shock when the shock passes the spacecraft. (3) The primary difference between the RQ and RL shocks can be traced to the different kinematic properties of the associated CMEs, although the shock properties measured at 1 AU are not too different for the RQ and RL cases. This can be attributed to the interaction with the IP medium, which seems to erase the difference. More details can be found in Astrophysical Journal 710, 1111, 2010 (http://adsabs.harvard.edu/abs/2009arXiv0912.4719G). Title: The Relation Between Coronal Holes and CMEs During the Rise, Maximum and Declining Phases of the Solar Cycle 23 Authors: Mohamed, Amaal Abd-Alla; Gopalswamy, N.; Yashiro, S.; Akiyama, S.; Makela, P.; Xie, H.; Jung, H. Bibcode: 2010shin.confE.141M Altcode: We investigate the influence of coronal holes on the propagation of CMEs considering both magnetic clouds (MCs) and non-magnetic clouds (non-MCs), during the three phases of the solar cycle 23. We consider events originating within a central meridian distance of 15o. The influence of the CHs is computed as a fictitious force that depends on the CH area, the distance between the CH and the eruption region, and the magnetic field within the CH at the photospheric level. We find that the influence parameter is the smallest during the rise phase of the cycle and increases during the maximum and then in the declining phases. The largest influence parameter was observed in the declining phase. However, the average influence parameter is only about half of what was computed for driverless shocks (Gopalswamy et al., 2009, JGR). Title: Relation between Magnetic Helicity and CME Speed in Solar Source Regions Authors: Jung, Hyewon; Gopalswamy, Nat; Akiyama, Sachiko; Yashiro, Seiji; Xie, Hong Bibcode: 2010shin.confE..88J Altcode: Coronal mass ejections (CMEs) are thought to be powered by the free energy in the solar source regions. The magnetic helicity in the source regions is one of the indicators of this free energy. In order to see the relationship between the magnetic helicity and CME energy, we considered a set of 41 solar source regions (from solar cycle 23) from which CMEs erupted and ended up as magnetic clouds near Earth. Using EUV and magnetogram data from the Solar and Heliospheric Observatory (SOHO) mission, we determined the most probable linear force free magnetic structure and its magnetic helicity for each CME source region. The magnetograms taken just prior to the CME eruption were used to compute the magnetic helicity. The CME speeds were obtained from the SOHO/LASCO CME catalog (http://cdaw.gsfc.nasa.gov). We found that the magnetic helicity is positively correlated with the speed of CMEs. This result suggests that the magnetic helicity of CME source regions maybe useful for predicting CME speed. Title: X-ray Flare Durations and CME Associations Authors: Yashiro, Seiji; Gopalswamy, N.; Akiyama, S.; Kahler, S. Bibcode: 2010shin.confE..86Y Altcode: We report on a statistical study assessing how the soft X-ray flare durations affect the flare-CME relationship. To this end, we considered 245 limb flares (central meridian distance > 60 degrees) that had soft X-ray importance in the narrow range M1.0 to M3.0. We chose the limb flares to avoid projection effects and the CME visibility issues; the medium flares were considered to avoid the influence of flare peak intensity on CME parameters. We examined the CME association of these flares using coronal images obtained by SOHO/LASCO. We found that the CME association rate of flares slowly increases with increasing flare durations. All the flares with very long duration (T>100 min) were associated with CMEs. However, 40% of the impulsive flares (T<10 min) were associated with CMEs, and 30% of the long-duration flares (60<T<100 min) did not have CME association. The duration distribution of flares with and without CMEs had a high degree of overlap. We conclude that the soft X-ray flare duration is not a good indicator of the CME association. Title: Type II radio emission and ESP events Authors: Makela, Pertti; Gopalswamy, Nat; Akiyama, Sachiko; Xie, Hong; Yashiro, Seiji Bibcode: 2010shin.confE..87M Altcode: We report on a survey of energetic storm particle (ESP) events associated with radio-quiet (RQ) and radio-loud (RL) interplanetary (IP) shocks observed during 1996-2006. Shocks were classified into RL or RQ events based on the existence of type II radio bursts. We consider only shocks driven by coronal mass ejections (CMEs). Particle observations are provided by the Electron, Proton and Alpha Monitor (EPAM) instrument on the Advanced Composition Explorer (ACE) spacecraft and the Energetic and Relativistic Nuclei and Electron (ERNE) experiment on the Solar and Heliospheric Observatoty (SOHO). We find that 32% of RQ shocks produced an ESP event at energies >1.8 MeV, compared to 52% of RL shocks. Electron enhancements were detected in 20% of RQ shocks and 39% of RL shocks. The ESP events associated with RQ shocks are less intense than those associated with RL shocks. In addition, RQ shocks with ESP events are predominately quasi-perpendicular shocks, and their solar sources located generally to the east of the central meridian. The size of ESP increases showed a modest positive correlation with the CME and shock speeds and with the Alfvenic Mach number. Our results indicate that some RQ shocks can accelerate particles at 1 AU, but less efficiently than RL shocks, even though they do not produce observable type II radio bursts. This variability is probably related to differences in the shock formation in the low corona, changes in the properties of the shocks as they propagate through interplanetary space, and the escape efficiency of accelerated particles from the shock front. Title: Expansion speed of Coronal Mass Ejections Authors: Michalek, Grzegorz; Gopalswamy, Nat; Yashiro, Seiji Bibcode: 2010EGUGA..12.5142M Altcode: A large set of limb CMEs has been used to determine the accurate relationship between radial (V rad) and expansion (V exp) speeds of CMEs. It was demonstrated that this relation is exceptionally well described by the function f(w)= 1/2 (1 + cot (w)) representing a full cone model for the CME with a half width, w. We also demonstrated that this relation for the halo CMEs could be very simple V rad = V exp. Title: Large Geomagnetic Storms Associated with Limb Halo Coronal Mass Ejections Authors: Gopalswamy, Nat; Yashiro, Seiji; Xie, Hong; Akiyama, Sachiko; Mäakelä, Pertti Bibcode: 2010aogs...21...71G Altcode: 2009arXiv0903.2776G Solar cycle 23 witnessed the observation of hundreds of halo coronal mass ejections (CMEs), thanks to the high dynamic range and extended field of view of the Large Angle and Spectrometric Coronagraph (LASCO) on board the Solar and Heliospheric Observatory (SOHO) mission. More than two thirds of halo CMEs originating on the front side of the Sun have been found to be geoeffective (Dst ≤ -50 nT). The delay time between the onset of halo CMEs and the peak of ensuing geomagnetic storms has been found to depend on the solar source location (Gopalswamy et al., 2007). In particular, limb halo CMEs (source longitude > 45°) have a 20% shorter delay time on the average. It was suggested that the geomagnetic storms due to limb halos must be due to the sheath portion of the interplanetary CMEs (ICMEs) so that the shorter delay time can be accounted for. We confirm this suggestion by examining the sheath and ejecta portions of ICMEs from Wind and ACE data that correspond to the limb halos. Detailed examination showed that three pairs of limb halos were interacting events. Geomagnetic storms following five limb halos were actually produced by other disk halos. The storms followed by four isolated limb halos and the ones associated with interacting limb halos, were all due to the sheath portions of ICMEs. Title: Polar Chromospheric Signatures of the Subdued Cycle 23/24 Solar Minimum Authors: Gopalswamy, N.; Yashiro, S.; Makela, P.; Shibasaki, K.; Hathaway, D. Bibcode: 2010AAS...21640103G Altcode: 2010BAAS...41..857G Coronal holes appear brighter than the quiet Sun in microwave images, with a brightness enhancement of 500 to 2000 K. The brightness enhancement corresponds to the upper chromosphere, where the plasma temperature is about 10000 K. We constructed a microwave butterfly diagram using the synoptic images obtained by the Nobeyama radioheliograph (NoRH) showing the evolution of the polar and low latitude brightness temperature. While the polar brightness reveals the chromospheric conditions, the low latitude brightness is attributed to active regions in the corona. When we compared the microwave butterfly diagram with the magnetic butterfly diagram, we found a good correlation between the microwave brightness enhancement and the polar field strength. The microwave butterfly diagram covers part of solar cycle 22, whole of cycle 23, and part of cycle 24, thus enabling comparison between the cycle 23/24 and cycle 22/23 minima. The microwave brightness during the cycle 23/24 minimum was found to be lower than that during the cycle 22/23 minimum by 250 K. The reduced brightness temperature is consistent with the reduced polar field strength during the cycle 23/24 minimum seen in the magnetic butterfly diagram. We suggest that the microwave brightness at the solar poles is a good indicator of the speed of the solar wind sampled by Ulysses at high latitudes. Title: Radioheliograph Observations of Metric Type II Bursts and the Kinematics of Coronal Mass Ejections Authors: Ramesh, R.; Kathiravan, C.; Kartha, Sreeja S.; Gopalswamy, N. Bibcode: 2010ApJ...712..188R Altcode: Assuming that metric type II radio bursts from the Sun are due to magnetohydrodynamic shocks driven by coronal mass ejections (CMEs), we estimate the average CME acceleration from its source region up to the position of the type II burst. The acceleration values are in the range ≈600-1240 m s^{-2}, which are consistent with values obtained using non-radio methods. We also find that (1) CMEs with comparatively larger acceleration in the low corona are associated with soft X-ray flares of higher energy; the typical acceleration of a CME associated with X1.0 class soft X-ray flare being ≈ 1020 m s^{-2}, and (2) CMEs with comparatively higher speed in the low corona slow down quickly at large distances from the Sun—the deceleration of a CME with a typical speed of 1000 km s-1 being ≈ -15 m s^{-2} in the distance range of ≈3-32 R sun. Title: Solar Sources of ``Driverless'' Interplanetary Shocks Authors: Gopalswamy, N.; Mäkelä, P.; Xie, H.; Akiyama, S.; Yashiro, S. Bibcode: 2010AIPC.1216..452G Altcode: We identify the solar sources of a large number of interplanetary (IP) shocks that do not have a discernible driver as observed by spacecraft along the Sun-Earth line. At the Sun, these ``driverless'' shocks are associated with fast and wide CMEs. Most of the CMEs were also driving shocks near the Sun, as evidenced by the association of IP type II radio bursts. Thus, all these shocks are driven by CMEs and they are not blast waves. Normally limb CMEs produce driverless shocks at 1 AU. But some disk-center CMEs also result in driverless shocks because of deflection by nearby coronal holes. We estimate the angular deflection to be in the range 20°-60°. We also compared the influence of nearby coronal holes on a set of CMEs that resulted in magnetic clouds. The influence is nearly three times larger in the case of driverless shocks, confirming the large deflection required. Title: The CME link to geomagnetic storms Authors: Gopalswamy, Nat Bibcode: 2010IAUS..264..326G Altcode: The coronal mass ejection (CME) link to geomagnetic storms stems from the southward component of the interplanetary magnetic field contained in the CME flux ropes and in the sheath between the flux rope and the CME-driven shock. A typical storm-causing CME is characterized by (i) high speed, (ii) large angular width (mostly halos and partial halos), and (iii) solar source location close to the central meridian. For CMEs originating at larger central meridian distances, the storms are mainly caused by the sheath field. Both the magnetic and energy contents of the storm-producing CMEs can be traced to the magnetic structure of active regions and the free energy stored in them. Title: Interplanetary Shocks Lacking Type II Radio Bursts Authors: Gopalswamy, N.; Xie, H.; Mäkelä, P.; Akiyama, S.; Yashiro, S.; Kaiser, M. L.; Howard, R. A.; Bougeret, J. -L. Bibcode: 2010ApJ...710.1111G Altcode: 2009arXiv0912.4719G We report on the radio-emission characteristics of 222 interplanetary (IP) shocks detected by spacecraft at Sun-Earth L1 during solar cycle 23 (1996 to 2006, inclusive). A surprisingly large fraction of the IP shocks (~34%) was radio quiet (RQ; i.e., the shocks lacked type II radio bursts). We examined the properties of coronal mass ejections (CMEs) and soft X-ray flares associated with such RQ shocks and compared them with those of the radio-loud (RL) shocks. The CMEs associated with the RQ shocks were generally slow (average speed ~535 km s-1) and only ~40% of the CMEs were halos. The corresponding numbers for CMEs associated with RL shocks were 1237 km s-1 and 72%, respectively. Thus, the CME kinetic energy seems to be the deciding factor in the radio-emission properties of shocks. The lower kinetic energy of CMEs associated with RQ shocks is also suggested by the lower peak soft X-ray flux of the associated flares (C3.4 versus M4.7 for RL shocks). CMEs associated with RQ CMEs were generally accelerating within the coronagraph field of view (average acceleration ~+6.8 m s-2), while those associated with RL shocks were decelerating (average acceleration ~-3.5 m s-2). This suggests that many of the RQ shocks formed at large distances from the Sun, typically beyond 10 Rs, consistent with the absence of metric and decameter—hectometric (DH) type II radio bursts. A small fraction of RL shocks had type II radio emission solely in the kilometric (km) wavelength domain. Interestingly, the kinematics of the CMEs associated with the km type II bursts is similar to those of RQ shocks, except that the former are slightly more energetic. Comparison of the shock Mach numbers at 1 AU shows that the RQ shocks are mostly subcritical, suggesting that they were not efficient in accelerating electrons. The Mach number values also indicate that most of these are quasi-perpendicular shocks. The radio-quietness is predominant in the rise phase and decreases through the maximum and declining phases of solar cycle 23. About 18% of the IP shocks do not have discernible ejecta behind them. These shocks are due to CMEs moving at large angles from the Sun-Earth line and hence are not blast waves. The solar sources of the shock-driving CMEs follow the sunspot butterfly diagram, consistent with the higher-energy requirement for driving shocks. Title: Prediction of the interplanetary Coronal Mass Ejection and it's associated shock by using neural network Authors: Mahrous, Ayman; Radi, Amr; Youssef, Mohamed; Faheem, Amin; Ahmed, Safinaz; Gopalswamy, Nat Bibcode: 2010cosp...38.1905M Altcode: 2010cosp.meet.1905M We determined the effective parameter that can be used to predict the estimated arrival time for both Interplanetary Coronal Mass Ejection (ICME) and its associated shock (using the list of Richardson/Cane ICMEs in 1996-2007). Neural network model is used to predict ICME/shock and its arrival time. The set of CME-IP shock pairs obtain from Richardson/Cane ICMEs list is used to construct our neural model from (1996-2005). Concurrently, we determined the effective parameter that used CME-IP shock pairs from (2005-2007) to test our neural networks model. We found that the model succeeded to predict 97 Title: Quasi-Periodic Oscillations in Lasco Coronal Mass Ejection Speeds Authors: Shanmugaraju, A.; Moon, Y. -J.; Cho, K. -S.; Bong, S. C.; Gopalswamy, N.; Akiyama, S.; Yashiro, S.; Umapathy, S.; Vrsnak, B. Bibcode: 2010ApJ...708..450S Altcode: Quasi-periodic oscillations in the speed profile of coronal mass ejections (CMEs) in the radial distance range 2-30 solar radii are studied. We considered the height-time data of the 307 CMEs recorded by the Large Angle and Spectrometric Coronagraph (LASCO) during 2005 January-March. In order to study the speed-distance profile of the CMEs, we have used only 116 events for which there are at least 10 height-time measurements made in the LASCO field of view. The instantaneous CME speed is estimated using a pair of height-time data points, providing the speed-distance profile. We found quasi-periodic patterns in at least 15 speed-distance profiles, where the speed amplitudes are larger than the speed errors. For these events we have determined the speed amplitude and period of oscillations. The periods of quasi-periodic oscillations are found in the range 48-240 minutes, tending to increase with height. The oscillations have similar properties as those reported by Krall et al., who interpreted them in terms of the flux-rope model. The nature of forces responsible for the motion of CMEs and their oscillations are discussed. Title: Coronal Mass Ejections from Sunspot and Non-Sunspot Regions Authors: Gopalswamy, N.; Akiyama, S.; Yashiro, S.; Mäkelä, P. Bibcode: 2010ASSP...19..289G Altcode: 2009arXiv0903.1087G; 2010mcia.conf..289G Coronal mass ejections (CMEs) originate from closed magnetic field regions on the Sun, which are active regions and quiescent filament regions. The energetic populations such as halo CMEs, CMEs associated with magnetic clouds, geoeffective CMEs, CMEs associated with solar energetic particles and interplanetary type II radio bursts, and shock-driving CMEs have been found to originate from sunspot regions. The CME and flare occurrence rates are found to be correlated with the sunspot number, but the correlations are significantly weaker during the maximum phase compared to the rise and declining phases. We suggest that the weaker correlation results from high-latitude CMEs from the polar crown filament regions that are not related to sunspots. Title: Estimation of coronal magnetic field using the type II radio burst associated with a fast CME Authors: Gopalswamy, Nat; Yashiro, Seiji; Akiyama, Sachiko; Freeland, Samuel; Davila, Joseph; Howard, Russell; Bougeret, J. -L. Bibcode: 2010cosp...38.1808G Altcode: 2010cosp.meet.1808G The 2008 March 25 coronal mass ejection (CME) was the second fastest among the 10 type II producing CMEs in the STEREO era. The CME was accompanied by a EUV wave and a shock discernible in the white-light data. The type II burst was observed in the metric and decameter-hectometer (DH) wavelength domains. The type II burst ended in the DH domain when the CME speed started declining at a heliocentric distance where the Alfven speed reached its peak value. Under the scenario that the type II burst was caused by a CME-driven shock, we see that the end of the type II burst corresponds to a significant weakening of the shock, making it subcritical. The standoff distance between the flux rope structure and the shock significantly increased at the time of the shock weakening. From the observed standoff distance, we estimated the upstream Alfvenic Mach number and hence the coronal magnetic field. The magnetic field derived (0.04 G) is consistent with typical quiet solar atmosphere at 7 solar radii. Title: Investigating the relation between Coronal Holes and CMEs during the Rise, Maximum and Declining Phases of the Solar Cycle 23 Authors: Shahin, Amaal; Gopalswamy, Nat Bibcode: 2010cosp...38.1918S Altcode: 2010cosp.meet.1918S In a study on the interaction between Coronal holes (CHs) and inter planetary coronal mass ejections (ICMEs) during the declining phase of solar cycle 23, Gopalswamy et al. [2009] showed that coronal holes (CHs) act as a magnetic wall that constrains the CME propagation. The CME trajectories are significantly affected when the eruptions occur in close proximity to CHs. Here, we investigate the influence of coronal holes on the propagation of CMEs through considering both ICMEs categories with and without flux rope structures during the rise and maximum phases of the solar cycle 23. We also, compare the results obtained with that of the declining phase and of the driverless shocks reported previously by Gopalswamy et al. [2009]. A list of ICMEs that are not classified as MCs has been developed from the Interplanetary (IP) shock list of the solar cycle 23 via selecting all disk center events (central meridian distance 15o ) that have been observed to be (MC s) which leaves us with another list includes the non MC events. The influence of the CHs is computed as a fictitious force that depends on the CH area, the distance between the CH and the eruption region, and the magnetic field within the CH at photospheric level. The open magnetic field distribution on the Sun is obtained for the MCs and non MCs solar events studied during the rise and maximum phases in addition to four magnetic cloud events were not included in Goplaswamy et al. [2009]. This open filed distribution is obtained through performing a potential field source surface extrapolation to the corona up to a heliocentric distance of 2.5 Rs. The Correlation Coefficient (CC) between the duration of the ICMEs and the resultant influence parameter F of the coronal holes is determined in the case of MCs and non MCs for rise, maximum and declining phases. The results show that the correlation coefficient in the case of magnetic cloud (MCs) events is very high at the rise phase ( 0.84) which confirms the correspondence between the non radial motion during the rise phase of the solar cycle and the higher magnetic field strength in the solar regions of the polar coronal holes existed in this phase. The difference between measured position angle (MPA) and the influence position angle (FPA) where F is pointing, () for the non MCs in the rise and maximum phases is found to be 34o and 35o ; respectively which is consistent with that for driverless shocks given by Gopalswamy et al. [2009] (where 37o ). These results together with the average influence parameter value (F av 2.53 G) for the declining phase which is found to be the highest compared to the other two phases and also to the MCs average values suggest that the non MCs are resembling in their behavior the driverless shocks (which have been proven by Gopalswamy et al., 2009 to be deflected by the near by CH s away from the Sun-Earth line) and that the non MCs may have flux rope structure as the MCs do have but this structure is hidden from observation due to the deflection by CH s. This finding may have bearing on the idea that all CMEs may be flux ropes and the difference is only due to the viewing angle variation. Title: The International Space Weather Initiative Authors: Davila, Joseph; Gopalswamy, Nat Bibcode: 2010cosp...38.4192D Altcode: 2010cosp.meet.4192D The International Space Weather Initiative (ISWI) is an international program of scientific collaboration to understand the external drivers of space weather. One of the major thrusts of the ISWI is to deploy arrays of small instruments such as magnetometers, radio antennas, GPS receivers, all-sky cameras, particle detectors, etc. around the world to provide global measurements of heliospheric phenomena. Scientists from approximately 70 countries now participate in the instrument operation, data collection, analysis, and publication of scientific results, working at the forefront of science research. The purpose of the ISWI is to continue the scientific study of universal processes in the solar system that affect space weather and the terrestrial environment, and to continue to coordinate the deployment and operation of new and existing instrument arrays aimed at understanding the impacts of Space Weather on Earth and the near-Earth environment. This project provides an excellent opportunity for potential instrument providers to engage collaborators from specific geographical locations, and to broaden the coverage of existing instrument arrays. By deploying instruments in strategically chosen locations new science and a more global view of heliophysical processes is obtained. These data will also provide new inputs for global ionospheric models in the future. Title: Recent STEREO Observations of Coronal Mass Ejections Authors: St Cyr, O. C.; Xie, H.; Mays, M. L.; Davila, J. M.; Gilbert, H. R.; Jones, S. I.; Pesnell, W. D.; Gopalswamy, N.; Gurman, J. B.; Yashiro, S.; Wuelser, J.; Howard, R. A.; Thompson, B. J.; Thompson, W. T. Bibcode: 2009AGUFMSH11A1491S Altcode: Over 400 CMEs have been observed by STEREO SECCHI COR1 during the mission's three year duration (2006-2009). Many of the solar activity indicators have been at minimal values over this period, and the Carrington rotation-averaged CME rate has been comparable to that measured during the minima between Cycle 21-22 (SMM C/P) and Cycle 22-23 (SOHO LASCO). That rate is about 0.5 CMEs/day. During the current solar minimum (leading to Cycle 24), there have been entire Carrington rotations where no sunspots were detected and the daily values of the 2800 MHz solar flux remained below 70 sfu. CMEs continued to be detected during these exceptionally quiet periods, indicating that active regions are not necessary to the generation of at least a portion of the CME population. In the past, researchers were limited to a single view of the Sun and could conclude that activity on the unseen portion of the disk might be associated with CMEs. But as the STEREO mission has progressed we have been able to observe an increasing fraction of the Sun's corona with STEREO SECCHI EUVI and were able to eliminate this possibility. Here we report on the nature of CMEs detected during these exceptionally-quiet periods, and we speculate on how the corona remains dynamic during such conditions. Title: Expansion Speed of Coronal Mass Ejections Authors: Michalek, G.; Gopalswamy, N.; Yashiro, S. Bibcode: 2009SoPh..260..401M Altcode: A large set of limb coronal mass ejections (CMEs) are used to determine the accurate relationship between radial (Vrad) and expansion (Vexp) speeds of CMEs. It is demonstrated that this relation is exceptionally well described by the function f(w)=1/2(1+cot w), representing a full cone model for the CME with a half-width, w. We also demonstrate that for extremely fast CMEs (Vexp>3000 km s−1), it is better to use the approximation Vrad≈VLE. This implies that such CMEs expand spherically above the solar surface. Title: Relation between Magnetic Helicity and CME Speed in Source Active Regions Authors: Jung, H.; Gopalswamy, N.; Akiyama, S.; Yashiro, S. Bibcode: 2009AGUFMSH41B1669J Altcode: We report on a study linking the speed of coronal mass ejections (CMEs) to the magnetic helicity in the source active regions. The motivation comes from the fact that the CME speed may depend on the active region free magnetic energy, which in turn may be represented by the helicity, a proxy for the nonpotentiality. We selected a set of active regions from solar cycle 23, measured their helicity, and identified CMEs from the CME catalog (http://cdaw.gsfc.nasa.gov). Using EUV and magnetogram data from the Solar and Heliospheric Observatory (SOHO) mission, we measured the coronal helicity content before CME eruptions. We extrapolated the photospheric magnetic field to the corona to obtain the coronal helicity that fits a EUV image before each CME eruption. The CME speeds used here corresponds to the average speed within the SOHO coronagraphic field of view. We found that magnetic helicity is positively correlated with the speed of CME. We cross-checked the helicity values using the principle of magnetic helicity conservation connecting helicity obtained from the Local Correlation Tracking (LCT) method, the helicity of the associated magnetic clouds and the coronal helicity. Title: The 26 April 2008 CME; a Case Study Tracking a CME into the Heliosphere Authors: Webb, D. F.; Galvin, A. B.; Gopalswamy, N.; Howard, T. A.; Reinard, A. A.; Jackson, B.; Davis, C. Bibcode: 2009AGUFMSH41A1640W Altcode: With the current unique constellation of spacecraft, we are studying the origins of CMEs, their 3D structure and how they propagate through the heliosphere. Here we present the results of a case study of one well observed event that occurred during the Whole Heliosphere Interval (WHI), originating at the Sun on 26 April 2008. The event arose from a cluster of 3 active regions that evolved over several solar rotations centered on WHI. The CME was moderately fast with evidence of a shock and was associated with a coronal arcade, coronal dimming and an EUV wave. The April 26 CME originated from disk center for STEREO-B and apparently caused a small SEP event and shock and possible magnetic cloud at STEREO-B on April 29. A brief IP type II suggests that this event had the lowest starting frequency ever observed, which has implications for the medium through which the shock propagates. Possible ejecta was detected in situ at STEREO-B. The Fe charge states suggest that there was a CIR-type interface with some bidirectional electron streaming present. This is confirmed by SMEI 3D reconstructions of density indicating that the ICME interacted with a preexisting CIR. The ICME was also imaged by the SECCHI HI imagers; both the SMEI and HI data permit us to track the dense material from the Sun past 1 AU. Title: Interplanetary Proton and Electron Enhancements Associated with Radio-loud and Radio-quiet CME-driven Shocks Authors: Makela, P. A.; Gopalswamy, N.; Xie, H.; Akiyama, S.; Yashiro, S. Bibcode: 2009AGUFMSH33A1477M Altcode: We present the results on electron and proton acceleration in association with radio-quiet (RQ) and radio-loud (RL) shocks driven by coronal mass ejections (CMEs) during 1996-2006. The CME-driven shocks are classified into RL or RQ shocks based on the presence or the lack of type II radio bursts in the metric and decameter-hectometric wavelength range. We studied proton flux enhancements at L1 in the 66 keV - 50 MeV energy range observed by the ACE/EPAM and SOHO/ERNE instruments. Electron flux enhancements were studied in the 38-53~keV energy channel of EPAM. In general, the RL shocks are more likely to be associated with an energetic storm particle (ESP) event than RQ shocks. Approximately one third of RQ shocks and slightly over a half of RL shocks produced an ESP event at energies above 1.8 MeV. In overall both RQ and RL electron ESP events are rarer, but they follow a similar pattern to the proton observations, i.e. ESP events are observed in approximately one fifth versus two fifths of shocks, respectively. We also studied correlations of ESP event size with CME and shock properties. As expected, the ESP events associated with the RQ shocks are less intense than those with RL shocks. In addition, particle acceleration in RQ shocks occurs predominately in quasi-perpendicular shocks. There is a modest positive correlation between ESP event size and the CME and shock speed and the Mach number. Again, the correlations are stronger for the RL shocks. It appears that shocks can accelerate particles, although less efficiently, even when they do not produce observable type II radio bursts. The variation between the presence of type IIs and ESP events is probably connected to variations in the coronal conditions of shock formation and to the consequent evolution of the shock as it travels through diverse coronal and interplanetary plasmas. Title: The subdued solar cycle 23/24 minimum revealed by microwave butterfly diagram Authors: Gopalswamy, N.; Yashiro, S.; Makela, P. A.; Shibasaki, K. Bibcode: 2009AGUFMSH13C..02G Altcode: The 17 GHz microwave brightness temperature in coronal holes is typically enhanced by 500 to 2000 K with respect to the quiet Sun. This is considered to be a property of the upper chromosphere, where the plasma temperature is ~10000 K. We constructed a microwave butterfly diagram using the synoptic images obtained by the Nobeyama Radioheliograph and compared it with the magnetic butterfly diagram. We found a good correlation between the microwave brightness enhancement and the polar field strength. We also performed a rotation-by-rotation comparison between the two data sets to obtain the correlation between the magnetic field strength and the microwave brightness temperature. The microwave butterfly diagram covers part of cycle 22, whole of cycle 23, and part of cycle 24, thus enabling comparison between the cycle 23/24 and cycle 22/23 minima. The microwave brightness during the cycle 23/24 minimum was found to be lower than that during the cycle 22/23 minimum by ~250 K. The reduced brightness temperature is consistent with the reduced polar field strength during the cycle 23/24 minimum seen e.g., in the SOHO/MDI magnetic butterfly diagram. We suggest that the microwave brightness at the solar poles is a good indicator of the speed of the solar wind sampled by Ulysses at high latitudes. Title: The relation between solar active region location and the lowest frequency of type III emission Authors: Kuroda, N.; Gopalswamy, N. Bibcode: 2009AGUFMSH23A1522K Altcode: We have investigated the relation between the lowest frequencies of type III bursts and the locations of source active regions from which the causal electron beams originate. We chose several active regions that produced coronal mass ejections (CMEs) and flares during their disk passage. The type III bursts considered in this study originated from these eruptions. The CMEs were detected by the Solar and Heliospheric Observatory (SOHO) mission’s Large Angle and Spectrometric coronagraph (LASCO). The type III bursts were observed by the Radio and Plasma Wave Experiment (WAVES) on board Wind. By tracking the type III bursts into the spectral range covered by the Thermal Noise Receiver (TNR) on board Wind, we were able to measure the lowest frequency reached by 104 type III bursts from 17 active regions. In addition, we were able to measure the frequency separation between the type III bursts and the local plasma frequency at the Wind spacecraft as measured by TNR. Because the type III bursts were produced when the source active regions were at various central meridian distances, we could study the lowest frequency at which the type III bursts occurred as a function of the source longitude. We found that the type III emission occurs at frequencies close to the local plasma frequency at the spacecraft when the source active regions are at the disk center or in the western hemisphere. Type III bursts from active regions close to the east limb of the Sun have a higher cutoff frequency. This can be explained by the fact that type III bursts from eastern active regions cannot propagate to the Wind spacecraft because of the intervening denser plasma regions Further investigation is needed to understand the large scatter in the data points, especially those that do not follow the expected tendency: a closer examination would reveal the condition of interplanetary medium and the state of solar wind at the time of these irregular points. Title: On the Origin, 3D Structure and Dynamic Evolution of CMEs Near Solar Minimum Authors: Xie, H.; St. Cyr, O. C.; Gopalswamy, N.; Yashiro, S.; Krall, J.; Kramar, M.; Davila, J. Bibcode: 2009SoPh..259..143X Altcode: We have conducted a statistical study 27 coronal mass ejections (CMEs) from January 2007 - June 2008, using the stereoscopic views of STEREO SECCHI A and B combined with SOHO LASCO observations. A flux-rope model, in conjunction with 3D triangulations, has been used to reconstruct the 3D structures and determine the actual speeds of CMEs. The origin and the dynamic evolution of the CMEs are investigated using COR1, COR2 and EUVI images. We have identified four types of solar surface activities associated with CMEs: i) total eruptive prominence (totEP), ii) partially eruptive prominence (PEP), iii) X-ray flare, and iv) X-type magnetic structure (X-line). Among the 27 CMEs, 18.5% (5 of 27) are associated with totEPs, 29.6% (8 of 27) are associated with PEPs, 26% (7 of 27) are flare related, and 26% (7 of 27) are associated with X-line structures, and 43% (3 of 7) are associated with both X-line structures and PEPs. Three (11%) could not be associated with any detectable activity. The mean actual speeds for totEP-CMEs, PEP-CMEs, flare-CMEs, and X-line-CMEs are 404 km s−1,247 km s−1,909 km s−1, and 276 km s−1, respectively; the average mean values of edge-on and broadside widths for the 27 CMEs are 52 and 85 degrees, respectively. We found that slow CMEs (V≤400 km s−1) tend to deflect towards and propagate along the streamer belts due to the deflections by the strong polar magnetic fields of corona holes, while some faster CMEs show opposite deflections away from the streamer belts. Title: Relation Between Type II Bursts and CMEs Inferred from STEREO Observations Authors: Gopalswamy, N.; Thompson, W. T.; Davila, J. M.; Kaiser, M. L.; Yashiro, S.; Mäkelä, P.; Michalek, G.; Bougeret, J. -L.; Howard, R. A. Bibcode: 2009SoPh..259..227G Altcode: The inner coronagraph (COR1) of the Solar Terrestrial Relations Observatory (STEREO) mission has made it possible to observe CMEs in the spatial domain overlapping with that of the metric type II radio bursts. The type II bursts were associated with generally weak flares (mostly B and C class soft X-ray flares), but the CMEs were quite energetic. Using CME data for a set of type II bursts during the declining phase of solar cycle 23, we determine the CME height when the type II bursts start, thus giving an estimate of the heliocentric distance at which CME-driven shocks form. This distance has been determined to be ∼1.5Rs (solar radii), which coincides with the distance at which the Alfvén speed profile has a minimum value. We also use type II radio observations from STEREO/WAVES and Wind/WAVES observations to show that CMEs with moderate speed drive either weak shocks or no shock at all when they attain a height where the Alfvén speed peaks (∼3Rs - 4Rs). Thus the shocks seem to be most efficient in accelerating electrons in the heliocentric distance range of 1.5Rs to 4Rs. By combining the radial variation of the CME speed in the inner corona (CME speed increase) and interplanetary medium (speed decrease) we were able to correctly account for the deviations from the universal drift-rate spectrum of type II bursts, thus confirming the close physical connection between type II bursts and CMEs. The average height (∼1.5Rs) of STEREO CMEs at the time of type II bursts is smaller than that (2.2Rs) obtained for SOHO (Solar and Heliospheric Observatory) CMEs. We suggest that this may indicate, at least partly, the density reduction in the corona between the maximum and declining phases, so a given plasma level occurs closer to the Sun in the latter phase. In two cases, there was a diffuse shock-like feature ahead of the main body of the CME, indicating a standoff distance of 1Rs - 2Rs by the time the CME left the LASCO field of view. Title: Investigating the relation between coronal holes and CMEs during the rise phase of the solar cycle 23 Authors: Shahin, Amaal Abd-Alla; Gopalswamy, N.; Yashiro, S.; Akiyama, S.; Makela, P.; Xie, H.; Jung, H. Bibcode: 2009shin.confE.126S Altcode: In a study on the interaction between CHs and ICMEs during the declining phase of solar cycle 23, Gopalswamy et al., (2009) showed that coronal holes (CHs) act as a magnetic wall that constrains the CME propagation. The CME trajectories are significantly affected when the eruptions occur in close proximity to CHs. Here, we extend this study to the rise phase of cycle 23. We consider the disk center CMEs (central meridian distance ?15o) that produced interplanetary shocks near Earth. We compute the influence of the CHs as a fictitious force that depends on the CH area, the distance between the CH and the eruption region, and the magnetic field within the CH at photospheric level. We compare the fictitious force acting on the CMEs to see if the appearance of the interplanetary counterparts of CMEs (ICMEs) is affected by the CHs. Title: Flux Rope CMEs Associated with Total and Partial Eruptive Prominences Authors: Xie, Hong; Gilbert, H.; Gopalswamy, N.; St Cyr, O. C. Bibcode: 2009shin.confE.168X Altcode: We present a statistical study involving 17 flux rope coronal mass ejections (CMEs) associated with 1) total eruptive prominence (TEP) and 2) partial eruptive prominence (PEP), observed by STEREO A and B. A flux rope model in conjunction with 3D triangulations has been used to reconstruct the 3D structures and determine the actual speeds of CMEs. The origins and the dynamic evolution of the CMEs are investigated using COR1 and COR2 coronagraphic images and EUVI images. Among the 17 CMEs, 29% (5 of 17) are associated with TEPs, 71% (12 of 17) are associated with PEPs, and 58 % (7 of 12) are associated with both the X-line magnetic structures and PEPs. It is the first direct observations of the X-line structures in EUV images. For comparison, we also study 7 flare related CMEs, which occurred during January 2007 - June 2008,;a CME is classified as a flare CME only when an A-class (or above) X-ray flare is reported by GOES. The mean actual speeds for TEP-CMEs, PEP-CMEs, X_line-CMEs, and flare CMEs are 404 km/s, 255 km/s, 276 km/s, and 909 km/s respectively. It is found that the mean speed of TEP-CMEs is greater than that of PEP-CMEs but smaller than that of flare-CMEs. In addition, we found that there is a good anti- correlation between mass and speed among the 17 EP-CMEs with correlation coefficient r = -0.63. However, no such correlation exists among the 7 flare-CMEs. The results of this study are preliminary and we intend to extend this work for a larger number of events. Title: Numerical simulation of interchange reconnection based on the May 12, 1997 CME event Authors: Cohen, Ofer; Schwadron, Nathan; Crooker, Nancy; Owens, Mathew; Gombosi, Tamas; Connick, D. E.; St Cyr, O. C.; Gopalswamy, N.; Yashiro, S.; Xie, H. Bibcode: 2009shin.confE.184C Altcode: We perform a high-resolution MHD simulation of the May 12, 1997 CME event. We focus on the detailed three-dimensional evolution of the coronal magnetic field as the CME propagates through. Our goal is to identify interchange reconnection events between the CME and the ambient field and in particular, we try to quantify the the change in the distribution of the open magnetic flux due to the interaction of magnetic flux carried by the CME with the ambient open flux. Title: Erratum to “Solar sources and geospace consequences of interplanetary magnetic clouds observed during solar cycle 23—Paper 1” [J. Atmos. Sol.-Terr. Phys. 70(2-4) (2008) 245-253] Authors: Gopalswamy, N.; Akiyama, S.; Yashiro, S.; Michalek, G.; Lepping, R. P. Bibcode: 2009JASTP..71.1005G Altcode: No abstract at ADS Title: Properties of Solar Active Regions and Their Relationship with Solar Eruption: a Statistical Study Authors: Liu, Yang; Akiyama, S.; Gopalswamy, N.; Mason, J.; Nitta, N.; Tylka, A.; Yashiro, S.; Yurchyshyn, V. Bibcode: 2009SPD....40.0920L Altcode: Using magnetograms taken by SOHO/MDI, we have calculated some parameters for solar active regions, and explored possible relationships between them and solar eruptions. The parameters of active regions we studied are magnetic flux, net flux, potential field energy, orientation and separation. We also estimated decay index of magnetic field overlying the neutral line, and the configuration of ambient field under which the active region sits. The data used were taken from 1996 to 2005. With these results as a reference, we studied the active regions that produced the large solar energetic particle (SEP) events, or produced ground level enhancement (GLE) events. Comparison is also made between the active regions that produced full eruption and confine eruption (based on an event list published by Yashiro et al 2005, JGR, 11012S05Y). We present our results here, together with a discussion. Title: Coronal mass ejections and space weather Authors: Gopalswamy, N. Bibcode: 2009cwse.conf...77G Altcode: Solar energetic particles (SEPs) and geomagnetic storms are the two primary space weather consequences of coronal mass ejections (CMEs) and their interplanetary counterparts (ICMEs). I summarize the observed properties of CMEs and ICMEs, paying particular attention to those properties that determine the ability of CMEs in causing space weather. Then I provide observational details of two the central issues: (i) for producing geomagnetic storms, the solar source location and kinematics along with the magnetic field structure and intensity are important, and (ii) for SEPs, the shock-driving ability of CMEs, the Alfven speed in the ambient medium, and the connectivity to Earth are crucial parameters Title: Halo coronal mass ejections and geomagnetic storms Authors: Gopalswamy, Nat Bibcode: 2009EP&S...61..595G Altcode: 2009EP&S...61L.595G In this letter, I show that the discrepancies in the geoeffectiveness of halo coronal mass ejections (CMEs) reported in the literature arise due to the varied definitions of halo CMEs used by different authors. In particular, I show that the low geoeffectiveness rate is a direct consequence of including partial halo CMEs. The geoeffectiveness of partial halo CMEs is lower because they are of low speed and likely to make a glancing impact on Earth. Title: The SOHO/LASCO CME Catalog Authors: Gopalswamy, N.; Yashiro, S.; Michalek, G.; Stenborg, G.; Vourlidas, A.; Freeland, S.; Howard, R. Bibcode: 2009EM&P..104..295G Altcode: 2009EM&P..tmp....8G Coronal mass ejections (CMEs) are routinely identified in the images of the solar corona obtained by the Solar and Heliospheric Observatory (SOHO) mission’s Large Angle and Spectrometric Coronagraph (LASCO) since 1996. The identified CMEs are measured and their basic attributes are cataloged in a data base known as the SOHO/LASCO CME Catalog. The Catalog also contains digital data, movies, and plots for each CME, so detailed scientific investigations can be performed on CMEs and the related phenomena such as flares, radio bursts, solar energetic particle events, and geomagnetic storms. This paper provides a brief description of the Catalog and summarizes the statistical properties of CMEs obtained using the Catalog. Data products relevant to space weather research and some CME issues that can be addressed using the Catalog are discussed. The URL of the Catalog is: <ExternalRef> <RefSource>http://cdaw.gsfc.nasa.gov/CME_list</RefSource> <RefTarget Address="http://cdaw.gsfc.nasa.gov/CME_list" TargetType="URL"/> </ExternalRef>. Title: Preface to the Proceedings of the European General Assembly and the United Nations Workshop Authors: Gopalswamy, N.; Eichhorn, G.; Sakurai, T.; Haubold, H. J. Bibcode: 2009EM&P..104..139G Altcode: 2009EM&P..tmp....4G No abstract at ADS Title: Statistical relationship between solar flares and coronal mass ejections Authors: Yashiro, Seiji; Gopalswamy, Nat Bibcode: 2009IAUS..257..233Y Altcode: We report on the statistical relationships between solar flares and coronal mass ejections (CMEs) observed during 1996-2007 inclusively. We used soft X-ray flares observed by the Geostationary Operational Environmental Satellite (GOES) and CMEs observed by the Large Angle and Spectrometric Coronagraph (LASCO) on board the Solar and Heliospheric Observatory (SOHO) mission. Main results are (1) the CME association rate increases with flare's peak flux, fluence, and duration, (2) the difference between flare and CME onsets shows a Gaussian distribution with the standard deviation σ = 17 min (σ = 15 min) for the first (second) order extrapolated CME onset, (3) the most frequent flare site is under the center of the CME span, not near one leg (outer edge) of the CMEs, (4) a good correlation was found between the flare fluence versus the CME kinetic energy. Implications for flare-CME models are discussed. Title: Modeling and prediction of fast CME/shocks associated with type II bursts Authors: Xie, H.; Gopalswamy, N.; Cyr, O. C. St. Bibcode: 2009IAUS..257..489X Altcode: A numerical simulation with ENLIL+Cone model was carried out to study the propagation of the shock driven by the 2005 May 13 CME. We then conducted a statistical analysis on a subset of similar events, where a decameter-hectometric (DH) type II radio burst and a counterpart kilometric type II have been observed to be associated with each CME (DHkm CME). The simulation results show that fast CME-driven shocks experienced a rapid deceleration as they propagated through the corona and then kept a nearly constant speed traveling out into the heliosphere. Two improved methods are proposed to predict the fast CME-driven shock arrival time, which give the prediction errors of 3.43 and 6.83 hrs, respectively. Title: SEPs and CMEs during cycle 23 Authors: Mäkelä, Pertti; Gopalswamy, Nat; Yashiro, Seiji; Akiyama, Sachiko; Xie, Hong; Valtonen, Eino Bibcode: 2009IAUS..257..475M Altcode: We present a study of solar energetic particles (SEPs) in association with coronal mass ejections (CMEs) and type II radio bursts. The particle and CME observations cover the years 1996-2007. We find that heavy-ion events in association with type II bursts and proton events are produced in more western and most energetic CMEs. In addition, the source distribution of type II associated proton events with heavy ions reminds the source distribution expected for events with flare particles. Therefore, the estimation of relative contributions by flares and shocks in SEP events and separation of suggested different particle acceleration models is complicated. Title: CME interactions with coronal holes and their interplanetary consequences Authors: Gopalswamy, N.; Mäkelä, P.; Xie, H.; Akiyama, S.; Yashiro, S. Bibcode: 2009JGRA..114.0A22G Altcode: 2009JGRA..11400A22G A significant number of interplanetary shocks (~17%) during cycle 23 were not followed by drivers. The number of such ``driverless'' shocks steadily increased with the solar cycle with 15%, 33%, and 52% occurring in the rise, maximum, and declining phase of the solar cycle. The solar sources of 15% of the driverless shocks were very close the central meridian of the Sun (within ~15°), which is quite unexpected. More interestingly, all the driverless shocks with their solar sources near the solar disk center occurred during the declining phase of solar cycle 23. When we investigated the coronal environment of the source regions of driverless shocks, we found that in each case there was at least one coronal hole nearby, suggesting that the coronal holes might have deflected the associated coronal mass ejections (CMEs) away from the Sun-Earth line. The presence of abundant low-latitude coronal holes during the declining phase further explains why CMEs originating close to the disk center mimic the limb CMEs, which normally lead to driverless shocks due to purely geometrical reasons. We also examined the solar source regions of shocks with drivers. For these, the coronal holes were located such that they either had no influence on the CME trajectories, or they deflected the CMEs toward the Sun-Earth line. We also obtained the open magnetic field distribution on the Sun by performing a potential field source surface extrapolation to the corona. It was found that the CMEs generally move away from the open magnetic field regions. The CME-coronal hole interaction must be widespread in the declining phase and may have a significant impact on the geoeffectiveness of CMEs. Title: Introduction to special section on Large Geomagnetic Storms Authors: Gopalswamy, N. Bibcode: 2009JGRA..114.0A00G Altcode: 2009JGRA..11400A00G Solar cycle 23 witnessed the accumulation of rich data sets that reveal various aspects of geomagnetic storms in unprecedented detail both at the Sun where the storm-causing disturbances originate and in geospace where the effects of the storms are directly felt. During two recent coordinated data analysis workshops (CDAWs) the large geomagnetic storms (Dst <= -100 nT) of solar cycle 23 were studied in order to understand their solar, interplanetary, and geospace connections. This special section grew out of these CDAWs with additional contributions relevant to these storms. Here I provide a brief summary of the results presented in the special section. Title: Major solar flares without coronal mass ejections Authors: Gopalswamy, N.; Akiyama, S.; Yashiro, S. Bibcode: 2009IAUS..257..283G Altcode: We examine the source properties of X-class soft X-ray flares that were not associated with coronal mass ejections (CMEs). All the flares were associated with intense microwave bursts implying the production of high energy electrons. However, most (85%) of the flares were not associated with metric type III bursts, even though open field lines existed in all but two of the active regions. The X-class flares seem to be truly confined because there was no material ejection (thermal or nonthermal) away from the flaring region into space. Title: Universal processes in heliophysics Authors: Davila, Joseph M.; Gopalswamy, Nat; Thompson, Barbara J. Bibcode: 2009IAUS..257...11D Altcode: The structure of the Universe is determined primarily by the interplay of gravity which is dominant in condensed objects, and the magnetic force which is dominant in the rarefied medium between condensed objects. Each of these forces orders the matter into a set of characteristic structures each with the ability to store and release energy in response to changes in the external environment. For the most part, the storage and release of energy proceeds through a number of Universal Processes. The coordinated study of these processes in different settings provides a deeper understanding of the underlying physics governing Universal Processes in astrophysics. Title: Universal Heliophysical Processes Authors: Gopalswamy, N.; Webb, D. F. Bibcode: 2009IAUS..257.....G Altcode: No abstract at ADS Title: Evolution of the anemone AR NOAA 10798 and the related geo-effective flares and CMEs Authors: Asai, Ayumi; Shibata, Kazunari; Ishii, Takako T.; Oka, Mitsuo; Kataoka, Ryuho; Fujiki, Ken'ichi; Gopalswamy, Nat Bibcode: 2009JGRA..114.0A21A Altcode: 2009JGRA..11400A21A; 2008arXiv0812.2063A We present a detailed examination of the features of the active region (AR) NOAA 10798. This AR generated coronal mass ejections (CMEs) that caused a large geomagnetic storm on 24 August 2005 with the minimum Dst index of -216 nT. We examined the evolution of the AR and the features on/near the solar surface and in the interplanetary space. The AR emerged in the middle of a small coronal hole, and formed a sea anemone like configuration. Hα filaments were formed in the AR, which have southward axial field. Three M class flares were generated, and the first two that occurred on 22 August 2005 were followed by Halo-type CMEs. The speeds of the CMEs were fast, and recorded about 1200 and 2400 km s-1, respectively. The second CME was especially fast, and caught up and interacted with the first (slower) CME during their travelings toward Earth. These acted synergically to generate an interplanetary disturbance with strong southward magnetic field of about -50 nT, which was followed by the large geomagnetic storm. Title: EUV Wave Reflection from a Coronal Hole Authors: Gopalswamy, N.; Yashiro, S.; Temmer, M.; Davila, J.; Thompson, W. T.; Jones, S.; McAteer, R. T. J.; Wuelser, J. -P.; Freeland, S.; Howard, R. A. Bibcode: 2009ApJ...691L.123G Altcode: We report on the detection of EUV wave reflection from a coronal hole, as observed by the Solar Terrestrial Relations Observatory mission. The EUV wave was associated with a coronal mass ejection (CME) erupting near the disk center. It was possible to measure the kinematics of the reflected waves for the first time. The reflected waves were generally slower than the direct wave. One of the important implications of the wave reflection is that the EUV transients are truly a wave phenomenon. The EUV wave reflection has implications for CME propagation, especially during the declining phase of the solar cycle when there are many low-latitude coronal holes. Title: The Expansion and Radial Speeds of Coronal Mass Ejections Authors: Gopalswamy, N.; Dal Lago, A.; Yashiro, S.; Akiyama, S. Bibcode: 2009CEAB...33..115G Altcode: We show the relation between radial (V_{rad}) and expansion (V_{exp}) speeds of coronal mass ejections (CMEs) depends on the CME width. As CME width increases, {V_{rad}/V_{exp}} decreases from a value >1 to <1. For widths approaching 180°, the ratio approaches 0 if the cone has a flat base, while it approaches 0.5 if the base has a bulge (ice cream cone). The speed difference between the limb and disk halos and the spherical expansion of super fast CMEs can be explained by the width dependence. Title: On the Characteristics of Shocks driven by limb CMEs Authors: Xie, H.; Gopalswamy, N.; Stcyr, C. Bibcode: 2008AGUFMSH23B1650X Altcode: We investigate the characteristics of bow shocks driven by limb CMEs near the Sun, including speed, width, compression ratio, and the relationshipof the standoff distance with CME size (the radius of curvature of a CME) and shock Mach number. We choose a subset of limb CMEs with distinct association of the decameter- hectometric (DH) type II burst, which is a good evidence of the existence CME-driven shock. The DH spectral domain corresponds to plasma frequencies within the field view of the SOHO/LASCO coronagraphs. Choosing limb events has several advantages: 1) there is no projection effects for CME speed measurements, 2) it is easier to determine the width of a CME and the front bow shock, 3) there is high confidence level for the plasma density determination from the white-light CME brightness. By studying the shock stand off distance and compression ratio, we obtain the shock Mach number and the Alfven speed profile in the corona. Title: Difference Between Magnetic Clouds and Non-cloud Ejecta in the Interplanetary Medium Authors: Gopalswamy, N. Bibcode: 2008AGUFMSH22A..01G Altcode: Solar cycle 23 has witnessed the accumulation of data on an unprecedented number of coronal mass ejections (CMEs) at the Sun and in the interplanetary (IP) medium, thanks to the large array of spaceborne observatories such as SOHO, Wind, and ACE. These observations have helped us make significant progress on the structure and evolution of CMEs in the inner heliosphere. One important question is whether the magnetic cloud (MC) and non-cloud ejecta have any difference in their solar origin. The ubiquitous nature of post-eruption arcades suggests that there should not be any difference. However, CMEs associated with MCs all originate from very close to the solar disk center (both in latitude and longitude). To zeroth order, the non-cloud ejecta seem to originate at larger central meridian distances (CMDs). In the extreme case of shocks without discernible ejecta, the corresponding CMEs have their solar sources near the limb. These observations suggest that whether one observes a flux rope (MC) or not depends mainly on the location of the observer with respect to the Sun-Earth line. Observations from solar cycle 23 indicate that there are significant deviations from the zeroth order picture, especially for non-cloud ejecta and the "driverless shocks": their solar sources near the disk center. The question is whether these ejecta do not have flux-rope structure by birth or they somehow got deflected away from the Sun-Earth line by other large- scale structures in the IP medium. The latter seems to be true for at least a subset of events, which seems to be affected by coronal holes located between the eruption center and the Sun-Earth line. This needs to be checked for all the events that deviate from the zeroth order picture. Charge-state signatures of MCs and non-cloud ejecta also support such a picture: the solar sources of IP CMEs with high charge states seem to originate close to the disk center, similar to the MC-associated CMEs. Another piece of evidence comes from the high correspondence between halo CMEs and MCs, both of which are highly geoeffective. Halo CMEs originating at larger CMDs produce geomagnetic storms via their sheath fields, again pointing to the importance of geometry. Contrary to importance of internal structure of CMEs for geoeffectiveness, the production of gradual solar energetic particle (SEP) should not depend on the internal structure of CMEs if the particles are accelerated by CME-driven shocks. In fact, there is a significant difference in the source distribution of SEP-producing CMEs (western sources) and MC CMEs (close to disk center). This paper illustrates these results using coronal and IP data. Title: Relation between Coronal Mass Ejection, Type II Radio Burst, and EUV Wave during the 2008 March 25 STEREO Event Authors: Gopalswamy, N.; Yashiro, S.; Akiyama, S.; Freeland, S.; Thompson, W. T.; Davila, J. M.; Howard, R. A.; Kaiser, M. L.; Bougeret, J. - Bibcode: 2008AGUFMSH12A..02G Altcode: STEREO and SOHO observations of the March 25, 2008 coronal mass ejection (CME) provide an excellent opportunity to study its early evolution from multiple view points. The CME was fast (980 km/s) and wide (112 degrees) from the east limb of the Sun as viewed by SOHO. The STEREO spacecraft were separated by about 50 degrees, so the CME was a disk event for the STEREO-behind spacecraft and a behind-the-limb event for STEREO-ahead. The CME was associated with a well defined EUV wave as observed by the STEREO/EUVI instrument, a metric type II burst, and a multi-component type II burst observed by the STEREO/WAVES and Wind/WAVES instruments. One of the important aspect of this CME is that it was well observed by STEREO/SECCHI inner coronagraph (COR1) when the metric type II burst was in progress, so we are able to obtain the shock height with respect t the CME. This enabled us to infer the connection the coronal shock driven by the CME (inferred from type II burst) and the EUV wave. It appears that the EUV wave steepened into a shock and produced the type II burst. The multiple components of the type II burst were not harmonically related, so we examined the circumstances of the eruption. CME was ejected in the region between two streamers, so the CME-driven shock is likely to simultaneously encounter high and low- density regions of the corona, thus producing type II bursts at widely separated frequencies. This paper summarizes these observations and explains how the CME, type II radio burst, and EUV waves all fit together. Title: Outreach activities during the 2006 total solar eclipse sponsored by the International Heliophysical Year Authors: Rabello Soares, M. C.; Rabiu, A. B.; Gopalswamy, N.; Thompson, B. J.; Davila, J. M.; Sobrinho, A. A. Bibcode: 2008AdSpR..42.1792R Altcode: The International Heliophysical Year (IHY) is an international program of scientific research to advance our understanding of the physical processes that govern the Sun, Earth and heliosphere. It has a strong educational component, linking research and education. Here, we describe the outreach activities during the 2006 total solar eclipse sponsored by IHY. Title: Conservation of open solar magnetic flux and the floor in the heliospheric magnetic field Authors: Owens, M. J.; Crooker, N. U.; Schwadron, N. A.; Horbury, T. S.; Yashiro, S.; Xie, H.; St. Cyr, O. C.; Gopalswamy, N. Bibcode: 2008AGUFMSH12A..05O Altcode: The near-Earth heliospheric magnetic field intensity, |B|, exhibits a strong solar cycle variation, but returns to the same "floor" value each solar minimum. The current minimum, however, has seen |B| drop below previous minima, bringing in to question the existence of a floor, or at the very least requiring a re-assessment of its value. In this study we assume heliospheric flux consists of a constant open flux component and a time-varying contribution from CMEs. In this scenario, the true floor is |B| with zero CME contribution. Using observed CME rates over the solar cycle, we estimate the "no-CME" |B| floor at ~4.2± 0.5 nT, lower than previous floor estimates and below |B| observed this solar minimum. We speculate that the drop in |B| observed this minimum may be due to a persistently lower CME rate than the previous minimum, though there are large uncertainties in the supporting observational data. Title: Solar connections of geoeffective magnetic structures Authors: Gopalswamy, N. Bibcode: 2008JASTP..70.2078G Altcode: Coronal mass ejections (CMEs) and high-speed solar wind streams (HSS) are two solar phenomena that produce large-scale structures in the interplanetary (IP) medium. CMEs evolve into interplanetary CMEs (ICMEs) and the HSS result in corotating interaction regions (CIRs) when they interact with preceding slow solar wind. This paper summarizes the properties of these structures and describes their geoeffectiveness. The primary focus is on the intense storms of solar cycle 23 because this is the first solar cycle during which simultaneous, extensive, and uniform data on solar, IP, and geospace phenomena exist. After presenting illustrative examples of coronal holes and CMEs, I discuss the internal structure of ICMEs, in particular the magnetic clouds (MCs). I then discuss how the magnetic field and speed correlate in the sheath and cloud portions of ICMEs. CME speed measured near the Sun also has significant correlations with the speed and magnetic field strengths measured at 1 AU. The dependence of storm intensity on MC, sheath, and CME properties is discussed pointing to the close connection between solar and IP phenomena. I compare the delay time between MC arrival at 1 AU and the peak time of storms for the cloud and sheath portions and show that the internal structure of MCs leads to the variations in the observed delay times. Finally, we examine the variation of solar-source latitudes of IP structures as a function of the solar cycle and find that they have to be very close to the disk center. Title: Conservation of open solar magnetic flux and the floor in the heliospheric magnetic field Authors: Owens, M. J.; Crooker, N. U.; Schwadron, N. A.; Horbury, T. S.; Yashiro, S.; Xie, H.; St. Cyr, O. C.; Gopalswamy, N. Bibcode: 2008GeoRL..3520108O Altcode: The near-Earth heliospheric magnetic field intensity, |B|, exhibits a strong solar cycle variation, but returns to the same ``floor'' value each solar minimum. The current minimum, however, has seen |B| drop below previous minima, bringing in to question the existence of a floor, or at the very least requiring a re-assessment of its value. In this study we assume heliospheric flux consists of a constant open flux component and a time-varying contribution from CMEs. In this scenario, the true floor is |B| with zero CME contribution. Using observed CME rates over the solar cycle, we estimate the ``no-CME'' |B| floor at ~4.0 +/- 0.3 nT, lower than previous floor estimates and below |B| observed this solar minimum. We speculate that the drop in |B| observed this minimum may be due to a persistently lower CME rate than the previous minimum, though there are large uncertainties in the supporting observational data. Title: International Heliophysical Year 2007: A Report from the UN/NASA Workshop Bangalore, India, 27 November 1 December 2006 Authors: Davila, Joe; Gopalswamy, Nat; Thompson, Barbara; Haubold, Hans J. Bibcode: 2008EM&P..103....9D Altcode: 2008EM&P..tmp...19D The IHY Secretariat and the United Nations Basic Space Science Initiative (UNBSSI) assist scientists and engineers from all over the world in participating in the International Heliophysical Year (IHY) 2007. A major thrust of IHY/UNBSSI is to deploy arrays of small, inexpensive instruments such as magnetometers, radio telescopes, GPS receivers, all-sky cameras, etc. around the world to allow global measurements of ionospheric and heliospheric phenomena. The small instrument programme is envisioned as a partnership between instrument providers and instrument hosts in developing nations. The IHY/UNBSSI can facilitate the deployment of several of these networks world-wide. Existing data bases and relevant software tools will be identified to promote space science activities in developing nations. Extensive data on space science have been accumulated by a number of space missions. Similarly, long-term data bases are available from ground-based observations. These data can be utilized in ways different from originally intended for understanding the heliophysical processes. This paper provides a comprehensive overview of IHY/UNBSSI, its achievements, future plans, and outreach to the 192 Member States of the United Nations as recorded in the UN/NASA workshop in India. Title: Coronal mass ejections, type II radio bursts, and solar energetic particle events in the SOHO era Authors: Gopalswamy, N.; Yashiro, S.; Akiyama, S.; Mäkelä, P.; Xie, H.; Kaiser, M. L.; Howard, R. A.; Bougeret, J. L. Bibcode: 2008AnGeo..26.3033G Altcode: Using the extensive and uniform data on coronal mass ejections (CMEs), solar energetic particle (SEP) events, and type II radio bursts during the SOHO era, we discuss how the CME properties such as speed, width and solar-source longitude decide whether CMEs are associated with type II radio bursts and SEP events. We discuss why some radio-quiet CMEs are associated with small SEP events while some radio-loud CMEs are not associated with SEP events. We conclude that either some fast and wide CMEs do not drive shocks or they drive weak shocks that do not produce significant levels of particle acceleration. We also infer that the Alfvén speed in the corona and near-Sun interplanetary medium ranges from <200 km/s to ~1600 km/s. Radio-quiet fast and wide CMEs are also poor SEP producers and the association rate of type II bursts and SEP events steadily increases with CME speed and width (i.e. energy). If we consider western hemispheric CMEs, the SEP association rate increases linearly from ~30% for 800 km/s CMEs to 100% for ≥1800 km/s. Essentially all type II bursts in the decametre-hectometric (DH) wavelength range are associated with SEP events once the source location on the Sun is taken into account. This is a significant result for space weather applications, because if a CME originating from the western hemisphere is accompanied by a DH type II burst, there is a high probability that it will produce an SEP event. Title: A comparison of coronal mass ejections identified by manual and automatic methods Authors: Yashiro, S.; Michalek, G.; Gopalswamy, N. Bibcode: 2008AnGeo..26.3103Y Altcode: Coronal mass ejections (CMEs) are related to many phenomena (e.g. flares, solar energetic particles, geomagnetic storms), thus compiling of event catalogs is important for a global understanding these phenomena. CMEs have been identified manually for a long time, but in the SOHO era, automatic identification methods are being developed. In order to clarify the advantage and disadvantage of the manual and automatic CME catalogs, we examined the distributions of CME properties listed in the CDAW (manual) and CACTus (automatic) catalogs. Both catalogs have a good agreement on the wide CMEs (width>120°) in their properties, while there is a significant discrepancy on the narrow CMEs (width≤30°): CACTus has a larger number of narrow CMEs than CDAW. We carried out an event-by-event examination of a sample of events and found that the CDAW catalog have missed many narrow CMEs during the solar maximum. Another significant discrepancy was found on the fast CMEs (speed>1000 km/s): the majority of the fast CDAW CMEs are wide and originate from low latitudes, while the fast CACTus CMEs are narrow and originate from all latitudes. Event-by-event examination of a sample of events suggests that CACTus has a problem on the detection of the fast CMEs. Title: Comment on ``Prediction of the 1-AU arrival times of CME-associated interplanetary shocks: Evaluation of an empirical interplanetary shock propagation model'' by K.-H. Kim et al. Authors: Gopalswamy, N.; Xie, H. Bibcode: 2008JGRA..11310105G Altcode: No abstract at ADS Title: Type II Radio Emission and Solar Energetic Particle Events Authors: Gopalswamy, Nat Bibcode: 2008AIPC.1039..196G Altcode: Type II radio bursts, solar energetic particle (SEP) events, and interplanetary (IP) shocks all have a common cause, viz., fast and wide (speed >=900 km/s and width >=60°)) coronal mass ejections (CMEs). Deviations from this general picture are observed as (i) lack of type II bursts during many fast and wide CMEs and IP shocks, (ii) slow CMEs associated with type II bursts and SEP events, and (iii) lack of SEP events during many type II bursts. I examine the reasons for these deviations. I also show that ground level enhancement (GLE) events are consistent with shock acceleration because a type II burst is present in every event well before the release of GLE particles and SEPs at the Sun. Title: Synthetic radio maps of CME-driven shocks below 4 solar radii heliocentric distance Authors: Schmidt, J. M.; Gopalswamy, N. Bibcode: 2008JGRA..113.8104S Altcode: We present 2 1/2 D numerical MagnetoHydroDynamic (MHD) simulations of coronal mass ejections (CMEs) in conjunction with plasma simulations of radio emission from the CME-driven shocks. The CME-driven shock extends to an almost spherical shape during the temporal evolution of the CME. Our plasma simulations can reproduce the dynamic spectra of coronal type II radio bursts, with the frequency drift rates corresponding to the shock speeds. We find further, that the CME-driven shock is an effective radio emitter at metric wavelengths, when the CME has reached a heliocentric distance of about two solar radii (?). We apply our simulation results to explain the radio images of type II bursts obtained by radio heliographs, in particular to the banana-shaped images of radio sources associated with fast CMEs. Title: Investigation of CME dynamics in the LASCO field of view Authors: Shanmugaraju, A.; Moon, Y. -J.; Cho, K. -S.; Gopalswamy, N.; Umapathy, S. Bibcode: 2008A&A...484..511S Altcode: Context: The speed-distance profile of CMEs is important for understanding the propagation of CMEs.
Aims: Our main aim is to study the initial speed of CMEs in the LASCO field of view and its role in subsequent CME propagation using the acceleration-speed profile. The secondary aim is to obtain the speed growth rate.
Methods: We considered the height-time data of 307 CMEs observed by SOHO/LASCO during January-March 2005. To study the CME speed profile, we used only 116 events for which there were at least 10 height-time measurements in the LASCO field of view. Using this data, we obtained their initial speed, extrapolated initial speed, and growth rate.
Results: The following results were found from this analysis. (i) The initial speed obtained from the first two data points is in the range 24-1208 km s-1, which is nearly similar to the range of linear speed (67-920 km s-1) obtained from a least squares fit through the entire h-t data set for each CME. (ii) However, the initial speed or extrapolated initial speed is much better correlated with acceleration and growth rate than the linear speed. (iii) Nearly two thirds of the events (74/116) are found to be accelerating. (iv) The speed growth rate is within the range -0.058 to 0.061 × 10-3 s-1, and it decreases with the distance. (v) The final observed distance in the LASCO field of view depends very weakly upon the initial speed, or extrapolated initial speed whereas it depends strongly on the linear speed. The above results demonstrate the role played by the initial speed of the CMEs. Title: Plasma Radiation and Acceleration Effectiveness of CME-driven Shocks Authors: Gopalswamy, N.; Schmidt, J. M. Bibcode: 2008AGUSMSH41A..18G Altcode: CME-driven shocks are effective radio radiation generators and accelerators for Solar Energetic Particles (SEPs). We present simulated 3 D time-dependent radio maps of second order plasma radiation generated by CME- driven shocks. The CME with its shock is simulated with the 3 D BATS-R-US CME model developed at the University of Michigan. The radiation is simulated using a kinetic plasma model that includes shock drift acceleration of electrons and stochastic growth theory of Langmuir waves. We find that in a realistic 3 D environment of magnetic field and solar wind outflow of the Sun the CME-driven shock shows a detailed spatial structure of the density, which is responsible for the fine structure of type II radio bursts. We also show realistic 3 D reconstructions of the magnetic cloud field of the CME, which is accelerated outward by magnetic buoyancy forces in the diverging magnetic field of the Sun. The CME-driven shock is reconstructed by tomography using the maximum jump in the gradient of the entropy. In the vicinity of the shock we determine the Alfven speed of the plasma. This speed profile controls how steep the shock can grow and how stable the shock remains while propagating away from the Sun. Only a steep shock can provide for an effective particle acceleration. Title: Geoeffective Solar Activity: Coronal Mass Ejections, SEP Events and Geomagnetic Storms Over Solar Cycle 23 Authors: M P; Gopalswamy, N.; Yashiro, S.; Akiyama, S.; Xie, H.; Valtonen, E. Bibcode: 2008AGUSMSH43A..07M Altcode: We present updated results for solar cycle 23 on coronal mass ejections (CMEs) and solar energetic particle (SEP) events and their correlations with solar sources and ensuing interplanetary disturbances and geomagnetic storms. The main data set consists of observations over the years 1996--2007 by the LASCO coronagraph and the ERNE particle detector, both on board the SOHO spacecraft. We study the properties of CMEs and the associated geomagnetic storms and the evolution of the properties during solar cycle 23. Especially we are interested with CMEs that are both geoeffective and SEPeffective. Special emphasis will be given to halo CMEs which are the most likely CMEs to be geoeffective. Title: Effects of solar wind dynamic pressure and preconditioning on large geomagnetic storms Authors: Xie, H.; Gopalswamy, N.; Stcyr, C.; Yashiro, S. Bibcode: 2008AGUSMSM31C..02X Altcode: We investigate the effects of solar wind dynamic pressure, Pdyn, and preconditioning in 88 large magnetic storms occurring during solar cycle 23. We have developed an improved model of the Dst profile, based on a modified Burton equation, where additional effects of Pdyn and diminished Dst pressure-correction have been taking into account. On the average, our model predicts the Dst peak values within 9% of observations and gives an overall RMS error of 11%, which is an improvement over those models whose injection functions only depend on the solar wind electric field. The results demonstrate that there is an increase in the Dst peak value when there is a large enhancement of Pdyn during the main phase of a storm. The average increase of the storm intensity is estimated to be 26% for 15 storms with the max (Pdyn) > 15 nPa. We find that the preconditioning in multi-step Dst storms plays no significant role in strengthening the storm intensity, but increases the storm duration. Title: Properties of Coronal Holes Associated With Large Geomagnetic Storms Authors: Akiyama, S.; Gopalswamy, N.; Yashiro, S. Bibcode: 2008AGUSMSP51A..15A Altcode: We study the characteristics of 11 equatorial coronal holes (CHs), which resulted in large (minimum Dst index < - 100 nT) geomagnetic storms in the interval 1996 to 2005. These storms were part of the Living with a Star (LWS) Coordinated Data-Analysis Workshop (CDAW) held in March 2005. Using 17 GHz microwave images obtained by the Nobeyama Radio Heliograph (NoRH) and EUV images obtained by the Extreme-ultraviolet Imaging Telescope (EIT), we find the EUV CH area and the CH radio enhancement area are linearly correlated with the solar wind speed. The solar wind speed is also related to the flux expansion factor obtained as the ratio between areas of radio enhancement and EUV CH. We study the temporal sequences of the solar wind parameters and show that the time of CH central meridian passage, peak total magnetic field strength, peak temperature, and peak speed are delayed by -2.5, 0.1, 0.6, 1.1 days from the time of peak CIR density, respectively. Title: Heating and Kinematics of an Eruptive Prominence Associated with a Fast Coronal Mass Ejection Authors: Gopalswamy, N.; Yashiro, S.; Shibasaki, K. Bibcode: 2008AGUSMSH31C..07G Altcode: The fast (1800 km/s) coronal mass ejection (CME) on 2005 July 27 had a bright bubble-shaped prominence core observed by the Nobeyama Radioheliograph (NoRH) in microwaves (17 and 34 GHz), TRACE at 171 A, and the Extreme-ultraviolet Imaging Telescope (EIT) on board SOHO. NoRH has the largest field of view among the non- white light instruments, so the prominence could be tracked until it reached a height of about 0.75 solar radii from the limb. The prominence remained optically thick at both 17 and GHz, even though it was significantly heated. Comparison with TRACE observations suggest that the prominence was heated in individual fibers within the prominence, making it multi-thermal plasma. The prominence maintained its overall shape as it entered into the field of view of SOHO/LASCO coronagraphs with a speed of about 1400 km/s, so the height-time history could be studied over a distance of more than 20 solar radii from the Sun. NoRH data indicated that the initial acceleration was extremely high (about1.4 km/s/s). During the slow-rise phase of the prominence, EUV loops overlying the prominence also moved out, which when combines with CME leading-edge measurements from LASCO/C2 yielded an acceleration of about 300 m/s/s. This was comparable to the average acceleration of the prominence over the same height range. When we consider the just the LASCO field of view, both the prominence core and the CME leading edge showed deceleration, but to vastly different extents (-32 m/s/s for the CME leading edge compared to -3 m/s/s for the prominence core). Our preliminary conclusion is that the prominence was insulated from interacting with the non-CME ambient medium, which might explain the weaker slowing down of the prominence. Title: Poor CME Productivity in Active Region 10960 Authors: Yashiro, S.; Gopalswamy, N.; Akiyama, S. Bibcode: 2008AGUSMSH31A..03Y Altcode: Larger flares are generally likely to be associated with coronal mass ejections (CMEs), but there are some CME- poor active regions, which produce many large flares without associated CMEs. We present once such active region NOAA 10960, which produced 10 M-class flares during the disk passage. We examined their CME associations using coronagraph observations obtained by LASCO on SOHO and SECCHI on STEREO. The three coronagraph observations help us to determine whether or not a flare has the associated CME. We found that two out of 10 M-class flares were associated with the CMEs. The rate (20%) is low compared to the average CME association rate (50%) of M-class flares during the solar cycle 23. In addition, the associated CMEs are slow (337 km/s and 208 km/s); further strengthening the conclusion that AR 10960 is CME-poor. We consider various possibilities to explain why the active region is CME-poor. Title: Space Weather Application Using Projected Velocity Asymmetry of Halo CMEs Authors: Michalek, G.; Gopalswamy, N.; Yashiro, S. Bibcode: 2008SoPh..248..113M Altcode: 2008arXiv0801.1977M; 2008SoPh..tmp...24M Halo coronal mass ejections (HCMEs) originating from regions close to the center of the Sun are likely to be responsible for severe geomagnetic storms. It is important to predict geoeffectiveness of HCMEs by using observations when they are still near the Sun. Unfortunately, coronagraphic observations do not provide true speeds of CMEs because of projection effects. In the present paper, we present a new technique to allow estimates of the space speed and approximate source location using projected speeds measured at different position angles for a given HCME (velocity asymmetry). We apply this technique to HCMEs observed during 2001 - 2002 and find that the improved speeds are better correlated with the travel times of HCMEs to Earth and with the magnitudes of ensuing geomagnetic storms. Title: Average Thickness of Magnetosheath Upstream of Magnetic Clouds at 1 AU versus Solar Longitude of Source Authors: Lepping, R. P.; Wu, C. -C.; Gopalswamy, N.; Berdichevsky, D. B. Bibcode: 2008SoPh..248..125L Altcode: 2008SoPh..tmp...35L Starting with a large number (N=100) of Wind magnetic clouds (MCs) and applying necessary restrictions, we find a proper set of N=29 to investigate the average ecliptic plane projection of the upstream magnetosheath thickness as a function of the longitude of the solar source of the MCs, for those cases of MCs having upstream shock waves. A few of the obvious restrictions on the full set of MCs are the need for there to exist a driven upstream shock wave, knowledge of the MC's solar source, and restriction to only MCs of low axial latitudes. The analysis required splitting this set into two subsets according to average magnetosheath speed: slow/average (300 - 500 km s−1) and fast (500 - 1100 km s−1) speeds. Only the fast set gives plausible results, where the estimated magnetosheath thickness (ΔS) goes from 0.042 to 0.079 AU (at 1 AU) over the longitude sector of 0° (adjusted source-center longitude of the average magnetic cloud) to 40° off center (East or West), based on N=11 appropriate cases. These estimates are well determined with a sigma (σ) for the fit of 0.0055 AU, where σ is effectively the same as \sqrt{} (chi-squared) for the appropriate quadratic fit. The associated linear correlation coefficient for ΔS versus |Longitude| was very good (c.c.=0.93) for the fast range, and ΔS at 60° longitude is extrapolated to be 2.7 times the value at 0°. For the slower speeds we obtain the surprising result that ΔS is typically more-or-less constant at 0.040±0.013 AU at all longitudes, indicating that the MC as a driver, when moving close to the normal solar wind speed, has little influence on magnetosheath thickness. In some cases, the correct choice between two candidate solar-source longitudes for a fast MC might be made by noting the value of the observed ΔS just upstream of the MC. Also, we point out that, for the 29 events, the average sheath speed was well correlated with the quantity ΔV[=(«VMC»−«VUPSTREAM»)], and also with both «VMC» and «VMC,T», where «VMC» is the first one-hour average of the MC speed, «VMC,T» is the average MC speed across the full MC, and «VUPSTREAM» is a five-hour average of the solar wind speed just upstream of the shock. Title: Effects of solar wind dynamic pressure and preconditioning on large geomagnetic storms Authors: Xie, H.; Gopalswamy, N.; St. Cyr, O. C.; Yashiro, S. Bibcode: 2008GeoRL..35.6S08X Altcode: We investigate the effects of solar wind dynamic pressure, P dyn , and preconditioning in 88 large magnetic storms (Dst < -100 nT) occurring during solar cycle 23. We have developed an improved model of the Dst profile, based on a modified Burton equation, where additional effects of P dyn and diminished Dst pressure-correction have been taking into account. On the average, our model predicts the Dst peak values within 9% of observations and gives an overall RMS error of 11%, which is an improvement over those models whose injection functions only depend on the solar wind electric field. The results demonstrate that there is an increase in the Dst peak value when there is a large enhancement of P dyn during the main phase of a storm. The average increase of the storm intensity is estimated to be 26% for 15 storms with the max (P dyn ) > 15 nPa. We find that the preconditioning in multi-step Dst storms plays no significant role in strengthening the storm intensity, but increases the storm duration. Title: Radio-Quiet Fast and Wide Coronal Mass Ejections Authors: Gopalswamy, N.; Yashiro, S.; Xie, H.; Akiyama, S.; Aguilar-Rodriguez, E.; Kaiser, M. L.; Howard, R. A.; Bougeret, J. -L. Bibcode: 2008ApJ...674..560G Altcode: We report on the properties of radio-quiet (RQ) and radio-loud (RL) coronal mass ejections (CMEs) that are fast and wide (FW). RQ CMEs lack type II radio bursts in the metric and decameter-hectometric (DH) wavelengths. RL CMEs are associated with metric or DH type II bursts. We found that ~40% of the FW CMEs from 1996 to 2005 were RQ. The RQ CMEs had an average speed of 1117 km s-1 compared to 1438 km s-1 for the RL, bracketing the average speed of all FW CMEs (1303 km s-1). The fraction of full halo CMEs (apparent width = 360°) was the largest for the RL CMEs (60%), smallest for the RQ CMEs (16%), and intermediate for all FW CMEs (42%). The median soft X-ray flare size for the RQ CMEs (C6.9) was also smaller than that for the RL CMEs (M3.9). About 55% of RQ CMEs were back sided, while the front-sided ones originated close to the limb. The RL CMEs originated generally on the disk with only ~25% being back sided. The RQ FW CMEs suggest that the Alfvén speed in the low-latitude outer corona can often exceed 1000 km s-1 and can vary over a factor of >=3. None of the RQ CMEs was associated with large solar energetic particle events, which is useful information for space weather applications. Title: Solar sources and geospace consequences of interplanetary magnetic clouds observed during solar cycle 23 Authors: Gopalswamy, N.; Akiyama, S.; Yashiro, S.; Michalek, G.; Lepping, R. P. Bibcode: 2008JASTP..70..245G Altcode: We present results of a statistical investigation of 99 magnetic clouds (MCs) observed during 1995-2005. The MC-associated coronal mass ejections (CMEs) are faster and wider on the average and originate within ±30o from the solar disk center. The solar sources of MCs also followed the butterfly diagram. The correlation between the magnetic field strength and speed of MCs was found to be valid over a much wider range of speeds. The number of south-north (SN) MCs was dominant and decreased with solar cycle, while the number of north-south (NS) MCs increased confirming the odd-cycle behavior. Two-thirds of MCs were geoeffective; the Dst index was highly correlated with speed and magnetic field in MCs as well as their product. Many (55%) fully northward (FN) MCs were geoeffective solely due to their sheaths. The non-geoeffective MCs were slower (average speed ), had a weaker southward magnetic field (average ), and occurred mostly during the rise phase of the solar activity cycle. Title: Spatial Relationship between Solar Flares and Coronal Mass Ejections Authors: Yashiro, S.; Michalek, G.; Akiyama, S.; Gopalswamy, N.; Howard, R. A. Bibcode: 2008ApJ...673.1174Y Altcode: 2007arXiv0710.3054Y We report on the spatial relationship between solar flares and coronal mass ejections (CMEs) observed during 1996-2005 inclusive. We identified 496 flare-CME pairs considering limb flares (distance from central meridian >=45°) with soft X-ray flare size >=C3 level. The CMEs were detected by the Large Angle and Spectrometric Coronagraph (LASCO) on board the Solar and Heliospheric Observatory (SOHO). We investigated the flare positions with respect to the CME span for the events with X-class, M-class, and C-class flares separately. It is found that the most frequent flare site is at the center of the CME span for all the three classes, but that frequency is different for the different classes. Many X-class flares often lie at the center of the associated CME, while C-class flares widely spread to the outside of the CME span. The former is different from previous studies, which concluded that no preferred flare site exists. We compared our result with the previous studies and conclude that the long-term LASCO observation enabled us to obtain the detailed spatial relation between flares and CMEs. Our finding calls for a closer flare-CME relationship and supports eruption models typified by the CSHKP magnetic reconnection model. Title: Origin of Geoeffective Coronal Mass Ejections during Solar Cycle 23 Authors: Gopalswamy, Nat Bibcode: 2008cosp...37.1057G Altcode: 2008cosp.meet.1057G The importance of coronal mass ejections (CMEs) in causing major geomagnetic storms has been well established in the 1990s due to the southward magnetic field contained in the sheath and ejecta portions of the interplanetary (IP) counterparts of CMEs (or ICMEs). The nice ordering of the internal structure of ICMEs revealed by in situ observations (shock followed by sheath and ejecta with or without flux rope structure) is far from clear at the Sun because the remote sensing technique reveals only the mass content of the CME rather than the magnetic properties. Nevertheless, there have been several attempts to relate the internal structure of CMEs to the magnetic properties of the source active regions on the Sun. For example, the filament marking the polarity inversion lines have been shown to be in the same direction as the axis of the flux rope observed in the IP medium. Such a correspondence is supported by the close relationship found between post eruption arcades at the Sun and the IP magnetic clouds (i.e., flux ropes). However, not all ICMEs or flux ropes, which may very well be an observational effect. The number of ICMEs with flux rope structure observed near Earth varies with the solar cycle and there are indications that the global magnetic field of the Sun and the active region field have varying contribution in deciding the magnetic properties of ICMEs. The sheath is most likely related to the global field of the Sun, while the ejecta is related to the active region magnetic field. The sheath is created by the ejecta portion as it compresses the overlying global field. We are still not in a position to resolve the sheath and ejecta portions of CMEs near the Sun, especially in those heading towards Earth and causing geomagnetic storms. Nevertheless, CME observations can help us infer the strength and orientation of the magnetic field in ICMEs, which are key parameters deciding the occurrence and strength of geomagnetic storms. This paper summarizes the current developments in the understanding of the CME-ICME relationship using the complete data sets on CMEs, ICMEs, and geomagnetic storms over one complete solar cycle that just ended in December 2007. Title: Width of Radio-Loud and Radio-Quiet CMEs Authors: Michalek, G.; Gopalswamy, N.; Xie, H. Bibcode: 2007SoPh..246..409M Altcode: 2007arXiv0710.4519M In the present paper we report on the difference in angular sizes between radio-loud and radio-quiet CMEs. For this purpose we compiled these two samples of events using Wind/WAVES and SOHO/LASCO observations obtained during 1996 - 2005. We show that the radio-loud CMEs are almost twice as wide as the radio-quiet CMEs (considering expanding parts of CMEs). Furthermore, we show that the radio-quiet CMEs have a narrow expanding bright part with a large extended diffusive structure. These results were obtained by measuring the CME widths in three different ways. Title: A Statistical Study of the Ejecta - Shock Standoff Distance of Geoeffective Events Authors: Lara, A.; Gopalswamy, N.; Yashiro, S.; Borgazzi, A. I. Bibcode: 2007AGUFMSH31A0236L Altcode: e study the interplanetary transport of 57 coronal mass ejections (CMEs), which are part of the events responsible for large geomagnetic storms of solar cycle 23 listed in the CDAW database. The interplanetary counterparts of these CMEs (ICMEs) were shock-driving and have caused intense (Dst < -100) geomagnetic storms. We study the statistical behavior of the standoff distance and time between the ICME and the shock. We divided our events into two groups, 1) events where there is likely a one-to-one relationship between the CMEs and ICMEs (unique events) and 2) events where multiple CMEs may be associated with a single ICME. We find that the standoff time of the unique events follows a normal distribution whit a mean of 7.6 hr. and a sigma σ = 4.7 hr. The standoff distance of unique events also follows a normal distribution with a mean of ~ 0.1 AU and a sigma of ~ 0.05 AU. We did not found any relationship between the position of the AR,associated to the low coronal CME activity, and the standoff distance. On the other hand there seems to be a linear relationship between the CME speed and the standoff distance. Title: Prediction of Space Weather Using an Asymmetric Cone Model for Halo CMEs Authors: Michalek, G.; Gopalswamy, N.; Yashiro, S. Bibcode: 2007SoPh..246..399M Altcode: 2007arXiv0710.4372M Halo coronal mass ejections (HCMEs) are responsible of the most severe geomagnetic storms. A prediction of their geoeffectiveness and travel time to Earth's vicinity is crucial to forecast space weather. Unfortunately, coronagraphic observations are subjected to projection effects and do not provide true characteristics of CMEs. Recently, Michalek (Solar Phys.237, 101, 2006) developed an asymmetric cone model to obtain the space speed, width, and source location of HCMEs. We applied this technique to obtain the parameters of all front-sided HCMEs observed by the SOHO/LASCO experiment during a period from the beginning of 2001 until the end of 2002 (solar cycle 23). These parameters were applied for space weather forecasting. Our study finds that the space speeds are strongly correlated with the travel times of HCMEs to Earth's vicinity and with the magnitudes related to geomagnetic disturbances. Title: Synoptic Solar Radio Burst Source Directions Derived by the Ulysses URAP Investigation Authors: MacDowall, R. J.; Gopalswamy, N.; Kaiser, M. L.; Hess, R. A.; Reiner, M. J.; Hoang, S. Bibcode: 2007AGUFMSH41A0308M Altcode: The Unified Radio and Plasma (URAP) investigation is one of 10 instruments on the Ulysses spacecraft. Ulysses, with its highly inclined orbit around the sun, provides URAP with a unique perspective on solar radio bursts, which are usually emitted at low heliolatitudes as the electron sources move outward from the sun. These radio bursts provide positional information relating to interplanetary coronal mass ejections (type II radio bursts), the initiation of CMEs (type III-L bursts), and solar flares (type III bursts). In this presentation, we use the routine radio direction-finding data from URAP to track radio bursts and locate their sources when Ulysses is near perihelion. Plots of these data are available on the URAP Goddard Space Flight Center web site (for example, http://urap.gsfc.nasa.gov/cgi/giffer?date=20070726&PLOT_TYPE= DIRFIND), as are ASCII data files. The results shown are derived from fitting the spin-plane antenna data only; we compare the source directions so derived to the more accurate determinations made by fitting to both URAP antennas. The accuracy of the radio source directions to identify flare locations, determine solar wind densities remotely, etc., will be compared to previously published determinations. Applications to Wind Waves and STEREO Waves data, for which the spacecraft are in-ecliptic, will be addressed briefly. Title: A Catalog of Halo Coronal Mass Ejections from SOHO Authors: Gopalswamy, N.; Yashiro, S.; Michalek, G.; Xie, H.; Vourlidas, A.; Howard, R. A.; Schmidt, J. Bibcode: 2007AGUFMSH51A0262G Altcode: Halo coronal mass ejections (CMEs) have become one of the important subsets of CMEs, thanks to the extensive data accumulated by the Solar and Heliospheric Observatory (SOHO) mission. Halo CMEs are inherently more energetic on the average, so they are important for producing geomagnetic storms and solar energetic particle events (Gopalswamy et al., 2007). One of the key aspects halo CMEs is their source location, which decides whether the halo is symmetric or not. When the source is closer to the solar limb, the CMEs tend to become asymmetric halos or partial halos. Halos with their sources nearer to the limb are also the fastest (because of projection effects), but are less geoeffective due to the glancing blow they deliver to Earth's magnetosphere. Thus, providing source information to all halo CMEs in a separate catalog is useful information in selecting candidate geoeffective CMEs. The second important quantity of CMEs is the space speed, which decides the arrival time of CMEs at Earth. Since CMEs change their width during their early evolution, it is not easy to correct for the projection effects from the geometry of eruption. One way of correcting for projection effects is to use a cone model for CMEs. There are at least 3 published cone models, all of them seem to remove the projection effects reasonably well. The geometric parameters of the cone are determined using different methods in each model. Here we use the model by Xie et al. (2004), which has generally less restrictions, and hence can be applied to more number of halos. This paper provides a brief description of the catalog of halo CMEs, which resides at the CDAW Data Center, NASA Goddard Space Flight Center, Greenbelt, MD. The catalog enhances the existing data services at the CDAW Data Center, which participates in the Virtual Solar Observatory. Work supported by NASA's Virtual Observatories for Solar and Space Physics Data Program. References Gopalswamy et al., JGR, 112, A06112, doi:10.1029/2006JA012149, 2007 Xie et al. JGR, 109, A03109, doi: 10.1029/2003JA010226, 2004 Title: Synthetic Radio Maps of CMEs up to 24 Solar Radii Heliocentric Distance Authors: Schmidt, J. M.; Gopalswamy, N. Bibcode: 2007AGUFMSH23B..01S Altcode: We present numerical MagnetoHydroDynamic (MHD) simulations of coronal mass ejections (CMEs) and plasma simulations of radio emission from the CME-driven shocks. The simulations correspond to an idealized system, where rotational symmetry around the rotation axis of the Sun is assumed. So the CME has a flux rope structure that extends like a torus around the symmetry axis, i.e. no geometrical effects due to a connection of footpoints of the flux rope with the solar surface are considered. The CME-driven shock extends to an almost spherical shape during the temporal evolution of the CME. We find that our simulations can reproduce the dynamic spectra of coronal radio type II bursts, where the frequency drift rates correspond to the CME-driven shock speeds. We find further, that the CME-driven shock is an effective radio emitter at metric wavelengths, when the CME has reached a heliocentric distance of about two solar radii (R\odot). Towards the center of the CME, where the plasma emission frequency drops significantly due to an over expansion of the core of the CME, the emission is eclipsed for a fixed frequency radio receiver. We apply our simulation results to explain the radio images of type II bursts obtained by radio heliographs, in particular to the banana-shaped images of radio sources associated with fast CMEs. The shock at the rear part of the CME can become an effective radio emitter, where reconnection of magnetic field lines leads to enhanced gradients of magnetic fields. Yet, this emission is usually at lower frequencies than that at the shock front. We apply our kinetic and analytic model of plasma radiation further to MHD simulations of CMEs in 3D. The differences between the 3D and 2D cases are discussed. Title: Division II / Working Group International Collaboration in Space Weather Authors: Webb, David F.; Gopalswamy, Nat; Liu, William; Sibeck, David G.; Schmieder, Brigitte; Wang, Jingxiu; Wang, Chi Bibcode: 2007IAUTB..26..107W Altcode: The IAU Division II WG on International Collaboration in Space Weather has as its main goal to help coordinate the many activities related to space weather at an international level. The WG currently includes the international activities of the International Heliospheric Year (IHY), the International Living with a Star (ILWS) program, the CAWSES (Climate and Weather of the Sun-Earth System) Working Group on Sources of Geomagnetic Activity, and Space Weather Studies in China. The coordination of IHY activities within the IAU is led by Division II under this working group. The focus of this half-day meeting was on the activities of the IHY program. About 20 people were in attendance. The Chair of the WG, David F. Webb, gave a brief introduction noting that the meeting would have two parts: first, a session on IHY activities emphasizing IHY Regional coordination and, second, a general discussion of the other programs of the WG involving international Space Weather activities. Title: Correction to ``Solar and interplanetary sources of major geomagnetic storms (Dst <= -100 nT) during 1996-2005'' Authors: Zhang, J.; Richardson, I. G.; Webb, D. F.; Gopalswamy, N.; Huttunen, E.; Kasper, J.; Nitta, N. V.; Poomvises, W.; Thompson, B. J.; Wu, C. -C.; Yashiro, S.; Zhukov, A. N. Bibcode: 2007JGRA..11212103Z Altcode: Abstract Available from http://www.agu.org Title: Solar and interplanetary sources of major geomagnetic storms (Dst <= -100 nT) during 1996-2005 Authors: Zhang, J.; Richardson, I. G.; Webb, D. F.; Gopalswamy, N.; Huttunen, E.; Kasper, J. C.; Nitta, N. V.; Poomvises, W.; Thompson, B. J.; Wu, C. -C.; Yashiro, S.; Zhukov, A. N. Bibcode: 2007JGRA..11210102Z Altcode: We present the results of an investigation of the sequence of events from the Sun to the Earth that ultimately led to the 88 major geomagnetic storms (defined by minimum Dst ≤ -100 nT) that occurred during 1996-2005. The results are achieved through cooperative efforts that originated at the Living with a Star (LWS) Coordinated Data-Analysis Workshop (CDAW) held at George Mason University in March 2005. On the basis of careful examination of the complete array of solar and in situ solar wind observations, we have identified and characterized, for each major geomagnetic storm, the overall solar-interplanetary (solar-IP) source type, the time, velocity, and angular width of the source coronal mass ejection (CME), the type and heliographic location of the solar source region, the structure of the transient solar wind flow with the storm-driving component specified, the arrival time of shock/disturbance, and the start and ending times of the corresponding IP CME (ICME). The storm-driving component, which possesses a prolonged and enhanced southward magnetic field (Bs), may be an ICME, the sheath of shocked plasma (SH) upstream of an ICME, a corotating interaction region (CIR), or a combination of these structures. We classify the Solar-IP sources into three broad types: (1) S-type, in which the storm is associated with a single ICME and a single CME at the Sun; (2) M-type, in which the storm is associated with a complex solar wind flow produced by multiple interacting ICMEs arising from multiple halo CMEs launched from the Sun in a short period; (3) C-type, in which the storm is associated with a CIR formed at the leading edge of a high-speed stream originating from a solar coronal hole (CH). For the 88 major storms, the S-type, M-type, and C-type events number 53 (60%), 24 (27%), and 11 (13%), respectively. For the 85 events for which the surface source regions could be investigated, 54 (63%) of the storms originated in solar active regions, 11 (13%) in quiet Sun regions associated with quiescent filaments or filament channels, and 11 (13%) were associated with coronal holes. Remarkably, nine (11%) CME-driven events showed no sign of eruptive features on the surface or in the low corona (e.g., no flare, no coronal dimming, and no loop arcade, etc.), even though all the available solar observations in a suitable time period were carefully examined. Thus while it is generally true that a major geomagnetic storm is more likely to be driven by a frontside fast halo CME associated with a major flare, our study indicates a broad distribution of source properties. The implications of the results for space weather forecasting are briefly discussed. Title: Energetic Phenomena on the Sun Authors: Gopalswamy, Nat Bibcode: 2007AIPC..919..275G Altcode: Solar flares, coronal mass ejections (CMEs), solar energetic particles (SEPs), and fast solar wind represent the energetic phenomena on the Sun. Flares and CMEs originate from closed magnetic field structures on the Sun typically found in active regions and quiescent filament regions. On the other hand, fast solar wind originates from open field regions on the Sun, identified as coronal holes. Energetic particles are associated with flares, CMEs, and fast solar wind, but the ones associated with CMEs are the most intense. The energetic phenomena have important consequences in the heliosphere and contribute significantly to adverse space weather. This paper provides an over view of the energetic phenomena on the Sun including their origin interplanetary propagation and space weather consequences. Title: The Early Life Of A Coronal Mass Ejection From SECCHI And SOHO Observations Authors: Gopalswamy, N.; Yashiro, S.; Davila, J. M.; Howard, R. A.; SECCHI/COR1 Team Bibcode: 2007AAS...210.2813G Altcode: 2007BAAS...39..324G One of the key advantages of STEREO/SECCHI is the inner coronagraph (COR1), which can observe CMEs in the coronal region where CMEs attain their maximum acceleration. The first CME observed by COR1 was on 2006 December 30. The CME was also observed by the C2 and C3 coronagraphs of SOHO. We compare the morphological and height-time histories between COR1 and SOHO/LASCO data. We find that the flux rope structure evolves significantly between the COR1 and LASCO/C2 FOVs, although we can track features to get a continuous height-time history of the CME. We find excellent agreement between the two sets of data which could be combined to obtain the kinematic properties of the CME. We also superposed a STEREO/COR1 image of the CME on a STEREO/EUVI image and SOHO/C2 image to compare the solar origin and morphology. The CME originated from the southwest quadrant of the Sun and was of flux-rope type moving with an average speed of 200 km/s and an acceleration of 6 m/s/s, with a characteristic two-ribbon structure and an extended post-eruption arcade. In addition to the similarity in CME features, there was excellent correspondence between the outlying streamers in the two coronagraph images. Title: Geoeffectiveness of halo coronal mass ejections Authors: Gopalswamy, N.; Yashiro, S.; Akiyama, S. Bibcode: 2007JGRA..112.6112G Altcode: 2007JGRA..11206112G We studied the geoeffectiveness, speed, solar source, and flare association of a set of 378 halo coronal mass ejections (CMEs) of cycle 23 (1996-2005, inclusive). We compiled the minimum Dst values occurring within 1-5 days after the CME onset. We compared the distributions of such Dst values for the following subsets of halo CMEs: disk halos (within 45 deg from disk center), limb halos (beyond 45 degrees but within 90 deg from disk center), and backside halo CMEs. Defining that a halo CME is geoeffective if it is followed by Dst ≤ -50 nT, moderately geoeffective if -50 nT < Dst < -100 nT, and strongly geoeffective if Dst ≤ -100 nT, we find that the disk halos are followed by strong storms, limb halos are followed by moderate storms, and backside halos are not followed by significant storms. The Dst distribution for a random sample is nearly identical to the case of backside halos. About 71% of all frontside halos are geoeffective, supporting the high rate of geoeffectiveness of halo CMEs. A larger fraction (75%) of disk halos are geoeffective. Intense storms are generally due to disk halos and the few intense storms from limb halos occur only in the maximum and declining phases. Most intense storms occur when there are successive CMEs. The delay time between CME onset and minimum Dst value is the smallest for limb halos, suggesting that the sheath is geoeffective in these cases. The geoeffectiveness rate has prominent dips in 1999 and 2002 (the beginning and end years of the solar maximum phase). The numbers of all frontside and geoeffective frontside halos show a triple peak structure similar to the number of intense geomagnetic storms. The difference in flare sizes among geoeffective and nongeoeffective halos is not significant. The nongeoeffective CMEs are generally slower and have more easterly or limbward solar sources compared to the geoeffective ones; source location and speed are the most important parameters for geoeffectiveness. Title: Why Some Fast and Wide Coronal Mass Ejections are Radio-quiet? Authors: Gopalswamy, N.; Xie, H.; Aguilar-Rodriguez, E.; Akiyama, S.; Yashiro, S.; Kaiser, M. L.; Howard, R. A.; Bougeret, J. L. Bibcode: 2007AAS...210.5801G Altcode: 2007BAAS...39..167G The radio-quiet CMEs lack type II radio burst association in the metric and decameter-hectometric (DH) wavelengths. We compiled CMEs faster than 900 km/s and wider than 60 degrees and checked against metric and interplanetary type II bursts and found that about one third of them were radio-quiet. We compared the radio-quiet CMEs with the radio-loud ones occurring over the same study period (1996-2005). The radio-quiet and radio-loud CMEs had average speeds of 1129 and 1524 km/s, respectively bracketing the average speed of all FW CMEs (1303 km/s). The width distributions also showed a similar behavior: the fraction of halo and partial halo CMEs was the largest for the radio-loud CMEs (54%), smallest for the radio-quiet CMEs (18%) and intermediate for all fast and wide CMEs (42%). The majority of radio-quiet CMEs (55%) were back-sided; most of the frontsided ones also originated close to the limb. This is in contrast to the radio-loud CMEs which originated generally on the disk with only a small fraction (13%) was back-sided. The average flare size was also slightly smaller for the radio-quiet CMEs compared to that of radio-loud CMEs. Back-sided and limb CMEs have only part of the shock surface visible to the observer. This seems to be an important factor deciding whether a CME is radio quiet. Title: IHY - An International Cooperative Program Authors: Rabello-Soares, M. Cristina; Davila, J.; Gopalswamy, N.; Thompson, B. Bibcode: 2007AAS...210.5701R Altcode: 2007BAAS...39..167R The International Heliophysical Year (IHY) in 2007/2008 involves thousands of scientists representing over 70 nations. It consists of four distinct elements that will be described here.

Taking advantage of the large amount of heliophysical data acquired routinely by a vast number of sophisticated instruments aboard space missions and at ground-based observatories, IHY aims to develop the basic science of heliophysics through cross-disciplinary studies of universal processes by means of Coordinated Investigation Programs (CIPs).

The second component is in collaboration with the United Nations Basic Space Science Initiative (UNBSSI) and consists of the deployment of arrays of small, inexpensive instruments such as magnetometers, radio antennas, GPS receivers, etc. around the world to provide global measurements. An important aspect of this partnership is to foster the participation of developing nations in heliophysics research.

IHY coincides with the commemoration of 50 years of the space age that started with launch of Sputnik on October 4, 1957 and it is on the brink of a new age of space exploration where the Moon, Mars and the outer planets will be the focus of the space programs in the next years. As a result, it presents an excellent opportunity to create interest for science among young people with the excitement of discovery of space. The education and outreach program forms another cornerstone of IHY.

Last but not least, an important part of the IHY activities, its forth component, is to preserve the history and memory of IGY 1957. Title: Commission 10: Solar Activity Authors: Melrose, Donald B.; Klimchuk, James A.; Benz, A. O.; Craig, I. J. D.; Gopalswamy, N.; Harrison, R. A.; Kozlovsky, B. Z.; Poletto, G.; Schrijver, K. J.; van Driel-Gesztelyi, L.; Wang, J. -X. Bibcode: 2007IAUTA..26...75M Altcode: Commission 10 aims at the study of various forms of solar activity, including networks, plages, pores, spots, fibrils, surges, jets, filaments/prominences, coronal loops, flares, coronal mass ejections (CMEs), solar cycle, microflares, nanoflares, coronal heating etc., which are all manifestation of the interplay of magnetic fields and solar plasma. Increasingly important is the study of solar activities as sources of various disturbances in the interplanetary space and near-Earth "space weather".Over the past three years a major component of research on the active Sun has involved data from the RHESSI spacecraft. This review starts with an update on current and planned solar observations from spacecraft. The discussion of solar flares gives emphasis to new results from RHESSI, along with updates on other aspects of flares. Recent progress on two theoretical concepts, magnetic reconnection and magnetic helicity is then summarized, followed by discussions of coronal loops and heating, the magnetic carpet and filaments. The final topic discussed is coronal mass ejections and space weather.The discussions on each topic is relatively brief, and intended as an outline to put the extensive list of references in context.The review was prepared jointly by the members of the Organizing Committee, and the names of the primary contributors to the various sections are indicated in parentheses. Title: Properties of Interplanetary Coronal Mass Ejections Authors: Gopalswamy, Nat Bibcode: 2007sdeh.book..145G Altcode: No abstract at ADS Title: International Heliophysical Year 2007: Basic space science initiatives Authors: Davila, Joe; Gopalswamy, Nat; Haubold, Hans J.; Thompson, Barbara Bibcode: 2007SpPol..23..121D Altcode: The UN Office for Outer Space Affairs, through the IHY Secretariat and the United Nations Basic Space Science Initiative (UNBSSI), assists scientists and engineers world-wide to participate in the International Heliophysical Year (IHY) 2007. A major thrust of IHY/UNBSSI is to deploy arrays of small, inexpensive instruments such as magnetometers, radio telescopes, GPS receivers, all-sky cameras, etc. around the world to allow global measurements of ionospheric and heliospheric phenomena. The small instrument program is envisioned as a partnership between instrument providers and instrument hosts in developing nations, with the former providing the instruments, the host nation the manpower, facilities and operational support, typically at a local university. Funds are not available through IHY/UNBSSI to build the instruments; these must be obtained through the normal proposal channels. All instrument operational support for local scientists, facilities, data acquisition, etc. will be provided by the host nation. The IHY/UNBSSI can facilitate the deployment of several of these networks and existing databases and relevant software tools will be identified to promote space science activities in developing nations. Extensive data on space science have been accumulated by a number of space missions. Similarly, long-term databases are available from ground-based observations. These data can be utilized in ways different from those originally intended for understanding the heliophysical processes. This report provides an overview of IHY/UNBSSI, its achievements, future plans and outreach to the 192 member states of the United Nations. Title: The United Nations Basic Space Science Initiative for IHY 2007 Authors: Gopalswamy, Nat; Davila, Joseph; Thompson, Barbara; Haubold, Hans Bibcode: 2007IAUSS...5..295G Altcode: No abstract at ADS Title: Scientific Justification For The Low- Frequency Radio Measurements By The Solar Orbiter Mission Authors: Gopalswamy, N.; MacDowall, R. J.; Kaiser, M. L.; Bale, S. D.; Maksimovic, M.; Bougeret, J. -L. Bibcode: 2007ESASP.641E..66G Altcode: The importance of the radio measurements in the frequency range 1-14 MHz has been demonstrated only recently by the Radio and Plasma Wave (WAVES) Experiment on board Wind. The shock-related radio emission below 14 MHz originates from a heliocentric distance beyond 2 solar radii in association with coronal mass ejections. Although several issues on the origin of shocks and their connection to solar eruptions have been clarified by the SOHO-Wind synergistic observations, some of them remain mainly because of lack of radio imaging and/or in situ observations at the shock source. The Solar Orbiter mission will be able to address these issues by directly sampling the shock at a location where the radio emission originates to provide measurements of physical parameters for direct comparison with theory and modelling. We highlight some of the science issues that can be addressed by a radio and plasma wave analyzer on board the Solar Orbiter mission in combination with in situ measurements close to the Sun. Title: The United Nations Basic Space Science Initiative: the TRIPOD concept Authors: Kitamura, Masatoshi; Wentzel, Don; Henden, Arne; Bennett, Jeffrey; Al-Naimiy, H. M. K.; Mathai, A. M.; Gopalswamy, Nat; Davila, Joseph; Thompson, Barbara; Webb, David; Haubold, Hans Bibcode: 2007IAUSS...5..277K Altcode: 2006physics..10149K Since 1990, the United Nations is annually holding a workshop on basic space science for the benefit of the worldwide development of astronomy. Additional to the scientific benefits of the workshops and the strengthening of international cooperation, the workshops lead to the establishment of astronomical telescope facilities through the Official Development Assistance (ODA) of Japan. Teaching material, hands-on astrophysics material, and variable star observing programmes had been developed for the operation of such astronomical telescope facilities in an university environment. This approach to astronomical telescope facility, observing programme, and teaching astronomy has become known as the basic space science TRIPOD concept. Currently, a similar TRIPOD concept is being developed for the International Heliophysical Year 2007, consisting of an instrument array, data taking and analysis, and teaching space science. Title: The CME-productivity associated with flares from two active regions Authors: Akiyama, S.; Yashiro, S.; Gopalswamy, N. Bibcode: 2007AdSpR..39.1467A Altcode: We report on two flare-productive adjacent active regions (ARs), with different levels of coronal mass ejection (CME) association. AR 10039 and AR 10044 produced strong X-ray flares during their disk passages. We examined the CME association rate of X-ray flares and found it to be different between the two ARs. AR 10039 was CME-rich with 72% association with flares, while AR 10044 was CME-poor with an association rate of only 14%. CMEs from the CME-rich AR were faster and wider than the ones from the CME-poor AR. The flare activity of AR 10044 was temporally concentrated over a short interval and spatially localized over a compact area between the major sun spots. We suggest that different pre-eruption evolution and magnetic configuration in the two regions might have contributed to the difference between the two ARs. Title: Energetic Particles Related with Coronal and Interplanetary Shocks Authors: Gopalswamy, N. Bibcode: 2007LNP...725..139G Altcode: Acceleration of electrons and ions at the Sun is discussed in the framework of CME-driven shocks. Based on the properties of coronal mass ejections associated with type II bursts at various wavelengths, the possibility of a unified approach to the type II phenomena is suggested. Two aspects of primary importance to shock accelerations are: (1) Energy of the driving CME and (2) the conditions in the medium that supports shock propagation. The high degree of overlap between CMEs associated with large solar energetic particle events and type II bursts occurring at all wavelengths underscores the importance of CME energy in driving shocks far into the interplanetary medium. Presence of preceding CMEs can alter the conditions in the ambient medium, which is shown to influence the intensity of large solar energetic particle events. Both statistical evidence and case studies are presented that underscore the importance of the ambient medium. Title: The International Heliophysical Year Authors: Davila, Joseph M.; Gopalswamy, Nat; Thompson, Barbara J. Bibcode: 2007RoAJ...17....3D Altcode: No abstract at ADS Title: Radio Observatory for Lunar Sortie Science (ROLSS) Authors: MacDowall, R. J.; Gopalswamy, N.; Kaiser, M. L.; Demaio, L. D.; Lazio, J.; Weiler, K. W.; Bale, S. D.; Burns, J. O.; Jones, D. L.; Kasper, J. C.; Reiner, M. J. Bibcode: 2006AGUFMSM43A1476M Altcode: It is widely recognized that the lunar surface is an ideal base for radio astronomy observations at frequencies below the terrestrial ionospheric cutoff frequency. The ionospheric cutoff (10-20 MHz) prevents observations of very low frequency radio sources outside the ionosphere from being conducted by ground-based observatories. Spacecraft or lunar-based observatories are the only alternative, with the lunar surface providing the real estate for establishing radio arrays with large dimensions (tens of kilometers) to perform high resolution imaging at the lowest frequencies (< 10 MHz). In this presentation, we describe a concept study for a pathfinder radio observatory to be deployed during a lunar sortie. The concept study focuses on appropriate antenna, receiver, deployment, power, and communication systems for the observatory. These systems must be low mass to permit the lunar sortie package to maximize science and engineering goals. Power requirements for the receiver systems and the downlink to Earth must also be minimized. The concept study also addresses in detail the science goals of this observatory, which include observations of solar radio bursts as proxies of solar and heliospheric particle acceleration, detailed measurement of the lunar ionosphere scale height as a function of time, integrated spectra of strong (extragalactic) sources to probe particle acceleration processes, and a survey of natural and man-made emissions from the Earth. These observations will enhance our understanding of the various radio sources and the lunar observing environment and pave the way for future larger-scale lunar radio astronomy arrays. Title: Investigating the state of the Sun-Earth system during extreme events: First science results of a worldwide online conference series Authors: Kozyra, J. U.; Shibata, K.; Fox, N. J.; Basu, S.; Coster, A. J.; Davila, J. M.; Gopalswamy, N.; Liou, K.; Lu, G.; Mann, I. R.; Pallamraju, D.; Paxton, L. J.; Peterson, W. K.; Talaat, E. R.; Weatherwax, A. T.; Young, C. A.; Zanetti, L. J. Bibcode: 2006AGUFMSA43A..01K Altcode: This presentation reports on new science results from an online conference entitled "Return to the Auroral Oval for the Anniversary of the IGY" designed to bring together researchers worldwide: (1) to investigate newly reported features in the auroral oval during substorms that occur in the main phase of superstorms and how these features map throughout geospace, (2) to explore implications for the state of the geospace system, (3) to identify signatures associated with this geospace state from equatorial to polar latitudes, (4) to investigate the unusual aspects of the solar sources, and (5) to understand how propagation from Sun to Earth modified the observed solar drivers. The main focus of the first conference is on worldwide data exchange, the construction of global data products and assimilative global views, and identifying coupled chains of events from sun-to-Earth. The collaborative conference data products and enhanced understanding of the observed features of the events will form the basis for a follow-on conference in 2007 focused primarily on theoretical studies and collaborative simulation efforts between modeling groups, observers and data analysts. This conference is the first in a series of sun-Earth connection online conferences, sponsored by CAWSES, IHY, eGY, ICESTAR, NASA/LWS, and NSF Atmospheric Science Programs, and designed to bring interdisciplinary researchers together with the vast developing cyber-infrastructure of large international data sets, high performance computing and advanced visualizations to address grand challenge science issues in a way not previously possible. Title: Relationships Among Magnetic Clouds, CMES, and Geomagnetic Storms Authors: Wu, C. C.; Lepping, R. P.; Gopalswamy, N. Bibcode: 2006SoPh..239..449W Altcode: 2006SoPh..tmp...93W During solar cycle 23, 82 interplanetary magnetic clouds (MCs) were identified by the Magnetic Field Investigation (MFI) team using Wind (1995 - 2003) solar wind plasma and magnetic field data from solar minimum through the maximum of cycle 23. The average occurrence rate is 9.5 MCs per year for the overall period. It is found that some of the anomalies in the frequency of occurrence were during the early part of solar cycle 23: (i) only four MCs were observed in 1999, and (ii) an unusually large number of MCs (17 events) were observed in 1997, just after solar minimum. We also discuss the relationship between MCs, coronal mass ejections (CMEs), and geomagnetic storms. During the period 1996 - 2003, almost 8000 CMEs were observed by SOHO-LASCO. The occurrence frequency of MCs appears to be related neither to the occurrence of CMEs as observed by SOHO LASCO nor to the sunspot number. When we included "magnetic cloud-like structures" (MCLs, defined by Lepping, Wu, and Berdichevsky, 2005), we found that the occurrence of the joint set (MCs + MCLs) is correlated with both sunspot number and the occurrence rate of CMEs. The average duration of the MCL structures is ~40% shorter than that of the MCs. The MCs are typically more geoeffective than the MCLs, because the average southward field component is generally stronger and longer lasting in MCs than in MCLs. In addition, most severe storms caused by MCs/MCLs with Dstmin≤ −100 nT occurred in the active solar period. Title: Consequences of Coronal Mass Ejections in the Heliosphere Authors: Gopalswamy, N. Bibcode: 2006SunGe...1b...5G Altcode: 2006SunGe...1....5G Coronal mass ejections (CMEs) are the most energetic events in the heliosphere. They carry large amounts of coronal magnetic fields and plasma with them and drive large-scale interplanetary shocks. The CMEs and shock have significant consequences at various locations in the heliosphere, including the production of intense geomagnetic storms and large energetic particle events. CMEs form merged interaction regions in the heliosphere, which act as magnetic barriers for the galactic cosmic rays entering the heliosphere. After a brief summary of the observed properties of CMEs at the Sun, I discuss the properties of the interplanetary CMEs (ICMEs) and their connection to shocks, radio bursts, solar energetic particles and the modulation of galactic cosmic rays. Title: Radio Observations of Solar Eruptions Authors: Gopalswamy, N. Bibcode: 2006spnr.conf...81G Altcode: Coronal mass ejections (CMEs) are composed of multithermal plasmas, which make them produce different radio signatures at different wavelengths. The prominence core of CMEs are of the lowest temperature and hence optically thick at microwave frequencies and hence are readily observed. The Nobeyama Radioheliograph has exploited this fact and observed a large number of prominence eruptions over most of solar cycle 23 and parts of cycle 22. This paper reviews recent studies on prominence eruptions and their contributions for understanding the CME phenomenon. In particular, the following issues are discussed: (i) the statistical and physical relationship between CMEs and the radio prominence eruptions, and how this relationship manifests as a function of the solar cycle; (ii) The asymmetry of prominence eruptions between northern and southern hemispheres; (iii) the relationship between prominence eruptions and CME cores; (iv) the implications of the cessation of high-latitude PEs before the reversal of the global solar magnetic field, and (v) the implications of the high-latitude PEs and CMEs for the modulation of galactic cosmic rays. Finally, the importance of the Nobeyama Radioheliograph data to future missions such as STEREO and Solar-B are discussed. Title: General Discussion on Donor Programs Authors: Gopalswamy, N. Bibcode: 2006ihy..workE..88G Altcode: No abstract at ADS Title: Coronal Mass Ejections in the Heliosphere Authors: Gopalswamy, N. Bibcode: 2006ihy..workE..46G Altcode: Coronal mass ejections (CMEs) are the most energetic events in the heliosphere. They carry large amounts of coronal magnetic fields and plasma with them and driving large-scale interplanetary shocks. The CMEs and shock have significant consequences at various locations in the heliosphere, including the production of intense geomagnetic storms and large energetic particle events. CMEs form merged interaction regions in the heliosphere, which act as magnetic barriers for the galactic cosmic rays entering the heliosphere. After a brief summary of the observed properties of CMEs at the Sun, I discuss the properties of the interplanetary CMEs (ICMEs) and their connection to shocks, radio bursts, solar energetic particles and modulation of galactic cosmic rays. Title: General Discussion on Donor Programs N. Gopalswamy Authors: Gopalswamy, N. Bibcode: 2006ihy..workE..86G Altcode: No abstract at ADS Title: IHY-CAWSES Data base Authors: Young, C. A.; Thompson, B. J.; Davila, J.; Gopalswamy, N. Bibcode: 2006ihy..workE..90Y Altcode: In partnership with the CAWSES (Climate And Weather of the Sun-Earth System) program, IHY is sponsoring a series of Virtual Workshops and a special IHY/CAWSES database to provide virtual access of data collected for IHY and CAWSES campaigns. The first of the virtual workshops occurred November 13-17, 2006, and had more than 200 online participants. Online presentation and discussion tools are being refined for future workshops. The IHY/CAWSES database provides a means of entering data into the Virtual Solar Observatory (to provide the maximum and easiest possible access to the data) while still maintaining a close connection to the other data sets used in IHY/CAWSES activities. Title: General Discussion on Donor Programs Authors: Gopalswamy, N. Bibcode: 2006ihy..workE..87G Altcode: No abstract at ADS Title: IHY/UNBSS Program: Success Stories Authors: Gopalswamy, N.; Davila, J.; Thompson, B. J.; Haubold, H. J. Bibcode: 2006ihy..workE..15G Altcode: The United Nations Office for Outer Space Affairs, through the IHY secretariat and the United Nations Basic Space Science Initiative (UNBSSI) is assisting scientists and engineers from all over the world in participating in the International Heliophysical Year (IHY) 2007. A major thrust of the IHY/UNBSSI program is to deploy arrays of small, inexpensive instruments such as magnetometers, radio telescopes, GPS receivers, etc. around the world to provide global measurements of ionospheric and heliospheric phenomena. The small instrument program is a partnership between instrument providers, and instrument hosts in developing countries. The lead scientist will provide the instruments (or fabrication plans for instruments) in the array; the host country will provide manpower, facilities, and operational support to obtain data with the instrument typically at a local university. Existing data bases and relevant software tools can be identified to promote space science activities in developing countries. Extensive data on space science have been accumulated by a number of space missions. Similarly, long-term data bases are available from ground based observations. These data can be utilized in ways different from originally intended for understanding the heliophysical processes. This paper provides an overview of the IHY/UNBSS program, its achievements and future plans. Title: Improved input to the empirical coronal mass ejection (CME) driven shock arrival model from CME cone models Authors: Xie, H.; Gopalswamy, N.; Ofman, L.; St. Cyr, O. C.; Michalek, G.; Lara, A.; Yashiro, S. Bibcode: 2006SpWea...410002X Altcode: We study the Sun-Earth travel time of interplanetary shocks driven by coronal mass ejections (CMEs) using empirical cone models. Three different cone models have been used to obtain the radial speeds of the CMEs, which are then used as input to the empirical shock arrival (ESA) model to obtain the Sun to Earth travel time of the shocks. We compare the predicted and observed shock transit times and find that the accuracy of the ESA model is improved by applying CME radial speeds from the cone models. There are two ways of calculating the shock travel time: using the ESA model or using the simplified ESA formula obtained by an exponential fit to the ESA model. The average mean error in the travel time with the cone model speeds is 7.8 hours compared to 14.6 hours with the sky plane speed, which amounts to an improvement of 46%. With the ESA formula, the corresponding mean errors are 9.5 and 11.7 hours, respectively, representing an improvement of 19%. The cone models minimize projection effects and hence can be used to obtain CME radial speeds. When input to the ESA model, the large scatter in the shock travel time is reduced, thus improving CME-related space weather predictions. Title: Solar Eruptions and Energetic Particles: An Introduction Authors: Gopalswamy, N.; Mewaldt, R.; Torsti, J. Bibcode: 2006GMS...165....1G Altcode: This introductory article highlights current issues concerning two related phenomena involving mass emission from the Sun: solar eruptions and solar energetic particles. A brief outline of the chapters is provided indicating how the current issues are addressed in the monograph. The sections in this introduction roughly group the chapters dealing with coronal mass ejections (CMEs), solar energetic particles (SEPs), shocks, and space weather. The concluding remarks include a brief summary of outstanding issues that drive current and future research on CMEs and SEPs. Title: Coronal Mass Ejections and Type II Radio Bursts Authors: Gopalswamy, Nat Bibcode: 2006GMS...165..207G Altcode: The simultaneous availability of white light data on CMEs from the Solar and Heliospheric Observatory (SOHO) and radio data on shock waves from the Radio and Plasma Wave experiment on board the Wind spacecraft over the past decade have helped in making rapid progress in understanding the CME-driven shocks. I review some recent developments in the type II-CME relationship, focusing on the properties of CMEs as shock drivers and those of the medium supporting shock propagation. I also discuss the solar cycle variation of the type II bursts in comparison with other eruptive phenomena such as CMEs, flares, large solar energetic particle events, and shocks detected in situ. The hierarchical relationship found between the CME kinetic energy and wavelength range of type II radio bursts, non-existence of CMEless type II bursts, and the explanation of type II burst properties in terms of shock propagation with a realistic profile of the fast mode speed suggest that the underlying shocks are driven by CMEs, irrespective of the wavelength domain. Such a unified approach provides an elegant understanding of the entire type II phenomenon (coronal and interplanetary). The blast wave scenario remains an alternative hypothesis for type II bursts only over a small spatial domain (within one solar radius above the solar surface) that is not accessible to in situ observation. Therefore the existence of blast waves cannot be directly confirmed. CMEs, on the other hand, can be remote sensed from this domain. Title: Different Power-Law Indices in the Frequency Distributions of Flares with and without Coronal Mass Ejections Authors: Yashiro, S.; Akiyama, S.; Gopalswamy, N.; Howard, R. A. Bibcode: 2006ApJ...650L.143Y Altcode: 2006astro.ph..9197Y We investigated the frequency distributions of flares with and without coronal mass ejections (CMEs) as a function of flare parameters (peak flux, fluence, and duration of soft X-ray flares). We used CMEs observed by the Large Angle and Spectrometric Coronagraph (LASCO) on board the Solar and Heliospheric Observatory (SOHO) mission and soft X-ray flares (C3.2 and above) observed by the Geostationary Operational Environmental Satellite (GOES) during 1996-2005. We found that the distributions obey a power law of the form dN/dX~X-α, where X is a flare parameter and dN is the number of events recorded within the interval [X, X+dX]. For the flares with (without) CMEs, we obtained the power-law index α=1.98+/-0.05 (α=2.52+/-0.03) for the peak flux, α=1.79+/-0.05 (α=2.47+/-0.11) for the fluence, and α=2.49+/-0.11 (α=3.22+/-0.15) for the duration. The power-law indices for flares without CMEs are steeper than those for flares with CMEs. The larger power-law index for flares without CMEs supports the possibility that nanoflares contribute to coronal heating. Title: Properties and geoeffectiveness of halo coronal mass ejections Authors: Michalek, G.; Gopalswamy, N.; Lara, A.; Yashiro, S. Bibcode: 2006SpWea...410003M Altcode: 2007arXiv0710.4526M Halo coronal mass ejections (HCMEs) originating from regions close to the center of the Sun are likely to be geoeffective. Assuming that the shape of HCMEs is a cone and that the HCMEs propagate with constant angular widths and velocities, at least in their early phase, we have developed a technique which allowed us to obtain the space speed, width, and source location. We apply this technique to obtain the parameters of all full HCMEs observed by the Solar and Heliospheric Observatory (SOHO) mission's Large Angle and Spectrometric Coronagraph (LASCO) experiment until the end of 2002. Using this data, we examine which parameters determine the geoeffectiveness of HCMEs. We show that in the considered period of time, only fast halo CMEs (with space velocities higher than ~1000 km/s) and originating from the Western Hemisphere close to the solar center could cause intense geomagnetic storms. We illustrate how the HCME parameters can be used for space weather forecast. It is also demonstrated that the strength of a geomagnetic storm does not depend on the determined width of HCMEs. This means that HCMEs do not have to be very large to cause major geomagnetic storms. Title: Coronal Mass Ejections of Solar Cycle 23 Authors: Gopalswamy, Nat Bibcode: 2006JApA...27..243G Altcode: I summarize the statistical, physical, and morphological properties of coronal mass ejections (CMEs) of solar cycle 23, as observed by the Solar and Heliospheric Observatory (SOHO) mission. The SOHO data is by far the most extensive data, which made it possible to fully establish the properties of CMEs as a phenomenon of utmost importance to Sun-Earth connection as well as to the heliosphere. I also discuss various subsets of CMEs that are of primary importance for their impact on Earth. Title: On the Rates of Coronal Mass Ejections: Remote Solar and In Situ Observations Authors: Riley, Pete; Schatzman, C.; Cane, H. V.; Richardson, I. G.; Gopalswamy, N. Bibcode: 2006ApJ...647..648R Altcode: We compare the rates of coronal mass ejections (CMEs) as inferred from remote solar observations and interplanetary CMEs (ICMEs) as inferred from in situ observations at both 1 AU and Ulysses from 1996 through 2004. We also distinguish between those ICMEs that contain a magnetic cloud (MC) and those that do not. While the rates of CMEs and ICMEs track each other well at solar minimum, they diverge significantly in early 1998, during the ascending phase of the solar cycle, with the remote solar observations yielding approximately 20 times more events than are seen at 1 AU. This divergence persists through 2004. A similar divergence occurs between MCs and non-MC ICMEs. We argue that these divergences are due to the birth of midlatitude active regions, which are the sites of a distinct population of CMEs, only partially intercepted by Earth, and we present a simple geometric argument showing that the CME and ICME rates are consistent with one another. We also acknowledge contributions from (1) an increased rate of high-latitude CMEs and (2) focusing effects from the global solar field. While our analysis, coupled with numerical modeling results, generally supports the interpretation that whether one observes a MC within an ICME is sensitive to the trajectory of the spacecraft through the ICME (i.e., an observational selection effect), one result directly contradicts it. Specifically, we find no systematic offset between the latitudinal origin of ICMEs that contain MCs at 1 AU in the ecliptic plane and that of those that do not. Title: Solar Energetic Particles and CME-driven Shocks Authors: Gopalswamy, N.; Yashiro, S.; Kaiser, M. L.; Bougeret, J. -L. Bibcode: 2006IAUJD...1E..54G Altcode: Large solar energetic particle (SEP) events are associated with coronal mass ejections (CMEs) of very high speed (~1500 km/s). A mass mtion of such high speeds in the coronal and interplanetary plasma has to drive fast mode MHD shocks. Direct evidence of such shocks come from in situ observations of shock arriving at 1 AU immediately followed by the driving CMEs. The energetic storm particle (ESP) events associated with these shocks present direct evidence for shock acceleration. Shocks near the Sun have to be remote-sensed using type II bursts of type II. Type II bursts occurring over wide range of wavelengths are known to be associated with very fast and wide CMEs (Gopalswamy et al., 2005). We analyze a set of such type II bursts observed during solar cycle 23 and the associated SEP and CME events to explore the relationship bewteen CME-driven shocks and SEPs near the Sun. We also study the association of the type II burst events with the interplanetary shocks observed in situ and ESP events. The main result is that when the CME associated with the type II bursts originate on the disk center of the Sun, they result in shocks at 1 AU followed by driving CMEs. We also discuss the relationship bewteen type II bursts and ESP events. Reference: Gopalswamy, N., E. Aguilar-Rodriguez, S. Yashiro, S. Nunes, M. L. Kaiser, and R. A. Howard, Type II radio bursts and energetic solar eruptions, JGRA, 110, 12, 2005 Title: Mission Concepts for Spacecraft and Lunar-based Radio Source Imaging at Frequencies below the Ionospheric Cutoff Authors: Gopalswamy, N.; MacDowall, R. J.; Kaiser, M. L.; Demaio, L. D.; Bale, S. D.; Howard, R. E.; Jones, D. L.; Kasper, J. C.; Kassim, N. E.; Lazio, J. W.; Weiler, K. W.; Reiner, M. J. Bibcode: 2006IAUJD..12E..21G Altcode: No present or approved spacecraft mission has the capability to provide high angular resolution imaging of solar or magnetospheric radio bursts or of the celestial sphere at frequencies below the ionospheric cutoff. In this presentation, we review briefly the history of space-based radio observations by single spacecraft. Although these missions did not produce images of discrete radio sources, they did establish important constraints for future imaging missions. Subsequently, we present in detail an active NASA mission proposal to perform such imaging in the frequency range ~30 kHz to 15 MHz. The focus of this mission, the Solar Imaging Radio Array (SIRA), is solar and NASA exploration-oriented, with emphasis on improved understanding and space weather application of radio bursts associated with solar energetic particle (SEP) events and on tracking shocks and other components of coronal mass ejections (CMEs). SIRA will also map the astrophysical sky. SIRA will require a minimum of 12 to 16 micro-satellites to establish a sufficient number of baselines with separations on the order of a kilometer. The baseline microsat is 3-axis stabilized with body-mounted solar arrays and an articulated, earth pointing high gain antenna. The constellation will likely be placed in an L1 halo orbit, which is the preferred location for full-time solar observations. We will also discuss follow-on missions that would be lunar-based, ultimately with of order 10,000 dipole antennas. The lunar missions would be adaptations of ground-based interferometric arrays like LOFAR, LWA, MWA, etc. Basic research in radio astronomy at the Naval Research Laboratory is supported by the Office of Naval Research; part of this work is being carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration. Title: The IHY Program and Associated IAU Activities Authors: Webb, D.; Gopalswamy, N. Bibcode: 2006IAUSS...5E..43W Altcode: The International Heliospheric Year is an international program of scientific collaboration planned for the time period starting next year, the 50th anniversary of the International Geophysical Year. The physical realm of the IHY encompasses all of the solar system out to the interstellar medium, representing a direct connection between in-situ and remote observations. The IHY is of great interest to the IAU because of this broad astronomical coverage as well as its emphasis on international cooperation and developing nations. The IHY program is promoting worldwide participation in its activities that include dispersing networks of inexpensive instrumentation to achieve its scientific goals. Within the IAU the IHY program is organized under Division II, which covers the Sun and Heliosphere. Nat Gopalswamy is the IHY International Coordinator and Chair of the IHY subgroup within the IAU's Working Group on International Collaboration on Space Weather. David Webb is the IAU representative for the IHY and the outgoing President of Division II. The United Nations IHY effort is led by Hans Haubold under the UNBSS program and will be discussed next by Dr. Gopalswamy. Under this program the IAU is supporting the annual IHY Workshops and is facilitating the communications between scientists in developed and developing countries. Title: Correction to ``Introduction to special section on corotating solar wind streams and recurrent geomagnetic activity'' Authors: Tsurutani, B. T.; McPherron, R. L.; Gonzalez, W. D.; Lu, G.; Sobral, J. H. A.; Gopalswamy, N. Bibcode: 2006JGRA..111.8S90T Altcode: 2006JGRA..11108S90T No abstract at ADS Title: Anemone structure of Active Region NOAA 10798 and related geo-effective flares/ CMEs Authors: Asai, A.; Ishii, T. T.; Shibata, K.; Gopalswamy, N. Bibcode: 2006IAUJD...3E..72A Altcode: Introduction: We report the evolution and the coronal features of an active region NOAA 10798, and the related magnetic storms. Method: We examined in detail the photospheric and coronal features of the active region by using observational data in soft X-rays, in extreme ultraviolet images, and in magnetogram obtained with GOES, SOHO satellites. We also examined the interplanetary disturbances from the ACE data. Results: This active region was located in the middle of a small coronal hole, and generated 3 M-class flares. The flares are associated with high speed CMEs up to 2000 km/s. The interplanetary disturbances also show a structure with southward strong magnetic field. These produced a magnetic storm on 2005 August 24. Conclusions: The anemone structure may play a role for producing the high-speed and geo-effective CMEs even the near limb locations. Title: The United Nations Basic Space Science Initiative for IHY 2007 Authors: Gopalswamy, N.; Davila, J. M.; Thompson, B. J.; Haubold, H. Bibcode: 2006IAUSS...5E..47G Altcode: The United Nations, in cooperation with national and international space-related agencies and organizations, has been organizing annual workshops since 1990 on basic space science, particularly for the benefit of scientists and engineers from developing nations. The United Nations Office for Outer Space Affairs, through the IHY Secretariat and the United Nations Basic Space Science Initiative (UNBSSI) will assist scientists and engineers from all over the world in participating in the International Heliophysical Year (IHY) 2007. A major thrust of the IHY/UNBSSI program is to deploy arrays of small, inexpensive instruments such as magnetometers, radio telescopes, GPS receivers, all-sky cameras, etc. around the world to provide global measurements of ionospheric and heliospheric phenomena. The small instrument program is envisioned as a partnership between instrument providers, and instrument hosts in developing countries. The lead scientist will provide the instruments (or fabrication plans for instruments) in the array; the host country will provide manpower, facilities, and operational support to obtain data with the instrument typically at a local university. Funds are not available through the IHY to build the instruments; these must be obtained through the normal proposal channels. However all instrument operational support for local scientists, facilities, data acquisition, etc will be provided by the host nation. It is our hope that the IHY/UNBSSI program can facilitate the deployment of several of these networks world wide. Existing data bases and relevant software tools that can will be identified to promote space science activities in developing countries. Extensive data on space science have been accumulated by a number of space missions. Similarly, long-term data bases are available from ground based observations. These data can be utilized in ways different from originally intended for understanding the heliophysical processes. This paper provides an overview of the IHY/UNBSS program, its achievements and future plans. Title: Observational Properties of CMEs from a Decade-Long Observations by SOHO Authors: Gopalswamy, N.; Yashiro, S.; Howard, R. A. Bibcode: 2006ESASP.617E.129G Altcode: 2006soho...17E.129G No abstract at ADS Title: Introduction to special section on corotating solar wind streams and recurrent geomagnetic activity Authors: Tsurutani, Bruce T.; McPherron, Robert L.; Gonzalez, Walter D.; Lu, Gang; Sobral, Jose H. A.; Gopalswamy, Nat Bibcode: 2006JGRA..111.7S00T Altcode: 2006JGRA..11107S00T No abstract at ADS Title: Corotating solar wind streams and recurrent geomagnetic activity: A review Authors: Tsurutani, Bruce T.; Gonzalez, Walter D.; Gonzalez, Alicia L. C.; Guarnieri, Fernando L.; Gopalswamy, Nat; Grande, Manuel; Kamide, Yohsuke; Kasahara, Yoshiya; Lu, Gang; Mann, Ian; McPherron, Robert; Soraas, Finn; Vasyliunas, Vytenis Bibcode: 2006JGRA..111.7S01T Altcode: 2006JGRA..11107S01T Solar wind fast streams emanating from solar coronal holes cause recurrent, moderate intensity geomagnetic activity at Earth. Intense magnetic field regions called Corotating Interaction Regions or CIRs are created by the interaction of fast streams with upstream slow streams. Because of the highly oscillatory nature of the GSM magnetic field z component within CIRs, the resultant magnetic storms are typically only weak to moderate in intensity. CIR-generated magnetic storm main phases of intensity Dst < -100 nT (major storms) are rare. The elongated storm "recovery" phases which are characterized by continuous AE activity that can last for up to 27 days (a solar rotation) are caused by nonlinear Alfven waves within the high streams proper. Magnetic reconnection associated with the southward (GSM) components of the Alfvén waves is the solar wind energy transfer mechanism. The acceleration of relativistic electrons occurs during these magnetic storm "recovery" phases. The magnetic reconnection associated with the Alfvén waves cause continuous, shallow injections of plasma sheet plasma into the magnetosphere. The asymmetric plasma is unstable to wave (chorus and other modes) growth, a feature central to many theories of electron acceleration. It is noted that the continuous AE activity is not a series of substorm expansion phases. Arguments are also presented why these AE activity intervals are not convection bays. The auroras during these continuous AE activity intervals are less intense than substorm auroras and are global (both dayside and nightside) in nature. Owing to the continuous nature of this activity, it is possible that there is greater average energy input into the magnetosphere/ionosphere system during far declining phases of the solar cycle compared with those during solar maximum. The discontinuities and magnetic decreases (MDs) associated with interplanetary Alfven waves may be important for geomagnetic activity. In conclusion, it will be shown that geomagnetic storms associated with high-speed streams/CIRs will have the same initial, main, and "recovery" phases as those associated with ICME-related magnetic storms but that the interplanetary causes are considerably different. Title: Coronal and Interplanetary Type II Bursts Authors: Gopalswamy, N.; Yashiro, S.; Kaiser, M. L. Bibcode: 2006SPD....37.2501G Altcode: 2006BAAS...38..251G The kinetic energy of coronal mass ejections (CMEs) has been shown to essentially decide the wavelength range over which type II radio emission occurs. The larger the kinetic energy the wider is the wavelength range over which emission takes place. In other words, CMEs with larger kinetic energy drive shocks farther into the interplanetary medium. We studied a set of about 70 type II bursts that had emission components in the three well-known wavelength domains: metric (m), decameter-hectometric (DH), and kilometric (km). We find that the properties of CMEs associated with the m-to-km type II bursts are nearly identical to those CMEs associated with solar energetic particle events. We suggest that this correlation is evidence for the same shock accelerating electrons and ions. Next we examined the time delay between the onsets of metric and interplanetary type II emission. This is an important parameter because only when a metric type II burst has IP counterpart, it is likely to have space weather consequences. We find that the typical delay is about 1 hour. This is sufficiently small that one can use the DH type II bursts to identify shocks that might impact various destinations in the inner heliosphere. Title: Comment on ``Interplanetary shocks unconnected with earthbound coronal mass ejections'' by T. A. Howard and S. J. Tappin Authors: Gopalswamy, Nat; Akiyama, Sachiko; Yashiro, Seiji; Kasper, J. Bibcode: 2006GeoRL..3311108G Altcode: Abstract Available from http://www.agu.org Title: Are halo coronal mass ejections special events? Authors: Lara, Alejandro; Gopalswamy, Nat; Xie, Hong; Mendoza-Torres, Eduardo; PéRez-EríQuez, RomáN.; Michalek, Gregory Bibcode: 2006JGRA..111.6107L Altcode: 2006JGRA..11106107L We revisited the properties of wide coronal mass ejections (CMEs) called halo CMEs. Using the large LASCO/SOHO CMEs data set, from 1996 to 2004, we examined the statistical properties of (partial and full) halo CMEs and compare with the same properties of "normal" width (lower than 120°) CMEs. We found that halo CMEs have different properties than "normal" CMEs, which cannot be explained merely by the current geometric interpretation that they are seen as halos because they are traveling in the Sun Earth direction. We found that the CME width distribution is formed by, at least, three different populations: Two gaussians: a narrow and a medium distribution centered at ∼17° and ∼38°, respectively; the narrow population most likely corresponds to the "true" observed widths, whereas the medium width population is the product of projection effects. The third distribution corresponds to wider CMEs (80° < W < 210°) which behaves as a power law. Partial and full halo CMEs wider than these do not follow any particular distribution. This lack of regularity may be due to the small number of such events. In particular, we found (and test by a statistical approach) that the number of observed full halo CMEs is lower than expected. The CME speed follows a log-normal distribution, except for the very low speed CME population, which follows a gaussian distribution centered at ∼100 km/s and is probably due to projection effects. When the CMEs are divided by width into nonhalo, partial halo, and full halo, we found that the peaks of the distributions are shifted toward higher speeds, ∼300, ∼400 and ∼600 km/s for nonhalo, partial halo, and full halo CMEs, respectively. This confirms that halo CMEs tend to be high speed CMEs. The acceleration of full halo CMEs tends to be more negative compared with nonhalo and partial halo CMEs. We introduce a new observational CME parameter: The final observed distance (FOD), i.e., the highest point within the coronograph field of view where a CME can be distinguished from the background. In other words, the highest CME altitude measured. The FOD for nonhalo CMEs decreases exponentially from ∼5 to ∼30 R⊙ in the LASCO field of view. On the other hand, the FOD of halo CMEs increase with distance. This means that it is more likely to see halo CMEs at large distances (from the Sun) than nonhalo CMEs. These halo CME properties may be explained if the white light wide enhancements (or halo) seen by coronographs correspond to a combination of an expanding (shock) wave which disturbs and/or compresses the ambient material and the CME material itself. Title: Preface Authors: Gopalswamy, Nat Bibcode: 2006JApA...27...57G Altcode: No abstract at ADS Title: Properties of Interplanetary Coronal Mass Ejections Authors: Gopalswamy, Nat Bibcode: 2006SSRv..124..145G Altcode: 2007SSRv..tmp...53G Interplanetary coronal mass ejections (ICMEs) originating from closed field regions on the Sun are the most energetic phenomenon in the heliosphere. They cause intense geomagnetic storms and drive fast mode shocks that accelerate charged particles. ICMEs are the interplanetary manifestations of CMEs typically remote-sensed by coronagraphs. This paper summarizes the observational properties of ICMEs with reference to the ordinary solar wind and the progenitor CMEs. Title: Solar Imaging Radio Array: Space-based Radio Imaging at Frequencies Below the Ionospheric Cutoff Authors: MacDowall, R. J.; Gopalswamy, N.; Kaiser, M. L.; Demaio, L. D.; Bale, S. D.; Kasper, J. C.; Lazarus, A. J.; Howard, R. E.; Jones, D. L.; Reiner, M. J.; Weiler, K. W. Bibcode: 2006AGUSMSH33A..11M Altcode: No present or approved spacecraft mission has the capability to provide high angular resolution imaging of solar or magnetospheric radio bursts or of the celestial sphere at frequencies below the ionospheric cutoff. In this presentation, we review a NASA MIDEX-class mission to perform such imaging in the frequency range 30 kHz to 15 MHz. The focus of the mission, the Solar Imaging Radio Array (SIRA), is solar and exploration- oriented, with emphasis on improved understanding and application of radio bursts associated with solar energetic particle (SEP) events and on tracking shocks and other components of coronal mass ejections (CMEs). The data stream will also permit high angular resolution mapping of the celestial sphere at frequencies below 15 MHz, permitting detection of numerous astrophysical objects and extension of their observed spectra to much lower frequencies. SIRA will require 12 to 16 micro-satellites to establish a sufficient number of baselines with separations on the order of kilometers. The constellation consists of microsats located quasi-randomly on a spherical shell, initially of radius 5 km. The baseline microsat is 3-axis stabilized with body-mounted solar arrays and an articulated, Earth-pointing high gain antenna. The constellation will likely be placed at L1, which is the preferred location for full-time solar observations. Detailed mission science and technology goals will be reviewed. Title: On the rates of coronal mass ejections: remote solar and in situ observations Authors: Riley, P.; Cane, H.; Richardson, I. G.; Gopalswamy, N.; Linker, J. A.; Mikic, Z.; Lionello, R. Bibcode: 2006AGUSMSA21A..01R Altcode: In this study we compare the rates of coronal mass ejections (CMEs) as inferred from remote solar observations and interplanetary CMEs (ICMEs) as inferred from in situ observations at both 1 AU and Ulysses for almost an entire solar cycle (1996 through 2004). We find that, while the rates of CMEs and ICMEs track each other well at solar minimum, they diverge significantly in early 1998, during the ascending phase of the solar cycle, with the remote solar observations yielding approximately 20 times more events than are seen in situ at 1 AU. This divergence persists through 2004. We discuss several possible causes, including: (1) the appearance of mid-latitude active regions; (2) the increased rate of high-latitude CMEs; and (3) the strength of the global solar field. We conclude that the most likely interpretation is that this divergence is due to the birth of mid-latitude active regions, which are the sites of a distinct population of CMEs that are only partially intercepted by Earth. This conclusion is supported by the following points: (1) A similar divergence occurs between ICMEs in which magnetic clouds are observed (MCs), and those that are not; and (2) a number of pronounced enhancements in the CME rate, separated by approximately one year, are also mirrored and in ICME rate, but not obviously in the MC rate. We provide a simple geometric argument that shows that the computed CME and ICME rates are consistent with each other. The origins of the individual peaks can be traced back to unusually strong active regions on the Sun. Taken together, these results suggest that whether one observes a flux rope within an ICME is sensitive to the trajectory of the spacecraft through the ICME, i.e., an observational selection effect. This conclusion is supported by models of CME eruption and evolution, which: (1) are incapable of producing a CME that does not contain an embedded flux rope; and (2) demonstrate that glancing intercepts can produce ICME-like signatures without the magnetic structures associated with a flux rope Title: A Sun-to-Earth Campaign Joining Observations from the Great Observatory with Worldwide Satellite and Ground-Based Resources to Investigate System Science Frontiers Authors: Kozyra, J. U.; Shibata, K.; Barnes, R. J.; Basu, S.; Davila, J. M.; Fox, N. J.; Gopalswamy, N.; Kuznetsova, M. M.; Pallamraju, D.; Paxton, L. J.; Ridley, A.; Weiss, M.; Young, C. A.; Zanetti, L. J. Bibcode: 2006AGUSMSM23A..03K Altcode: An Internet-based cross-disciplinary analysis campaign that will make heavy use of Great Observatory missions as well as international satellite and ground-based assets is being undertaken with joint support from the CAWSES, IHY, LWS, and ICESTAR programs planned for late April or early May 2006. An evolving list of open science questions that serve as sun-to-Earth focus areas for the worldwide campaign were identified during a small interdisciplinary CAWSES workshop at Stanford University in December 2005 as well as during a joint CAWSES/ICESTAR session at the CEDAR meeting in Boulder the preceding summer. The analysis campaign will take place over the Internet in the form of virtual poster sessions with message boards and monitors that summarize the important science issues and new results daily. Poster authors will be asked to closely monitor their message boards during the day of their poster session as well as the following day. Outreach to other disciplines and international students will take the form of tutorial talks that place campaign science issues into the context of the current state of knowledge in each discipline area. Global models and data sets (TEC, magnetometer maps, ULF wave maps, assimilative models, MHD model outputs, continuous solar images) will be available to provide context for local and regional observations. The Community Coordinated Data Center (CCMC) is developing a small number of new data display formats that extract data from global models and place it in the same format as the observations either for ground-based stations or along satellite tracks. Other ideas being explored include real time upload of additional posters in response to issues raised during the poster session, library of related articles, reference archive of observations, etc. A summary of which aspects and/or tools worked and which were less useful will be presented. Title: Radio manifestation of the interaction between ultra-fast CMEs Authors: Gopalswamy, N.; Yashiro, S.; Akiyama, S. Bibcode: 2006AGUSMSH24A..03G Altcode: Active region 720 was one of the super active regions of cycle 23 in that it produced large numbers of coronal mass ejections (CMEs) and major flares. The average recurrence time between flares in the region was about 2.5 h, but several flares and CMEs occurred with much shorter recurrence time. In this paper, we are concerned with two ultra-fast CMEs (speed > 2000 km/s) originating within 45 minutes. The CMEs merged with each other within the field of view of SOHO coronagraphs. Both CMEs were associated with long wavelength type II radio bursts. The type II burst associated with the first CME was normal, while that associated with the second CME showed irregular spectral behavior, including a characteristic broadband enhancement. Solar energetic particles (SEPs) associated with the two CMEs also showed some peculiarities, which are consistent with the interaction between the two CMEs. The SEP intensity reached a very high value around the time of interaction. We present radio and white light observations of the CMEs and provide an interpretation of the observed spectral features in the radio dynamic spectrum. Work supported by NASA's LWS TR&T and SR&T programs. Title: Science Plans for the International Heliophysical Year Authors: Davila, J. M.; Gopalswamy, N.; Harrison, R. A.; Stamper, R.; Briand, C.; Potgieter, M. S. Bibcode: 2006AGUSM.U34A..04D Altcode: On October 4, 1957, only 53 years after the beginning of flight in Kitty Hawk, the launch of Sputnik 1 marked the beginning of the space age; as mankind took the first steps to leaving the protected environment of Earth's atmosphere. Discovery of the radiation belts, the solar wind, and the structure of Earth's magnetosphere prepared the way for the inevitable human exploration to follow. Soon, Cosmonauts and Astronauts orbited Earth, and then in 1969, Astronauts landed on the Moon. Today a similar story is unfolding, the spacecraft Voyager has crossed the termination shock, and will soon leave the heliosphere. For the first time, man will begin to explore the local interstellar medium. It is inevitable that, during the next 50 years, exploration of the solar system including the Moon, Mars and the outer planets will be the focus of the space program, and like 50 years ago, unmanned probes will lead the way, followed by human exploration. The International Geophysical Year (IGY) of 1957, a broad-based and all-encompassing effort to push the frontiers of geophysics, resulted in a tremendous increase of knowledge in space physics, Sun-Earth Connection, planetary science and the heliosphere in general. Now, 50 years later, we have the unique opportunity to further advance our knowledge of the global heliosphere and its interaction with the interstellar medium through the International Heliophysical Year (IHY) in 2007, and to raise public awareness of space physics. This presentation will focus on global science planning efforts and campaigns for all participating IHY nations. Title: United Nations Basic Space Science Initiative Programme for the International Heliophysical Year 2007 Authors: Gopalswamy, Nat Bibcode: 2006UNPSA..17...47G Altcode: No abstract at ADS Title: The Pre-CME Sun Authors: Gopalswamy, N.; Mikić, Z.; Maia, D.; Alexander, D.; Cremades, H.; Kaufmann, P.; Tripathi, D.; Wang, Y. -M. Bibcode: 2006SSRv..123..303G Altcode: 2006SSRv..tmp...77G The coronal mass ejection (CME) phenomenon occurs in closed magnetic field regions on the Sun such as active regions, filament regions, transequatorial interconnection regions, and complexes involving a combination of these. This chapter describes the current knowledge on these closed field structures and how they lead to CMEs. After describing the specific magnetic structures observed in the CME source region, we compare the substructures of CMEs to what is observed before eruption. Evolution of the closed magnetic structures in response to various photospheric motions over different time scales (convection, differential rotation, meridional circulation) somehow leads to the eruption. We describe this pre-eruption evolution and attempt to link them to the observed features of CMEs. Small-scale energetic signatures in the form of electron acceleration (signified by nonthermal radio bursts at metric wavelengths) and plasma heating (observed as compact soft X-ray brightening) may be indicative of impending CMEs. We survey these pre-eruptive energy releases using observations taken before and during the eruption of several CMEs. Finally, we discuss how the observations can be converted into useful inputs to numerical models that can describe the CME initiation. Title: Coronal Observations of CMEs. Report of Working Group A Authors: Schwenn, R.; Raymond, J. C.; Alexander, D.; Ciaravella, A.; Gopalswamy, N.; Howard, R.; Hudson, H.; Kaufmann, P.; Klassen, A.; Maia, D.; Munoz-Martinez, G.; Pick, M.; Reiner, M.; Srivastava, N.; Tripathi, D.; Vourlidas, A.; Wang, Y. -M.; Zhang, J. Bibcode: 2006SSRv..123..127S Altcode: 2006SSRv..tmp...58S CMEs have been observed for over 30 years with a wide variety of instruments. It is now possible to derive detailed and quantitative information on CME morphology, velocity, acceleration and mass. Flares associated with CMEs are observed in X-rays, and several different radio signatures are also seen. Optical and UV spectra of CMEs both on the disk and at the limb provide velocities along the line of sight and diagnostics for temperature, density and composition. From the vast quantity of data we attempt to synthesize the current state of knowledge of the properties of CMEs, along with some specific observed characteristics that illuminate the physical processes occurring during CME eruption. These include the common three-part structures of CMEs, which is generally attributed to compressed material at the leading edge, a low-density magnetic bubble and dense prominence gas. Signatures of shock waves are seen, but the location of these shocks relative to the other structures and the occurrence rate at the heights where Solar Energetic Particles are produced remains controversial. The relationships among CMEs, Moreton waves, EIT waves, and EUV dimming are also cloudy. The close connection between CMEs and flares suggests that magnetic reconnection plays an important role in CME eruption and evolution. We discuss the evidence for reconnection in current sheets from white-light, X-ray, radio and UV observations. Finally, we summarize the requirements for future instrumentation that might answer the outstanding questions and the opportunities that new space-based and ground-based observatories will provide in the future. Title: Planning the International Heliophysical Year (IHY) Authors: Davila, Joseph M.; Thompson, Barbara J.; Gopalswamy, Nat Bibcode: 2006UNPSA..17...37D Altcode: No abstract at ADS Title: Long-lived geomagnetic storms and coronal mass ejections Authors: Xie, H.; Gopalswamy, N.; Manoharan, P. K.; Lara, A.; Yashiro, S.; Lepri, S. Bibcode: 2006JGRA..111.1103X Altcode: 2006JGRA..11101103X Coronal mass ejections (CMEs) are major solar events that are known to cause large geomagnetic storms (Dst < -100 nT). Isolated geomagnetic storms typically have a main phase of 3-12 hours and a recovery phase of around 1 day. However, there are some storms with main and recovery phases exceeding ∼3 days. We trace the origin of these long-lived geomagnetic storms (LLGMS) to frontside halo CMEs. We studied 37 LLGMS events with Dst < -100 nT and the associated CMEs which occurred during 1998-2002. It is found that LLGMS events are caused by (1) successive CMEs, accounting for ∼64.9% (24 of 37); (2) single CMEs, accounting for ∼21.6% (8 of 37); and (3) high-speed streams (HSS) in corotating interaction regions (CIRs) with no related CME, accounting for ∼13.5% (5 of 37). The long duration of the LLGMS events was found to be due to successive CMEs and HSS events; the high intensity of the LLGMS events was related to the interaction of CMEs with other CMEs and HSS events. We find that the duration of LLGMS is well correlated to the number of participating CMEs (correlation coefficient r = 0.78). We also find that the intensity of LLGMS has a good correlation with the degree of interaction (the number of CMEs interacting with a HSS event or with themselves) (r = 0.67). The role of preconditioning in LLGMS events, where the Dst development occurred in multiple steps in the main and recovery phases, has been investigated. It is found that preconditioning does not affect the main phase of the LLGMS events, while it plays an important role during the recovery phase of the LLGMS events. Title: Composition and magnetic structure of interplanetary coronal mass ejections at 1 AU Authors: Aguilar-Rodriguez, E.; Blanco-Cano, X.; Gopalswamy, N. Bibcode: 2006AdSpR..38..522A Altcode: We study the magnetic structure and charge state ratio of interplanetary coronal mass ejections (ICMEs) observed by ACE and Wind spacecraft. Measurements of abundances and charge state ratio of heavy ions (e.g. O7+/O6+, C6+/C5+, and Mg10+/O6+) in the plasma as well as magnetic field structure are important tracers for physical conditions and processes in the source regions of ICMEs. We used ion composition (from ACE), plasma (from Wind) and magnetic field (from Wind and ACE) data from 1998 to 2002. Using the low proton temperature criterion, a common plasma signature of ICMEs, we identified 154 events which include magnetic clouds, non-cloud ejecta and complex ICMEs. The latter one refers to compound events resulting from the overtaking of successive ICMEs which can include both magnetic clouds and non-cloud ejecta. We find that there is a close relationship between the increase in the charge state ionization factor and the magnetic structure of ICMEs. Events with magnetic cloud topology show higher QandQ charge state ratios than those with non-magnetic cloud structure. However, both magnetic cloud and non-cloud events show an increase in these ratios when compared with the ambient solar wind. In contrast, perhaps due to instrumental effects, the charge state ratio Q for all events does not show a real enhancement when compared with the ambient solar wind. The difference in ionization states between non-cloud ejecta and magnetic clouds is more pronounced in fast solar wind than when events are embedded in slow wind. Title: Associations of Coronal Mass Ejections as a function of X-ray Flare Properties Authors: Yashiro, S.; Gopalswamy, N.; Akiyama, S.; Howard, R. A. Bibcode: 2006cosp...36.1778Y Altcode: 2006cosp.meet.1778Y We examined the associations between coronal mass ejections CMEs and X-ray flares using data from the Large Angle Spectrometric Coronagraph LASCO on board the Solar and Heliospheric Observatory SOHO The CME association of 1540 X-ray flares M classand above detected by GOES satellite were examined As reported in previous studies the CME association rate clearly increased with the peak X-ray intensity the total X-ray intensity and the decay time The CME association rate increased from 40 flare size between M1 0 and M1 7 to 98 flare size above X1 8 Except for an X3 6 flare on July 16 2004 all the 50 huge flares above X1 8 definitely have associated CMEs Furthermore all the X-ray flares with a decay time exceeding 90 min were associated CMEs We discuss which X-ray parameters are essential in order to have CME association Title: Solar wind speed within 20 RS of the Sun estimated from limb coronal mass ejections Authors: Nakagawa, Tomoko; Gopalswamy, Nat; Yashiro, Seiji Bibcode: 2006JGRA..111.1108N Altcode: 2006JGRA..11101108N An estimation of the solar wind speed in the vicinity of the Sun is carried out using the initial speed and acceleration of coronal mass ejections (CMEs) that appeared close to the solar limb. A linear relationship was found between the initial acceleration and the speed of the limb CMEs. It appears that a dragging force is acting on the CMEs, depending on the speed difference between the CMEs and the ambient plasma. The ambient solar wind speed within 20 solar radii estimated from low-latitude CMEs during 1998-2003 ranged from 100 to 700 km s-1, while the solar wind speed measured at 1 AU ranged from 300 to 700 km s-1. The estimated solar wind speeds in the vicinity of the Sun sometimes agreed with the simultaneous in situ measurements at 1 AU, but in other periods they were slower than the speeds measured at 1 AU. It is suggested that most of the time the low-latitude solar wind completes accelerating within 20 solar radii, but occasionally additional acceleration is present beyond 20 solar radii. Title: Coronal mass ejections and space weather due to extreme events Authors: Gopalswamy, N.; Yashiro, S.; Akiyama, S. Bibcode: 2006ilws.conf...79G Altcode: This paper summarizes the extreme solar activity and its space weather implications during the declining phase of the solar cycle 23: October-November 2003 (AR 486), November 2004 (AR 696), January 2005 (AR 720), and September 2005 (AR 808). We have compiled and compared the properties of eruptions and the underlying active regions. All these are super active regions, but the flare and CME productivity varied significantly. While the CMEs from all the regions kept the level of solar energetic particles (SEPs) at storm level for several days, their geoeffectiveness (the ability to produce geomagnetic storms) was significantly different, probably due to the location of the eruptions on the Sun. Title: Coronal Observations of CMEs Authors: Schwenn, R.; Raymond, J. C.; Alexander, D.; Ciaravella, A.; Gopalswamy, N.; Howard, R.; Hudson, H.; Kaufmann, P.; Klassen, A.; Maia, D.; Munoz-Martinez, G.; Pick, M.; Reiner, M.; Srivastava, N.; Tripathi, D.; Vourlidas, A.; Wang, Y. -M.; Zhang, J. Bibcode: 2006cme..book..127S Altcode: CMEs have been observed for over 30 years with a wide variety of instruments. It is now possible to derive detailed and quantitative information on CME morphology, velocity, acceleration and mass. Flares associated with CMEs are observed in X-rays, and several different radio signatures are also seen. Optical and UV spectra of CMEs both on the disk and at the limb provide velocities along the line of sight and diagnostics for temperature, density and composition. From the vast quantity of data we attempt to synthesize the current state of knowledge of the properties of CMEs, along with some specific observed characteristics that illuminate the physical processes occurring during CME eruption. These include the common three-part structures of CMEs, which is generally attributed to compressed material at the leading edge, a low-density magnetic bubble and dense prominence gas. Signatures of shock waves are seen, but the location of these shocks relative to the other structures and the occurrence rate at the heights where Solar Energetic Particles are produced remains controversial. The relationships among CMEs, Moreton waves, EIT waves, and EUV dimming are also cloudy. The close connection between CMEs and flares suggests that magnetic reconnection plays an important role in CME eruption and evolution. We discuss the evidence for reconnection in current sheets from white-light, X-ray, radio and UV observations. Finally, we summarize the requirements for future instrumentation that might answer the outstanding questions and the opportunities that new space-based and ground-based observatories will provide in the future. Title: Coronal mass ejections and space weather Authors: Webb, D. F.; Gopalswamy, N. Bibcode: 2006ilws.conf...71W Altcode: Coronal mass ejections (CMEs) are a key feature of coronal and interplanetary (IP) dynamics. Major CMEs inject large amounts of mass and magnetic fields into the heliosphere and, when aimed Earthward, can cause major geomagnetic storms and drive IP shocks, a key source of solar energetic particles. Studies over this solar cycle using the excellent data sets from the SOHO, TRACE, Yohkoh, Wind, ACE and other spacecraft and ground-based instruments have improved our knowledge of the origins and early development of CMEs at the Sun and how they affect space weather at Earth. A new heliospheric experiment, the Solar Mass Ejection Imager, has completed 3 years in orbit and has obtained results on the propagation of CMEs through the inner heliosphere and their geoeffectiveness. We review key coronal properties of CMEs, their source regions, their manifestations in the solar wind, and their geoeffectiveness. Halo-like CMEs are of special interest for space weather because they suggest the launch of a geoeffective disturbance toward Earth. However, not all halo CMEs are equally geoeffective and this relationship varies over the solar cycle. Although CMEs are involved with the largest storms at all phases of the cycle, recurrent features such as interaction regions and high speed wind streams can also be geoeffective. Title: Preparing for the International Heliophysical Year (IHY) 2007 Authors: Davila, J. M.; Gopalswamy, N.; Thompson, B. J. Bibcode: 2006ilws.conf..231D Altcode: The International Geophysical Year (IGY) of 1957, a broad-based and all-encompassing effort to push the frontiers of geophysics, resulted in a tremendous increase of knowledge in space physics, Sun-Earth Connection, planetary science and the heliosphere in general. Now, 50 years later, we have the unique opportunity to advance our knowledge of the global heliosphere and its interaction with planetary bodies and the interstellar medium through the International Heliophysical Year (IHY) in 2007. This will be an international effort, which will raise public awareness of space physics. Title: The IHY/United Nations Distributed Observatory Development Program Authors: Haubold, H.; Thompson, B. J.; Al-Naimiy, H.; Davila, J. M.; Gopalswamy, N.; Groves, K.; Scherrer, D. Bibcode: 2006cosp...36.3304H Altcode: 2006cosp.meet.3304H A major thrust of the International Heliophysical Year IHY is to deploy arrays of small inexpensive instruments such as magnetometers radio antennas GPS receivers all-sky cameras etc around the world to provide global measurements of ionospheric magnetospheric and heliospheric phenomena This program is a collaboration between the IHY and the United Nations Basic Space Science Initiative UNBSSI which has been dedicated to the IHY through 2009 The small instrument program consists of a partnership between instrument providers and instrument host countries The lead scientist provides the instrumentation or fabrication plans for instruments in the array the host country provides manpower facilities and operational support to obtain data with the instrument typically at a local university This program has been active in deploying instrumentation developing plans for new instrumentation and identifying educational opportunities for the host nations in association with this program We will discuss the program s status significant deployment activities and plans for 2007-2009 Title: Geoeffectiveness of CMEs: A simple analysis using halo CMEs from SOHO Authors: Gopalswamy, N.; Yashiro, S.; Akiyama, S. Bibcode: 2006cosp...36.2723G Altcode: 2006cosp.meet.2723G We considered the geoeffectiveness of a set of all halo coronal mass Ejections CMEs detected by the Solar and Heliospheric Observatory SOHO during 1996-2003 inclusive Since CMEs take 1-4 days to reach Earth we chose the minimum Dst value over an interval of 1-5 days after the onset of a halo CME Distributions of these Dst values were compared for the following subsets of halo CMEs 1 front-side halos whose solar sources were within 45 degrees from the central meridian 2 Asymmetric halos or limb halos whose sources are front-sided but located beyond 45 degrees from the central meridian and 3 backside halo CMEs We find that the average and median Dst values following the front-side halos are at the intense storm level -100 nT those following the asymmetric halos are at weak storm level -60 nT and those following the backside halos are not indicative of storms Note that we did not eliminate moderate storms caused by high speed streams from coronal holes When we compiled the minimum Dst values during 1-5 days following a set of random days we found that the Dst distribution is nearly identical to the case of backside halos This simple analysis clearly demonstrates that the front-side halos are highly geoeffective whereas the asymmetric halos are marginally geoeffective The backside halo CMEs are not geoeffective at all because the CME plasma is unlikely to reach Earth from backside CMEs Title: Magnetic Storms Caused by Corotating Solar Wind Streams Authors: Tsurutani, Bruce T.; McPherron, Robert L.; Gonzalez, Walter D.; Lu, Gang; Gopalswamy, Nat; Guarnieri, Fernando L. Bibcode: 2006GMS...167....1T Altcode: Geomagnetic activity at Earth due to corotating high speed solar wind streams are reviewed. High density plasma regions in the vicinity of the heliospheric current sheet in the slow solar wind impinge upon the magnetosphere and create magnetic storm intial phases. Dst increases can be higher than those associated with shocks in front of interplanetary coronal mass ejections. High speed streams following the high density interplanetary plasma interact with the upstream slow speed streams and create magnetic field compression regions called corotating interaction regions (CIRs). The southward components of the typically rapid Bz fluctuations within the CIRs, through sporadic magnetic reconnection with the Earth's magnetic fields, lead to weak to moderate intensity magnetic storm main phases, typically Dst >-100 nT. Some CIRs (without southward component Bz fields) cause no perceptible Dst changes at all. The "recovery" phases of CIR-induced magnetic storms can last for a few days up to 27 days. The cause of these particularly long duration storm "recoveries" is near-continuous shallow plasma injections into the magnetosphere. Magnetic reconnection associated with the southward component of the Alfvén waves within the high speed streams with magnetopause fields is the cause of these injections. The auroras during these intervals are continuous and global auroral zone features. The AE/AL maxima are not substorms or convection bays. Relativistic electrons are accelerated/observed during these high speed stream intervals. The electrons first appear in the beginning of the lengthy storm "recovery" phases. Geomagnetic quiet is due to weak interplanetary magnetic fields with a lack of Alfvénic fluctuations. These interplanetary regions generally occur in the decay portion of high speed streams. Title: The CME-productivity associated with flares from two ARs Authors: Akiyama, S.; Gopalswamy, N.; Yashiro, S. Bibcode: 2006cosp...36..556A Altcode: 2006cosp.meet..556A NOAA active region AR 10039 appeared at the east limb on 21 July 2002 and rotated out of the earthside on 4 August This AR was magnetically complex consisting of a spot group with a beta-gamma delta BGD configuration from the start It produced 3 X- and 8 M-Class X-ray flares during its disk passage NOAA AR 10044 located just to the southwest of AR 10039 developed gradually into a BGD configuration on 26 July and produced 9 M-class flares We examined the coronal mass ejection CME associations rate R of these X-ray flares using data from the Large Angle Spectrometric Coronagraph LASCO on board the Solar and Heliospheric Observatory SOHO We found the CME-productivity to be different between the two ARs AR 10039 was CME-rich with 72 association with flares while AR 10044 was CME-poor with an association rate of only 13 We also calculated the average velocity and angular width of CMEs from the two ARs On the average the CMEs from the CME-rich AR were faster 1195 km s and wider 246 deg than the ones from the CME-poor AR 282 km s and 12 deg We discuss the characteristics of the ARs which might have resulted in the observed differences Title: International coordinated efforts for IHY 2007 Authors: Gopalswamy, N.; Davila, J.; Thompson, B. Bibcode: 2006cosp...36.2743G Altcode: 2006cosp.meet.2743G The International Heliophysical Year IHY in 2007 marks the enormous progress made since the International Geophysical Year IGY in 1957 The philosophy behind IHY is similar to that of IGY in studying the environment of our habitat except that the scope has increased to the physical space extending to the interstellar medium This paper describes the international organization of the IHY and planning for a successful program in 2007 In particular we describe the national regional and global efforts in pooling the resources to address the universal processes that govern the solar system and its interaction with the surrounding medium The efforts include identifying science questions of immediate concern and the data sets needed to address these questions The data will be acquired using a truly distributed observatory consisting of all the ground and space-based instruments that exist today and those to be constructed before 2007 The international planning also involves coordinating with the United Nations which through its Basic Space Science Initiative is facilitating the participation of the developing nations in the IHY program An update of the current status of the planning activities at the international level will be presented Title: Anemone structure of AR NOAA 10798 and related geo-effective flares and CMEs Authors: Asai, A.; Ishii, T. T.; Shibata, K.; Gopalswamy, N. Bibcode: 2006cosp...36.2406A Altcode: 2006cosp.meet.2406A We report coronal features of an active region NOAA 10798 This active region was located in the middle of a small coronal hole and generated 3 M-class flares The flares are associated with high speed CMEs which produced a magnetic storm on 2005 August 24 We examined the coronal features by using observational data in soft X-rays in extreme ultraviolets and in microwaves obtained with GOES SOHO TRACE satellites and Nobeyama Radioheliograph Title: The Pre-CME Sun Authors: Gopalswamy, N.; Mikić, Z.; Maia, D.; Alexander, D.; Cremades, H.; Kaufmann, P.; Tripathi, D.; Wang, Y. -M. Bibcode: 2006cme..book..303G Altcode: The coronal mass ejection (CME) phenomenon occurs in closed magnetic field regions on the Sun such as active regions, filament regions, transequatorial interconnection regions, and complexes involving a combination of these. This chapter describes the current knowledge on these closed field structures and how they lead to CMEs. After describing the specific magnetic structures observed in the CME source region, we compare the substructures of CMEs to what is observed before eruption. Evolution of the closed magnetic structures in response to various photospheric motions over different time scales (convection, differential rotation, meridional circulation) somehow leads to the eruption. We describe this pre-eruption evolution and attempt to link them to the observed features of CMEs. Small-scale energetic signatures in the form of electron acceleration (signified by nonthermal radio bursts at metric wavelengths) and plasma heating (observed as compact soft X-ray brightening) may be indicative of impending CMEs. We survey these pre-eruptive energy releases using observations taken before and during the eruption of several CMEs. Finally, we discuss how the observations can be converted into useful inputs to numerical models that can describe the CME initiation. Title: Preface Authors: Tsurutani, Bruce T.; McPherron, Robert L.; Gonzalez, Walter D.; Lu, Gang; Sobral, José Humberto A.; Gopalswamy, Nat Bibcode: 2006GMS...167D...1T Altcode: No abstract at ADS Title: Solar Influence on the Heliosphere and Earth's Environment: Recent Progress and Prospects Authors: Gopalswamy, N.; Bhattacharyya, A. Bibcode: 2006ilws.conf.....G Altcode: No abstract at ADS Title: The International Heliophysical Year (IHY) 2007 Authors: Davila, J. M.; Thompson, B. J.; Gopalswamy, N. Bibcode: 2006AfrSk..10....4D Altcode: The International Geophysical Year (IGY) of 1957, a broad-based and all-encompassing effort to push the frontiers of geophysics, resulted in a tremendous increase of knowledge in space physics, the Sun-Earth connection, planetary science, and the heliosphere in general. Now, fifty years later, we have the unique opportunity to advance our knowledge of the global heliosphere and its interaction with planetary bodies and the interstellar medium through the International Heliophysical Year (IHY) in 2007. This will be an international effort which will raise public awareness of space physics. Because of its unique geographic position, Africa is well-positioned to play a critical role. Title: Microsat and Lunar-Based Imaging of Radio Bursts Authors: MacDowall, R. J.; Gopalswamy, N.; Kaiser, M. L.; Demaio, L. D.; Bale, S. D.; Hewitt, J.; Kasper, J. C.; Lazarus, A. J.; Howard, R. E.; Jones, D. L.; Reiner, M. J.; Weiler, K. W. Bibcode: 2006pre6.conf..491M Altcode: 2006pre4.conf..491M No present or approved spacecraft mission has the capability to provide high angular resolution imaging of solar or magnetospheric radio bursts or of the celestial sphere at frequencies below the ionospheric cutoff. Here, we describe a spacecraft mission to perform such imaging in the frequency range ∼30 kHz to 15 MHz. This mission, the Solar Imaging Radio Array (SIRA), is solar and exploration-oriented, with emphasis on improved understanding and application of radio bursts associated with solar energetic particle (SEP) events and on tracking shocks and other components of coronal mass ejections (CMEs). SIRA will require 12 to 16 micro- satellites to establish a sufficient number of baselines. The proposed microsat is 3-axis stabilized with body-mounted solar arrays and an articulated, Earth pointing high gain antenna. Crossed dipoles and simple radio receivers are the detectors for the aperture synthesis imaging. The microsats will be located quasi-randomly on a spherical shell, initially of ∼10 km diameter. This constellation will likely be placed in a halo orbit around L1, which is the preferred location for full-time solar observations. We also discuss briefly follow-on missions such as a lunar-based radio interferometer with of order 10 000 dipole antennas. Title: The Solar Imaging Radio Array: Space-Based Imaging of Solar, Heliospheric, Magnetospheric, and Astrophysical Sources at Frequencies below the Ionospheric Cutoff Authors: MacDowall, R. J.; Gopalswamy, N.; Kaiser, M. L.; Bale, S. D.; Demaio, L. D.; Hewitt, J. N.; Kasper, J. C.; Lazarus, A. J.; Howard, R. E.; Jones, D. L.; Reiner, M. J.; Weiler, K. W. Bibcode: 2005ASPC..345..476M Altcode: Solar Imaging Radio Array (SIRA) is a mission concept for space-based, interferometric imaging of solar and interplanetary radio emission at frequencies below the Earth's ionospheric cutoff. Observing in a frequency range of ∼30 kHz to 15 MHz, SIRA will observe the radio emission from shocks driven by fast coronal mass ejections (CMEs). The radio emissions permit tracking the leading boundaries of CMEs from ∼2 Rs to 1 AU. When a CME impacts Earth's magnetosphere, the dynamic response will be imaged in the light of magnetospheric radio emissions, such as auroral kilometric radiation (AKR), scattered on magnetospheric density gradients. The near-term possibility for a SIRA mission is based on a NASA MIDEX-class mission, consisting of a single constellation of ∼16 microsats located quasi-randomly on a spherical shell of ∼10 km diameter. Such a mission is the logical next step in space-based solar radio observations, as well as offering a unique space weather prediction capability for the NASA Exploration Initiative. SIRA will also serve a valuable role as a pathfinder for more complex constellation and interferometry missions. Title: Introduction to special section on Solar Coronal Mass Ejections and Energetic Particles Authors: Gopalswamy, Nat; Torsti, J. Bibcode: 2005JGRA..11012S00G Altcode: No abstract at ADS Title: Space-based Radio Imaging at Frequencies below the Ionospheric Cutoff with SIRA Authors: MacDowall, R. J.; Gopalswamy, N.; Kaiser, M. L.; Demaio, L. D.; Bale, S. D.; Howard, R. E.; Jones, D. L.; Kasper, J. C.; Reiner, M. J.; Weiler, K. W. Bibcode: 2005AAS...207.2308M Altcode: 2005BAAS...37Q1197M No present or approved spacecraft mission has the capability to provide high angular resolution imaging of solar or magnetospheric radio bursts or of the celestial sphere at frequencies below the ionospheric cutoff. In this presentation, we review a MIDEX-class mission to perform such imaging in the frequency range 30 kHz to 15 MHz. The focus of the mission, the Solar Imaging Radio Array (SIRA), is solar and exploration-oriented, with emphasis on improved understanding and application of radio bursts associated with solar energetic particle (SEP) events and on tracking shocks and other components of coronal mass ejections (CMEs). SIRA will require 12 to 16 micro-satellites to establish a sufficient number of baselines with separations on the order of kilometers. The constellation consists of microsats located quasi-randomly on a spherical shell, initially of radius 5 km. The baseline microsat is 3-axis stabilized with body-mounted solar arrays and an articulated, earth pointing high gain antenna. The constellation will likely be placed at L1, which is the preferred location for full-time solar observations. Detailed mission science and technology goals will be reviewed. Title: Visibility of coronal mass ejections as a function of flare location and intensity Authors: Yashiro, S.; Gopalswamy, N.; Akiyama, S.; Michalek, G.; Howard, R. A. Bibcode: 2005JGRA..11012S05Y Altcode: We report the visibility (detection efficiency) of coronal mass ejections (CMEs) of the Large Angle Spectrometric Coronagraph (LASCO) on board the Solar and Heliospheric Observatory (SOHO). We collected 1301 X-ray flare events (above C3 level) detected by the GOES satellite and examined their CME associations using data from LASCO coronagraphs. The CME visibility was examined using the longitudinal variation of CME association of X-ray flares, under the assumption that all CMEs associated with limb flares are detectable by LASCO. Our findings are (1) the CME association rate clearly increased with X-ray flare size from 20% for C-class flares (between C3 and C9 levels) to 100% for huge flares (above X3 level), (2) all CMEs associated with X-class flares were detected by the LASCO coronagraphs, while half (25-67%) of CMEs associated with C-class flares were invisible. We examined the statistical properties of the flare-associated CMEs and compared them by flare size and longitude. CMEs associated with X-class flares were significantly faster (median 1556 km/s) and wider (median 244°) than those of CMEs associated with disk C-class flares (432 km/s, 68°). We conclude that all fast and wide CMEs are detectable by LASCO, but slow and narrow CMEs may not be visible when the CMEs originate from the disk center. Title: Workshop Highlights Progress in Solar-Heliospheric Physics Authors: Gopalswamy, Nat Bibcode: 2005EOSTr..86..525G Altcode: The Solar, Heliospheric, and Interplanetary Environment (SHINE) group is an affiliation of researchers dedicated to promoting an enhanced understanding of the processes by which magnetic fields, plasmas, and energetic particles are produced near the Sun and propagated through the interplanetary medium to Earth and other locations in the heliosphere. The group conducted its annual workshop in July to discuss recent developments in the study of solar variability and its impact on Earth's space environment. One hundred fifty-five scientists, including 27 students, participated in the plenary, working group, and poster sessions. Student Day activities on 10 July consisted of tutorials given by experienced scientists: solar flares and particle acceleration (Robert Lin, University of California Berkeley), the origin of coronal mass ejections (CMEs) (Spiro Antiochos, Naval Research Laboratory, Washington, D.C.), connecting the Sun and heliosphere (Thomas Zurbuchen, University of Michigan, Ann Arbor), and acceleration and transport of solar energetic particles (SEPs) (Christina Cohen, California Institute of Technology, Pasadena). The tutorials were followed by student presentations on CMEs near the sun and in the interplanetary medium, solar wind, and SEPs. Title: Type II radio bursts and energetic solar eruptions Authors: Gopalswamy, N.; Aguilar-Rodriguez, E.; Yashiro, S.; Nunes, S.; Kaiser, M. L.; Howard, R. A. Bibcode: 2005JGRA..11012S07G Altcode: We report on a study of type II radio bursts from the Wind/WAVES experiment in conjunction with white-light coronal mass ejections (CME) from the Solar and Heliospheric Observatory (SOHO). The type II bursts considered here have emission components in all the spectral domains: metric, decameter-hectometric (DH) and kilometric (km), so we refer to them as m-to-km type II bursts. CMEs associated with the m-to-km type II bursts were more energetic than those associated with bursts in any single wavelength regime. CMEs associated with type II bursts confined to the metric domain were more energetic (wider and faster) than the general population of CMEs but less energetic than CMEs associated with DH type II bursts. Thus the CME kinetic energy seems to organize the life time of the type II bursts. Contrary to previous results, the starting frequency of metric type II bursts with interplanetary counterparts seems to be no different from that of type II bursts without interplanetary counterparts. We also verified this by showing that the average CME height at the onset time of the type II bursts is the same for the two metric populations. The majority (78%) of the m-to-km type II bursts were associated with solar energetic particle (SEP) events. The solar sources of the small fraction of m-to-km type II bursts without SEP association were poorly connected to the observer near Earth. Finally, we found that the m-to-km type II bursts were associated with bigger flares compared to the purely metric type II bursts. Title: A universal characteristic of type II radio bursts Authors: Aguilar-Rodriguez, E.; Gopalswamy, N.; MacDowall, R.; Yashiro, S.; Kaiser, M. L. Bibcode: 2005JGRA..11012S08A Altcode: We present a study on the spectral properties of interplanetary type II radio bursts observed by the Radio and Plasma Wave (WAVES) experiment on board the Wind spacecraft. We investigated the relative bandwidth of the type II radio bursts observed by WAVES from 1997 up to 2003. We obtained three sets of events, based on the frequency domain of occurrence: 109 events in the low-frequency domain (30 KHz to 1000 kHz, detected by the RAD1 receiver), 216 events in the high-frequency domain (1-14 MHz, observed by the RAD2 receiver), and 73 events that spanned both domains (RAD1 and RAD2). Statistical results show that the average bandwidth-to-frequency ratio (BFR) was 0.28 ± 0.15, 0.26 ± 0.16, and 0.32 ± 0.15 for RAD1, RAD2, and RAD1 + RAD2, respectively. We compared our results with those obtained for ISEE-3 type II bursts and found a difference in the average BFR, which seems to be due to a selection effect. The BFR of the WAVES type II bursts is similar to that of metric type II bursts reported in published works. This suggests that the BFR is a universal characteristic, irrespective of the spectral domain. Finally, we also studied the BFR evolution with heliocentric distance using white-light observation of the associated coronal mass ejections. We found that the BFR remains roughly constant in the SOHO/LASCO field of view (i.e., from 2.1 to 32 solar radii), while the bandwidth itself decreases. Title: What is Unusual About the 2005 January 20 SEP Event? Authors: Gopalswamy, N.; Xie, H.; Yashiro, S.; Usoskin, I. Bibcode: 2005AGUFMSH23A0318G Altcode: We report on the solar energetic particle (SEP) event of 2005 January 20 that had an associated ground level enhancement (GLE). The Solar and Heliospheric Observatory (SOHO) spacecraft observed a CME, which was among the fastest of cycle 23 CMEs. This event is consistent with the results that the GLE-associated CMEs represent the fastest known population of CMEs. A metric type II burst started before the proton injection time, suggesting that a coronal shock was formed before high-energy protons were released at the Sun. These 2005 January 20 event is consistent with the current paradigm that large SEP events originate in CME-driven shocks. We also determined the height of the CME at two time marks: the metric type II onset (2.1 Rs) and the proton injection time (4.5 Rs). At a height of 4.5 Rs the CME should have attained the maximum speed, thus driving the strongest shocks. We discuss the estimation of the CME speed given that the coronagraph observations were hampered by the SEPs arriving at the SOHO spacecraft. We also discuss the arrival of the CME-associated plasma and shock at 1 AU. Work supported by NASA/LWS and NSF/SHINE programs. Title: Distributed Instrumentation Deployment During the IHY Authors: Davila, J. M.; Thompson, B. J.; Gopalswamy, N. Bibcode: 2005AGUFMSM21A0347D Altcode: A major thrust of the International Heliophysical Year (IHY) is to deploy arrays of small, inexpensive instruments such as magnetometers, radio antennas, GPS receivers, all-sky cameras, etc. around the world to provide global measurements of ionospheric and heliospheric phenomena. This program is a collaboration between the IHY and the United Nations Basic Space Science (UNBSS) program, which has been dedicated to the IHY through 2009. The small instrument program is envisioned as a partnership between instrument providers, and instrument host countries. The lead scientist will provide the instruments (or fabrication plans for instruments) in the array; the host country will provide manpower, facilities, and operational support to obtain data with the instrument typically at a local university. Instrument operational support for local scientists, facilities, data acquisition, etc will be provided by the host nation. Title: Introduction to violent Sun-Earth connection events of October-November 2003 Authors: Gopalswamy, N.; Barbieri, L.; Cliver, E. W.; Lu, G.; Plunkett, S. P.; Skoug, R. M. Bibcode: 2005JGRA..110.9S00G Altcode: 2005JGRA..11009S00G The solar-terrestrial events of late October and early November 2003, popularly referred to as the Halloween storms, represent the best observed cases of extreme space weather activity observed to date and have generated research covering multiple aspects of solar eruptions and their space weather effects. In the following article, which serves as an abstract for this collective research, we present highlights taken from 61 of the 74 papers from the Journal of Geophysical Research, Geophysical Research Letters, and Space Weather which are linked under this special issue. (An overview of the 13 associated papers published in Geophysics Research Letters is given in the work of Gopalswamy et al. (2005a)). Title: A Study of the Drift Rate of Type II Radio Bursts at Different Wavelengths Authors: Aguilar-Rodriguez, E.; Gopalswamy, N.; MacDowall, R.; Yashiro, S.; Kaiser, M. I. Bibcode: 2005ESASP.592..393A Altcode: 2005soho...16E..65A; 2005ESASP.592E..65A No abstract at ADS Title: Coronal mass ejections and other extreme characteristics of the 2003 October-November solar eruptions Authors: Gopalswamy, N.; Yashiro, S.; Liu, Y.; Michalek, G.; Vourlidas, A.; Kaiser, M. L.; Howard, R. A. Bibcode: 2005JGRA..110.9S15G Altcode: 2005JGRA..11009S15G Fast coronal mass ejections (CMEs), X-class flares, solar energetic particle (SEP) events, and interplanetary shocks were abundantly observed during the episode of intense solar activity in late October and early November 2003. Most of the 80 CMEs originated from three active regions (NOAA ARs 484, 486, and 488). We compare the statistical properties of these CMEs with those of the general population of CMEs observed during cycle 23. We find that (1) the 2003 October-November CMEs were fast and wide on the average and hence were very energetic, (2) nearly 20 percent of the ultrafast CMEs (speed ≥2000 km s-1) of cycle 23 occurred during the October-November interval, including the fastest CME of the study period (∼2700 km s-1 on 4 November 2003 at 1954 UT), (3) the rate of full-halo CMEs was nearly four times the average rate during cycle 23, (4) at least sixteen shocks were observed near the Sun, while eight of them were intercepted by spacecraft along the Sun-Earth line, (5) the CMEs were highly geoeffective: the resulting geomagnetic storms were among the most intense of cycle 23, (6) the CMEs were associated with very large SEP events, including the largest event of cycle 23. These extreme properties were commensurate with the size and energy of the associated active regions. This study suggests that the speed of CMEs may not be much higher than ∼3000 km s-1, consistent with the free energy available in active regions. An important practical implication of such a speed limit is that the Sun-Earth travel times of CME-driven shocks may not be less than ∼0.5 day. Two of the shocks arrived at Earth in <24 hours, the first events in ∼30 years and only the 14th and 15th documented cases of such events since 1859. Title: Flare-generated shock evolution and geomagnetic storms during the ``Halloween 2003 epoch'': 29 October to 2 November Authors: Wu, Chin-Chun; Wu, S. T.; Dryer, M.; Fry, C. D.; Berdichevsky, D.; Smith, Z.; Detman, T.; Gopalswamy, N.; Skoug, R.; Zurbuchen, T.; Smith, C. Bibcode: 2005JGRA..110.9S17W Altcode: 2005JGRA..11009S17W The October/November 2003 ("Halloween 2003") epoch of intense solar flares provided an opportunity to test the results of earlier parametric 1.5 MHD studies of interacting interplanetary shock waves. These preliminary studies used an adaptive numerical grid that made it possible to identify products of these interactions. During 28 October to 2 November 2003, three shocks generated by four solar flares were observed at the L1 libration point by ACE/SWEPAM/SWICS/MAG. Two very distinct geomagnetic storms, associated with two of these flares (X17/4B and X10/2B), rank as two of the largest storms of solar cycle 23. The purpose of this paper is to present the use of an adaptive grid 1.5-dimensional MHD model that is initiated at the solar surface to study in detail the three shocks observed at L1 that were generated by the four solar flares. Accordingly, four separate pressure pulses, at the appropriate times and with different strengths and duration, determined via a trial and error procedure, are introduced on the Sun to mimic the four flares. The results show that the simulated solar wind velocity temporal profiles successfully matched the observations at L1. The major objective, to demonstrate the detailed nature of interacting shocks and some of their products after origination from closely spaced solar events, is achieved. In addition, the MHD model is able to suggest the solar sources that are associated with specific geomagnetic storms at Earth. Title: Coronal Mass Ejections and Galactic Cosmic-Ray Modulation Authors: Lara, A.; Gopalswamy, N.; Caballero-López, R. A.; Yashiro, S.; Xie, H.; Valdés-Galicia, J. F. Bibcode: 2005ApJ...625..441L Altcode: We present a study of the long-term evolution of coronal mass ejections (CMEs) observed by the Large Angle and Spectrometric Coronograph (LASCO) on board SOHO during the ascending, maximum, and part of the descending phases of solar cycle 23 and their relation with the modulation of galactic cosmic-ray (GCR) intensity observed at 1 AU by the Climax neutron monitor and IMP-8 spacecraft. We compare the long-term GCR modulation with the CME occurrence rate at all, low, and high latitudes, as well as the observed CME parameters (width and speed). Twenty-seven day averages of CME occurrence rates and CME properties from 1996 January to 2003 December are presented in the Appendix. The general anticorrelation between GCR intensity and the CME rate is relatively high (~-0.88). However, when we divide the CME rate into low- and high-latitude rates and compare them with the GCR intensity during the ascending phase of solar cycle 23, we find a lower anticorrelation between the low-latitude the CME rate and GCR intensity (~-0.71) and a very high anticorrelation between the high-latitude CME rate and GCR intensity (~-0.94). This suggests that, in general, CMEs could cause the decrease in the GCR flux in the inner heliosphere, as stated by the global merged interaction region (GMIR) theory. In particular, during the ascending phase of cycle 23 (qA>0), this flux comes mainly from heliospheric polar regions. Thus, high-latitude CMEs may play a central role in the long-term cosmic-ray modulation during this phase of the cycle by blocking the polar entrance of GCRs to the inner heliosphere. This study supports the scenario in which CMEs, among other structures, are the building blocks of GMIRs, although we propose that the spherical shells (GMIRs) are closed separately at polar and equatorial regions by CMEs of different latitudes. Our results suggest that all CME properties show some correlation with the GCR intensity, although there is no specific property (width, speed, or a proxy of energy) that definitely has a higher correlation with GCR intensity. Title: Statistical Study of Shocks and CMEs Associated With Interplanetary Type II Bursts Authors: Aguilar-Rodriguez, E.; Gopalswamy, N.; MacDowall, R.; Yashiro, S.; Kaiser, M. L. Bibcode: 2005AGUSMSH43A..04A Altcode: We present a study of some spectral properties associated with interplanetary Type II radio emission. Type II radio bursts are signatures of violent eruptions from the Sun that result in shock waves propagating through the corona and the interplanetary medium. We investigated the relative bandwidth of all the type II bursts observed by the Radio and Plasma Wave Experiment (WAVES) on board the Wind spacecraft from 1997 up to 2003. We obtained three sets of events, based on the frequency domain of occurrence: 109 events in the low frequency domain (30 KHz to 1000 kHz detected by the RAD1 receiver), 216 events in the high frequency domain (1-14 MHz, observed by the RAD2 receiver), and 73 events that spanned both domains (RAD1 and RAD2). We present statistical results for the bandwidth-to-frequency ratio (BFR) in the three subsets as well as a comparision of our results with the Type II solar radio bursts observed by ISEE-3 radio experiment, which is similar to WAVES/RAD1. We analyzed the bandwidth and BFR evolution with the heliocentric distance as well as an analysis of drift rate magnitude of type II radio bursts and its starting frequency. We also present some properties of shocks and coronal mass ejections associated with interplanetary type II bursts. This work is partially supported by NSF/SHINE (ATM 0204588) Title: Sun-Earth Propagation Time of CMEs Originated at different Helio Longitudes Authors: Lara, A.; Gopalswamy, N.; Xie, H.; Gonzalez-Esparza, A. Bibcode: 2005AGUSMSH53A..10L Altcode: We present a study of the transport of coronal mass ejections (CMEs) in the interplanetary medium and the probability that they, or the associated shocks, reach the Earth surroundings when they are ejected in different Helio-longitudes. To reach this goal we choose the CME events associated with the active region 0486 which crosses the solar disk during October - November 2003 and produced several CMEs during its crossing from East to West limb. We measured and analyzed the speed profile of each event, we found that the speed profile of halos and partial-halo CMEs are very symmetric and an elliptical model seems to fit the profiles very well. Using a cone model we determine the space direction of CMEs and then, the most probable speed in the Sun-Earth direction. Using these speeds, we applied the CME travel time empirical model to determine the near Earth arrival times of both interplanetary CME and related shock. We found that the difference between the predicted and observed arrival times increase with the Helio-longitude of the CME. To help in the identification of CME - 1 AU shocks and to validate the empirical model, we use 2D numerical simulations of the events. Title: Solar source of the largest geomagnetic storm of cycle 23 Authors: Gopalswamy, N.; Yashiro, S.; Michalek, G.; Xie, H.; Lepping, R. P.; Howard, R. A. Bibcode: 2005GeoRL..3212S09G Altcode: The largest geomagnetic storm of solar cycle 23 occurred on 2003 November 20 with a Dst index of -472 nT, due to a coronal mass ejection (CME) from active region 0501. The CME near the Sun had a sky-plane speed of ~1660 km/s, but the associated magnetic cloud (MC) arrived with a speed of only 730 km/s. The MC at 1 AU (ACE Observations) had a high magnetic field (~56 nT) and high inclination to the ecliptic plane. The southward component of the MC's magnetic field was made up almost entirely of its axial field because of its east-south-west (ESW) chirality. We suggest that the southward pointing strong axial field of the MC reconnected with Earth's front-side magnetic field, resulting in the largest storm of the solar cycle 23. Title: Putting the Rubber to the Road: The Whos, Whys and Hows of the International Heliophysical Year 2007 Authors: Thompson, B. J.; Davila, J. M.; Drobnes, E.; Gopalswamy, N.; Wesenberg, R. P. Bibcode: 2005AGUSM.U23A..07T Altcode: In 1957 a program of international research, inspired by the International Polar Years of 1882 and 1932, was organized as the International Geophysical Year (IGY) to study global phenomena of the Earth and geospace. Fifty years later, the world's science community will again come together for international programs of scientific collaboration: the International Heliophysical Year (IHY), the electronic Geophysical Year (eGY), and the International Polar Year (IPY) 2007. This time, research will extend out into the heliosphere to focus on solar-terrestrial-planetary interactions. The ambitious plans for the IHY, eGY and IPY incorporate the activities of scientists in 191 nations, the "IGY Gold" Historical Preservation initiative, a series of coordinated campaigns involving more than 100 instruments and models, education and public outreach programs, a developing nations instrument development program, and opportunities for supported research worldwide. The presentation will focus on the efforts and operations which will make these activities possible. Title: Improved Empirical CME Arrival Time Model Via Cone Model Authors: Xie, H.; Gopalswamy, N.; Ofman, L.; Michalek, G.; Lara, A.; Yashiro, S. Bibcode: 2005AGUSMSH53A..09X Altcode: In this study, we compare the results obtained from two cone models and carry out the statistical study of the distribution of the actual size and space speed of Coronal Mass Ejections (CMEs). We improved the existing empirical CME arrival (ECA) model, based on previously developed empirical models and provided the prediction of CME transit time from the Sun to the Earth. The previous ECA model was in good agreement with the observations for high-speed CMEs. However, the agreement was not as good for low-speed events. One of possible reasons may be due to errors caused by the significant scatter of CME projection speeds in low projected-speed events. Using the cone models we reduced the errors and improved the accuracy of the ECA model by applying the cone models to halo CMEs erupted from near disk center of the Sun (within < 30 deg.) to determine the actual speed. We found that both cone models provide similar improved accuracy for the arrival time. Title: Photospheric sources of very fast coronal mass ejections Authors: Yurchyshyn, V.; Yashiro, S.; Gopalswamy, N. Bibcode: 2005AGUSMSH51C..04Y Altcode: We identified photospheric sources for 39 very fast (v > 1100 km/s) front-side coronal mass ejections that erupted between 1999 and 2001. For our study we used data on CMEs and their sources provided by the CME Catalog, SOHO spacecraft (LASCO, EIT, MDI), Big Bear Solar Observatory (Halpha, magnetograms), Mount Wilson Observatory (sunspot drawings) and Joint USAF/NOAA active region summary. Our results are as follows. We distinguished three different groups of active regions which are responsible for very fast CMEs: 1) Complex delta spots (21 events). This group of active regions is characterized by the presence of at least two large opposite polarity sunspots located close to each other. 2) Simple delta spots (8 events). A typical configuration of this type consists of one large twisted tadpole-shaped sunspot, surrounded by many small satellite-sunspots. 3) Extended magnetic regions, which consist of two adjacent decaying active regions or a new active region emerging inside a decaying active region. Title: Estimation of Projection Effect of CMEs from the Onset Time of the Shock-Associated Type III Radio Burst Authors: Michalek, G.; Gopalswamy, N.; Yashiro, S. Bibcode: 2005AcA....55..151M Altcode: We present a new possibility to estimate the projection effects on coronal mass ejection (CME) measurements. It is well known that coronagraphic observations of CMEs are subject to projection effects. Fortunately, the WIND/WAVES observations of type III radio bursts associated with shock waves are free from projection effects. We assume that (1) high energy electrons are produced at the shock front ahead of the CME, and (2) the radio burst starts when the shock reaches open field lines (approx 3 R_odot). In other words, the onset time of the radio burst corresponds to the time when the CME leading edge reaches 3 R_odot. The difference between the onset times of CMEs and radio bursts should be strongly correlated with the position of CMEs on the Sun. This correlation seems to be strongly dependent on solar activity. Using particular linear fits on the scatter plots, we can determine the source location of CMEs and tell how much the projection effect can really affect CME measurements. Title: Introduction to the special section: Violent Sun-Earth connection events of October-November 2003 Authors: Gopalswamy, N.; Barbieri, L.; Lu, G.; Plunkett, S. P.; Skoug, R. M. Bibcode: 2005GeoRL..32.3S01G Altcode: 2005GeoRL..3203S01G During 2003 October and November, a series of solar eruptions occurred from three solar active regions. Some of these eruptions were extreme in terms of their origin (source properties) and heliospheric consequences. This paper summarizes the first results of the analysis of these violent Sun-Earth connection events. Title: CMEs and Long-Lived Geomagnetic Storms: A Case Study Authors: Xie, H.; Gopalswamy, N.; Manoharan, P. K.; Yashiro, S.; Lara, A.; Lepri, S. Bibcode: 2005IAUS..226..475X Altcode: We studied the relationship between successive coronal mass ejections (CMEs) and a long-lived geomagnetic storm (LLGMS) by examining the 1998 May 4 event. Five successive CMEs from the same active region and four interplanetary shocks were found to be associated with this LLGMS. We investigated the effect of successive and interacting CMEs on the LLGMS. Title: An empirical model to predict the 1-AU arrival of interplanetary shocks Authors: Gopalswamy, N.; Lara, A.; Manoharan, P. K.; Howard, R. A. Bibcode: 2005AdSpR..36.2289G Altcode: We extend the empirical coronal mass ejection (CME) arrival model of Gopalswamy et al. [Gopalswamy, N. et al. Predicting the 1-AU arrival times of coronal mass ejections, J. Geophys. Res. 106, 29207, 2001] to predict the 1-AU arrival of interplanetary (IP) shocks. A set of 29 IP shocks and the associated magnetic clouds observed by the Wind spacecraft are used for this study. The primary input to this empirical shock arrival model is the initial speed of white-light CMEs obtained using coronagraphs. We use the gas dynamic piston-shock relationship to derive the ESA model which provides a simple means of obtaining the 1-AU speed and arrival times of interplanetary shocks using CME speeds. Title: CME Interaction and the Intensity of Solar Energetic Particle Events Authors: Gopalswamy, N.; Yashiro, S.; Krucker, S.; Howard, R. A. Bibcode: 2005IAUS..226..367G Altcode: Large Solar Energetic Particles (SEPs) are closely associated with coronal mass ejections (CMEs). The significant correlation observed between SEP intensity and CME speed has been considered as the evidence for such a close connection. The recent finding that SEP events with preceding wide CMEs are likely to have higher intensities compared to those without was attributed to the interaction of the CME-driven shocks with the preceding CMEs or with their aftermath. It is also possible that the intensity of SEPs may also be affected by the properties of the solar source region. In this study, we found that the active region area has no relation with the SEP intensity and CME speed, thus supporting the importance of CME interaction. However, there is a significant correlation between flare size and the active region area, which probably reflects the spatial scale of the flare phenomenon as compared to that of the CME-driven shock. Title: Statistical Distributions of Speeds of Coronal Mass Ejections Authors: Yurchyshyn, V.; Yashiro, S.; Abramenko, V.; Wang, H.; Gopalswamy, N. Bibcode: 2005ApJ...619..599Y Altcode: We studied the distribution of plane-of-sky speeds determined for 4315 coronal mass ejections (CMEs) detected by the Large Angle and Spectrometric Coronagraph Experiment on board the Solar and Heliospheric Observatory (SOHO LASCO). We found that the speed distributions for accelerating and decelerating events are nearly identical and to a good approximation they can be fitted with a single lognormal distribution. This finding implies that, statistically, there is no physical distinction between the accelerating and the decelerating events. The lognormal distribution of the CME speeds suggests that the same driving mechanism of a nonlinear nature is acting in both slow and fast dynamical types of CMEs. Title: Coronal Mass Ejections and Ground Level Enhancements Authors: Gopalswamy, N.; Xie, H.; Yashiro, S.; Usoskin, I. Bibcode: 2005ICRC....1..169G Altcode: 2005ICRC...29a.169G No abstract at ADS Title: Solar Imaging Radio Array (SIRA): a multispacecraft mission Authors: MacDowall, R. J.; Bale, S. D.; Demaio, L.; Gopalswamy, N.; Jones, D. L.; Kaiser, M. L.; Kasper, J. C.; Reiner, M. J.; Weiler, K. W. Bibcode: 2005SPIE.5659..284M Altcode: The Solar Imaging Radio Array (SIRA) is a mission to perform aperture synthesis imaging of low frequency solar, magnetospheric, and astrophysical radio bursts. The primary science targets are coronal mass ejections (CMEs), which drive shock waves that may produce radio emission. A space-based interferometer is required, because the frequencies of observation (<15 MHz) are cutoff by the ionosphere. SIRA will require a 12 to 16 microsatellite constellation to establish a sufficient number of baselines with separations on the order of kilometers. The microsats will be located quasi-randomly on a spherical shell, initially of diameter 10 km or less. The baseline microsat, as presented here, is 3-axis stabilized with a body-mounted, earth-directed high gain antenna and an articulated solar array; this design was developed by the Integrated Mission Design Center (IMDC) at NASA Goddard Space Flight Center (GSFC). A retrograde orbit at a distance of ~500,000 km from Earth was selected as the preferred orbit because the 8 Mbps downlink requirement is easy to meet, while keeping the constellation sufficiently distant from terrestrial radio interference. Also, the retrograde orbit permits imaging of terrestrial magnetospheric radio sources from varied perspectives. The SIRA mission serves as a pathfinder for space-based satellite constellations and for spacecraft interferometry at shorter wavelengths. It will be proposed to the NASA MIDEX proposal opportunity in mid-2005. Title: The Solar Imaging Radio Array (SIRA) Mission Authors: Jones, D. L.; MacDowall, R.; Gopalswamy, N.; Kaiser, M.; Reiner, M.; Demaio, L.; Weiler, K.; Kasper, J.; Bale, S.; Howard, R. Bibcode: 2004AAS...205.1012J Altcode: 2004BAAS...36.1351J The Solar Imaging Radio Array will be proposed to NASA as a Medium Explorer (MIDEX) mission by a team of investigators at GSFC, JPL, NRL, MIT, and UC Berkeley. The main science goal of the mission is imaging and tracking of solar radio bursts, particularly those associated with coronal mass ejections, and understanding their evolution and influence on Earth's magnetosphere. Related goals are mapping the 3-dimensional morphology of the interplanetary magnetic field and improving the prediction of geomagnetic storms. A number of topics in galactic and extragalactic astrophysics will also be addressed by SIRA. The mission concept is a free-flying array of about 16 small, inexpensive satellites forming an aperture synthesis interferometer in space. By observing from above the ionosphere, and far from terrestrial radio interference, SIRA will cover frequencies between a few tens of kHz up to 15 MHz. This wide spectral window is essentially unexplored with high angular resolution.

Part of this work is being carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration. Title: Intensity variation of large solar energetic particle events associated with coronal mass ejections Authors: Gopalswamy, N.; Yashiro, S.; Krucker, S.; Stenborg, G.; Howard, R. A. Bibcode: 2004JGRA..10912105G Altcode: We studied the coronal mass ejections (CMEs) and flares associated with large solar energetic particle (SEP) events of solar cycle 23 (1996-2002) in order to determine what property of the solar eruptions might order the SEP intensity. The SEP events were divided into three groups: (1) events in which the primary CME was preceded by one or more wide CMEs from the same solar source, (2) events with no such preceding CMEs, and (3) events in which the primary CME might have interacted with a streamer or with a nearby halo CME. The SEP intensities are distinct for groups 1 and 2 although the CME properties were nearly identical. Group 3 was similar to group 1. The primary findings of this study are as follows: (1) Higher SEP intensity results whenever a CME is preceded by another wide CME from the same source region. (2) The average flare size was also larger for high-intensity SEP events. (3) The intensity of SEP events with preceding CMEs showed a tighter correlation with CME speed. The extent of scatter in the CME speed versus SEP intensity plots was reduced when various subgroups were considered separately. (4) The intensities of energetic electrons were better correlated with flare size than with CME speed. (5) The SEP intensity showed poor correlation with the flare size, except for group 3 events. Since only a third of the events did not have preceding CMEs, we conclude that the majority of SEP producing CMEs propagate through the near-Sun interplanetary medium severely disturbed and distorted by the preceding CMEs. Furthermore, the preceding CMEs are faster and wider on the average, so they may provide seed particles for CME-driven shocks that follow. Therefore we conclude that the differing intensities of SEP events in the two groups may not have resulted due to the inherent properties of the CMEs. The presence of preceding CMEs seems to be the discriminating characteristic of the high- and low-intensity SEP events. Title: Improved Empirical CME Arrival Time Prediction Model Authors: Xie, H.; Gopalswamy, N.; Lara, A.; Yashiro, S. Bibcode: 2004AGUFMSH53B0324X Altcode: We have successfully developed an innovative analytical method to determine the angular width and propagation orientation of Halo Coronal Mass Ejections (Xie et al. 2003). We will apply this new method to improve the existing empirical space weather forecasting models (e.g., Gopalswamy et al., 2001). Gopalswamy et al. (2001) presented an empirical model to provide the predication of CME transit time from the Sun to the Earth. The model is in good agreement with the observations for high-speed CMEs. However, the agreement is not good for low-speed events. One of possible reasons may be due to errors caused by the significant scatter of CME prjection speeds used in the model. Using our new method can determine the actual speed of CMEs and thus reduce the errors and improve the model. Title: Association of Coronal Mass Ejections and Type II Radio Bursts with Impulsive Solar Energetic Particle Events Authors: Yashiro, S.; Gopalswamy, N.; Cliver, E. W.; Reames, D. V.; Kaiser, M. L.; Howard, R. A. Bibcode: 2004ASPC..325..401Y Altcode: We report the association of impulsive solar energetic particle (SEP) events with coronal mass ejections (CMEs) and metric type II radio bursts. We identified 38 impulsive SEP events using the WIND/EPACT instrument and their CME association was investigated using white light data from SOHO/LASCO. We found that (1) at least ∼ 28--39 % of impulsive SEP events were associated with CMEs, (2) only 8--13 % were associated with metric type II radio bursts. The statistical properties of the associated CMEs were investigated and compared with those of general CMEs and CMEs associated with large gradual SEP events. The CMEs associated with impulsive SEP events were significantly slower (median speed of 613 kmps) and narrower (49 deg) than those of CMEs associated with large gradual SEP events (1336 kmps, 360 deg), but faster than the general CMEs (408 kmps). Title: Brightness Characteristics of Halo CMEs Authors: Lara, A.; Gopalswamy, N.; Michalek, G.; Xie, H.; Yashiro, S. Bibcode: 2004AGUFMSH53B0316L Altcode: It is generally accepted that halo Coronal Mass Ejections (CMEs) are regular, low latitude, CMEs traveling towards (or away FROM) the observer. The association between halo CMEs and solar energetic particles events (SEPs) and Type II bursts is higher compared to regular CMEs. Halo CMEs are observed up to large heliocentric distances as compared to the regular CMEs. This is somewhat contradictory to the theory of Thomson scattering because the visibility conditions for halo CMEs are rather poor, assuming that the longitudinal widths of halo CMEs are the similar to those of regular CMEs. In this paper, we present some observational characteristics of halo CMEs, such as high brightness at large distances and symmetry in the velocity space. The CMEs were observed by the Solar and Heliospheric Observatory (SOHO) mission's Large Angle and Spectrometric Coronagraph (LASCO). We also present a possible model that explains the apparent contradiction Title: Radio-quiet Fast Coronal Mass Ejections Authors: Gopalswamy, N.; Aguilar-Rodriguez, E.; Kaiser, M. L.; Howard, R. A. Bibcode: 2004AGUFMSH23A..05G Altcode: Coronal mass ejections (CMEs) drive shocks in the interplanetary medium that produce type II radio emission. These CMEs are faster and wider on the average, than the general population of CMEs. However, when we start from fast (speed > 900 km/s) and wide (angular width > 60 degrees), more than half of them are not associated with radio bursts. In order to understand why these CMEs are radio quiet, we collected all the fast and wide (FW) CMEs detected by the Solar and Heliospheric Observatory (SOHO) mission's Large Angle and Spectrometric Coronagraph (LASCO) and isolated those without associated type II radio bursts. The radio bursts were identified in the dynamic spectra of the Radio and Plasma Wave (WAVES) Experiment on board the Wind spacecraft. We also checked the list against metric type II radio bursts reported in Solar Geophysical Data and isolated those without any radio emission. This exercise resulted in about 140 radio-quiet FW CMEs. We identified the source regions of these CMEs using the Solar Geophysical Data listings, cross-checked against the eruption regions in the SOHO/EIT movies. We explored a number of possibilities for the radio-quietness: (i) Source region being too far behind the limb, (ii) flare size, (iii) brightness of the CME, and (iv) the density of the ambient medium. We suggest that a combination of CME energy and the Alfven speed profile of the ambient medium is primarily responsible for the radio-quietness of these FW CMEs. Title: Solar Imaging Radio Array (SIRA): Imaging solar, magnetospheric, and astrophysical sources at < 15 MHz Authors: Howard, R.; MacDowall, R.; Gopalswamy, N.; Kaiser, M. L.; Reiner, M. J.; Bale, S.; Jones, D.; Kasper, J.; Weiler, K. Bibcode: 2004DPS....36.1424H Altcode: 2004BAAS...36Q1097H The Solar Imaging Radio Array (SIRA) is a mission to perform aperture synthesis imaging of low frequency solar, magnetospheric, and astrophysical radio bursts. The primary science targets are coronal mass ejections (CMEs), which drive radio emission producing shock waves. A space-based interferometer is required, because the frequencies of observation (<15 MHz) do not penetrate the ionosphere. As such, the SIRA mission serves as a lower frequency counterpart to LWA, LOFAR, and similar ground-based radio imaging arrays. SIRA will require 12 to 16 microsatellites to establish a sufficient number of baselines with separations on the order of kilometers. The microsat constellation consists of microsats located quasi-randomly on a spherical shell, initially of radius 5 km or less. The baseline microsat is 3-axis stabilized with body-mounted solar arrays and an articulated, earth pointing high gain antenna. A retrograde orbit at 500,000 km from Earth was selected as the preferred orbit because it reduces the downlink requirement while keeping the microsats sufficiently distant from terrestrial radio interference. Also, the retrograde orbit permits imaging of terrestrial magnetospheric radio sources from varied perspectives. The SIRA mission serves as a pathfinder for space-based satellite constellations and for spacecraft interferometry at shorter wavelengths. It will be proposed to the NASA MIDEX proposal opportunity in mid-2005. Title: Recent advances in the long-wavelength radio physics of the Sun Authors: Gopalswamy, N. Bibcode: 2004P&SS...52.1399G Altcode: Solar radio bursts at long wavelengths provide information on solar disturbances such as coronal mass ejections (CMEs) and shocks at the moment of their departure from the Sun. The radio bursts also provide information on the physical properties (density, temperature and magnetic field) of the medium that supports the propagation of the disturbances with a valuable cross-check from direct imaging of the quiet outer corona. The primary objective of this paper is to review some of the past results and highlight recent results obtained from long-wavelength observations. In particular, the discussion will focus on radio phenomena occurring in the outer corona and beyond in relation to those observed in white light. Radio emission from nonthermal electrons confined to closed and open magnetic structures and in large-scale shock fronts will be discussed with particular emphasis on its relevance to solar eruptions. Solar cycle variation of the occurrence rate of shock-related radio bursts will be discussed in comparison with that of interplanetary shocks and solar proton events. Finally, case studies describing the newly-discovered radio signatures of interacting CMEs will be presented. Title: A Global Picture of CMEs in the Inner Heliosphere Authors: Gopalswamy, N. Bibcode: 2004ASSL..317..201G Altcode: 2004shis.conf..201G No abstract at ADS Title: Energy partition in two solar flare/CME events Authors: Emslie, A. G.; Kucharek, H.; Dennis, B. R.; Gopalswamy, N.; Holman, G. D.; Share, G. H.; Vourlidas, A.; Forbes, T. G.; Gallagher, P. T.; Mason, G. M.; Metcalf, T. R.; Mewaldt, R. A.; Murphy, R. J.; Schwartz, R. A.; Zurbuchen, T. H. Bibcode: 2004JGRA..10910104E Altcode: Using coordinated observations from instruments on the Advanced Composition Explorer (ACE), the Solar and Heliospheric Observatory (SOHO), and the Ramaty High Energy Solar Spectroscopic Imager (RHESSI), we have evaluated the energetics of two well-observed flare/CME events on 21 April 2002 and 23 July 2002. For each event, we have estimated the energy contents (and the likely uncertainties) of (1) the coronal mass ejection, (2) the thermal plasma at the Sun, (3) the hard X-ray producing accelerated electrons, (4) the gamma-ray producing ions, and (5) the solar energetic particles. The results are assimilated and discussed relative to the probable amount of nonpotential magnetic energy available in a large active region. Title: Interplanetary Radio Bursts Authors: Gopalswamy, N. Bibcode: 2004ASSL..314..305G Altcode: Nonthermal radio bursts in the interplanetary medium indicate the far-reaching effect of solar eruptions that inject energetic particles, plasmas and shock waves into the inner heliosphere. More than half a century of ground-based observations and subsequent space-based observations exist on this phenomena. In this paper, I summarize the understanding we have gained on the type III and type II radio bursts, which are indicative of electron beams and shocks, respectively. Observations in the new radio window (1-14 MHz) from Wind/WAVES have not only confirmed previous results, but also led to a number of new discoveries. Availability of simultaneous white light (SOHO) and radio (Wind) observations from the same spatial domain in the near-Sun IP medium is largely responsible for these discoveries on the IP propagation of CMEs, so this paper discusses radio bursts in the context of white light observations. After exploring the origin of normal, complex and storm type III bursts, I discuss the type II bursts and their relation to coronal mass ejections. Finally I discuss some of the recent developments on IP radio emission. Title: Kinematics of coronal mass ejections between 2 and 30 solar radii. What can be learned about forces governing the eruption? Authors: Vršnak, B.; Ruždjak, D.; Sudar, D.; Gopalswamy, N. Bibcode: 2004A&A...423..717V Altcode: Kinematics of more than 5000 coronal mass ejections (CMEs) measured in the distance range 2-30 solar radii is investigated. A distinct anticorrelation between the acceleration, a, and the velocity, v, is found. In the linear form, it can be represented as a=-k1(v-v0), where v0=400 km s-1, i.e., most of CMEs faster than 400 km s-1 decelerate, whereas slower ones generally accelerate. After grouping CMEs into the width and mean-distance bins, it was found that the slope k1 depends on these two parameters: k1 is smaller for CMEs of larger width and mean-distance. Furthermore, the obtained CME subsets show distinct quadratic-form correlations, of the form a= -k2 (v-v0)| v-v0|. The value of k2 decreases with increasing distance and width, whereas v0 increases with the distance and is systematically larger than the slow solar wind speed by 100-200 km s-1. The acceleration-velocity relationship is interpreted as a consequence of the aerodynamic drag. The excess of v0 over the solar wind speed is explained assuming that in a certain fraction of events the propelling force is still acting in the considered distance range. In most events the inferred propelling force acceleration at 10 solar radii ranges between aL=0 and 10 m s-2, being on average smaller at larger distances. However, there are also events that show aL>50 m s-2, as well as events indicating aL<0. Implications for the interplanetary motion of CMEs are discussed, emphasizing the prediction of the 1 a.u. arrival time.

Appendices A and B are only available in electronic form at http://www.edpsciences.org Title: Arrival time of halo coronal mass ejections in the vicinity of the Earth Authors: Michałek, G.; Gopalswamy, N.; Lara, A.; Manoharan, P. K. Bibcode: 2004A&A...423..729M Altcode: We describe an empirical model to predict the 1-AU arrival time of halo CMEs. This model is based on the effective acceleration described by Gopalswamy et al. (\cite{Gopalswamy00}a, Geophys. Res. Lett., 27, 145). We verify the Helios/Pioneer Venus Orbiter(PVO) estimation of the effective acceleration profile (Gopalswamy et al. \cite{Gopalswamy01}a, J. Geophys. Res., 106, 29207) by considering all full halo CMEs recorded by SOHO/LASCO coronagraphs until the end of 2002. In comparison with previous studies, the present work includes CMEs of a wider range of initial velocities. To improve the accuracy of prediction, we propose to introduce the effective acceleration from two groups of CMEs only, which are expected to have no acceleration cessation at any place between the Sun and Earth. In addition, we consider acceleration cessation distance dependent on initial velocities of a given event CME. For a detailed analysis of this model, we examine projected sky-plane and space speeds (Michałek et al. \cite{Michalek03}, ApJ, 584, 472) of CMEs. We show that a correct acceleration profile is crucial for the estimation of 1 AU arrival time of halo CMEs. We estimate that the CME arrival times can be predicted with an average error of 9 and 11 h for space and sky-plane initial velocities, respectively.

Table 1 is only available in electronic form at

http://www.edpsciences.org Title: A catalog of white light coronal mass ejections observed by the SOHO spacecraft Authors: Yashiro, S.; Gopalswamy, N.; Michalek, G.; St. Cyr, O. C.; Plunkett, S. P.; Rich, N. B.; Howard, R. A. Bibcode: 2004JGRA..109.7105Y Altcode: The Solar and Heliospheric Observatory (SOHO) mission's white light coronagraphs have observed nearly 7000 coronal mass ejections (CMEs) between 1996 and 2002. We have documented the measured properties of all these CMEs in an online catalog. We describe this catalog and present a summary of the statistical properties of the CMEs. The primary measurements made on each CME are the apparent central position angle, the angular width in the sky plane, and the height (heliocentric distance) as a function of time. The height-time measurements are then fitted to first- and second-order polynomials to derive the average apparent speed and acceleration of the CMEs. The statistical properties of CMEs are (1) the average width of normal CMEs (20° < width ≤ 120°) increased from 47° (1996; solar minimum) to 61° (1999; early phase of solar maximum) and then decreased to 53° (2002; late phase of solar maximum), (2) CMEs were detected around the equatorial region during solar minimum, while during solar maximum CMEs appear at all latitudes, (3) the average apparent speed of CMEs increases from 300 km s-1 (solar minimum) to 500 km s-1 (solar maximum), (4) the average apparent speed of halo CMEs (957 km s-1) is twice of that of normal CMEs (428 km s-1), and (5) most of the slow CMEs (V ≤ 250 km s-1) show acceleration while most of the fast CMEs (V > 900 km s-1) show deceleration. Solar cycle variation and statistical properties of CMEs are revealed with greater clarity in this study as compared with previous studies. Implications of our findings for CME models are discussed. Title: Influence of coronal mass ejection interaction on propagation of interplanetary shocks Authors: Manoharan, P. K.; Gopalswamy, N.; Yashiro, S.; Lara, A.; Michalek, G.; Howard, R. A. Bibcode: 2004JGRA..109.6109M Altcode: We studied 91 interplanetary (IP) shocks associated with coronal mass ejections (CMEs) originating within about ±30° in longitude and latitude from the center of the Sun during 1997-2002. These CMEs cover a wide range of initial speeds of about 120 to 2400 kms-1 and they also include a special population of 25 interacting CMEs. This study provides the characteristics of propagation effects of more number of high-speed CMEs (VCME > 1500 kms-1) than the data used in earlier studies. It enables to extend the shock-arrival prediction model to high-speed CMEs. The results on comparison of IP shock speed and transit time at 1 AU suggest that the shock transit time is not controlled by its final speed but is primarily determined by the initial speed of the CME and effects encountered by it during the propagation. It is found that the CME interaction tends to slow the shock and associated CME. The deviations of shock arrival times from the empirical model are considerably large for slow (VCME < 300 kms-1) and fast (VCME > 800 kms-1) CMEs. Results show that the slow and fast CMEs experience stronger effective acceleration. Title: Coronal Mass Ejections When the Sun Went Wild Authors: Gopalswamy, N.; Yashiro, S.; Vourlidas, A.; Lara, A.; Stenborg, G.; Kaiser, M. L.; Howard, R. A. Bibcode: 2004AAS...204.4709G Altcode: 2004BAAS...36..738G The Large Angle and Spectrometric Coronagraph (LASCO) on board SOHO detected more than five dozen CMEs from three active regions (NOAA ARs 0484, 0486, and 0488) during the October-November 2003 super storms. The CMEs were accompanied by X-class flares, solar energetic particles, and interplanetary shocks. We compare the statistical properties of these super-storm CMEs with those of the general population of CMEs observed during cycle 23. We find that (i) the super-storm CMEs are faster and wider than average, and hence possess enormous energy, (ii) nearly 20 percent of the ultra-fast CMEs (speed > 2000 km/s) occurred during the October-November interval, including the fastest CME of cycle 23 (2700 km/s), and (iii) the rate of full-halo CMEs was nearly four times the average rate during cycle 23. As expected, many of these CMEs were driving shocks near the Sun as inferred from the Wind/WAVES radio data and at least eight of them impacted Earth. These strong shocks accelerated solar energetic particles, which remained at hazardous levels for many days. We discuss the implications of these extreme properties of CMEs for the solar energy source. Title: Shock Evolution During 29 - 06 November 2003 period of Solar-Flare-CME-Shock-Geomagnetic Storms Authors: Wu, C.; Wu, S.; Dryer, M.; Fry, C.; Berdichevsky, D.; Smith, Z.; Gopalswamy, N.; Zurbuchen, T.; Smith, C.; Detman, T. Bibcode: 2004AGUSMSH51A..14W Altcode: During the period 29 October - 6 November four shocks were observed at Earth by ACE/SWEPAM/MAG and ACE/SWICS on 29 October, 30 October, 4 November, and 6 November. Two distinct and very intense geomagnetic storms, associated with the X17.2 and X10/2B flares, rank as the largest storms of Solar Cycle 23. For example, the X17.2 flare (28 October, S16E08 in AR0486), via its associated halo CME and shock wave, was responsible for the Dst = -347 nT index on 30 October 2003. We will present the use of an adaptive grid 2D MHD model to study these four shocks in detail. Accordingly, four separate pressure pulses, at the appropriate times and with different strengths and duration are introduced at the Sun to mimic the four flares. The results show that the simulated solar wind velocity time series successfully match the observations at L1. Title: Sun-Earth Propagation Time of the October - November 2003 Shocks Authors: Lara, A.; Gopalswamy, N.; Yashiro, S. Bibcode: 2004AGUSMSH51A..06L Altcode: We computed the radial and expansion speed profiles of the CMEs that resulted in shocks detected at 1 AU, in order to evaluate the empirical shock arrival (ESA) model. The CMEs were observed by the Large Angle and Spectrometric Coronagraph (LASCO) on board SOHO during October - November 2003 period. The shocks were detected by CELIAS/MTOF Proton Monitor on board SOHO and ACE spacecraft. The basic input to the ESA model is the CME speed. For limb events, we assume axial symmetry in order to obtain the most probable CME speed in the Sun-Earth direction. We apply the ESA model to obtain the travel times of shocks driven by Earth-directed and limb CMEs which had in situ observations at 1AU. For most cases the difference between the predicted and observed shock arrival times is negligible. We discuss these differences and their possible causes. Work supported by NASA/LWS and NSF/SHINE programs Title: Characteristic Periodicities in the Coronal Mass Ejection Production Authors: Lara, A.; Gopalswamy, N.; Yashiro, S. Bibcode: 2004AAS...204.3806L Altcode: 2004BAAS...36..713L The solar activity is cyclic by nature, some periods of activity are obvious and well known and some are hidden, but all of them should be related to fundamental processes in the solar interior like the dynamo. The search for hidden periodicities, which can give us information about the solar activity causes, has been done for many years with different degrees of success. Almost all measurable solar parameters have been subject to a power spectral analysis and now there are some well known periodicities related to such parameters. On the other hand there are some events like Coronal Mass Ejections (CMEs) which, until recently, were difficult to observe routinely and then, we did not have a reliable database to perform a power spectrum analysis. Using the LASCO/SOHO CME list, which contains the information of the CME characteristics observed from 1996 to 2003, we have now a reliable time series of the CME production during 8 years covering the minimum, maximum and part of the declining phases of solar activity cycle 23, in this work we present preliminary results of the power spectral analysis of the CME activity.

This work work was supported by NASA/LWS and NSF/SHINE (ATM 0204588) programs Title: Plasma and magnetic field of the solar wind Authors: Gopalswamy, N. Bibcode: 2004cosp...35.2396G Altcode: 2004cosp.meet.2396G Earth is always embedded in one of the three types of flows related to coronal mass ejections (CMEs), slow solar wind or fast solar wind. The topology of the magnetic field is different in the CME-related flows compared to the other two. I discuss the solar sources of the three types of flows. In particular, the relationship between CMEs in the solar wind and their solar counterparts will be explored to understand the possible reasons for the different number and speed distributions. Earth-directed CMEs constitute a special population of CMEs because they directly impact Earth. Earth-directed halo CMEs also seem to have properties different from the ordinary CMEs: their average speed is twice that of the general population. Finally, the solar cycle variation of the number of instances of CME-related flows at Earth will be compared with the occurrence rates of CMEs, solar energetic particle events, and interplanetary type II radio bursts produced by CME-driven shocks. Title: Variability of solar eruptions during cycle 23 Authors: Gopalswamy, N.; Nunes, S.; Yashiro, S.; Howard, R. A. Bibcode: 2004AdSpR..34..391G Altcode: We report on the solar cycle variation of the rate of coronal mass ejections (CMEs), their mean and median speeds, and the rate of type II radio bursts. We found that both CME rate and speed (mean and median) increased from solar minimum to maximum by factors of 10 and 2, respectively. The CME rate during solar maximum is nearly twice the rates quoted previously. Large spikes in the speed variation were due to active regions that were highly active. The poor correlation between metric and DH type II bursts is confirmed, and the difference is attributed to the different Alfven speeds in the respective source regions. Title: Prominence eruptions and coronal mass ejection: a statistical study using microwave observations Authors: Gopalswamy, N.; Lu, W.; Yashiro, S.; Shimojo, M.; Shibasaki, K. Bibcode: 2004naoj.book...18G Altcode: No abstract at ADS Title: On coronal streamer changes Authors: Gopalswamy, N.; Shimojo, M.; Lu, W.; Yashiro, S.; Shibasaki, K.; Howard, R. A. Bibcode: 2004AdSpR..33..676G Altcode: Coronal streamer represents one of the pre-eruption configurations of coronal mass ejections (CMEs), because they overlie prominences and often possess all the substructures of CMEs. In this paper, we report on a study of streamer changes associated with prominence eruptions. The prominence eruptions and streamer changes were observed by the Nobeyama radioheliograph and Solar and Heliospheric Observatory (SOHO), respectively. Multiwavelength data showed that at least one of the streamer events involved heating and small-scale material ejection that subsequently stalled. After presenting illustrative examples, we compare the properties of the streamer-related events with those of general population of prominence events. We find that the properties of streamer-related prominence events are closer to those of prominence eruptions with transverse trajectories. Title: Composition and magnetic structure of interplanetary coronal mass ejections at 1 AU Authors: Aguilar-Rodriguez, E.; Blanco-Cano, X.; Gopalswamy, N. Bibcode: 2004cosp...35.2411A Altcode: 2004cosp.meet.2411A We present a combined study of magnetic structure and charge state ratio of interplanetary coronal mass ejections (ICMEs) observed in interplanetary space by ACE and Wind spacecrafts. Measurements of abundances and charge state ratio of heavy ions (e.g. O+7/O+6, C+5/C+6, and Mg/O) in the solar wind as well as magnetic field structure are important tracers for physical conditions and processes in the source regions of the solar wind. We used ion composition (ACE), plasma (Wind) and magnetic field (Wind and ACE) data over a period of time from 1998 to 2002. Using the low proton temperature criterion, a common plasma signature of ICMEs, we identified 154 events which were classified as magnetic cloud, non-cloud and complex ICMEs. The later one is refered to the overtaking of succesive ICMEs which can include both magnetic clouds and non-cloud ejecta. We discuss the differences and similarities of our results with those of previous studies. Supported by NSF/SHINE, NASA/LWS, and CONACyT. Title: Coronal Mass Ejections and Galactic Cosmic Ray Modulation Authors: Lara, A.; Gopalswamy, N.; Caballero, R.; Yashiro, S. Bibcode: 2004cosp...35.2926L Altcode: 2004cosp.meet.2926L We present a study of the long term evolution of Coronal Mass Ejections (CME) observed by LASCO/SOHO during the ascending, maximum and part of the descending phase of cycle 23 and its relation with the galactic cosmic ray (GCR) intensity modulation observed at one astronomical unit by Climax Neutron Monitor and IMP-8 spacecraft. We compare the long term GCR modulation with the CME production at low and high latitudes and CME parameters (width and speed). We found a very high (∼ 0.94) correlation between the number of high latitude CMEs and GCR during the ascending phase of solar cycle 23. Title: Coronal Mass Ejections and Solar Particle Events in Solar Cycle 23 Authors: Gopalswamy, N. Bibcode: 2004cosp...35.2358G Altcode: 2004cosp.meet.2358G I provide an overview of the coronal mass ejection (CME) phenomenon as recorded primarily by the Solar and Heliospheric Observatory (SOHO) mission during the current solar activity cycle (23). After summarizing the statistical properties of CMEs and their solar-cycle variation, a discussion on the CME-associated activities will be presented. Particular emphasis will be placed on solar energetic particles (SEPs), which are related to CMEs that are faster and wider on average. Even though it is generally accepted that large SEP events are due to CME-driven shocks, the correlation between the two phenomena is less than perfect. Reasons for this poor correlation will be explored, including the influence of preceding CMEs. Fast and wide CMEs also produce long-wavelength radio bursts, so the connection between SEP events and radio bursts will be explored. Finally, I will discuss the implications of CMEs to the evolution of the global solar magnetic field and to the 22-year cosmic ray modulation cycle. Title: Estimation of solar wind speed within 20Rs of the Sun by using limb CMEs Authors: Nakagawa, T.; Gopalswamy, N.; Yashiro, S.; Matsuoka, A.; Nozomi/Mgf Team Bibcode: 2004cosp...35.1632N Altcode: 2004cosp.meet.1632N The speeds of propagation of CMEs in interplanetary space are less distributed than their initial speeds measured on their departure from the limb of the Sun. Gopalswamy et al.(2000, 2001) presented a linear relationship between initial speeds of limb CMEs and their average acceleration during their travel time in interplanetary space. The linear relationship suggests that some dragging force is acting on CMEs, depending on difference in speed between the CME and their ambient plasmas. The ambient speed obtained from the coeficcients of the linear relationship was 406 km/s, which is nearly the same as the real solar wind speed. If similar relationship holds within 20 solar radii from the Sun, it would give information on the initial speed of 'ambient' solar wind in the vicinity of the Sun. The relationship between the initial acceleration and the initial speeds of limb CMEs was examined by using SOHO/LASCO CME Catalogue (http://cdaw.gsfc.nasa.gov/CME_list/). Coefficients of correlation between the initial acceleration and the initial speeds of low-latitude CMEs were calculated by sliding 27-day windows in 1999. Although there were many cases where linear relationship was not clear, we found significant number of periods for which correlation coefficient was fairly good (from -0.6 to -1). For such cases, the 'ambient' solar wind speed within 20 solar radii was estimated to be 150 - 570 km/s. It is somewhat slower than but close to the speeds of real solar wind measured in interplanetary space. It suggests that low-latitude solar wind plasma was accelerated within a short distance. It may also indicate that coronal holes are not the only source of the solar wind. The 'ambient' speeds thus obtained did not always agreed with simultaneous, in-situ measurements by NOZOMI and ACE. Estimation of 'ambient' speed was also carried out by using CMEs that appeared in higher latitude, but no latitudinal dependence was found. Acknowledgments:This CME catalog is generated and maintained by NASA and The Catholic University of America in cooperation with the Naval Research Laboratory. SOHO is a project of international cooperation between ESA and NASA. Reference: Gopalswamy et al., GRL, 27, p145, 2000. Gopalswamy et al., JGR, 106, p29207, 2001. Title: Type II Radio Bursts and Energetic Solar Eruptions Authors: Gopalswamy, N.; Nunes, S.; Yashiro, S.; Howard, R. A.; Kaiser, M. L. Bibcode: 2003AGUFMSH42C0556G Altcode: Type II radio bursts at decameter-hectometric (DH) and kilometric wavelengths are indicative of CME-driven shocks in the interplanetary medium. Only a subset of these type II bursts continue from the DH to the km regimes. We report on a study of these long-lasting type II bursts using data from the Wind/WAVES experiment in conjunction with white-light coronal mass ejection (CME) data from SOHO. We find the majority of these events (80 percent) are also associated with metric Type II bursts. We also studied the properties of the associated CMEs and found them to be the most energetic when compared to CMEs associated with bursts in any single wavelength regime. Title: Merged interaction regions at 1 AU Authors: Burlaga, L.; Berdichevsky, D.; Gopalswamy, N.; Lepping, R.; Zurbuchen, T. Bibcode: 2003JGRA..108.1425B Altcode: We discuss the existence of large, complex merged interaction regions (MIRs) in the solar wind near Earth. MIRs can have configurations that cause more prolonged geomagnetic effects than a single flow structure. A MIR or successive MIRs can produce relatively long lasting Forbush decreases at 1 AU. We illustrate MIRs at 1 AU with two examples (MIR-1 and MIR-2) seen by WIND and ACE in the interval from 18 March through 29 March 2002. We determined the probable structure and origin of each in terms of interacting flows and shocks using in situ and solar observations, but we emphasize that there are uncertainties that cannot be resolved with these data alone. The MIRs were relatively large structures with radial extent ~2/3 and 3/4 AU, respectively. MIR-1 was formed by interactions related to at least two complex ejecta, a magnetic cloud, and two shocks. MIR-2 was related to a corotating stream, the heliospheric plasma sheet (HPS), two complex ejecta, a magnetic cloud and at least two shocks. A MIR can evolve significantly while it moves to 1 AU, and memory of the conditions near the Sun is lost in the process. Thus one cannot unambiguously determine the structure of a MIR and the manner in which it formed using observations from a single spacecraft at 1 AU. The magnetic field strength profiles in MIRs are not correlated with the speed and density profiles so that one cannot infer the magnetic field strength in MIRs from remote sensing observation that give density and speed information. It will be possible to better understand the dynamical processes leading to the formation of MIRs with remote sensing observations, but they cannot measure the magnetic fields in MIRs. Title: Radio Coverage from Chromosphere to Earth: FASR-LOFAR-SIRA Synergy Authors: Gary, D. E.; Kassim, N.; Gopalswamy, N.; Aschwanden, M. J. Bibcode: 2003AGUFMSH42E..02G Altcode: Radio emission is uniquely sensitive to a number of key plasma parameters (magnetic field, temperature, density, high-energy electrons, and various plasma waves) over heights ranging without gaps from the chromosphere, throughout the corona and heliosphere, to the Earth. Two ground-based radio arrays, the Frequency Agile Solar Radiotelescope (FASR) and the Low Frequency Array (LOFAR), together with the space-based Solar Imaging Radio Array (SIRA) are planned that will for the first time provide direct imaging of disturbances over this vast height range through interferometric imaging over their equally impressive frequency range of 24 GHz to 30 kHz. We describe the science goals of these instruments, focusing especially on the science addressed jointly by all three instruments. Among the examples are (1) simultaneous imaging of CMEs, flaring loops, and shock-associated (type II) emission and (2) imaging the propagation of electrons on open field lines (type III), from their acceleration point through the corona and heliosphere to the point where they are measured in situ by near-Earth spacecraft. In addition to spatially relating the different phenomena, the spectral information is rich in quantitative diagnostics. We give some examples of the revolutionary results we can expect from the combined instruments. Title: Comment on ``Coronal mass ejections, interplanetary ejecta and geomagnetic storms'' by H. V. Cane, I. G. Richardson, and O. C. St. Cyr Authors: Gopalswamy, N.; Manoharan, P. K.; Yashiro, S. Bibcode: 2003GeoRL..30.2232G Altcode: 2003GeoRL..30xSSC1G Abstract Available from AGU Title: Key Issues Related to Solar Sources and Interplanetary Propagation of the April 2002 Events Authors: Gopalswamy, N. Bibcode: 2003AGUFMSM41A..02G Altcode: A summary of the solar events such as coronal mass ejections (CMEs) and flares associated with the April 2002 storms will be provided. In particular events from the primary active region, AR9906 and the underlying magnetic configuration will be discussed. The connection of these CMEs to the interplanetary shocks and the solar energetic particles events will be explored. Based on the arrival times of the interplanetary CMEs and shocks, the evolution of these disturbances as they propagated between the Sun and Earth will be described. Finally, a comparison of the April 2002 events with other geoeffective events will be made. Title: Probing Solar Energetic Particles with SIRA Authors: Aschwanden, M. J.; Nitta, N.; Lemaster, E.; Byler, E.; Gary, D.; Kassim, N.; Gopalswamy, N. Bibcode: 2003AGUFMSH42C0555A Altcode: The space-based SIRA (Solar Imaging Radio Array) will provide a powerful capability to track high energy particles from solar flare and CME sites through interplanetary/heliospheric space all the way to Earth. Together with two other overlapping planned radio interferometers, i.e., FASR (Frequency-Agile Solar Radiotelescope) and LOFAR (Low-Frequency Array) the entire plasma frequency range from 30 GHz all the way down to the plasma frequency cutoff of 30 kHz at 1 AU will be covered. These instruments will track the magnetic trajectory of high energy particles, beam-driven radio emission, and localize the acceleration sites in the corona or interplanetary shocks. We simulate some CME and type III events, as they will be mapped with these instruments, using realistic scattering functions of radio waves on coronal and heliospheric density inhomogeneities. Title: Coronal Mass Ejections, Flares and Type II Radio Bursts Authors: Rosas, A. M.; Gopalswamy, N.; Kaiser, M. L.; Yahsiro, S.; Nunes, S. Bibcode: 2003AGUFMSH42C0559R Altcode: An investigation of 210 interplanetary type II radio bursts and the associated white-light coronal mass ejections (CMEs) is presented. The radio bursts were detected by the Wind/WAVES experiment in the 1-14 MHz (decameter-hectometric, DH) range, while the CMEs were observed by the Solar and Heliospheric Observatory (SOHO). The study period, 1997-2002, encompasses the current solar cycle (23) between minimum and beyond maximum. We could only find 108 solar flares associated with DH type IIs. We obtained the difference onset times (solar flare - DH type II) and found that DH type IIs start at the same time as the flares. On the other hand the difference between CME and DH type II onset times is indicates that the type II bursts occur well after the CME onset. The present study suggests that the CMEs are more likely to be the source of the shocks responsible for the type II bursts. We extend the study to metric type II bursts and obtained similar results. Title: Coronal Mass Ejections and Solar Polarity Reversal Authors: Gopalswamy, N.; Lara, A.; Yashiro, S.; Howard, R. A. Bibcode: 2003ApJ...598L..63G Altcode: We report on a close relationship between the solar polarity reversal and the cessation of high-latitude coronal mass ejections (CMEs). This result holds good for individual poles of the Sun for cycles 21 and 23, for which CME data are available. The high-latitude CMEs provide a natural explanation for the disappearance of the polar crown filaments (PCFs) that rush the poles. The PCFs, which are closed field structures, need to be removed before the poles could acquire open field structure of the opposite polarity. Inclusion of CMEs along with the photospheric and subphotospheric processes completes the full set of phenomena to be explained by any solar dynamo theory. Title: Dynamics of coronal mass ejections in the near-Sun interplanetary space Authors: Vrsnak, B.; Ruzdajak, D.; Sudar, D.; Gopalswamy, N. Bibcode: 2003ESASP.535..517V Altcode: 2003iscs.symp..517V Kinematics of more than 5000 coronal mass ejections (CMEs) measured between 2 and 30 solar radii is investigated. A distinct relationship between the late-phase acceleration of CMEs and their velocities is found. It can be represented in the form a[m s-2] = -0.02(v-400)[km s-1]. The relationship is interpreted in terms of coupling of the CME motion and the solar wind, i.e., by the action of the aerodynamic drag. The results indicate that in the considered radial distance range the Lorentz force acceleration becomes weak, in the majority of the events spanning between 0 and 10 m s-2. Implications for the interplanetary motion of CMEs are discussed, emphasising the prediction of the 1 a.u. arrival time. Title: Variations of magnetic clouds and CMEs with solar activity cycle Authors: Wu, Chin-Chun; Lepping, R. P.; Gopalswamy, N. Bibcode: 2003ESASP.535..429W Altcode: 2003iscs.symp..429W Sixty-eight magnetic clouds were observed by Wind during November 1994 - May 2002. The average occurrence rate is ~9 magnetic clouds per year for the overall period (68 events/7.6 years). It is found that some of the frequency of occurrence anomalies were during the early part of solar cycle 23: (I) only 4 clouds were observed in 1999, (II) an unusually large number of clouds (16 events) were observed in 1997 in which the Sun was starting to leave solar minimum. During the period of 1996-2001, the results also show: (1) the occurrence frequency of magnetic cloud appears to be related neither to the occurrence of solar coronal mass ejections (CMEs) as observed by SOHO nor to solar activity cycle, (2) the intensity of geomagnetic storms related to magnetic clouds is affected by both solar activity and the occurrence frequency of CMEs, and (3) ~91% of magnetic clouds induced geomagnetic storms. Title: Effect of CME Interactions on the Production of Solar Energetic Particles Authors: Gopalswamy, N.; Yashiro, S.; Michalek, G.; Kaiser, M. L.; Howard, R. A.; Leske, R.; von Rosenvinge, T.; Reames, D. V. Bibcode: 2003AIPC..679..608G Altcode: We analyzed a set of 52 fast and wide, frontside western hemispheric (FWFW) CMEs in conjunction with solar energetic particle (SEP) and radio burst data and found that 42 of these CMEs were associated with SEPs. All but two of the 42 SEP-associated FWFW CMEs (95%) were interacting with preceding CMEs or dense streamers. Most of the remaining 10 SEP-poor FWFW CMEs had either insignificant or no interaction with preceding CMEs or streamers, and were ejected into a tenuous corona. There is also a close association between type II radio bursts in the near-Sun interplanetary medium and SEP-associated FWFW CMEs suggesting that electron accelerators are also good proton accelerators. Title: A Numerical Study on the Evolution of CMEs and Shocks in the Interplanetary Medium Authors: González-Esparza, J. A.; Lara, A.; Santillán, A.; Gopalswamy, N. Bibcode: 2003AIPC..679..206G Altcode: We studied the evolution in the solar wind of four CMEs detected by SOHO-LASCO which were associated with ICMEs and interplanetary (IP) shocks detected afterward by Wind at 1 AU. The study is based on a 1-D hydrodynamic single fluid model using the ZEUS code. These simple numerical simulations of CME like pulses illuminate several aspects of the heliocentric evolution of the ICME front and its associated IP shock and we were able to reproduce some characteristics of the IP shocks and ICMEs inferred from the two-point measurements from spacecraft. The simulation shows that ICMEs and IP shocks follow different evolutions in the interplanetary medium both having phases of about constant speed propagation followed by an exponential deceleration with heliocentric distance. IP shocks always propagate faster than their associated ICME drivers and the former began to decelerate well before the IP shock. The results indicate that, in general, although an IP shock is driven by its ICME in the inner heliosphere in most of the cases this is not true any more when they approach to 1 AU. Title: Coronal mass ejection activity during solar cycle 23 Authors: Gopalswamy, Nat; Lara, Alejandro; Yashiro, Seiji; Nunes, Steven; Howard, Russell A. Bibcode: 2003ESASP.535..403G Altcode: 2003iscs.symp..403G We studied the solar cycle varition of various properties of coronal mass ejections (CMEs), such as daily CME rate, mean and median speeds, and the latitude of solar sources for cycle 23 (1996-2002). We find that (1) there is an order of magnitude increase in CME rate from the solar minimum (0.5/day) to maximum (6/day), (2) the maximum rate is significantly higher than previous estimates, (3) the mean and median speeds of CMEs also increase from minimum to maximum by a factor of 2, (4) the number of metric type II bursts (summed over CR) tracks CME rate, but the CME speed seems to be only of secondary importance, (5) for type II bursts originating farther from the Sun the CME speed is important, (6) the latitude distribution of CMEs separate the prominence-associated (high-latitude) and active-region associated CMEs, and (7) the rate of high-latitude CMEs shows north-south asymmetry and the cessation eruptions in the north and south roughly mark the polarity reversals. We compared the rates of the fast-and-wide CMEs, major solar flares, interplanetary (IP) shocks, long-wavelength type II bursts and large SEP events. This comparison revealed that the number of major flares is generally too large compared to all the other numbers. In other words, fast-and-wide CMEs, long-wavelength type II bursts, large SEP events, and IP shocks have a close physical relationship. Title: Coronal and Interplanetary Environment of Large Solar Energetic Particle Events Authors: Gopalswamy, Nat; Yashiro, S.; Stenborg, G.; Howard, R. A. Bibcode: 2003ICRC....6.3549G Altcode: 2003ICRC...28.3549G We studied the properties of coronal mass ejections (CMEs) associated with large solar energetic particle (SEP) events during 1997-2002 and compared them with those of preceding CMEs from the same source region. The primary findings of this study are (1) High-intensity (> 50 protons cm-2 s-1 sr-1 ) events are more likely to be preceded by other wide CMEs. (2) The preceding CMEs are faster and wider than average CMEs. (3) The primary CMEs often propagate through the near-Sun interplanetary medium severely disturb ed and distorted by the preceding CMEs. Title: Large solar energetic particle events of cycle 23: A global view Authors: Gopalswamy, N.; Yashiro, S.; Lara, A.; Kaiser, M. L.; Thompson, B. J.; Gallagher, P. T.; Howard, R. A. Bibcode: 2003GeoRL..30.8015G Altcode: 2003GeoRL..30lSEP3G We report on a study of all the large solar energetic particle (SEP) events that occurred during the minimum to maximum interval of solar cycle 23. The main results are: 1. The occurrence rate of the SEP events, long-wavelength type II bursts and the fast and wide frontside western hemispheric CMEs is quite similar, consistent with the scenario that CME-driven shocks accelerate both protons and electrons; major flares have a much higher rate. 2. The SEP intensity is better correlated with the CME speed than with the X-ray flare class. 3. CMEs associated with high-intensity SEPs are about 4 times more likely to be preceded by wide CMEs from the same solar source region, suggesting the importance of the preconditioning of the eruption region. We use a specific event to demonstrate that preceding eruption from a nearby source can significantly affect the properties of SEPs and type II radio bursts. Title: Solar and geospace connections of energetic particle events Authors: Gopalswamy, N. Bibcode: 2003GeoRL..30.8013G Altcode: 2003GeoRL..30lSEP1G A Coordinated Data Analysis Workshop (CDAW) was conducted recently to study the solar and geospace connections of large solar energetic particle (SEP) events of solar cycle 23 (up to the end of 2001). This paper summarizes the properties these events, the scientific issues discussed, and some of the results obtained during the workshop. Title: A statistical study of CMEs associated with metric type II bursts Authors: Lara, A.; Gopalswamy, N.; Nunes, S.; Muñoz, G.; Yashiro, S. Bibcode: 2003GeoRL..30.8016L Altcode: 2003GeoRL..30lSEP4L We present a statistical study of the characteristics of CMEs which show temporal association with type II bursts in the metric domain but not in the decameter/hectometric (DH) domain. This study is based on a set of 80 metric (m) type II bursts associated with surface events in the solar western hemisphere. It was found that in general, the distribution of the widths and speeds of the CMEs associated with metric (but not DH) type II bursts are shifted towards higher values compared to those of all CMEs observed by LASCO in the 1996-2001 period. We also found that these distributions have lower values than the same distributions of the CMEs associated with DH type II bursts. In terms of energy, this means that the CMEs associated only with metric type II bursts are more energetic (wider and faster) than regular CMEs but less energetic than the CMEs associated with DH type II bursts. Title: Solar Imaging Radio Array (SIRA): Radio Aperture Synthesis from Space Authors: MacDowall, R.; Kaiser, M.; Gopalswamy, N. Bibcode: 2003SPD....34.2022M Altcode: 2003BAAS...35Q.848M SIRA, the Solar Imaging Radio Array, will be a constellation of about 16 microsats designed to image radio sources in the solar corona and heliosphere using aperture synthesis techniques. These images will permit the mapping and tracking of CME-driven shocks (type II radio bursts) and solar flare electrons (type III radio bursts) as a function of time from near the sun to 1 AU. Two dimensional imaging of the CME-driven shock front is important for determination of space weather effects of CMEs, whereas imaging of the ubiquitous type III bursts will permit the derivation of density maps in the outer corona and solar wind. This will be the first mission to image the heliosphere (and the celestial sphere) with good angular resolution at frequencies below the ionospheric cutoff ( 10 MHz). The radio images are intrinsically complementary to white-light coronograph data, such as those of SDO, and can play a valuable role in the NASA Living with a Star program. Title: Analysis of Onset Times between CMEs and Associated DH Type II Bursts Authors: Rosas, A. M.; Gopalswamy, N.; Yashiro, S.; Kaiser, M. L.; Howard, R. L. Bibcode: 2003SPD....34.0506R Altcode: 2003BAAS...35..815R An investigation of 210 interplanetary type II radio bursts and the associated white-light coronal mass ejections (CMEs) is presented.The radio bursts were detected by the Wind/WAVES experiment in the 1-14 MHz (decameter-hectometric,DH) range, while the CMEs were observed by the Solar and Heliospheric Observatory (SOHO).The study period, 1997-2002, encompasses the current solar cycle (23) between minimum and beyond maximum. We find that 91% of CMEs have speeds greater than 450 km/s and 94% have angular widths greater than 60 degrees obtained from SOHO/LASCO C2 and C3 CME measurements.We made a linear and quadratic fit using CME height time measurements to extrapolate CME onset times to 2 and 1 solar radius. We find that the quadratic onset times (QOTs) illustrates less scatter in the difference times (CME onset time - DH onset time) than the linear onset times (LOTs). Both the QOT and LOT for 1 solar radius shows that ∼ 80% DH type II bursts occurred within 1 hour of CME onset time and for 2 solar radius extrapolation shows ∼ 87%. Correlation coefficients were found to be very weak between difference times and CME longitude, speed, angular width, and DH type II starting frequency. We are continuing to investigate the outlier (DH type II bursts occurring more than 2 hours after CMEs) events.(1) The onset times and starting frequency of DH type IIs with respect to CME onset times provides insight into the coronal density distribution.(2) The relationship between CME onset time and the occurrence of the DH type II will be discussed in terms of the radial distribution of the Alfven speed near the Sun.

This work is supported by NASA living with a Star and NSF/SHINE (ATM 0204588) and AFOSR Programs. Title: Towards Automatic Tracking of Coronal Mass Ejections Authors: Stenborg, G. A.; Cobelli, P. J.; Gopalswamy, N.; Yashiro, S. Bibcode: 2003SPD....34.0306S Altcode: 2003BAAS...35..809S Tracing identifiable features of dynamical phenomena such as coronal mass ejections (CMEs), as they propagate through the corona, is a real challenge. In particular, different features from a single event usually display different velocities. Moreover, the lack of sharpness of the structures involved on top of the subjective nature of the measuring process makes it difficult to track the event unambiguously. To overcome the lack of sharpness, we developed a multiresolution image processing technique applicable to any 2D data set to enhance both boundaries and internal details of originally faint and diffuse structures. The method implemented employs a multi-level decomposition scheme (splitting algorithm of a wavelet packet on non-orthogonal wavelets) via the `a trous' wavelet transform, local noise reduction and interactive weighted recomposition. This approach represents a major advance towards unambiguous image interpretation and provides a means for the quantification of stationary and dynamic coronal structures required for conducting morphological studies. Moreover, it proved to be a necessary step in the development of a non-subjective technique for automatic tracking of CMEs. Examples based on LASCO-C1, -C2, -C3, and EIT data sets are shown. Different reconstruction strategies are also discussed.

This work is supported by NASA living with a Star and NSF/SHINE (ATM 0204588) Programs. Title: Long Lasting Type II Radio Bursts Authors: Nunes, S.; Gopalswamy, N.; Yashiro, S.; Howard, R. Bibcode: 2003SPD....34.0607N Altcode: 2003BAAS...35..818N Plasma frequencies starting in the decameter-hectametric (DH) regime and continuing into the kilometric (km) regime correspond to approximately to the entire Sun-Earth distance. Accordingly, we consider Type II radio bursts observed by the WAVES experiment on the WIND spacecraft that are observed from the DH to the km regimes and their association with white-light coronal mass ejections (CMEs). We find that approximately 80% of these events are associated with metric Type II bursts observed on Earth. We also consider correlations of DH/km Type II's with sunspot numbers and other cyclical measures of solar activity, and properties of CMEs associated with DH/km Type II bursts.

This work is supported by the Air Force Office of Scientific Research, the National Science Foundation's SHINE Program, and NASA. Title: Why was there no Solar Energetic Particle Event Associated with the Gamma-ray-line Flare of 2002 July 23? Authors: Gopalswamy, N.; Dennis, B. R.; Kaiser, M. L.; Krucker, S.; Lin, R. P.; Vourlidas, A. Bibcode: 2003SPD....34.2202G Altcode: 2003BAAS...35..850G We investigated the coronal and interplanetary (IP) events associated with two X-class flares on 2002 July 20 and 23. Both flares were associated with ultra-fast (>2000 km s-1) coronal mass ejections (CMEs) and IP shocks. We use white-light, EUV, hard X-ray and radio observations to trace the origin of the CMEs to active region 0039 located close to the east limb. The July 20 flare was partly occulted by the east limb, yet it resulted in a major solar energetic particle event with intensity ∼ 20 pfu in the >10 MeV channel (1 pfu = 1 particle per (cm2 s sr MeV)). The July 23 event was the first gamma-ray-line flare detected by RHESSI, but it did not show any enhancement in SEPs above the elevated background from the July 20 event. We identified two distinguishing factors between the July 2 and July 23 CMEs: (1) The July 20 CME had a higher kinetic energy, and (2) The July 20 CME was interacting with another fast CME (1350 km s-1) that preceded by less than an hour from the same region; there were also two other CMEs on July 19 from the same region. Thus the coronal and IP environment of the July 20 event was highly disturbed due to preceding CMEs (as compared to the July 23 event). We suggest that the different coronal/IP environments may be responsible for the lack of SEP event associated with the July 23 event. Title: Influence of CME interaction on the Propagation of Interplanetary Shocks Authors: Manoharan, P. K.; Gopalswamy, N.; Yashiro, S.; Howard, R. A. Bibcode: 2003SPD....34.0610M Altcode: 2003BAAS...35Q.819M We studied a large number of coronal mass ejections (CMEs) and their associated interplanetary (IP) shocks for the period 1996-2002, using white-light images from the Large Angle and Spectrometric Coronagraph (LASCO) on the Solar Heliospheric Observatory (SOHO) spacecraft and solar wind measurements from the Mass Time-of-Flight spectrometer (MTOF on SOHO) and Solar Wind Experiment (SWE on the WIND satellite) instrument. The 1-AU arrival times of the CME and its shock are obtained from the initial CME speed. We studied the influence of preceding CMEs on the propagation of the IP shocks. We note that the propagation characteristics of some of the fast CMEs and their shocks are modified by the interaction with the preceding CMEs. We also find that the arrival times of IP shocks show deviation from that of non-interacting cases. We use an empirical model to explain the change in the travel time of shocks. We also discuss other consequences in the solar wind caused by the CME interactions.

This work is supported by NASA living with a Star, NSF/SHINE (ATM 0204588), and AFOSR Programs. Title: Recent advances in long-wavelength radio physics of the Sun Authors: Gopalswamy, N. Bibcode: 2003EAEJA.....4473G Altcode: Low frequency imaging of the solar radio bursts provides the best means of studying the solar disturbances such as coronal mass ejections and shocks at the moment of their departure from the Sun. The radio bursts also provide information on the physical properties of the medium such as the density, temperature and magnetic field. Direct imaging of the quiet Sun also provides information on the outer corona. I review some of the results obtained from recent long-wavelength observations and summarize the relevance of these results to LOFAR. In addition, I discuss the significance of LOFAR to future low frequency imaging observations from space such as the Solar Imaging Radio Array (SIRA). Title: The Solar Radio Imaging Array (SIRA) microsatellite mission Authors: MacDowall, R.; Gopalswamy, N.; Kaiser, M. Bibcode: 2003EAEJA....12917M Altcode: SIRA, the Solar Imaging Radio Array, will be a constellation of about 16 microsats designed to image radio sources in the solar corona and heliosphere using aperture synthesis techniques. These images will permit the mapping and tracking of CME-driven shocks (type II radio bursts) and solar flare electrons (type III radio bursts) as a function of time from near the sun to 1 AU. Two dimensional imaging of the CME-driven shock front is important for determination of space weather effects of CMEs, whereas imaging of the ubiquitous type III bursts will permit the derivation of density maps in the outer corona and solar wind. This will be the first mission to image the heliosphere (and the celestial sphere) with good angular resolution at frequencies below the ionospheric cutoff (~10 MHz). In this presentation, we highlight the ways in which SIRA is complementary to LOFAR and FASR. Title: Coronal mass ejections as a source of space Weather Authors: Gopalswamy, N. Bibcode: 2003EAEJA.....4456G Altcode: White-light and radio observations of solar eruptions obtained by SOHO and Wind, respectively have helped us understand the space weather aspect of coronal mass ejections (CMEs). From space weather point of CMEs are important in two respects: (1) CMEs departing from close to the disk center are important for producing geomagnetic storms, so it is important to understand how they evolve and when they arrive at the earth, (2) Fast and wide CMEs drive shocks and hence accelerate solar energetic particles detected in situ or via the long wavelength type II radio bursts. The SEP-associated CMEs can depart from the Sun from any longitude, but western events are more geoeffective. Recent results show that only 1-2 percent of all CMEs are important for space weather purposes. In this paper, we review the recent results obtained on these two populations of CMEs in comparison with the general population. Title: Low frequency radio astronomy from space: the Solar Radio Imaging Array Authors: MacDowall, R.; Gopalswamy, N.; Kaiser, M. Bibcode: 2003EAEJA....12863M Altcode: SIRA, the Solar Imaging Radio Array, will be a constellation of about 16 microsats designed to image radio sources in the solar corona and heliosphere using aperture synthesis techniques. Using crossed dipoles and high dynamic range radio receivers, SIRA will observe solar radio emissions in the frequency range from ~15 MHz to ~30 kHz. These frequencies correspond to distances of 2 R_sun to 1 AU. Frequency spacing and time resolution will be optimized for solar burst analysis. The quasi-spherical constellation (diameter 25-50 km) will provide appropriate baselines for angular resolution of ~10 arcsec at 15 MHz . Several orbit possibilities are currently under consideration. Rapid data processing for space weather prediction of CME arrival at 1 AU is a major goal. It is anticipated that this mission will be proposed for the next NASA MIDEX opportunity. Title: Prominence Eruptions and Coronal Mass Ejection: A Statistical Study Using Microwave Observations Authors: Gopalswamy, N.; Shimojo, M.; Lu, W.; Yashiro, S.; Shibasaki, K.; Howard, R. A. Bibcode: 2003ApJ...586..562G Altcode: We present the results of a statistical study of a large number of solar prominence events (PEs) observed by the Nobeyama Radioheliograph. We studied the association rate, relative timing, and spatial correspondence between PEs and coronal mass ejections (CMEs). We classified the PEs as radial and transverse, depending on whether the prominence moved predominantly in the radial or horizontal direction. The radial events were faster and attained a larger height above the solar surface than the transverse events. Out of the 186 events studied, 152 (82%) were radial events, while only 34 (18%) were transverse events. Comparison with white-light CME data revealed that 134 (72%) PEs were clearly associated with CMEs. We compare our results with those of other studies involving PEs and white-light CMEs in order to address the controversy in the rate of association between CMEs and prominence eruptions. We also studied the temporal and spatial relationship between prominence and CME events. The CMEs and PEs seem to start roughly at the same time. There was no solar cycle dependence of the temporal relationship. The spatial relationship was, however, solar cycle dependent. During the solar minimum, the central position angle of the CMEs had a tendency to be offset closer to the equator as compared to that of the PE, while no such effect was seen during solar maximum. Title: A New Method for Estimating Widths, Velocities, and Source Location of Halo Coronal Mass Ejections Authors: Michałek, G.; Gopalswamy, N.; Yashiro, S. Bibcode: 2003ApJ...584..472M Altcode: 2007arXiv0710.4524M It is well known that coronagraphic observations of halo coronal mass ejections (CMEs) are subject to projection effects. Viewing in the plane of the sky does not allow us to determine the crucial parameters that define the geoeffectiveness of CMEs, such as the space speed, width, or source location. Assuming that halo CMEs have constant velocities, are symmetric, and propagate with constant angular widths, at least in their early phase, we have developed a technique that allows us to obtain the required parameters. This technique requires measurements of sky-plane speeds and the moments of the first appearance of the halo CMEs above opposite limbs. We apply this technique to obtain the parameters of all the halo CMEs observed by the Solar and Heliospheric Observatory (SOHO) mission's Large Angle and Spectrometric Coronagraph experiment until the end of 2000. We also present a statistical summary of these derived parameters of the halo CMEs. Title: Coronal mass ejection interaction and particle acceleration during the 2001 April 14 15 events Authors: Gopalswamy, N.; Yashiro, S.; Kaiser, M. L.; Howard, R. A. Bibcode: 2003AdSpR..32.2613G Altcode: Two successive solar energetic particle (SEP) events associated with fast and wide coronal mass ejections (CMEs) on 2001 April 14 and 15 are compared. The weak SEP event of April 14 associated with an 830 km/s CME and an M1.0 flare was the largest impulsive event of cycle 23. The April 15 event, the largest ground level event of cycle 23, was three orders of magnitude more intense than the April 14 th event and was associated with a faster CME (1200 km/s) and an X14.4 flare. We compiled and compared all the activities (flares, CMEs, interplanetary conditions and radio bursts) associated with the two SEP events to understand the intensity difference between them. Different coronal and interplanetary environments of the two events (presence of preceding CME and seed particles ahead of the April 15 event) may explain the intensity difference. Title: Properties of narrow coronal mass ejections observed with LASCO Authors: Yashiro, S.; Gopalswamy, N.; Michalek, G.; Howard, R. A. Bibcode: 2003AdSpR..32.2631Y Altcode: We report the statistical properties of narrow coronal mass ejections (CMEs, angular width < 20°) withparticular emphasis on comparison with normal CMEs. We investigated 806 narrow CMEs from an online LASCO/CME catalog and found that (1) the fraction of narrow CMEs increases from 12% to 22% towards solar maximum, (2) during the solar maximum, the narrow CMEs are generally faster than normal ones, (3) the maximum speed of narrow CMEs (1141 km s -1) is much smaller than that of the normal CMEs (2604 km s -1). These results imply that narrow CMEs do not form a subset of normal CMEs and have a different acceleration mechanism from normal CMEs. Title: A numerical study on the acceleration and transit time of coronal mass ejections in the interplanetary medium Authors: GonzáLez-Esparza, J. AméRico; Lara, Alejandro; PéRez-Tijerina, Eduardo; SantilláN, Alfredo; Gopalswamy, Nat Bibcode: 2003JGRA..108.1039G Altcode: Recently, an empirical model of the acceleration/deceleration of coronal mass ejections (CMEs) as they propagate through the solar wind was developed using near-Sun (coronagraphic) and near-Earth (in situ) observations [, 2000, 2001a]. This model states and quantifies the fact that slow CMEs are accelerated and fast CMEs are decelerated toward the ambient solar wind speed (∼400 km/s). In this work we study the propagation of CMEs from near the Sun (0.083 AU) to 1 AU using numerical simulations and compare the results with those of the empirical model. This is a parametric study of CME-like disturbances in the solar wind using a one-dimensional, hydrodynamic single-fluid model. Simulated CMEs are propagated through a variable ambient solar wind and their 1 AU characteristics are derived to compare with observations and the empirical CME arrival model. We were able to reproduce the general characteristics of the prediction model and to obtain reasonable agreement with two-point measurements from spacecraft. Our results also show that the dynamical evolution of fast CMEs has three phases: (1) an abrupt and strong deceleration just after their injection against the ambient wind, which ceases before 0.1 AU, followed by (2) a constant speed propagation until about 0.45 AU, and, finally, (3) a gradual and small deceleration that continues beyond 1 AU. The results show that it is somewhat difficult to predict the arrival time of slow CMEs (Vcme < 400 km/s) probably because the travel time depends not only on the CME initial speed but also on the characteristics of the ambient solar wind and CMEs. However, the simulations show that the arrival time of very fast CMEs (Vcme > 1000 km/s) has a smaller dispersion so the prediction can be more accurate. Title: Coronal mass ejections: Initiation and detection Authors: Gopalswamy, N. Bibcode: 2003AdSpR..31..869G Altcode: Coronal mass ejections (CMEs) are large-scale magnetic structures expelled from the Sun due to MHD processes involving interaction between plasma and magnetic field in closed field regions. I provide a summary of the observational signatures and current models on CME initiation. I also discuss the multiwavelength signatures of CMEs, which have helped us obtain a global picture of the CME phenomenon in the inner heliosphere. Title: Arrival time of coronal mass ejections Authors: Michalek, G.; Gopalswamy, N.; Chane, E. Bibcode: 2002ESASP.506..177M Altcode: 2002svco.conf..177M; 2002ESPM...10..177M Halo coronal mass ejections (CMEs), originating near the disk center, cause the severest geomagnetic storms. Thus, estimation of the arrival of magnetic clouds in the Earth vicinity is very important in space weather investigation. We describe an empirical model to predict the 1 AU arrival time of CMEs. This model is based on the effective acceleration described by Gopalswamy et. al (2000). It was improved by considering halo CMEs for which the space velocities are determined. This allowed us to receive the more accurate estimations. The new model reduces the average prediction error from ≍10 to ≍5 hours. Title: Solar, Interplanetary, and Geospace Disturbances Associated with the April 2002 Coronal Mass Ejections Authors: Gopalswamy, N.; Yashiro, S.; St. Cyr, O.; Lawrence, G.; Kaiser, M. L.; Gurman, J. B.; Howard, R. A. Bibcode: 2002AGUFMSA12A..02G Altcode: The Solar and Heliospheric Observatory (SOHO) detected a large number of coronal mass ejections (CMEs) during the April 14-24, 2002 period. We describe the properties of these CMEs and contrast them with those of the general population of CMEs. We explore the connection of these CMEs to the interplanetary shocks and the solar energetic particles events using Wind and GOES data, respectively. We assess the extent of preconditioning of the corona by repeated flaring and mass ejections from the active regions involved. Based on the arrival times of the interplanetary CMEs and shocks, we discuss the evolution of these disturbances as they propagated between the Sun and Earth. We compare the extended nature of the main phase of the complex geomagnetic storm to other other similar extended storm periods Title: A Statistical Study of Two Classes of Coronal Mass Ejections Authors: Moon, Y. -J.; Choe, G. S.; Wang, Haimin; Park, Y. D.; Gopalswamy, N.; Yang, Guo; Yashiro, S. Bibcode: 2002ApJ...581..694M Altcode: A comprehensive statistical study is performed to address the question of whether two classes of coronal mass ejections (CMEs) exist. A total of 3217 CME events observed by SOHO/LASCO in 1996-2000 have been analyzed. We have examined the distributions of CMEs according to speed and acceleration, respectively, and investigated the correlation between speed and acceleration of CMEs. This statistical analysis is conducted for two subsets containing those CMEs that show a temporal and spatial association either with GOES X-ray solar flares or with eruptive filaments. We have found that CMEs associated with flares have a higher median speed than those associated with eruptive filaments and that the median speed of CMEs associated with strong flares is higher than that of weak-flare-associated CMEs. The distribution of CME acceleration shows a conspicuous peak near zero, not only for the whole data set, but also for the two subsets associated either with solar flares or with eruptive filaments. However, we have confirmed that the CMEs associated with major flares tend to be more decelerated than the CMEs related to eruptive filaments. The fraction of flare-associated CMEs has a tendency to increase with the CME speed, whereas the fraction of eruptive-filament-associated CMEs tends to decrease with the CME speed. This result supports the concept of two CME classes. We have found a possibility of two components in the CME speed distribution for both the CME data associated with flares larger than M1 class and the CME data related with limb flares. Our results suggest that the apparent single-peak distribution of CME speed can be attributed to the projection effect and possibly to abundance of small flares too. We also note that there is a possible correlation between the speed of CMEs and the time-integrated X-ray flux of the CME-associated limb flares. Title: The International Heliophysical Year (IHY) Authors: Davila, J. M.; Harrison, R.; Poland, A.; Thompson, B.; Gopalswamy, N. Bibcode: 2002AGUFMSH21A0518D Altcode: In 1957 a program of international research, inspired by the International Polar Years of 1882-83 and 1932-33, was organized as the International Geophysical Year (IGY) to study global phenomena of the Earth and geospace. The IGY involved about 60,000 scientists from 66 nations, working at thousands of stations, from pole to pole to obtain simultaneous, global observations on Earth and in space. There had never been anything like it before. The fiftieth anniversary of the International Geophysical Year will occur in 2007. We propose to organize an international program of scientific collaboration for this time period called the International Heliophysical Year (IHY). Like it predecessors, the IHY will focus on fundamental global questions of Earth science. Title: MHD modelling of CME and CME interactions in a bi-modal solar wind: a preliminary analysis of the 20 January 2001 two CMEs interaction event Authors: Wu, S. T.; Wang, A. H.; Gopalswamy, N. Bibcode: 2002ESASP.505..227W Altcode: 2002solm.conf..227W; 2002IAUCo.188..227W Observations from SOHO and WIND reveal that coronal mass ejections (CMEs) cannibalize and deflect one another. CMEs also are accelerated and decelerated due to their interactions with the solar wind. These CME interactions with CME and with the solar wind result in producing significant differences in solar wind signatures as compared to isolated CME events. To understand these dynamical evolutionary processes, we have constructed a magnetohydrodynamic (MHD) simulation model based on a flux-rope and streamer model including bi-modal solar wind to investigate the physical processes of CME interactions. Specifically, the January 20, 2001 CME-CME interaction event recorded by SOHO/LASCO/C2/C3 are used to guide this simulation study. The results showed that CME cannibalism is caused by magnetic reconnection. The CME's acceleration and deceleration are caused by solar wind and the CME's deflection of one another. Title: Measurements of Three-dimensional Coronal Magnetic Fields from Coordinated Extreme-Ultraviolet and Radio Observations of a Solar Active Region Sunspot Authors: Brosius, Jeffrey W.; Landi, Enrico; Cook, John W.; Newmark, Jeffrey S.; Gopalswamy, N.; Lara, Alejandro Bibcode: 2002ApJ...574..453B Altcode: We observed NOAA Active Region 8108 around 1940 UT on 1997 November 18 with the Very Large Array and with three instruments aboard the NASA/ESA Solar and Heliospheric Observatory satellite, including the Coronal Diagnostic Spectrometer, the EUV Imaging Telescope, and the Michelson Doppler Imager. We used the right-hand and left-hand circularly polarized components of the radio observing frequencies, along with the coordinated EUV observations, to derive the three-dimensional coronal magnetic field above the region's sunspot and its immediate surroundings. This was done by placing the largest possible harmonic (which corresponds to the smallest possible magnetic field strength) for each component of each radio frequency into appropriate atmospheric temperature intervals such that the calculated radio brightness temperatures at each spatial location match the corresponding observed values. The temperature dependence of the derived coronal magnetic field, B(x,y,T), is insensitive to uncertainties on the observed parameters and yields field strengths in excess of 580 G at 2×106 K and in excess of 1500 G at 1×106 K. The height dependence of the derived coronal magnetic field, B(x,y,h), varies significantly with our choice of magnetic scale height LB. Based on LB=3.8×109 cm derived from the relative displacements of the observed radio centroids, we find magnetic field strengths in excess of 1500 G at heights of 15,000 km and as great as 1000 G at 25,000 km. By observing a given target region on several successive days, we would obtain observations at a variety of projection angles, thus enabling a better determination of LB and, ultimately, B(x,y,h). We compare coronal magnetic fields derived from our method with those derived from a potential extrapolation and find that the magnitudes of the potential field strengths are factors of 2 or more smaller than those derived from our method. This indicates that the sunspot field is not potential and that currents must be present in the corona. Alfvén speeds between 25,000 and 57,000 km s-1 are derived for the 1×106 K plasma at the centroids of the radio observing frequencies. Filling factors between 0.003 and 0.1 are derived for the 1×106 K plasma at the centroids of the radio observing frequencies. Title: Estimation of projection effect of CMEs from the onset time of shock-associated type III radio burst Authors: Michalek, G.; Gopalswamy, N.; Reiner, M.; Yashiro, S.; Kaiser, M. L.; Howard, R. A. Bibcode: 2002ESASP.508..449M Altcode: 2002soho...11..449M We present a new possibility to estimate the projection effects on CME measurements. We assume that (1) high energy electrons are produced at the shock front ahead of the CME, and (2) the radio burst starts when the shock reaches open field lines (~3 Rsolar). In other words, the onset time of the radio burst corresponds to the time when the CME leading edge reaches 3 Rsolar. It is well known that coronagraphic observations of halo CMEs are subject to projection effects. Fortunately, the Wind/WAVES observations of type III radio bursts associated with shock waves are free from projection effects. The difference between the onset times of CMEs and radio bursts should be strongly correlated with the position of CMEs on the Sun. We found this correlation and showed that it strongly depends on a period of solar activity and source location on the Sun. Particular linear fits to the considered scattered plots can be used to further determination of source location and projection of CMEs on the plane of sky. Title: A new possibility to estimate the width, source location and velocity of halo CMEs Authors: Michalek, G.; Gopalswamy, N.; Yashiro, S. Bibcode: 2002ESASP.508..453M Altcode: 2002soho...11..453M It is well known that the coronagraphic observations of halo CMEs are subject to projection effects. Viewing in the plane of the sky does not allow us to determine the crucial parameters defining geoeffectivness of CMEs, such as the velocity, width or source location. We assume that halo CMEs at the beginning phase of propagation have constant velocities, are symmetric and propagate with constant angular widths. Using these approximations and determining projected velocities and difference between times when CME appears on the opposite sides of the occultation disk we are able to get necessary parameters. We present consideration for the whole halo CMEs from SOHO/LASCO catalog until the end of 2000. Title: Interacting Coronal Mass Ejections and Solar Energetic Particles Authors: Gopalswamy, N.; Yashiro, S.; Michałek, G.; Kaiser, M. L.; Howard, R. A.; Reames, D. V.; Leske, R.; von Rosenvinge, T. Bibcode: 2002ApJ...572L.103G Altcode: We studied the association between solar energetic particle (SEP) events and coronal mass ejections (CMEs) and found that CME interaction is an important aspect of SEP production. Each SEP event was associated with a primary CME that is faster and wider than average CMEs and originated from west of E45°. For most of the SEP events, the primary CME overtakes one or more slower CMEs within a heliocentric distance of ~20 Rsolar. In an inverse study, we found that for all the fast (speed greater than 900 km s-1) and wide (width greater than 60°) western hemispheric frontside CMEs during the study period, the SEP-associated CMEs were ~4 times more likely to be preceded by CME interaction than the SEP-poor CMEs; i.e., CME interaction is a good discriminator between SEP-poor and SEP-associated CMEs. We infer that the efficiency of the CME-driven shocks is enhanced as they propagate through the preceding CMEs and that they accelerate SEPs from the material of the preceding CMEs rather than from the quiet solar wind. We also found a high degree of association between major SEP events and interplanetary type II radio bursts, suggesting that proton accelerators are also good electron accelerators. Title: Prominence Eruptions and CMEs: A Statistical Study Authors: Gopalswamy, N.; Shimojo, M.; Yashiro, S.; Shibasaki, K. Bibcode: 2002AAS...200.3705G Altcode: 2002BAAS...34..695G Prominence eruptions are thought to be an integral part of coronal mass ejections. However, recent statistical studies obtained conflicting conclusions regarding this relationship: a nearly one-to-one correspondence to a poor association. We revisited this problem using all the eruptive prominences detected automatically from the daily images obtained by the Nobeyama Radioheliograph. The images were made with a 10 min cadence so only slower eruptions could be detected from these images. During January 1996 to December 2001, there were 226 prominence eruptions detected this way and 182 of them had white light observations from the Solar and Heliospheric Observatory (SOHO) mission. When we compared the radio and white light data, we found that 76 CMEs, while only 16 remaining 8 suggesting partial eruption. We conclude that there is good association between CMEs when the prominence eruptions have a radial component of the velocity is dominant. Title: Properties of coronal mass ejections and relationship with solar flares Authors: Yashiro, S.; Gopalswamy, N.; Michalek, G.; Howard, R. A. Bibcode: 2002AAS...200.3704Y Altcode: 2002BAAS...34..695Y Coronal mass ejections (CMEs) associated with flares are thought to be faster than those associated with filament eruptions. However, Hundhausen (1997) examined that the relationship between CME kinetic energy and X-ray flare peak intensity, and found that there is only a weak correlation. We have measured the speed, size, location, and acceleration of more than 4000 CMEs observed by the SOHO LASCO Coronagraph from January 1996 through December 2001, providing a good opportunity to revisit the relationship between CMEs and flares. We identified flare-CME pairs as follows: Since the field of view of the LASCO C2 coronagraph limited to heliocentric distances over 2 solar radii (Ro), we cannot obtain the CME start time accurately. So, we assume that the CMEs start from 1 Ro, and estimate the start time from their height-time trajectories. Then, we looked for CMEs that occurred within flare impulsive phase. This way, we found 239 flare-CME pairs. We found a weak correlation between the CME speed and flare X-ray peak flux (correlation coefficient = 0.52). When we isolated the limb events (based on the solar source of the CMEs), we found the correlation to be poorer (0.44). We compare our results with those of Hundhausen. Title: Interplanetary Radio Bursts Authors: Gopalswamy, N. Bibcode: 2002AAS...200.4908G Altcode: 2002BAAS...34..722G Radio bursts in the interplanetary (IP) medium are indicative of solar eruptions that expel shock-driving coronal material or energetic electron beams. Type II radio bursts originate from fast-mode MHD shocks driven by coronal mass ejections (CMEs). Type III bursts are produced by energetic electrons escaping along open magnetic field lines. Occasionally, type IV bursts are also observed in the near-Sun IP medium. Radio and Plasma Waves (WAVES) experiment on board the Wind spacecraft routinely observes these radio bursts at frequencies below 14 MHz since 1994. This new radio window in the 1-14 MHz band has helped us confirm several of the well known solar-terrestrial processes and discover new processes such as the nonthermal radio emission due to colliding CMEs. The IP type II bursts are indicative of faster and wider CMEs, which are important from a space weather point of view. There is also a high degree of association between solar energetic particles and type II radio bursts implying that the same shocks accelerate protons and electrons. I provide a summary of the recent results obtained using radio and white light data. Title: Relationship Between DH Type II Radio Bursts and Energetic Particle Events Authors: Rosas, A. M.; Gopalswamy, N.; Kaiser, M. L. Bibcode: 2002AAS...200.3703R Altcode: 2002BAAS...34Q.695R A comparison of 134 interplanetary type II bursts detected by the WIND/WAVES experiment in the 1-14 MHz range is made with the solar energetic particle (SEP) events. The study period is from 1996 to 2001, which is between minimum and slightly above maximum of the current solar cycle (23). We find that approximately 74% of the IP type II bursts are related to an energetic particle event. We are continuing to investigate the reasons why some interplanetary type II radio bursts do not have energetic particle events. A longitudinal distribution of the solar sources of these events will be used to discriminate between the SEP and non-SEP type II bursts. The study will be able to tell us whether electron accelerators are also proton accelerators. This research was supported by NASA. Travel to this meeting is partly supported by the SPD Studentship Award. Title: Influence of CME Interaction on Solar Proton Events During Cycle 23 Authors: Gopalswamy, N.; Yashiro, S.; Michalek, G.; Kaiser, M. L.; Howard, R. A.; Reames, D. V.; Leske, R. A.; Von Rosenvinge, T. Bibcode: 2002AGUSMSH41A..06G Altcode: We studied the association between solar proton events and white-light coronal mass ejections (CMEs) that occurred during the solar cycle 23 until November 2001. Each of the SEP events was associated with a large-scale primary CME, that were faster and wider than average CMEs. For most of the proton events, the primary CME overtakes one or more slower CMEs. In order to confirm this result, we examined the association and CME interaction and energetic proton events for all the fast (speed > 900 km~s-1) and wide (width > 60 deg) western hemispheric and halo CMEs during the study period. CMEs with energetic protons are 3 times more likely to be preceded by CME interaction than those without. We conclude that CME interaction is an important aspect of SEP acceleration. We infer that CME-driven shocks accelerate SEPs from the material of the preceding CMEs rather than from the quiet solar wind. Title: New Measurements of 3-D Sunspot Coronal Magnetic Fields From Coordinated SOHO EUV and VLA Radio Observations Authors: Brosius, J. W.; White, S. M.; Landi, E.; Cook, J. W.; Newmark, J. S.; Gopalswamy, N.; Lara, A. Bibcode: 2002AAS...200.0307B Altcode: 2002BAAS...34..642B Three-dimensional sunspot coronal magnetograms were derived from coordinated extreme-ultraviolet (EUV) and radio observations of NOAA regions 8108 (N21E18 on 1997 November 18) and 8539 (N20W12 on 1999 May 13). The EUV spectra and images, obtained with the Coronal Diagnostic Spectrometer (CDS) and the Extreme-ultraviolet Imaging Telescope (EIT) aboard the Solar and Heliospheric Observatory (SOHO) satellite, were used to derive the differential emission measure (DEM) and the plasma electron density for each spatial pixel (along each line of sight) within both regions. These were subsequently used to calculate maps of the expected thermal bremsstrahlung brightness temperature at the Very Large Array (VLA) radio observing frequencies of 1.4, 4.9, 8.4, and 15 GHz. The thermal bremsstrahlung maps reproduce neither the structure nor the intensity of the observed maps, and indicate that thermal gyroemission must dominate the observed radio emission. The radio observations were used to constrain the magnetic scale height and the gross temperature structure of the atmosphere. These, along with the DEM, electron density, and observed radio brightness temperature maps, were used to derive the temperature distribution of the coronal magnetic field strength B(T) that reproduced simultaneously the observed right-hand and left-hand circularly polarized emission at the radio observing frequencies for each spatial pixel in the images. Magnetic field strengths corresponding to 3rd harmonic gyroemission at 4.9 GHz (580 Gauss) are found in coronal plasmas at temperatures as high as 3.2 MK, while magnetic field strengths corresponding to 3rd harmonic gyroemission at 15 GHz (1800 Gauss) are found in coronal plasmas at temperatures as high as 1.6 MK. B(T) was ultimately converted to B(h) and compared with extrapolations from photospheric magnetograms. Title: Evidence from Coronal Observations of Magnetic Field Structure in CMEs Authors: Gopalswamy, N. Bibcode: 2002AAS...200.6509G Altcode: 2002BAAS...34..752G The magnetic nature of coronal mass ejections has been inferred from the fact that they originate from closed magnetic field regions on the Sun such as active regions and filament regions. Although we have no direct measurement of the magnetic fields of CMEs, we can obtain useful information on the magnetic structure of CMEs from coronal observations at various wavelengths. The CME is a multithermal structure with temperatures ranging from a few kilokelvin to several megakelvin, so we need multi-wavelength observations to get a global picture of CMEs. A wide range of ground and space based instruments routinely observe CMEs. We present several examples of CMEs observed in X-ray, white light, EUV and radio wavelengths that help us understand the magnetic structure of CMEs. Title: Properties of coronal mass ejections observed by SOHO Authors: Yashiro, S.; Gopalswamy, N.; Michalek, G.; St. Cyr, O. C.; Plunkett, S. P.; Howard, R. A. Bibcode: 2002AGUSMSH32A..03Y Altcode: We report the characteristics of more than 4000 coronal mass ejections (CMEs) observed by the SOHO LASCO Coronagraph from January 1996 through December 2001. We have measured the speed, size, location, and acceleration of each CME, and examined the annual variation of their distributions. All of CME measurements are shown in the online catalog (http://cdaw.gsfc.nasa.gov/). Using this CME catalog, we found that (1) almost of CMEs occurred around equator during the solar minimum, while CME appeared at all latitudes during the solar maximum. (2) the average speed increases toward solar maximum from 306 km/s to 500 km/s, and slightly decreases to 482 km/s in 2001. (3) The width distribution become wider toward solar maximum. These results are consistent with those of Solwind and Skylab. Title: Motion of an Eruptive Prominence in the Solar Corona Authors: Filippov, B. P.; Gopalswamy, N.; Lozhechkin, A. V. Bibcode: 2002ARep...46..417F Altcode: A model for the nonradial motion of an eruptive prominence in the solar corona is proposed. Such motions, which can sometimes be inaccessible to observation, result in an apparent break in the causal link between eruptive prominences and coronal mass ejections. The global magnetic field of the Sun governs coronal plasma motions. The complex structure of this field can form prominence trajectories that differ considerably from a simple vertical rise (i.e., radial motion). A solar filament is modeled as a current-carrying ring or twisted toroidal magnetic rope in equilibrium with the coronal magnetic field. The global field is described using two spherical harmonics. A catastrophic violation of the filament equilibrium followed by its rapid acceleration—eruption—is possible in this nonlinear system. The numerical solution of the equations of motion corresponds well to the eruption pattern observed on December 14, 1997. Title: Interplanetary radio emission due to interaction between two coronal mass ejections Authors: Gopalswamy, Nat; Yashiro, Seiji; Kaiser, Michael L.; Howard, Russell A.; Bougeret, J. -L. Bibcode: 2002GeoRL..29.1265G Altcode: 2002GeoRL..29h.106G We report on the detection of a new class of nonthermal radio emission due to the interaction between two coronal mass ejections (CMEs). The radio emission was detected by the Radio and Plasma Wave Experiment (WAVES) on board the Wind satellite, while the CMEs were observed by the white-light coronagraphs of the Solar and Heliospheric Observatory (SOHO) mission. There was no type II radio burst (metric or interplanetary) preceding the nonthermal emission. The radio emission occurred at a distance beyond 10 Rs from the Sun, where the two CMEs came in contact. Using H-alpha and EUV images, we found that the two CMEs were ejected roughly along the same path. We argue that the nonthermal electrons responsible for the new type of radio emission were accelerated due to reconnection between the two CMEs and/or due to the formation of a new shock at the time of the collision between the two CMEs. Title: Influence of the aerodynamic drag on the motion of interplanetary ejecta Authors: Vršnak, Bojan; Gopalswamy, Nat Bibcode: 2002JGRA..107.1019V Altcode: A simple semi-empirical model for the motion of interplanetary ejecta is proposed to advance the prediction of their arrival times at Earth. It is considered that the driving force and the gravity are much smaller than the aerodynamic drag force. The interaction with the ambient solar wind is modeled using a simple expression for the acceleration $[\dot \upsilon \]$ = -γ(υ-w), where w = w(R) is the distance-dependent solar wind speed. It is assumed that the coefficient γ decreases with the heliocentric distance as γ = αR-β, where α and β are constants. The equation of motion is integrated numerically to relate the Earth transit time and the associated in situ velocity with the velocity of coronal mass ejection. The results reproduce well the observations in the whole velocity range of interest. The model values are compared with some other models in which the interplanetary acceleration is not velocity dependent, as well as with the model where the drag acceleration is quadratic in velocity $\[\dot \upsilon \]$ = -γ2(υ - w)|υ - w|. Title: Colliding coronal mass ejections and particle acceleration Authors: Gopalswamy, N.; Yashiro, S.; Kaiser, M.; Reames, D.; Howard, R. Bibcode: 2002cosp...34E1253G Altcode: 2002cosp.meetE1253G Colliding Coronal Mass Ejections (CMEs) have important implications to a number of physical processes in the near-Sun interplanetary medium: Shock propagation, particle acceleration and solar wind composition. We present statistical results on large solar energetic particle events, associated CMEs and CME interaction during solar cycle 23. We show that most of the large SEP events are preceded by CME interaction. As an inverse study, we identified all the fast and wide front side CMEs from the western hemisphere and examined the SEP association and CME interaction. We found that fast and wide CMEs interacting with preceding CMEs are more likely to be associated with SEPs. We discuss the implications of the statistical results to the understanding of particle acceleration by CME-driven shocks. Title: Propagation of coronal mass ejections from Sun to 1 AU Authors: Manoharan, P.; Gopalswamy, N.; Yashiro, S.; Howard, R. Bibcode: 2002cosp...34E2699M Altcode: 2002cosp.meetE2699M We report on the study of propagation characteristics of a large number of CMEs over the entire range of Sun-Earth distance. Using white-light (LASCO) and interplanetary scintillation (IPS) observations, we investigate the radial variation of the speed of CMEs. In the case of fast CMEs (initial speed 800 kms-1 ), speed declines slowly with distance (VcmeR-a where a0.05-0.1) within about 100 Rsun . Beyond this distance, the speed declines as VcmeR-b where b0.5 - 1. The evolution of size of CMEs with distance, LcmeR, suggests a pressure balance maintained between the CME and ambient solar wind at distances greater than 50 Rsun . We also report the detection of interaction between fast and slow CMEs outside the LASCO field of view. The interaction signature is seen as an unusual enhancement in the density turbulence. Title: Space Weather Study Using Combined Coronagraphic and in Situ Observations Authors: Gopalswamy, N. Bibcode: 2002swsm.conf...39G Altcode: Coronal mass ejections (CMEs) play an important role in space weather studies because of their ability to cause severe geoeffects, such as magnetic storms. Shocks driven by CMEs may also accelerate solar energetic particles. Prediction of the arrival of these CMEs is therefore of crucial importance for space weather applications. After a brief review of the prediction models currently available, a description of an empirical model to predict the 1 AU arrival CMEs is provided. This model was developed using two-point measurements: (i) the initial speeds and onset times of Earth-directed CMEs obtained by white-light coronagraphs, and (ii) the corresponding interplanetary CME speeds and onset times at 1 AU obtained in situ. The measurements yield an empirical relationship between the interplanetary acceleration faced by the CMEs and their initial speeds, which forms the basis of the model. Use of archival data from spacecraft in quadrature is shown to refine the acceleration versus initial speed relationship, and hence the prediction model. A brief discussion on obtaining the 1-AU speed of CMEs from their initial speeds is provided. Possible improvements to the prediction model are also suggested. Title: Relation Between Coronal Mass Ejections and their Interplanetary Counterparts Authors: Gopalswamy, N. Bibcode: 2002stma.conf..157G Altcode: Our current knowledge on coronal mass ejections (CMEs) comes from two spatial domains: the near-Sun (up to 30 solar radii) region remote-sensed by coronagraphs and the geospace and beyond where in situ observations are made by spacecraft. Comparing observations from these two domains has helped us understand the propagation and evolution of CMEs through the interplanetary (IP) medium and develop an empirical model to predict the 1-AU arrival of CMEs. In this paper, we review the available information on the relation between CMEs and their IP counterparts. In particular, we concentrate on issues related to the prediction of the arrival of ICMEs in the geospace. We discuss the solar sources of the three largest geomagnetic storms of year 2000 and compare the predicted and observed arrival times of the associated CMEs. Title: CMEs: observations of all kinds Authors: Gopalswamy, Nat Bibcode: 2002ocnd.confE..13G Altcode: No abstract at ADS Title: Properties of Narrow Coronal Mass Ejections Observed with LASCO Authors: Yashiro, S.; Gopalswamy, N.; Howard, R. Bibcode: 2002cosp...34E2602Y Altcode: 2002cosp.meetE2602Y More than 4500 coronal mass ejections (CMEs) have been observed with SOHO LASCO coronagraph from January 1996 to December 2001. We have measured properties of all these CMEs and published them in an online catalog. In this paper, we describe the properties of narrow CMEs (width < 20 deg.). We investigated 675 narrow CMEs from the catalog and found that (1) the fraction of narrow CMEs increases from 5% to 15% towards solar maximum, (2) the average speed of the narrow CMEs is higher than that of the wide ones, (3) the maximum speed of narrow CMEs (1141 km/s) is much smaller than that of the wide CMEs (2604 km/s). We also found that the wide CMEs are likely to have the well known three-part structure, but narrow ones do not. Wide CMEs can be explained as due to the expansion of flux tubes, but the narrow CMEs seem to be mass flows in vertical flux tubes (streamers). Title: Statistical Properties of Radio-Rich Coronal Mass Ejections Authors: Gopalswamy, N.; Yashiro, S.; Michalek, G.; Kaiser, M. L.; Howard, R. A.; Bougeret, J. -L. Bibcode: 2002stma.conf..169G Altcode: No abstract at ADS Title: Origin of coronal streamer distention Authors: Gopalswamy, N.; Shimojo, M.; Lu, W.; Yashiro, S.; Shibasaki, K.; Howard, R. Bibcode: 2002cosp...34E1257G Altcode: 2002cosp.meetE1257G Distention of coronal streamers is considered to be one of the pre-eruption evolution of coronal mass ejections (CMEs), although how mass is added to the streamers is poorly understood. During our study of eruptive prominences and their relation to CMEs, we observed a large number of prominences associated with significant changes in the helmet streamers overlying the prominences. We used the white light images of the corona obtained by the Solar and Heliospheric Mission's Large Angle and Spectrometric Coronagraph images and the microwave images from the Nobeyama radioheliograph in Japan. We found that the streamer distention is associated with prominence eruption with mostly horizontal motion (parallel to the solar limb) or with eruptive prominences with most of the mass falling back to the solar surface. We suggest that the physical process which activates the prominences also add mass to the streamers. Title: Variability of solar eruptions during cycle 23 Authors: Gopalswamy, N.; Nunes, S.; Yashiro, S.; Howard, R. Bibcode: 2002cosp...34E1260G Altcode: 2002cosp.meetE1260G Nearly 5000 coronal mass ejections (CMEs) were observed by the Solar and Heliospheric Observatory from the minimum to maximum of the current solar cycle (19962001). We have measured and cataloged the properties of all these CMEs. We have studied the variation of mean and median speeds and the rate of CMEs (averaged over Carrington rotations) as a function time. We compare the CME rate with those of other energetic solar events such as interplanetary type II bursts, solar energetic particle (SEP) events and metric type II bursts. This study is useful in identifying the phases of the solar cycle which show rapid variability. CMEs associated with radio bursts and SEPs belong to a separate group characterized by high speed and large width. We discuss the solar cycle variability of this energetic group in comparison with the general population of CMEs. Title: An empirical model to predict the 1-AU arrival of interplanetary shocks Authors: Gopalswamy, N.; Lara, A.; Manoharan, P.; Howard, R. Bibcode: 2002cosp...34E1256G Altcode: 2002cosp.meetE1256G We describe an empirical model to predict the 1-AU arrival of interplanetary shocks of solar origin. This model is an extension of Gopalswamy et al.'s [2001] empirical CME arrival model based on an effective acceleration acting on the CMEs as they propagate through the interplanetary medium. We measured the properties of a large number IP shocks, their solar sources and associated CMEs. Using in situ observations from Wind and ACE, we obtained the physical conditions upstream and down stream of the shock. Combining the shock data with the known piston-shock relation, we estimate the shock arrival times. We compare the estimated and actual arrival times of shocks to determine the error in our shock-arrival estimates. Reference: Gopalswamy, N., A. Lara, S. Yashiro, M. L. Kaiser, and R. A. Howard, Predicting the 1-AU Arrival Times of Coronal Mass Ejections, J. Geophys. Res., 106, 29,207, 2001 Title: Phenomena Associated with EIT Waves Authors: Thompson, B.; Biesecker, D.; Gopalswamy, N. Bibcode: 2002cosp...34E2672T Altcode: 2002cosp.meetE2672T We discuss phenomena associated with "EIT Wave" transients. "EIT Waves" are propagating disturbances first observed in SOHO/EIT EUV images. However, a number of studies have been conducted to determine their relationship to other observations, using data from a variety of instruments. These phenomena include coronal mass ejections, flares, EUV/SXR dimmings,chromospheric waves, Moreton waves, solar energetic particle events, energetic electron events, and radio signatures. Although the occurrence of many phenomena correlate with the appearance of EIT waves, it is difficult to infer which associations are causal. The presentation will include a discussion of the correlation statistics of these phenomena. Title: Solar eruptions and long wavelength radio bursts: The 1997 May 12 event Authors: Gopalswamy, N.; Kaiser, M. L. Bibcode: 2002AdSpR..29..307G Altcode: We report on the cause of the 1997 May 12 type II bursts observed by ground based and space-based radio instruments. We estimate the fast mode speed in the corona as a function of heliocentric distance to identify the regions where fast mode shocks can be driven by CMEs. We find that both the coronal and the interplanetary type II bursts can be explained by shocks driven by the same CME at two different spatial domains. The fast mode speed in the corona has a peak at a heliocentric distance of ∼ 3 R⊙ which does not allow the coronal shock wave to propagate beyond this distance. When the CME continues to travel beyond the fast mode peak, another shock forms in the interplanetary medium where the fast mode speed falls sufficiently. From the radio observations we can infer that the plane of the sky speed of the CME is smaller than the space speed by at least a factor of 2, consistent with the location of the eruption at N21 W08. The inferred CME speed is also consistent with previous deprojected speed estimates. Title: A Statistical Study for Two Classes of CMEs Authors: Moon, Y.; Choe, G.; Park, Y.; Yang, G.; Wang, H.; Goode, P.; Yashiro, S.; Gopalswamy, N. Bibcode: 2001AGUFMSH12B0747M Altcode: MacQueen and Fisher (1983) noted the existence of two classes of CMEs; flare-associated CMEs show the highest speeds with little acceleration, wheras eruption-associated ones exhibit large accelerations. A statistical study has been performed to examine the bimodality of CMEs using the CME catalogue based on SOHO/LASCO observations from 1996 to 2000 by Yashiro and Michalek (2001). In the catalogue, we have used the speed and acceleration data obtained from height-time plots with 2nd order fits. We present the histogram of CME speed, the histogram of CME acceleration, and their speed-acceleration diagram. We have also conducted the same analysis for two different sets of data which have both time and spatial association with GOES solar flares and filaments activities (e.g., disappearing filaments), respectively. The filament data were collected from the NGDC and Big Bear Solar Observatory. Major results from this study are as follows. (1) The speed histogram for all the CMEs has a major peaks near 300km/s but does not show any double peaks. (2) Their acceleration histogram has a strong peak near zero, even for the two data sets associated with solar flares and filaments. (3) The number of CMEs with deceleration is comparable to that of CMEs with acceleration. (4) Their acceleration distribution has a maximum near zero regardless of their speed. (5) The ratio of flare-associated ones to all the CMEs increases with CME speed, wheras the ratio of filament-associated ones decreases. Finally we compare our results with previous ones and discuss their implications on the bimodality of CMEs. Title: Interplanetary Acceleration of Coronal Mass Ejections: Comparison between numerical simulations and observations Authors: Lara, A.; Gonzalez-Esparza, A.; Perez-Tijerina, E.; Santillan, A.; Gopalswamy, N. Bibcode: 2001AGUFMSH11D..10L Altcode: For a set of 50 Coronal Mass Ejections (CMEs) observed with the Large Angle and Spectrometric COrongraph (LASCO) on board of the SOlar and Heliospheric Observatory (SOHO) mission, we estimate the density and measure the sky-plane speed at 18 solar radii (Rsun). We feed these parameters to a one dimensional, single fluid, hydrodynamic model to simulate the CME propagation from 18 Rsun to one AU, and iteratively adjust the initial temperature and ambient solar wind speed using in situ measurements by the Wind mission prior to and during the ICMEs that pair with the white-light CMEs. Following the evolution of the nose of the ejecta we are able to construct an acceleration model for the simulated ICMEs. We compare and discuss the simulated acceleration profile with the observed mean acceleration in order to obtain a general ICME acceleration model. Title: CME Interactions Near the Sun Authors: Gopalswamy, N. Bibcode: 2001AGUFMSH11D..01G Altcode: The phenomenon of interaction between coronal mass ejections in the near-Sun interplanetary medium is surveyed using data from SOHO and Wind missions. Long wavelength radio data (1-14 MHz) reveal CME-CME and CME-shock interactions. CME interactions may result in change of CME trajectories or merger ("cannibalism"). Typically, slower CMEs are overtaken by faster CMEs. Occasionally, multiple interactions are observed. Solar cycle variation of the CME interaction rate will be presented based on a careful examination of all the available CME data from SOHO. Finally, consequences of the CME interaction in the interplanetary medium will be discussed briefly. Research supported by NASA, AFOSR and NSF. Title: Interacting CMEs and Solar Energetic Particles Authors: Gopalswamy, N.; Yashiro, S.; von Rosenvinge, T. T.; Leske, R. Bibcode: 2001AGUFMSH12A0735G Altcode: We examined the solar sources of a set of large solar energetic particle (SEP) events with mixed (impulsive + gradual) abundance signatures. The SEP events were detected by the Solar Isotope Spectrometer (SIS) on board the Advanced Composition Explorer (ACE) spacecraft. For each of the SEP events, we identified a "primary" coronal mass ejection (CME), detected by the Solar and Heliospheric observatory (SOHO). Then we examined a set of CMEs preceding the primary CME, potentially interacting with the primary CME in the near-Sun interplanetary medium. Twenty events from a list of 27 recently compiled von Rosenvinge et al. (Proc. ICRC 2001, p. 3136) overlapped with SOHO observations. Preliminary results indicate that a large majority of the primary CMEs were preceded by slower CMEs, suggesting that CME interaction may result in abundance enhancements in the source material. Research supported by NASA and AFOSR. Title: Characteristics of coronal mass ejections associated with long-wavelength type II radio bursts Authors: Gopalswamy, N.; Yashiro, S.; Kaiser, M. L.; Howard, R. A.; Bougeret, J. -L. Bibcode: 2001JGR...10629219G Altcode: We investigated the characteristics of coronal mass ejections (CMEs) associated with long-wavelength type II radio bursts in the near-Sun interplanetary medium. Type II radio bursts in the decameter-hectometric (DH) wavelengths indicate powerful MHD shocks leaving the inner solar corona and entering the interplanetary medium. Almost all of these bursts are associated with wider and faster than average CMEs. A large fraction of these radio-rich CMEs were found to decelerate in the coronagraph field of view, in contrast to the prevailing view that most CMEs display either constant acceleration or constant speed. We found a similar deceleration for the fast CMEs (speed>900kms-1) in general. We suggest that the coronal drag could be responsible for the deceleration, based on the result that the deceleration has a quadratic dependence on the CME speed. About 60% of the fast CMEs were not associated with DH type II bursts, suggesting that some additional condition needs to be satisfied to be radio-rich. The average width (66°) of the ratio-poor, fast CMEs is much smaller than that (102°) of the radio-rich CMEs, suggesting that the CME width plays an important role. The special characteristics of the radio-rich CMEs suggest that the detection of DH radio bursts may provide a useful tool in identifying the population of geoeffective CMEs. Title: Predicting the 1-AU arrival times of coronal mass ejections Authors: Gopalswamy, Nat; Lara, Alejandro; Yashiro, Seiji; Kaiser, Mike L.; Howard, Russell A. Bibcode: 2001JGR...10629207G Altcode: We describe an empirical model to predict the 1-AU arrival of coronal mass ejections (CMEs). This model is based on an effective interplanetary (IP) acceleration described by Gopalswamy et al. [2000b] that the CMEs are subject to, as they propagate from the Sun to 1 AU. We have improved this model (1) by minimizing the projection effects (using data from spacecraft in quadrature) in determining the initial speed of CMEs, and (2) by allowing for the cessation of the interplanetary acceleration before 1 AU. The resulting effective IP acceleration was higher in magnitude than what was obtained from CME measurements from spacecraft along the Sun-Earth line. We evaluated the predictive capability of the CME arrival model using recent two-point measurements from the Solar and Heliospheric Observatory (SOHO), Wind, and ACE spacecraft. We found that an acceleration cessation distance of 0.76 AU is in reasonable agreement with the observations. The new prediction model reduces the average prediction error from 15.4 to 10.7 hours. The model is in good agreement with the observations for high-speed CMEs. For slow CMEs the model as well as observations show a flat arrival time of ~4.3 days. Use of quadrature observations minimized the projection effects naturally without the need to assume the width of the CMEs. However, there is no simple way of estimating the projection effects based on the surface location of the Earth-directed CMEs observed by a spacecraft (such as SOHO) located along the Sun-Earth line because it is impossible to measure the width of these CMEs. The standard assumption that the CME is a rigid cone may not be correct. In fact, the predicted arrival times have a better agreement with the observed arrival times when no projection correction is applied to the SOHO CME measurements. The results presented in this work suggest that CMEs expand and accelerate near the Sun (inside 0.7 AU) more than our model supposes; these aspects will have to be included in future models. Title: Momentum Coupling Between Coronal Mass Ejections and the Solar Wind Authors: Chen, J.; Gopalswamy, N.; Yashiro, S. Bibcode: 2001AGUFMSH12A0740C Altcode: The interaction of coronal mass ejections (CMEs) and the ambient solar wind plays a critically important role in determining the CME acceleration near the Sun and the subsequent evolution through the interplanetary medium. In particular, the speed and the magnetic field of associated magnetic clouds at 1 AU are dependent on the momentum transfer from the CME to the solar wind (SW) during the transit. Theoretically, because of the high magnetic Reynold's number, turbulent drag has been used to model the integrated drag (retarding or accelerating depending on the velocity differential) force on CMEs exerted by the SW (Chen 1996). The drag coefficient has been previously estimated to be of order unity using a 2-D MHD simulation of flux-rope interactions with an ambient magnetizid plasma consistent with SW conditions near 1 AU (Cargill et al. 1996). Such treatments posit that the momentum coupling between a flux rope and the ambient plasma is proportional to (V-Vsw)2, where V is the speed of the flux rope and Vsw is the ambient SW speed. Recently, Gopalswamy et al. (2001) found that the observationally inferred drag force is approximately quadratic in CME speed, based on 61 decelerating CME events. In this paper, we examine specific events using LASCO data and determine the drag coefficient: for each event, we measure the speed-height profile and the minor radius at the leading edge; then using a model of the coronal density and SW outflow speed, estimate the drag coefficient. Work supported by ONR and NASA. Chen, J., JGR, 101, 27499, 1996 Cargill, P. J., J. Chen, D. S. Spicer, and S. T. Zalesak, JGR, 101, 4855, 1996. Gopalswamy, N., S. Yashiro, M. L. kaiser, R. A. Howard, and J.-L. Bougeret, in press, JGR, 2001. Title: Limb Flares, CMEs & Metric Type II Radio Bursts: A New Statistical Study Authors: Hammer, D.; Gopalswamy, N.; Yashiro, S.; Nunes, S.; Michalek, G. Bibcode: 2001AGUFMSH42A0767H Altcode: Past studies of the relationship between flares, coronal mass ejections(CMEs), and metric typeII radio bursts have been accomplished without the significantly larger and more detailed CME database that is available today through SOHO/LASCO observations. This abundance of CME data allows us to more accurately study the flare-CME-typeII relationship thereby permitting better substantiated conclusions. Our study examines the relationship between solar flares and their correlated CMEs and metric typeII bursts by sampling all (approximately 900) X-ray/H-alpha limb flares occurring between January 1996 and June 2001. Flare events are collected from Solar Geophysical Data (SGD) and flare location is confirmed with SOHO EIT, Yokhoh SXT, and Nobeyama Radioheliograph movies. All correlated CMEs are confirmed in LASCO/EIT movies and their parameters are obtained from the CSPSW/NRL maintained, SOHO/LASCO CME catalog. Metric typeII burst data are also obtained from SGD and from the websites of several individual observatories (Potsdam, Hiraiso, Learmonth, Izmiran, and Nancay). We will present statistical analysis on the occurrences between all three solar phenomena and how these relationships change when flare, CME, and typeII parameters change. Additionally, we will analyze how the data relates to past results (e.g. CME Speed vs. Flare Intensity, CME Speed vs. TypeII Occurrence, TypeII Onset - Flare Start vs. Starting Frequency, etc.). We will also present relationships between CME-flare-typeII onset times in addition to solar cycle effects. Title: Numerical Study on the Acceleration of Coronal Mass Ejections in the Interplanetary Medium Authors: Gonzalez-Esparza, A.; Lara, A.; Perez-Tijerina, E.; Santillan, A.; Gopalswamy, N. Bibcode: 2001AGUFMSH11D..09G Altcode: Recently Gopalswamy et al. [2000] studied observations of ICMEs by WIND spacecraft and correlated these observations with CMEs detected previously by SOHO coronographs. They found that the Sun-Earth mean acceleration of these events was approximately proportional to their initial speeds, and they suggest that this result could be used for space weather forecasting. In this work we perform a parametric study of several CME like disturbances propagating in two different ambient winds using a one dimensional, single fluid, hydrodynamic model, to study the kinematics of the CME fronts near the Sun to 1 AU. These 1-D simulations of interplanetary disturbances have shown to be very useful to understand the basic physical aspects of the injection and heliospheric evolution of these phenomena. In this work we explore how the CME acceleration and transit time from near the Sun to 1 AU varies depending on the CME initial conditions and the ambient solar wind. Title: Statistical analysis of coronal shock dynamics implied by radio and white-light observations Authors: Reiner, M. J.; Kaiser, M. L.; Gopalswamy, N.; Aurass, H.; Mann, G.; Vourlidas, A.; Maksimovic, M. Bibcode: 2001JGR...10625279R Altcode: For 19 solar eruptive events we present a statistical comparison of the shock dynamics derived from the measured frequency drift rates of metric and decametric-hectometric (D-H) type II radio bursts with the dynamics of the associated coronal mass ejection (CME). We find that the shock speed parameters derived from the D-H type II radio emissions generated in the high corona (~2-4RsolarRsolar=696,000km) are well correlated with the corresponding CME plane-of-the-sky speeds (correlation coefficient=0.71). On the other hand, we find no obvious correlation between the shock speed parameters derived from the metric type II radio bursts, generated in the middle corona (1.4-2Rsolar), and the corresponding CME speeds (correlation coefficient=-0.07). In general, we also find no clear correlation between the shock speed parameters derived from the metric type II bursts and the D-H radio emissions (correlation coefficient=0.3). However, the metric type II radio bursts sometimes include a second component that is possibly related to the D-H radio emissions. These statistical comparisons of the shock dynamics, implied by the observed metric and D-H type II frequency drift rates, provide further evidence for two distinct coronal shocks. Our statistical analyses are proceeded by two specific examples that illustrate the methodology used in this study. Title: A multi-wavelength study of solar coronal-hole regions showing radio enhancements Authors: Moran, T.; Gopalswamy, N.; Dammasch, I. E.; Wilhelm, K. Bibcode: 2001A&A...378.1037M Altcode: We observed 17 GHz microwave-enhanced regions in equatorial coronal holes (ECH) together with extreme-ultraviolet (EUV), far-ultraviolet (FUV) and visible emissions in a search for temperature increases which might explain the bright spots in radio wavelengths. The ultraviolet (UV) observations span a wide range of formation temperatures (8000 K to 630 000 K). Increased UV emission was observed at the approximate location of the radio enhancements, but unlike the radio brightening, the UV emission did not exceed the mean quiet sun level. However, there were two observations showing increased Hα brightness in radio enhancements above mean quiet sun levels. No Hα bright spots were detected in ECHs outside of radio enhancement regions. The ECH Hα bright spots were caused by bright fibrils, bright points and a lack of dark fibrils. Since the 17 GHz and Hα enhancements are co-spatial, have equal integrated normalized enhanced emission and brightness temperatures, the observations suggest that the radio enhancements are caused by increased fibril radio emission. In addition, increased Fe XII EUV emission was recorded at the location of some well-defined radio enhancements, which were the bases of coronal plumes. Since the radio brightness temperature is much lower than the Fe xii formation temperature, the radio and EUV enhancements are likely both related to the presence of concentrated magnetic flux, but do not arise from the same physical layer. Title: Near-Sun and near-Earth manifestations of solar eruptions Authors: Gopalswamy, N.; Lara, A.; Kaiser, M. L.; Bougeret, J. -L. Bibcode: 2001JGR...10625261G Altcode: We compare the near-Sun and near-Earth manifestations of solar eruptions that occurred during November 1994 to June 1998. We compared white-light coronal mass ejections, metric type II radio bursts, and extreme ultraviolet wave transients (near the Sun) with interplanetary (IP) signatures such as decameter-hectometric type II bursts, kilometric type II bursts, IP ejecta, and IP shocks. We did a two-way correlation study to (1) look for counterparts of metric type II bursts that occurred close to the central meridian and (2) look for solar counterparts of IP shocks and IP ejecta. We used data from Wind and Solar and Heliospheric Observatory missions along with metric radio burst data from ground-based solar observatories. Analysis shows that (1) most (93%) of the metric type II bursts did not have IP signatures, (2) most (80%) of the IP events (IP ejecta and shocks) did not have metric counterparts, and (3) a significant fraction (26%) of IP shocks were detected in situ without drivers. In all these cases the drivers (the coronal mass ejections) were ejected transverse to the Sun-Earth line, suggesting that the shocks have a much larger extent than the drivers. Shocks originating from both limbs of the Sun arrived at Earth, contradicting earlier claims that shocks from the west limb do not reach Earth. These shocks also had good type II radio burst association. We provide an explanation for the observed relation between metric, decameter-hectometric, and kilometric type II bursts based on the fast mode magnetosonic speed profile in the solar atmosphere. Title: Introduction to special section: Global picture of solar eruptive events Authors: Gopalswamy, Nat Bibcode: 2001JGR...10625135G Altcode: This introduction highlights some of the scientific results reported in this special section on solar eruptive events and provides a brief description of issues related to the new results. Most of these papers grew out of the coordinated data analysis workshop held at the Goddard Space Flight Center during April 27-30, 1999, and the subsequent International Conference on Solar Eruptive Events held at the Catholic University of America, Washington, D. C. during March 6-9, 2000. Title: X-ray Ejecta, White-Light CMEs and a Coronal Shock Wave Authors: Gopalswamy, N.; Cyr, O. C. St.; Kaiser, M. L.; Yashiro, S. Bibcode: 2001SoPh..203..149G Altcode: We report on a coronal shock wave inferred from the metric type II burst of 13 January 1996. To identify the shock driver, we examined mass motions in the form of X-ray ejecta and white-light coronal mass ejections (CMEs). None of the ejections could be considered fast (> 400 km s−1) events. In white light, two CMEs occurred in quick succession, with the first one associated with X-ray ejecta near the solar surface. The second CME started at an unusually large height in the corona and carried a dark void in it. The first CME decelerated and stalled while the second one accelerated, both in the coronagraph field of view. We identify the X-ray ejecta to be the driver of the coronal shock inferred from metric type II burst. The shock speed reported in the Solar Geophysical Data (1000-2000 km s−1) seems to be extremely large compared to the speeds inferred from X-ray and white-light observations. We suggest that the MHD fast-mode speed in the inner corona could be low enough that the X-ray ejecta is supermagnetosonic and hence can drive a shock to produce the type II burst. Title: Non-radial motion of eruptive filaments Authors: Filippov, B. P.; Gopalswamy, N.; Lozhechkin, A. V. Bibcode: 2001SoPh..203..119F Altcode: We develop a simple model to explain the non-radial motion of eruptive solar filaments under solar minimum conditions. The global magnetic field is derived from the first and third components of the spherical harmonic expansion of a magnetic scalar potential. The filament is modeled as a toroidal current located above the mid-latitude polarity inversion line. We investigate the stability of the filament against changes in the filament current and attempt to explain the non-radial motion and acceleration of the eruptive filament. We also discuss the limitations of this model. Title: Band-splitting of coronal and interplanetary type II bursts. I. Basic properties Authors: Vršnak, B.; Aurass, H.; Magdalenić, J.; Gopalswamy, N. Bibcode: 2001A&A...377..321V Altcode: Patterns analogous to the band-splitting of metric type II bursts are found in a number of type II bursts observed in the dekameter-kilometer wavelength range. A similarity of morphological and frequency-time characteristics of two emission components are indicative of a common source. Relative frequency splits span in the range Delta f/f=0.05-0.6. At radial distances between 2 and 4 Rsun only small splits around 0.1 can be found. In the interplanetary space the relative split on average increases with the radial distance, whereas the inferred shock velocity decreases. In three events extrapolations of the split components point to the base and the peak of the jump in the local plasma frequency caused by the associated shock passage at 1 AU. This is suggestive of the plasma radiation from the regions upstream and downstream of the shock. Adopting this interpretation, one finds that the drop of Delta f/f at 2-4 Rsun is congruent with the Alfvén velocity maximum expected there. The split increase and the velocity decrease at larger distances can be explained as a consequence of declining Alfvén speed in the interplanetary space. Title: Estimation of projection effect of CMEs from onset time of type III radio bursts. Authors: Michalek, G.; Gopalswamy, N.; Reiner, M.; Yashiro, S. Bibcode: 2001AGUSM..SH22A05M Altcode: We present a new possibility to estimate the projection effect on CME measurements. We assume that (1) high energy electrons are produced at the shock front ahead of the CME, and (2) the radio burst starts when the shock reaches open field lines ( ~ 3 R). In other words, the onset time of the radio burst corresponds to the time when the CME leading edge reaches 3 R. It is well known that white light observations of halo CMEs with the LASCO coronagraph are subject projection effects. Fortunately, the Wind/WAVES experiment observations of type III radio burst associated with shock waves are free from this problems. The difference between onset times of CMEs and radio bursts should be strongly correlated with the position of CMEs on the Sun. We try to determine this correlation and use it to estimate the real starting position of CMEs. Title: Development of SOHO/LASCO CME Catalog and Study of CME Trajectories Authors: Yashiro, S.; Gopalswamy, N.; St. Cyr, O. C.; Lawrence, G.; Michalek, G.; Young, C. A.; Plunkett, S. P.; Howard, R. A. Bibcode: 2001AGUSM..SH31C10Y Altcode: We present a catalog of coronal mass ejections (CMEs) based on SOHO/LASCO observations. This catalog covers the period from 1998 October to the present time. For each of the observed CMEs, the catalog contains the following information: LASCO C2 appearance time, Central Position Angle, Angular Width, height-time plots with Linear (constant speed) and 2nd order (constant acceleration) fits and corresponding speeds, and acceleration. The catalog will be open to the public via World Wide Web after proper validation. Using a preliminary version of this data set, we investigated the CME trajectories based on linear and quadratic fits to the data points. We estimated the error in the computed trajectories as follows: Generally speaking, the error in each height measurement depends on the quality of the CME feature that is tracked. So we grouped the observations into 5 classes based on the quality of the features on a 1-5 scale: Poor, Fair, Typical, Good, and Excellent. For a CME with a clear leading edge (excellent quality), the error in the measured height is small (5% of the measured height). On the other hand, for a CME with a ragged leading edge (poor quality), the error becomes larger (20% of the measured height). Based on this scheme, we assigned errorbars to the measured heights and then performed a weighted least-squares fit to the height-time trajectories. We found that for 90% of the CMEs, the linear (constant speed) fit is preferable. For the remaining 10%, quadratic fit (constant acceleration) is better than the linear fit. Title: Lasco CME Speeds and Metric Type II Radio Bursts Authors: Hammer, D.; Gopalswamy, N.; Yashiro, S. Bibcode: 2001AGUSM..SH22C01H Altcode: We are using images obtained with LASCO to study correlations between CME parameters and the occurrence of metric Type II radio bursts. In particular, contemporary theories, based on SMM data, suggest a strict causal relationship between CME speeds and the production of metric Type II's. We will analyze how this relationship unfolds for Type II events occurring since the beginning of the LASCO mission in 1996, and look for solar cycle effects. We will also examine the speed of metric Type II's in comparison to LASCO derived CME speeds. Title: Origin and Early Evolution of Coronal Mass Ejections Authors: Gopalswamy, N. Bibcode: 2001AGUSM..SH61A01G Altcode: Simultaneous observations at multiple wavelengths over a large field of view have dramatically improved our understanding of coronal mass ejections. Extreme ultraviolet and soft X-ray observations reveal the source regions of Earth-directed CMEs. Microwave and H-alpha observations provide information on the cool components of the CMEs. Radio observations at long decametric and hectometric wavelengths trace CME-driven shock waves that just enter into the interplanetary medium. This paper summarizes recent findings on CMEs using SOHO, Yohkoh and Wind observations and discusses how near-Sun CME observations are useful in interpreting transient events in the inner heliosphere. Title: Measurements of 3-D Sunspot Coronal Magnetic Fields From Coordinated SOHO EUV and VLA Radio Observations Authors: Brosius, J. W.; Landi, E.; Cook, J. W.; Newmark, J.; Gopalswamy, N.; Lara, A. Bibcode: 2001AGUSM..SH32C02B Altcode: Three-dimensional sunspot coronal magnetograms were derived from coordinated extreme-ultraviolet (EUV) and radio observations of NOAA region 8108 (N21 E18) on 1997 November 18. The EUV spectra and images, obtained with the Coronal Diagnostic Spectrometer (CDS) and the Extreme-ultraviolet Imaging Telescope (EIT) aboard the Solar and Heliospheric Observatory (SOHO) satellite, were used to derive differential emission measure (DEM) distributions for each spatial pixel (i.e., along each line of sight) of the region's images. These were subsequently used to calculate maps of the expected thermal bremsstrahlung brightness temperature at the Very Large Array (VLA) radio observing frequencies of 4.9 and 8.4 GHz. The thermal bremsstrahlung maps reproduce neither the structure nor the intensity of the observed maps, and indicate that thermal gyroemission must also contribute to the observed radio emission. Under the assumptions of a monotonic increase in temperature and a monotonic decrease in magnetic field strength with height above the sunspot, we derived the temperature distribution of the coronal magnetic field strength that reproduced simultaneously the observed right-hand and left-hand circularly polarized radio emission at 4.9 and 8.4 GHz for each spatial pixel in the sunspot maps. This was done by placing harmonics of the radio observing frequencies in appropriate plasma temperature intervals, integrating along the line of sight, and iterating until a solution was obtained. Magnetic field strengths corresponding to 3rd harmonic gyroemission at 4.9 GHz (580 Gauss) are found in coronal plasmas at temperatures as high as 2.2*E6 K, while magnetic field strengths corresponding to 2nd harmonic gyroemission at 8.4 GHz (1500 Gauss) are found in coronal plasmas at temperatures as high as 1.1*E6 K. Title: An Observational Study of Solar Coronal-hole Regions Showing Radio Enhancements Authors: Moran, T. G.; Gopalswamy, N.; Dammash, I.; Wilhelm, K. Bibcode: 2001AGUSM..SH41A13M Altcode: We observed 17~GHz microwave-enhanced regions in equatorial coronal holes (ECH) together with extreme-ultraviolet (EUV), far-ultraviolet (FUV) and visible emissions in a search for temperature increases which might explain the bright spots in radio wavelengths. The ultraviolet (UV) observations span a wide range of formation temperatures (8000~K to 630 000~K). Increased UV emission was observed at the approximate location of the radio enhancements, but unlike the radio brightening, the UV emission did not exceed the mean quiet sun level. However, there were two observations showing increased Hα brightness in radio enhancements above mean quiet sun levels. No Hα bright spots were detected in ECHs outside of radio enhancement regions. The ECH Hα bright spots were caused by bright fibrils, bright points and a lack of dark fibrils. Since the 17~GHz and Hα enhancements are co-spatial, have equal integrated normalized enhanced emission and brightness temperatures, the observations suggest that the radio enhancements are caused by increased fibril radio emission. In addition, increased Fe xii EUV emission was recorded at the location of some well-defined radio enhancements, which were the bases of coronal plumes. Since the radio brightness temperature is much lower than the Fe xii formation temperature, the radio and EUV enhancements are likely both related to the presence of concentrated magnetic flux, but do not arise from the same physical layer. Title: Acceleration and Deceleration of CMEs Associated with Long Wavelength Radio Bursts Authors: Gopalswamy, N.; Yashiro, S.; Kaiser, M. L.; Howard, R. Bibcode: 2001AGUSM..SH31C07G Altcode: Type II radio bursts in the Decameter-Hectometric (DH) wavelengths indicate powerful MHD shocks leaving the inner corona. Almost all of these bursts are associated with massive and faster-than-average coronal mass ejections (CMEs). A particularly interesting characteristic of these DH CMEs is that they are predominantly decelerating in the coronagraph field of view. In the past, it was thought that there are mainly constant speed and accelerating CMEs. We discuss the possible explanations for the CME deceleration in the near-Sun interplanetary medium. Research supported by NASA, NSF and Air Force Office of Scientific Research Title: Testing the Empirical CME Arrival Model Using Earth Directed Events Authors: Lara, A.; Gopalswamy, N.; Dasso, S.; Yashiro, S. Bibcode: 2001AGUSM..SH61A05L Altcode: An empirical model to predict the arrival of coronal mass ejections at 1 AU was developed recently (Gopalswamy et al. 2000), based on SOHO and Wind observations. The model was further improved by correcting for the intrinsic projection effects on CME initial speed. This correction was performed using archival data from Helios-1, Pioneer Venus Orbiter and P78-1 (Solwind) spacecraft which were in quadrature so that the projection effects were minimal. In this work we use the corrected CME arrival model to predict the travel time of a large set of Earth directed halo CMEs observed by SOHO/LASCO from January 1997 to December 2000. We search for interplanetary signatures around the predicted arrival times. In particular, one of the most commonly observed characteristics of interplanetary CMEs (ICME) is their low temperature with respect to the ambient (fast and slow) solar wind. We search for low temperature regions from in situ data obtained by Wind, ACE, and IMP8 spacecraft, as a proxy to the ICMEs. Finally, we compare the predicted CME arrival times with the detected ICME times and perform a statistical analysis of the errors in the predicted time. Title: Radio Signatures of Coronal Mass Ejection Interaction: Coronal Mass Ejection Cannibalism? Authors: Gopalswamy, N.; Yashiro, S.; Kaiser, M. L.; Howard, R. A.; Bougeret, J. -L. Bibcode: 2001ApJ...548L..91G Altcode: We report the first detection at long radio wavelengths of interaction between coronal mass ejections (CMEs) in the interplanetary medium. The radio signature is in the form of intense continuum-like radio emission following an interplanetary type II burst. At the time of the radio enhancement, coronagraphic images show a fast CME overtaking a slow CME. We interpret the radio enhancement as a consequence of shock strengthening when the shock ahead of the fast CME plows through the core of the preceding slow CME. The duration of the radio enhancement is consistent with the transit time of the CME-driven shock through the core of the slow CME. As a consequence of the interaction, the core of the slow CME changed its trajectory significantly. Based on the emission characteristics of the radio enhancement, we estimate the density of the core of the slow CME to be ~4×104 cm-3. The CME interaction has important implications for space weather prediction based on halo CMEs: some of the false alarms could be accounted for by CME interactions. The observed CME interaction could also explain some of the complex ejecta at 1 AU, which have unusual composition. Title: Early life of coronal mass ejections Authors: Gopalswamy, N.; Thompson, B. J. Bibcode: 2000JASTP..62.1457G Altcode: 2000JATP...62.1457G Coronal mass ejections (CMEs) are large-scale magnetized plasma structures ejected from closed magnetic field regions of the Sun. White light coronagraphic observations from ground and space have provided extensive information on CMEs in the outer corona. However, our understanding of the solar origin and early life of CMEs is still in an elementary stage because of lack of adequate observations. Recent space missions such as Yohkoh and Solar and Heliospheric Observatory (SOHO) and ground-based radioheliographs at Nobeyama and Nancay have accumulated a wealth of information on the manifestations of CMEs near the solar surface. We review some of these observations in an attempt to relate them to what we already know about CMEs. Our discussion relies heavily on non-coronagraphic data combined with coronagraphic data. Specifically, we discuss the following aspects of CMEs: (i) coronal dimming and global disk signatures, (ii) non-radial propagation during the early phase, (iii) Photospheric magnetic field changes during CMEs, and (iv) acceleration of fast CMEs. The relative positions and evolution of coronal dimming, arcade formation, prominence eruption will be discussed using specific events. The magnitude and spatial extent of CME acceleration may be an important parameter that distinguishes fast and slow CMEs. Title: Soft X-Ray and Gyroresonance Emission above Sunspots Authors: Nindos, A.; Kundu, M. R.; White, S. M.; Shibasaki, K.; Gopalswamy, N. Bibcode: 2000ApJS..130..485N Altcode: Using Yohkoh SXT and Nobeyama 17 GHz data, we have studied the soft X-ray and microwave emission above several stable, large sunspots near central meridian passage. Our study confirms the well-known fact that soft X-ray emission is depressed above sunspots. It also shows that the distribution of their soft X-ray intensity is not uniform; usually the darkest pixels are associated with the umbra or the far edges of the leading part of the penumbra while the following part of the penumbra may contain higher intensity pixels associated with brighter loops. For the first time, we present a systematic survey of the temperatures and emission measures of the soft X-ray material above sunspots. Sunspots always contain the lowest temperatures and emission measures in the active regions. The mean umbral temperature is 1.8×106 K, and the mean penumbral temperature is 2.4×106 K. The mean umbral and penumbral emission measures are logEM=26.60 cm-5 and logEM=27.00 cm-5, respectively. The differences between the umbral and penumbral plasma temperatures are physically significant. The higher penumbral values imply that the loops associated with the penumbrae are generally hotter and denser than the loops associated with the umbrae. The highest sunspot temperatures and emission measures are still lower than the average active region parameters but higher than the quiet-Sun plasma parameters. The coronal radiative energy loss rate above the umbrae is 15% higher than the radiative loss rate of the quiet-Sun plasma but a factor of 8.3 lower than the typical active region radiative loss rate. The radio emission comes from the gyroresonance mechanism, and, as expected, it is sensitive to the magnetic field rather than the soft X-ray-emitting plasma. Title: Correction to “Change in photospheric magnetic flux during coronal mass ejections” Authors: Lara, Alejandro; Gopalswamy, Nat; DeForest, Craig Bibcode: 2000GeoRL..27.1863L Altcode: No abstract at ADS Title: Microwave Enhancement in Coronal Holes: Statistical Propeties Authors: Gopalswamy, N.; Shibasaki, K.; Salem, M. Bibcode: 2000JApA...21..413G Altcode: No abstract at ADS Title: SOHO and radio observations of a CME shock wave Authors: Raymond, John C.; Thompson, Barbara J.; St. Cyr, O. C.; Gopalswamy, Nat; Kahler, S.; Kaiser, M.; Lara, A.; Ciaravella, A.; Romoli, M.; O'Neal, R. Bibcode: 2000GeoRL..27.1439R Altcode: A 1200 km s-1 Coronal Mass Ejection was observed with the SOHO instruments EIT, LASCO and UVCS on June 11, 1998. Simultaneously, Type II radio bursts were observed with the WAVES experiment aboard the Wind spacecraft at 4 MHz and by ground-based instruments at metric wavelengths. The density in the shock wave implied by the higher frequency is close to that inferred from the SOHO/UVCS experiment. The drift rates of the Type II radio bursts suggest shock speeds lower than the speed derived from SOHO observations. The SOHO/UVCS spectrum shows enhanced emission in lines of O5+ and Si11+, consistent with modest compression in an MHD shock. Title: Radio-rich solar eruptive events Authors: Gopalswamy, N.; Kaiser, M. L.; Thompson, B. J.; Burlaga, L. F.; Szabo, A.; Lara, A.; Vourlidas, A.; Yashiro, S.; Bougeret, J. -L. Bibcode: 2000GeoRL..27.1427G Altcode: We report on the analysis of a large number of solar eruptive events that produced radio emission in the dekameter-hectometric (DH) radio window (1-14 MHz), newly opened by the Wind/WAVES experiment. The distinguishing characteristics of coronal mass ejections (CMEs) associated with the DH type II radio bursts are larger-than-average width and speed. Flares of all sizes (X-ray importance B to X) occurring at all longitudes were associated with the DH type II bursts and CMEs. We found a global enhancement in EUV over an area much larger than the flaring active region in the beginning many events. A comparison between the ‘Shock Associated’ events and microwave bursts shows that at least half of the events do not have temporal relation. A majority of the DH type II bursts were associated with IP shocks and kilometric type II bursts. In particular, we found a very close relationship between the kilometric type II bursts and the IP shocks. Title: Change in photospheric magnetic flux during coronal mass ejections Authors: Lara, Alejandro; Gopalswamy, Nat; DeForest, Craig Bibcode: 2000GeoRL..27.1435L Altcode: We report on the variations of photospheric magnetic flux during coronal mass ejections (CMEs). Using magneograms from the SOHO/MDI instrument, we have computed the magnetic flux of 7 active regions and one disappearing filament region associated with CMEs. When we plotted the flux versus time over a period of few days before, during and after the CME event, we found changes in the mean magnetic flux per pixel (∼4 arcsec²), ranging from ∼0.4 to ∼3.1 × 1017 Mx, in structures of size smaller than the active region. Flare onsets and the filament disappearance clearly occurred during periods of significant variations in the measured magnetic flux. Title: An Empirical Model to Predict the Arrival of CMEs at 1 AU Authors: Gopalswamy, N.; Lara, A.; Kaiser, M. L. Bibcode: 2000SPD....31.0283G Altcode: 2000BAAS...32..825G We describe an empirical model to predict the arrival of coronal mass ejections (CMEs) at 1 AU based on the initial speed of CMEs obtained from coronagraphs. The only input needed in this model is the measured initial speed of CMEs. This model is based on an effective acceleration that CMEs are subject to, as they propagate from the Sun to 1 AU. We developed this model based on the two-point measurements made from SOHO and Wind spacecraft. We validate our model based on older data obtained by Helios-1, P78-1, Pioneer Venus Orbiter and Solar Maximum Mission spacecraft. We discuss the merits and limitations of this model. Research supported by the National Research Council, NSF, and NASA. Title: Magnetic Evolution and Eruptive Events Associated to Active Region 8210 Authors: Lara, A.; Gopalswamy, N. Bibcode: 2000SPD....31.1403L Altcode: 2000BAAS...32..846L We present a study of one active region with high flare and CME activity. From April 27 to May 5, 1998, AR8210 was crossing the south solar hemisphere and produced many flares, and at least five CMEs were related to activity in this region, some of them were homologous events. We use magnetograms from the Michelson Doppler Imager (MDI) experiment on board of the Solar Heliospheric Observatory (SOHO) to construct the time series of the photospheric magnetic elements. We compute the line of sight magnetic flux over the entire active region, and over localized areas inside the active region in which activity was detected in EUV (198 Angstroms) maps from the Extreme ultraviolet Imaging Telescope (EIT) on board of SOHO. We found considerable differences between the positive and negative fluxes computed over the entire region, the mean negative flux per pixel was 50 to 100 % greater than the positive flux. Using microwave polarization measures from Nobeyama Radio Heliograph, we were able to confirm such differences. The magnetic flux computed over AR8210 also showed a considerable increasing phase when the flare and CME activity of the region was increasing. On the other hand, we found that in general, flares occur during a maximum phase in the magnetic flux computed over localized subregions and that the major changes on this magnetic flux seems to be related to CMEs. Finally we discuss the flare and CME production, with special emphasis in the homologous events. Title: Observations of the 24 September 1997 Coronal Flare Waves Authors: Thompson, B. J.; Reynolds, B.; Aurass, H.; Gopalswamy, N.; Gurman, J. B.; Hudson, H. S.; Martin, S. F.; St. Cyr, O. C. Bibcode: 2000SoPh..193..161T Altcode: We report coincident observations of coronal and chromospheric `flare wave' transients in association with a flare, large-scale coronal dimming, metric radio activity and a coronal mass ejection. The two separate eruptions occurring on 24 September 1997 originate in the same active region and display similar morphological features. The first wave transient was observed in EUV and Hα data, corresponding to a wave disturbance in both the chromosphere and the solar corona, ranging from 250 to approaching 1000 km s−1 at different times and locations along the wavefront. The sharp wavefront had a similar extent and location in both the EUV and Hα data. The data did not show clear evidence of a driver, however. Both events display a coronal EUV dimming which is typically used as an indicator of a coronal mass ejection in the inner corona. White-light coronagraph observations indicate that the first event was accompanied by an observable coronal mass ejection while the second event did not have clear evidence of a CME. Both eruptions were accompanied by metric type II radio bursts propagating at speeds in the range of 500-750 km s−1, and neither had accompanying interplanetary type II activity. The timing and location of the flare waves appear to indicate an origin with the flaring region, but several signatures associated with coronal mass ejections indicate that the development of the CME may occur in concert with the development of the flare wave. Title: Space VLBI at Low Frequencies Authors: Jones, D. L.; Allen, R.; Basart, J.; Bastian, T.; Blume, W.; Bougeret, J. -L.; Dennison, B.; Desch, M.; Dwarakanath, K.; Erickson, W.; Farrell, W.; Finley, D.; Gopalswamy, N.; Howard, R.; Kaiser, M.; Kassim, N.; Kuiper, T.; MacDowall, R.; Mahoney, M.; Perley, R.; Preston, R.; Reiner, M.; Rodriguez, P.; Stone, R.; Unwin, S.; Weiler, K.; Woan, G.; Woo, R. Bibcode: 2000aprs.conf..265J Altcode: 2000astro.ph..3120J At sufficiently low frequencies, no ground-based radio array will be able to produce high resolution images while looking through the ionosphere. A space-based array will be needed to explore the objects and processes which dominate the sky at the lowest radio frequencies. An imaging radio interferometer based on a large number of small, inexpensive satellites would be able to track solar radio bursts associated with coronal mass ejections out to the distance of Earth, determine the frequency and duration of early epochs of nonthermal activity in galaxies, and provide unique information about the interstellar medium. This would be a ``space-space" VLBI mission, as only baselines between satellites would be used. Angular resolution would be limited only by interstellar and interplanetary scattering. Title: Structure of a Large low-Latitude Coronal Hole Authors: Bromage, B. J. J.; Alexander, D.; Breen, A.; Clegg, J. R.; Del Zanna, G.; DeForest, C.; Dobrzycka, D.; Gopalswamy, N.; Thompson, B.; Browning, P. K. Bibcode: 2000SoPh..193..181B Altcode: Coronal holes on the Sun are the source of high-speed solar wind streams that produce magnetic disturbances at the Earth. A series of multi-wavelength, multi-instrument observations obtained during the 1996 `Whole Sun Month' campaign examined a large coronal hole in greater detail than ever before. It appeared on the Sun in August, and extended from the north pole to a large active region in the southern hemisphere. Its physical and magnetic structure and subsequent evolution are described. Title: Radial Evolution and Turbulence Characteristics of a Coronal Mass Ejection Authors: Manoharan, P. K.; Kojima, M.; Gopalswamy, N.; Kondo, T.; Smith, Z. Bibcode: 2000ApJ...530.1061M Altcode: We investigate a coronal mass ejection (CME) associated with an X3.9 solar flare that occurred on 1992 June 25. This long-duration event showed a system of large postflare loops at the activity site throughout the period of the enhanced X-ray emission. The drift rate of the metric type IV radio burst observed near the X-ray maximum suggests the speed of the ejecta to be ~350 km s-1 at heights <=2 solar radii. The solar proton intensities, in the energy range 1-100 MeV observed in the interplanetary medium, show gradual-decay profiles lasting for more than two days and suggest CME-driven acceleration near the Sun. The inference on the spatial and kinematical characteristics of the propagating CME in the inner heliosphere (0.2-1 AU) is primarily based on the interplanetary scintillation observations at 327 MHz, obtained from the Ooty Radio Telescope and the Solar-Terrestrial Environment Laboratory. The scintillation data show the deceleration of propagating disturbance speed, VCME~R-0.8, in the interplanetary medium. The speeds obtained from the radio and scintillation measurements also suggest that the coronal shock may not be directly related to the interplanetary shock. The size of the CME in the interplanetary medium seems to follow a simple scaling with distance from the Sun, indicating the pressure balance maintained between the ejecta and the ambient solar wind. The density turbulence spectrum of the plasma carried by the propagating disturbance seems to be flat, ΦNe(IPD)~κ-2.8, also having a small dissipative scale length, Si(IPD)<=5 km. The spectrum is significantly different from that of high-speed flow from coronal holes and low-speed wind originating above closed-field coronal streamers. Title: The ALFA Medium Explorer Mission Authors: Jones, D. L.; Allen, R. J.; Basart, J. P.; Bastian, T.; Blume, W. H.; Bougeret, J. -L.; Dennison, B. K.; Desch, M. D.; Dwarakanath, K. S.; Erickson, W. C.; Farrell, W.; Finley, D. G.; Gopalswamy, N.; Howard, R. E.; Kaiser, M. L.; Kassim, N. E.; Kuiper, T. B. H.; MacDowall, R. J.; Mahoney, M. J.; Perley, R. A.; Preston, R. A.; Reiner, M. J.; Rodriguez, P.; Stone, R. G.; Unwin, S. C.; Weiler, K. W.; Woan, G.; Woo, R. Bibcode: 2000AdSpR..26..743J Altcode: The frequency range below a few tens of MHz is unexplored with high angular resolution due to the opacity of Earth's ionosphere. An interferometer array in space providing arcminute angular resolution images at frequencies of a few MHz would allow a wide range of problems in solar, planetary, galactic, and extragalactic astronomy to be attacked. These include the evolution of solar radio emissions associated with shocks driven by coronal mass ejections and searches for coherent radio emission from supernova remnants and relativistic jets. In addition, it is likely that unexpected objects or emission processes will be discovered by such an instrument, as has always happened when high resolution astronomical observations first become possible in a new region of the electromagnetic spectrum. The Astronomical Low Frequency Array (ALFA) mission will consist of 16 identical small satellites forming an aperture synthesis array. The satellites will cover the surface of a spherical region. ~100 km in diameter, thus providing good aperture plane coverage in all directions simultaneously. The array will operate in two modes: 1) ``snapshot'' imaging of strong, rapidly changing sources such as solar radio bursts and 2) long-term aperture synthesis observations for maximum sensitivity, high dynamic range imaging. In both cases a large number of array elements is needed Title: Time Evolution of Microwave and Hard X-ray Spectral Indexes Authors: Lara, A.; Gopalswamy, N. Bibcode: 2000ASPC..206..355L Altcode: 2000hesp.conf..355L No abstract at ADS Title: The Catholic University of America, Institute for Astrophysics and Computational Sciences, Department of Physics, Washington, District of Columbia 20064. Report for the period Sep 1998 - Sep 1999. Authors: Gopalswamy, N. Bibcode: 2000BAAS...32...32G Altcode: No abstract at ADS Title: The Astronomical Low Frequency Array: A Proposed Explorer Mission for Radio Astronomy Authors: Jones, D.; Allen, R.; Basart, J.; Bastian, T.; Blume, W.; Bougeret, J. -L.; Dennison, B.; Desch, M.; Dwarakanath, K.; Erickson, W.; Finley, D.; Gopalswamy, N.; Howard, R.; Kaiser, M.; Kassim, N.; Kuiper, T.; MacDowall, R.; Mahoney, M.; Perley, R.; Preston, R.; Reiner, M.; Rodriguez, P.; Stone, R.; Unwin, S.; Weiler, K.; Woan, G.; Woo, R. Bibcode: 2000GMS...119..339J Altcode: 2000ralw.conf..339J A radio interferometer array in space providing high dynamic range images with unprecedented angular resolution over the broad frequency range from 0.03 - 30 MHz will open new vistas in solar, terrestrial, galactic, and extragalactic astrophysics. The ALFA interferometer will image and track transient disturbances in the solar corona and interplanetary medium - a new capability which is crucial for understanding many aspects of solar-terrestrial interaction and space weather. ALFA will also produce the first sensitive, high-angular-resolution radio surveys of the entire sky at low frequencies. The radio sky will look entirely different below about 30 MHz. As a result, ALFA will provide a fundamentally new view of the universe and an extraordinarily large and varied science return. Title: Commission 10: Solar Activity: (Activite Solaire) Authors: Ai, G.; Benz, A.; Dere, K. P.; Engvold, O.; Gopalswamy, N.; Hammer, R.; Hood, A.; Jackson, B. V.; Kim, I.; Marten, P. C.; Poletto, G.; Rozelot, J. P.; Sanchez, A. J.; Shibata, K.; van Driel-Geztelyi, L. Bibcode: 2000IAUTA..24...67A Altcode: No abstract at ADS Title: Type II Solar Radio Bursts Authors: Gopalswamy, N. Bibcode: 2000GMS...119..123G Altcode: 2000ralw.conf..123G Solar radio bursts of type II are thought to be caused by MHD shock waves propagating through the corona and interplanetary medium. They are identified as slowly drifting features in the dynamic spectra recorded by ground based and spaceborne radio instruments. The radio emission itself occurs as a final step in a series of physical processes: initiation of the shock, particle acceleration, generation of plasma waves and finally, conversion of the plasma waves into electromagnetic waves. Type II bursts play an important role in understanding the Sun-Earth connection, because of their association with flares and coronal mass ejections (CMEs). Images of type II bursts made by radioheliographs are crucial to understand the physical relationship between shocks, CMEs and solar flares. Observations of a new type of coronal waves by the EIT instrument on board the SOHO mission and long-decametric and hectometric type II bursts by the WIND/WAVES experiment have added new dimensions to the study of type II radio bursts. In this review, I summarize the basic properties and associated solar activities of type II bursts and discuss some of the current issues. Title: Shock Wave and EUV Transient During a Flare Authors: Gopalswamy, N.; Kaiser, M. L.; Sato, J.; Pick, Monique Bibcode: 2000ASPC..206..351G Altcode: 2000STIN...0032759G A metric type II burst and a 'brow' type enhancement in EUV were observed during the hard X-ray flare of 1997 April 15 from a newly emerging region, AR 8032. The position of the type II burst obtained from the Nancay radioheliograph coincided with the EUV transient. The type II burst and the EUV transient were in the equatorial streamer region to the north of the flaring region. This observation suggests that the EUV transient may be the manifestation of the MHD shock responsible for the type II burst. Title: Structure and Dynamics of the Corona Surrounding an Eruptive Prominence Authors: Gopalswamy, N.; Hanaoka, Y.; Hudson, H. S. Bibcode: 2000AdSpR..25.1851G Altcode: We report on the 1997 December 14 prominence eruption event that was accompanied by eruptive signatures in X-rays, EUV and white light: coronal dimming, X-ray arcade formation , X-ray brightenings, EUV eruption, and a white light CME. The data used were obtained by the Nobeyama Radioheliograph, Yohkoh Soft X-ray Telescope (SXT) and SOHO/LASCO and EIT. We identified various substructures of the eruption and their inter-relationships. We found that the pre-disruption swelling of the equatorial streamer was caused by the outward displacement of the coronal material around the prominence location. The dynamical behaviors of the CME and the accompanying eruptive prominence seem to be very different Title: Interplanetary acceleration of coronal mass ejections Authors: Gopalswamy, N.; Lara, A.; Lepping, R. P.; Kaiser, M. L.; Berdichevsky, D.; St. Cyr, O. C. Bibcode: 2000GeoRL..27..145G Altcode: Using an observed relation between speeds of CMEs near the Sun and in the solar wind, we determine an “effective” acceleration acting on the CMEs. We found a linear relation between this effective acceleration and the initial speed of the CMEs. The acceleration is similar to that of the slow solar wind in magnitude. The average solar wind speed naturally divides CMEs into fast and slow ones. Based on the relation between the acceleration and initial speed, we derive an empirical model to predict the arrival of CMEs at 1 AU. Title: Multi-wavelength Signatures of Coronal Mass Ejection Authors: Gopalswamy, N.; Yashiro, S.; Kaiser, M. L.; Thompson, B. J.; Plunkett, S. Bibcode: 1999spro.proc..207G Altcode: We report on the near-surface and outer coronal manifestations of the 1998 January 25 coronal mass ejection (CME) using white light, EUV, X-ray and hectometric radio data which reveal the three dimensional structure and long term evolution of the CME. We find that (i) the substructures of the CME (prominence core, cavity, frontal structure and the arcade formation) are clearly observed in X-ray and EUV wavelengths. (ii) The filament heats up early on and is observed as a backbone in X-rays. (iii) The filament also expands considerably as it erupts. (iv) The CME is observed through direct leading edge signature as well as through dimming process in X-rays and in EUV. Title: 17 GHz Mode Coupling in the Solar Corona Authors: Lara, A.; Gopalswamy, N.; Pérez-Enríquez, R.; Shibasaki, K. Bibcode: 1999spro.proc...83L Altcode: We studied the development of microwave polarization of a group of active regions for a period of 10 days during April, 1993 using data obtained by the Nobeyama radioheliograph. The observed sense of polarization at 17 GHz changed with the active region position on the solar disk. This change of polarization can be explained by the mode coupling theory according to which a weak coupling between the ordinary and extraordinary electromagnetic modes takes place when the radiation crosses a region of transverse magnetic field and results in a polarization reversal. Since the strength of the mode coupling depends on the physical parameters (and their gradients) of the quasi-transverse region, observations of polarization changes can be used to obtain key values of the magnetic field and field gradient in the active region corona. Using the intensity and polarization images of active regions, we found that the coupling constant is typically > 103 corresponding to a weak coupling regime. We determined the mean value of the transition frequency to be ~ 5.3 × 1011 Hz, below which the weak coupling effect is important. For all the active regions studied in this paper, there seems to be a similarity in the position on the solar disk where the mode coupling effects become important. The polarization reversal always occurred when the active regions were farther than the 500 arc sec mark from the disk center. Using this fact and extrapolated photospheric magnetic field we are able to estimate heights of both the quasi-transverse layer and the source region. Assuming a value of ~ 70 G, we obtain a value of 2.2 × 104 km for the Q-T layer height. Title: Solar Physics with Radio Observations Authors: Bastian, T. S.; Gopalswamy, N.; Shibasaki, K. Bibcode: 1999spro.proc.....B Altcode: Radio observations contribute a unique perspective on the many physical phenomena, which occur on the Sun. From thermal bremsstrahlung emission in the quiet solar atmosphere and filaments, to thermal gyroresonance emission in strongly magnetized solar active regions, to the nonthermal emission from MeV electrons accelerated in flares, observations of radio emission provide a powerful probe of physical conditions on the Sun and provide an additional means of understanding the myriad phenomena which occur there. Moreover, radio observing techniques have led the way in developing and exploiting Fourier synthesis imaging techniques. The Nobeyama Radioheliograph, commissioned in June, 1992, soon after the launch of Yohkoh satellite in August, 1991, is the most powerful, solar-dedicated Fourier synthesis in the world, now capable of imaging the full disk of the Sun simultaneously at frequencies of 17 and 34 GHz, with an angular resolution as much as 10" and 5", respectively, and with a time resolution as fine as 100 msec. Between 27-30 October, 1998, the Nobeyama Radio Observatory and the National Astronomical Observatory of Japan hosted the Nobeyama Symposium on Solar Physics with Radio Observations, an international meeting bringing more than sixty participants together at the Seisenryo Hotel in Kiyosato, for a meeting devoted to reviewing recent progress in outstanding problems in solar physics. Emphasis was placed on radio observations and, in particular, radio observations from the very successful Nobeyama Radioheliograph. These results were compared and contrasted with those that have emerged from the Yohkoh mission. In addition, looking forward to the next solar maximum, new instruments, upgrades, and collaborative efforts were discussed. The result is the more than seventy invited and contributed papers that appear in this volume. Title: The Astronomical Low Frequency Array (ALFA): Imaging from Space Authors: Gopalswamy, N.; Kaiser, M. L.; Jones, D. L.; Alfa Team Bibcode: 1999spro.proc..447G Altcode: The ALFA mission is a proposed astronomical observatory in space to make high resolution radio images at frequencies below the ionospheric cutoff (~ 20 MHz). This multi-satellite interferometric array will image solar as well as non-solar phenomena in the frequency range 0.03 - 30 MHz. In this paper, we provide an overview of the ALFA mission, with particular emphasis on solar studies to be undertaken. Title: X-ray and Microwave Signatures of Coronal Mass Ejections Authors: Gopalswamy, N. Bibcode: 1999spro.proc..141G Altcode: X-ray and microwave imaging of structures associated with coronal mass ejections (CMEs) have provided a wealth of new information towards a better understanding of solar eruptions. I review the recent research based on microwave imaging from the Nobeyama Radioheliograph and X-ray imaging from the Yohkoh Soft X-ray Telescope. I shall discuss the advances made towards understanding the near surface manifestations of CMEs best observed in X-rays and microwaves. In particular, I discuss (i) observability of CMEs in X-rays and microwaves, (ii) coronal dimming, (iii) relation between CME substructures, (iv) heating and expansion of eruptive prominences, (v) timing of flare, CME and prominence eruptions, and (vi) CME mass estimates from non-optical observations. Title: Microwave Enhancement in Coronal Holes: Structure, Variability and Magnetic Nature Authors: Gopalswamy, N.; Shibasaki, K. Bibcode: 1999STIN...0011601G Altcode: The microwave enhancement in coronal holes in comparison with the quiet Sun is a distinct and easily observed signature related to the magnetic activity. This has proven to be a new tool to study the solar atmospheric layer where the fast solar wind originates. We have developed a catalog of a large number of coronal holes using images obtained by SOHO's Extreme-ultraviolet Imaging Telescope in EUV and by the Nobeyama radioheliograph in microwaves. We also have high resolution longitudinal magnetograms obtained by SOHO's Michelson Doppler Imager. We present the statistical properties of the microwave enhancements and discuss the small-scale dynamics as revealed by the magnetograms and radioheliograms. We also discuss the geoeffectiveness of these coronal holes. Title: "Driverless" Shocks in the Interplanetary Medium Authors: Gopalswamy, N.; Kaiser, M. L.; Lara, A. Bibcode: 1999STIN...0011206G Altcode: Many interplanetary shocks have been detected without an obvious driver behind them. These shocks have been thought to be either blast waves from solar flares or shocks due to sudden increase in solar wind speed caused by interactions between large scale open and closed field lines of the Sun. We investigated this problem using a set of interplanetary shock detected in situ by the Wind space craft and tracing their solar origins using low frequency radio data obtained by the Wind/WAVES experiment. For each of these "driverless shocks" we could find a unique coronal mass ejections (CME) event observed by the SOHO (Solar and Heliospheric Observatory) coronagraphs. We also found that these CMEs were ejected at large angles from the Sun-Earth line. It appears that the "driverless shocks" are actually driver shocks, but the drivers were not intercepted by the spacecraft. We conclude that the interplanetary shocks are much more extended than the driving CMEs. Title: X-ray and radio manifestations of a solar eruptive event Authors: Gopalswamy, N.; Nitta, N.; Manoharan, P. K.; Raoult, A.; Pick, M. Bibcode: 1999A&A...347..684G Altcode: We report on a study of the changes in the vicinity of a disappearing solar filament (DSF) that occurred on 1993 April 30. The DSF was associated with a long duration X-ray event (LDE) observed by the GOES and Yohkoh spacecraft. A detailed analysis of the X-ray images obtained by the Yohkoh Soft X-ray Telescope revealed that X-ray manifestations of the eruption were wide-spread: (i) X-ray enhancement over a coronal volume several times larger than that of the eruption region, probably the X-ray counterpart of a coronal mass ejection (CME), (ii) X-ray ejecta accelerating to 670 km s(-1) into the corona, and (iii) quasi-stationary X-ray loops as in long decay events (LDEs) were observed. One of the important findings of this study is the large-scale X-ray enhancement which we identify with the frontal structure of a CME, apart from the well-known X-ray ejecta and post-eruption arcade formation. There is evidence for triggering of a sympathetic flare in an adjoining active region due to the X-ray ejecta from the eruption region. Stationary metric radio continuum observed by the Nançay Radioheliograph was found to be associated with the brightest X-ray loops that formed following the filament eruption. The unpolarized continuum radio emission was found to be bremsstrahlung radiation from the hot plasma observed in X-rays. The event was also associated with a low frequency metric type II radio burst due to a coronal shock wave from the eruption region. The onset time of the type II emission precludes the possibility of a CME-driven shock causing it. Although we do not have positional information for the type II burst, we found that the X-ray ejecta was fast enough to drive the coronal shock. We confirmed this by comparing the speed of the X-ray ejecta with the shock speed obtained from the radio data which agreed within 10%. Title: Is the chromosphere hotter in coronal holes? Authors: Gopalswamy, N.; Shibasaki, K.; Thompson, B. J.; Gurman, J. B.; Deforest, C. E. Bibcode: 1999AIPC..471..277G Altcode: 1999sowi.conf..277G Coronal holes are brighter than the quiet Sun in microwaves. Microwave emission from the quiet Sun is optically thick thermal bremsstrahlung from the upper chromosphere. Therefore, the optically thick layer in the coronal hole chromosphere must be hotter than the corresponding layer in the quiet chromosphere. We present microwave and SOHO observations in support of this idea. Because of the availability of simultaneous EUV and microwave images it is now possible to obtain more details of this enigmatic phenomenon. In this paper, we highlight the primary properties of the microwave enhancement in coronal holes and point out some related phenomena. Finally, we summarize the possible explanations of the radio enhancement. Title: Dynamical phenomena associated with a coronal mass ejection Authors: Gopalswamy, N.; Kaiser, M. L.; MacDowall, R. J.; Reiner, M. J.; Thompson, B. J.; Cyr, O. C. St. Bibcode: 1999AIPC..471..641G Altcode: 1999sowi.conf..641G The flare-CME-shock relationship has been controversial for more than two decades. This issue was traditionally addressed using white light coronagraphic data on CMEs, H-alpha or GOES data on flares and radio spectrographic data on shocks (inferred from metric type II radio bursts). A wealth of new information has become available after the advent of Yohkoh, SOHO and WIND missions that can be used to address the dynamical phenomena associated with CMEs. We present multiwavelength observations of the 1998 April 27 CME associated with coronal dimming, an X-class flare and type II radio bursts. We find that the coronal dimming observed in X-rays and EUV is indeed a CME signature and that the CME clearly precedes the accompanying flare. Title: The Long Wavelength Array: Imaging Solar Bursts and CMEs Authors: Gopalswamy, N.; Lazio, T. J. W.; Kassim, N. E.; Erickson, W. C. Bibcode: 1999AAS...19410308G Altcode: 1999BAAS...31.1002G Almost all of the transient disturbances in the Sun-Earth connected space are amenable to probing by metric and decametric radio wavelengths (150 MHz down to ionospheric cut-off at 15 MHz). The long wavelength radio imaging with polarization capability is virtually the only way of measuring magnetic fields in the outer corona and hence an important tool in the study of long-term evolution of the Sun as it sheds its magnetic field through coronal mass ejections (CMEs). Shocks generated during the CMEs are detected as type II radio bursts; some of the energetic electrons are detected as type III bursts; ejected plasmoids are observed as type IV bursts. Ionospheric effects used to pose a major problem for long wavelength imaging. We now know that most of the shortcomings due to ionospheric effects can be virtually eliminated, thanks to the development in image restoration such as self-calibration (Kassim and Erickson, 1998). Low frequency technologies are relatively cheap and well proven. A synergistic combination of a ground based Long Wavelength Array (LWA) and the space-borne coronagraphs such as on board the STEREO mission could prove to be an extremely powerful tool to understand the interplanetary propagation of solar disturbances. Passive imaging of solar emissions can also be combined with radar imaging to increase the scientific return of the LWA (see poster by Lazio et al). The low frequency regime has also the advantage of combining solar physics with non-solar radio astronomy: Sun in the day time and the rest of the universe at night (see poster by Kassim et al). NG is an NAS/NRC Senior Research Associate at NASA/GSFC on leave from the Catholic University. Basic research in radio astronomy at the Naval Research Laboratory is supported by the Office of Naval Research. Title: Microwave enhancement and variability in the elephant's trunk coronal hole: Comparison with SOHO observations Authors: Gopalswamy, N.; Shibasaki, K.; Thompson, B. J.; Gurman, J.; DeForest, C. Bibcode: 1999JGR...104.9767G Altcode: We report on an investigation of the microwave enhancement and its variability in the elephant's trunk coronal hole observed during the Whole Sun Month campaign (August 10 to September 9, 1996). The microwave images from the Nobeyama radioheliograph were compared with magnetograms and EUV images obtained simultaneously by the Michelson Doppler imager and the extreme ultraviolet imaging telescope (EIT) on board the SOHO spacecraft. The combined data set allowed us to understand the detailed structure of the microwave enhancement in the spatial and temporal domains. We find that the radio enhancement is closely associated with the enhanced unipolar magnetic regions underlying the coronal hole. The radio enhancement consists of a smooth component originating from network cell interiors and a compact component associated with network magnetic elements. When a minority polarity is present near a majority polarity element, within the coronal hole, the resulting mixed polarity region is associated with a bright-point-like emission in coronal EUV lines such as the Fe XII 195 Å. These coronal bright points are also observed distinctly in the EIT 304 Å band, but not in microwaves. On the other hand, the lower-temperature line emission (304 Å) and the microwave enhancement are associated with the unipolar magnetic flux elements in the network. We found strong time variability of the radio enhancement over multiple timescales, consistent with the initial results obtained by SOHO instruments. The microwave enhancement is most probably due to temperature enhancement in the chromosphere and may be related to the origin of solar wind. Title: Synoptic Sun during the first Whole Sun Month Campaign: August 10 to September 8, 1996 Authors: Biesecker, D. A.; Thompson, B. J.; Gibson, S. E.; Alexander, D.; Fludra, A.; Gopalswamy, N.; Hoeksema, J. T.; Lecinski, A.; Strachan, L. Bibcode: 1999JGR...104.9679B Altcode: A large number of synoptic maps from a variety of instruments are used to show the general morphology of the Sun at the time of the First Whole Sun Month Campaign. The campaign was conducted from August 10 to September 8, 1996. The synoptic maps cover the period from Carrington rotation 1912/253° to Carrington rotation 1913/45°. The synoptic maps encompass both on-disk data and limb data from several heights in the solar atmosphere. The maps are used to illustrate which wavelengths and data sets show particular features, such as active regions and coronal holes. Of particular interest is the equatorial coronal hole known as the ``elephant's trunk,'' which is clearly evident in the synoptic maps of on-disk data. The elephant's trunk is similar in appearance to the Skylab-era, ``Boot of Italy,'' equatorial coronal hole. The general appearance of the limb maps is explained as well. The limb maps also show evidence for equatorial coronal holes. Title: Radio Imaging of the Sun from Space Authors: Rodriguez, P.; Kassim, N. E.; Weiler, K. W.; Kaiser, M. L.; Reiner, M. J.; MacDowall, R. A.; Jones, D. L.; Unwin, S. C.; Kuiper, T. B.; Gopalswamy, N. Bibcode: 1999AAS...194.7604R Altcode: 1999BAAS...31R.956R Since the 1960s, ground-based radio astronomers have had the capability to image solar radio emissions using aperture synthesis techniques. These images show the two-dimensional time history of CME-driven shock fronts, for example. However, ground-based observations are limited by the terrestrial ionosphere to frequencies above about 15 MHz, which corresponds to a maximum solar altitude of about one solar radius. To probe the altitude range from one solar radius to one AU requires space-based radio telescopes. Many space-based low-frequency radio telescopes have flown over the past three decades, but they all suffered from lack of angular resolution because they consisted of single spacecraft carrying simple dipole antennas. Even with this limitation, much progress has been made by utilizing spacecraft spin to deduce source location and size, thereby permitting tracking of solar radio sources between the sun and Earth. However, no structural detail is available from this technique, only source centroids and approximate angular size. To provide a greater level of structural detail, we need to take the next logical step in low-frequency solar radio astronomy: aperture synthesis from space. We believe this can be done with currently-available hardware as a medium-class Explorer (MIDEX) mission. This mission would consist of approximately 16 identical and quite simple micro-spacecraft in a spherical array approximately 100 km in diameter. The array should be situated relatively far from Earth (to lessen terrestrial interference), such as at the distant retrograde class of orbits at about one million kilometers from Earth. This array will be capable of imaging not only solar transient events to unprecedented altitudes, but also the quiet sun, the entire terrestrial magnetosphere via scattering in the magnetosheath, and the low-frequency cosmic background, the latter being a totally unexplored radio window. This work is supported in part by ONR and NASA. Title: The Long Wavelength Array: A Ground-Based Coronal Mass Ejection Detector Authors: Lazio, T. J. W.; Kassim, N. E.; Rodriguez, P.; Gopalswamy, N.; Erickson, W. C. Bibcode: 1999AAS...194.7605L Altcode: 1999BAAS...31..956L We describe the Long Wavelength Array (LWA), a ground-based radio interferometer capable of serving as a coronal mass ejection (CME) detector. Previous low-frequency (nu < 50 MHz) coronal sounding experiments have shown that CMEs exhibit large radar cross sections. The LWA will serve as the imaging receiver for a bi-static radar observatory that will open an entirely new field of CME research. Because the LWA will be a synthesis interferometer, it will be capable of imaging the return echo as well as measuring its Doppler shift. The combination of Doppler shift, to provide the radial velocity, and the imaging, to provide the transverse velocity, means that the LWA will determine the total space velocity of the CME, crucial for inferring arrival times of Earthward-bound events for geomagnetic storm predictions. A ground-based system operating with low cost HF/VHF technology, the LWA will be considerably less expensive and more reliable than planned stereoscopic space-based CME detection schemes. In addition to the practical importance to spacecraft, communication, and electrical power systems, the reliable detection and monitoring of CMEs will allow the study of the angular distribution, ranges, and line-of-sight velocities of CMEs. Additional papers at this meeting describe possibilities of the LWA for astrophysical applications (Kassim et al.) and passive solar observations (Gopalswamy et al.). Basic research in radio astronomy at the Naval Research Laboratory is supported by the Office of Naval Research. Title: Reply Authors: Gopalswamy, N.; Kaiser, M. L.; Lepping, R. P.; Berdichevsky, D.; Ogilvie, K.; Kahler, S. W.; Kondo, T.; Isobe, T.; Akioka, M. Bibcode: 1999JGR...104.4749G Altcode: No abstract at ADS Title: The Catholic University of America Institute for Astrophysics and Computational Sciences, Department of Physics, Washington, District of Columbia 20064. Report for the period Sep 1997 - Sep 1998. Authors: Gopalswamy, N. Bibcode: 1999BAAS...31...13G Altcode: No abstract at ADS Title: Study of the dynamics of the solar RA(7794) during october 29 1994 with VLA at 2 and 20 cm. Authors: Torres Papaqui, J. P.; Gopalswamy, N.; Mendoza-Torres, J. E. Bibcode: 1998larm.confE..16T Altcode: We report VLA observation made at 2 and 20 cm of a solar active region (AR) where flares, were observed in October 29, 1994. The aim of the work is to study the variations in intensity and polarization, during this day, of different zones in the AR. The zones under study are: 1) Those where the flares took place, 2) the zones of the AR where the maximum intensities, during the day, were observed and 3) the zones of higher polarization. The zones where the flares occurred were selected to follow the time variati ons before and after the flares. The other zones were selected to look for possible variables that could be related to the flares. An IDL programm that allows systematically analyse temporal variations of different zones was made. The program was applied to images made for time intervals of 10 sec. The whole interval of observations was of about 6 hours. The results of this analysis are presented in this work. Title: On the relationship between coronal mass ejections and magnetic clouds Authors: Gopalswamy, N.; Hanaoka, Y.; Kosugi, T.; Lepping, R. P.; Steinberg, J. T.; Plunkett, S.; Howard, R. A.; Thompson, B. J.; Gurman, J.; Ho, G.; Nitta, N.; Hudson, H. S. Bibcode: 1998GeoRL..25.2485G Altcode: We compare the substructures of the 1997 February 07 coronal mass ejection (CME) observed near the Sun with a corresponding event in the interplanetary medium to determine the origin of magnetic clouds (MCs). We find that the eruptive prominence core of the CME observed near the Sun may not directly become a magnetic cloud as suggested by some authors and that it might instead become the ”pressure pulse” following the magnetic cloud. We substantiate our conclusions using time of arrival, size and composition estimates of the CME-MC substructures obtained from ground based, SOHO and WIND observations. Title: Type II radio emissions in the frequency range from 1-14 MHz associated with the April 7, 1997 solar event Authors: Kaiser, M. L.; Reiner, M. J.; Gopalswamy, N.; Howard, R. A.; St. Cyr, O. C.; Thompson, B. J.; Bougeret, J. -L. Bibcode: 1998GeoRL..25.2501K Altcode: We present an analysis of radio emissions associated with the April 7, 1997 solar eruptive event. The event consisted of a filament disappearance, a complex two-phase coronal mass ejection (CME), and a C6.9, 2N flare. At the same time, intermittent type II radio emissions in the frequency range 1-10 MHz, corresponding to an altitude range of 2-15 Ro, were observed by the Wind/WAVES radio receiver. Using the onset times and inferred heights and speeds of the radio bursts, we considered both a CME-driven shock and a flare-associated blast wave shock as possible causes of the type II radio emissions. We conclude that some of the radio emissions in the WAVES data are associated with each shock. The type II radio emissions associated with the blast wave shock were farther from the sun than any emission of this type that has been reported previously. Title: The solar origin of the January 1997 coronal mass ejection, magnetic cloud and geomagnetic storm Authors: Webb, D. F.; Cliver, E. W.; Gopalswamy, N.; Hudson, H. S.; St. Cyr, O. C. Bibcode: 1998GeoRL..25.2469W Altcode: The magnetic cloud and geomagnetic storm on January 10-11, 1997 were associated with a halo-type Coronal Mass Ejection (CME) observed by the SOHO/LASCO coronagraphs near the sun on January 6. We summarize the solar activity related to this CME and the subsequent storm at Earth. This solar activity was remarkably weak and unimpressive. If the wide CME had not been observed, the storm would not have been forecast. Thus this case represents an extreme example of so-called “problem” magnetic storms that lack obvious surface signatures of eruptive solar activity. It supports the view that CMEs involve the destabilization of large-scale coronal structures which may or may not have associated surface activity, and that CMEs, not the surface activity, are the key causal link between solar eruptions and space weather at Earth. Title: Spatial Structure of Solar Coronal Magnetic Loops Revealed by Transient Microwave Brightenings Authors: Zhang, J.; Gopalswamy, N.; Kundu, M. R.; Schmahl, E. J.; Lemen, J. R. Bibcode: 1998SoPh..180..285Z Altcode: We present the measurement of magnetic field gradient in magnetic loops in the solar corona, based on the multi-wavelength Very Large Array observations of two transient microwave brightenings (TMBs) in the solar active region 7135. The events were observed at 2 cm (spatial resolution ∼ 2=) and 3.6 cm (spatial resolution ∼ 3=) with a temporal resolution of 3.3 s in a time-sharing mode. Soft X-ray data (spatial resolution ∼ 2.5=) were available from the Soft X-ray Telescope on board the Yohkoh satellite. The three-dimensional structure of simple magnetic loops, where the transient brightenings occurred, were traced out by these observations. The 2-cm and 3.6-cm sources were very compact, located near the footpoint of the magnetic loops seen in the X-ray images. For the two events reported in this paper, the projected angular separation between the centroids of 2 and 3.6-cm sources is about 2.3= and 3.1=, respectively. We interpret that the 2 and 3.6-cm sources come from thermal gyro-resonance emission. The 2-cm emission is at the 3rd harmonic originating from the gyro-resonance layer where the magnetic field is 1800 G. The 3.6-cm emission is at the 2nd harmonic, originating from the gyro-resonance layer with a magnetic field of 1500 G. The estimated magnetic field gradient near the footpoint of the magnetic loop is about 0.09 G km=1 and 0.12 G km=1 for the two events. These values are smaller than those observed in the photosphere and chromosphere by at least a factor of 2. Title: Coronal Dimming Associated with a Giant Prominence Eruption Authors: Gopalswamy, N.; Hanaoka, Y. Bibcode: 1998ApJ...498L.179G Altcode: We report the results of our investigation of a giant eruptive prominence (initial mass ~6×1016 g) using microwave, X-ray, and white-light observations. The prominence erupted from the northwest limb of the Sun on 1994 April 5. The speed of the prominence was only ~70 km s-1 when it reached a height of ~0.5 Rsolar above the solar surface. In X-rays, a large region with reduced X-ray emission was observed enveloping the initial location of the prominence and extending to much larger heights. At the bottom of this depletion and beneath the eruptive prominence, an X-ray arcade formed, progressively spreading from south to north along the limb. This is the first time a direct detailed comparison is made between coronal dimming and a prominence eruption. We were able to confirm that the coronal dimming is indeed a near-surface manifestation of the coronal mass ejection (CME). The orientation of the structures involved did not allow the observations of the coronal cavity, but all the other substructures of the CME could be identified. The mass expelled from the Sun in the form of the eruptive prominence and the coronal dimming are comparable. The estimated total mass is somewhat larger than that reported in other X-ray-dimming events. Title: Microwave and Soft X-ray Study of Solar Active Region Evolution Authors: Lara, A.; Gopalswamy, N.; Kundu, M. R.; Pérez-Enríquez, R.; Koshiishi, H.; Enome, S. Bibcode: 1998SoPh..178..353L Altcode: We have studied the properties and evolution of several active regions observed at multiple wavelengths over a period of about 10 days. We have used simultaneous microwave (1.5 and 17 GHz) and soft X-ray measurements made with the Very Large Array (VLA), the Nobeyama Radio Heliograph (NRH) and the Soft X-ray Telescope (SXT) on board the Yohkoh spacecraft, as well as photospheric magnetograms from KPNO. This is the first detailed comparison between observations at radio wavelengths differing by one order of magnitude. We have performed morphological and quantitative studies of active region properties by making inter-comparison between observations at different wavelengths and tracking the day-to-day variations. We have found good general agreement between the 1.5 and 17 GHz radio maps and the soft X-rays images. The 17 GHz emission is consistent with thermal bremsstrahlung (free-free) emission from electrons at coronal temperatures plus a small component coming from plasma at lower temperatures. We did not find any systematic limb darkening of the microwave emission from active regions. We discuss the difference between the observed microwave brightness temperature and the one expected from X-ray data and in terms of emission of a low temperature plasma at the transition region level. We found a coronal optical thickness of ∼ 10-3 and ∼ 1 for radiation at 17 and 1.5 GHz, respectively. We have also estimated the typical coronal values of emission measure (∼ 5 × 1028 cm-5), electron temperature (∼ 4.5 × 1066 K) and density (∼ 1.2 × 109 cm3). Assuming that the emission mechanism at 17 GHz is due to thermal free-free emission, we calculated the magnetic field in the source region using the observed degree of polarization. From the degree of polarization, we infer that the 17 GHz radiation is confined to the low-lying inner loop system of the active region. We also extrapolated the photospheric magnetic field distribution to the coronal level and found it to be in good agreement with the coronal magnetic field distribution obtained from microwave observations. Title: Multiwavelength Observations of a Coronal Hole Authors: Gopalswamy, N.; Shibasaki, K.; Deforest, C. E.; Bromage, B. J. I.; Del Zanna, G. Bibcode: 1998ASPC..140..363G Altcode: 1998ssp..conf..363G No abstract at ADS Title: Comparison of Microwave and SOHO Synoptic Maps of the Sun During the Whole Sun Month, 1996 Authors: Gopalswamy, N.; Thompson, B. J.; Shibasaki, K. Bibcode: 1998ASPC..140..401G Altcode: 1998ssp..conf..401G No abstract at ADS Title: The Catholic University of America, Institute for Astrophysics and Computational Sciences, Department of Physics, Washington, DC 20064. Report for the period Sep 1996 - Sep 1997. Authors: Gopalswamy, N. Bibcode: 1998BAAS...30...32G Altcode: No abstract at ADS Title: Radio and X-ray Investigations of Erupting Prominences (Review) Authors: Gopalswamy, N.; Hanoka, Y.; Lemen, J. R. Bibcode: 1998ASPC..150..358G Altcode: 1998IAUCo.167..358G; 1998npsp.conf..358G No abstract at ADS Title: Birth Place of the 1998 January 21 CME Authors: Gopalswamy, N.; Hanaoka, Y.; Kaiser, M.; Gurman, J.; Hudson, H.; Howard, R. A. Bibcode: 1998cee..workE..40G Altcode: The 1998 January 21 halo coronal mass ejection was launched from high southern latitudes in association with a filament disappearance observed by the Nobeyama Radioheliograph. Signatures of the initial destabilization of the filament were observed by the Extreme-ultraviolaet Imaging Telescope (EIT) on board the SOHO spacecraft and by the Soft X-ray Telescope (SXT) on board Yohkoh. The Wind/WAVES experiment observed a type II burst in the 600-300 kHz range. The data coverage for this event is unusually high and we make use of it to understand the origin and evolution of the eruption. We address several issues based on these data: (i) relation between filament eruption and arcade formation beneath the filament, (ii) comparison between the hot arcade formation in X-rays and EUV, (iii) relation between the filament eruption and the white light CME, (iv) relation between the CME and the interplanetary shock inferred from the WAVES data. A summary of near-surface activities associated with the eruption can be seen in the Figure 1. Figure 1. SOHO/MDI longitudinal magnetogram, with radio filament (white contours) and X-ray emission (enclosed by dark lines) are overlaid. The thick white line from E to W is the neutral line over which the eruption took place. North is to the top and east is to the left. F is the location where the filament split at the time of eruption. Title: Microwave Imaging in Support of the SERTS'97 Flight Authors: Gopalswamy, N.; Hanaoka, Y. Bibcode: 1998AAS...191.7317G Altcode: 1998BAAS...30..758G The Solar Extreme-ultraviolet Rocket Telescope and Spectrograph flown successfully on 1997 November 18 at 19:35 UT and an observing campaign was conducted to support the flight. Coordinated observations were obtained by SOHO and YOHKOH and many ground based instruments. Radio observations were obtained by the Very Large Array (VLA) and the Nobeyama Radioheliograph in microwaves. The SERTS target was the trailing portion of a large active region (NOAA AR 8108) close to the disk center (N19E17 at 19:40 UT on 1997 November 18). The VLA obtained microwave images at 20, 6 and 3.6 cm wavelengths with a spatial resolution of about 40", 12" and 7" respectively. The Nobeyama images (spatial resolution 10") were obtained a few hours later at 1.7 cm. The microwave images (in total intensity and circular polarization) provide information on the physical conditions (temperature, density and magnetic field) in the active region corona and in sunspots at various heights above the solar surface. The AR was relatively quiet during the SERTS flight, so we can determine its quiescent properties. We present preliminary radio images of AR 8108 and the physical conditions derived from them. We thank T. Bastian for help in obtaining VLA observing time. This research was supported by NASA grant NAG-5-6139. Title: Origin of coronal and interplanetary shocks: A new look with WIND spacecraft data Authors: Gopalswamy, N.; Kaiser, M. L.; Lepping, R. P.; Kahler, S. W.; Ogilvie, K.; Berdichevsky, D.; Kondo, T.; Isobe, T.; Akioka, M. Bibcode: 1998JGR...103..307G Altcode: We have investigated type II radio bursts in the solar corona using data from ground-based radio telescopes (>18MHz) and from the Radio and Plasma Wave experiment (WAVES) on board the WIND spacecraft (<14MHz). The wavelength range of the WAVES experiment includes the 2- to 14-MHz band, previously unobserved from space. We found that all 34 coronal type II bursts observed over a period of 18 months (November 1, 1994, to April 30, 1996), decayed within a few solar radii and did not propagate into the interplanetary medium. On the other hand, most of the accompanying type III radio bursts observed by the ground-based instruments were observed to continue into the interplanetary medium as the electron beams propagated freely along open magnetic field lines. Over the same period of time, other instruments on board the WIND spacecraft detected about 18 interplanetary shock candidates, which seem to be unrelated to the coronal type II bursts. This result confirms the idea that the coronal and interplanetary shocks are two different populations and are of independent origin. We reexamine the data and conclusions of Gosling et al. [1976], Munro et al. [1979], and Sheeley et al. [1984] and find that their data are consistent with our result that the coronal type II bursts are due to flares. We also briefly discuss the implications of our result to the modeling studies of interplanetary shocks based on input from coronal type II radio bursts. Title: Fast Time Structure during Transient Microwave Brightenings: Evidence for Nonthermal Processes Authors: Gopalswamy, N.; Zhang, J.; Kundu, M. R.; Schmahl, E. J.; Lemen, J. R. Bibcode: 1997ApJ...491L.115G Altcode: 1997astro.ph.10200G Transient microwave brightenings (TMBs) are small-scale energy releases from the periphery of sunspot umbrae with a flux density 2 orders of magnitude smaller than that from a typical flare. Gopalswamy et al. first reported the detection of the TMBs, and it was pointed out that the radio emission implied a region of very high magnetic field so that the emission mechanism has to be gyroresonance or nonthermal gyrosynchrotron, but not free-free emission. It was not possible to decide between gyroresonance and gyrosynchrotron processes because of the low time resolution (30 s) used in the data analysis. We have since performed a detailed analysis of the Very Large Array data with full time resolution (3.3 s) at two wavelengths (2 and 3.6 cm), and we can now adequately address the question of the emission mechanism of the TMBs. We find that nonthermal processes indeed take place during the TMBs. We present evidence for nonthermal emission in the form of temporal and spatial structure of the TMBs. The fast time structure cannot be explained by a thermodynamic cooling time and therefore requires a nonthermal process. Using the physical parameters obtained from X-ray and radio observations, we determine the magnetic field parameters of the loop and estimate the energy released during the TMBs. The impulsive components of TMBs imply an energy release rate of ~1.3×1022 ergs s-1, so the thermal energy content of the TMBs could be less than ~1024 ergs. Title: X-Ray and Radio Studies of a Coronal Eruption: Shock Wave, Plasmoid, and Coronal Mass Ejection Authors: Gopalswamy, N.; Kundu, M. R.; Manoharan, P. K.; Raoult, A.; Nitta, N.; Zarka, P. Bibcode: 1997ApJ...486.1036G Altcode: On 1994 July 31, a fast (900 km s-1) eruptive structure was observed in X-rays, followed by a slower plasmoid (180 km s-1). They were associated with a coronal mass ejection, prominence eruption, and a host of metric radio bursts. The X-ray structure seems to be a part of a white light coronal mass ejections (CME), as inferred from the white light images of July 30 and 31. A type II burst was observed at the leading edge of the X-ray eruption, while a type IV burst was spatially associated with the detached plasmoid. The type III radio bursts occurred on thin overdense structures associated with the eruption. We detected the rise of plasma levels because of mass addition to the type III burst sources as a result of the eruption. This event further clarifies the manifestation of a CME in X-rays. We identify the X-ray eruption as the driver of the coronal shock wave. This provides answer to the long-standing question regarding the origin of coronal and interplanetary shock waves. We have also found evidence to support the idea that herringbone bursts are produced when the coronal shock wave crosses open magnetic field lines. Title: Signatures of Coronal Currents in Microwave Images Authors: Lee, Jeongwoo; White, Stephen M.; Gopalswamy, N.; Kundu, M. R. Bibcode: 1997SoPh..174..175L Altcode: Microwave emission from solar active regions at frequencies above 4 GHz is dominated by gyroresonance opacity in strong coronal magnetic fields, which allows us to use radio observations to measure coronal magnetic field strengths. In this paper we demonstrate one powerful consequence of this fact: the ability to identify coronal currents from their signatures in microwave images. Specifically, we compare potential-field (i.e., current-free) extrapolations of photospheric magnetic fields with microwave images and are able to identify regions where the potential extrapolation fails to predict the magnetic field strength required to explain the microwave images. Comparison with photospheric vector magnetic field observations indicates that the location inferred for coronal currents agrees with that implied by the presence of vertical currents in the photosphere. The location, over a neutral line exhibiting strong shear, is also apparently associated with strong heating. Title: Tracking a CME from Cradle to Grave: A Multi-wavelength Analysis of the February 6-7, 1997 Event Authors: Gopalswamy, N.; Kundu, M. R.; Hanaoka, Y.; Kosugi, T.; Hudson, H.; Nitta, N.; Thompson, B.; Gurman, J.; Plunkett, S.; Howard, R.; Burkepile, J. Bibcode: 1997SPD....28.0501G Altcode: 1997BAAS...29..908G The partially earth-directed coronal mass ejection (CME) event of 1997 February 6-7 originated from the southwest quadrant of the sun. The CME accelerated from 170 km/s to about 830 km/s when it reached a distance of 25 solar radii. The CME was an arcade eruption followed by bright prominence core structures. The prominence core was tracked continuously from the solar surface to the interplanetary medium by combining data from the Nobeyama radioheliograph (microwaves), Mauna Loa Solar Observatory (He 10830 { Angstroms}), SOHO/EIT (EUV) and SOHO/LASCO (white light). The CME was accompanied by an arcade formation, fully observed by the YOHKOH/SXT (soft X-rays) and SOHO/EIT (EUV). The X-ray and EUV observations suggest that the reconnection proceeded from the northwest end to the southeast end of a filament channel. In the SOHO/EIT images, the the feet of the soft X-ray arcade were observed as EUV ribbons. The CME event also caused a medium sized geomagnetic storm: The hourly equatorial Dst values attained storm level during 18:00-19:00 UT on February 09. This means the disturbance took about 2.25 days to reach the Earth. The first signatures of an IP shock was a pressure jump in the WIND data around 13:00 UT on Feb 09, 1997 which lasted for about 14 hours, followed by flux rope signatures. This CME event confirms a number of ideas about CMEs: The three part structure (frontal bright arcade, dark cavity and prominence core), disappearing filament, elongated arcade formation, and terrestrial effects. We make use of the excellent data coverage from the solar surface to the Earth to address a number of issues regarding the origin and propagation of the geoeffective solar disturbances. We benefited from discussions at the first SOHO-Yohkoh Coordinated Data Analysis Workshop, held March 3-7, 1997, at Goddard Space Flight Center. Title: The Solar Source of the January 1997 CME/Magnetic Cloud; Recurrent Activity on a Polar Crown Filament Channel Authors: Webb, David; Cliver, E.; McIntosh, P.; Gopalswamy, N.; Hudson, H. Bibcode: 1997SPD....28.1501W Altcode: 1997BAAS...29..918W The magnetic cloud and geomagnetic storm on 10-11 January 1997 was associated with a halo-type CME observed by LASCO near the sun on 6 January. As part of the ISTP and SHINE collaboration on this event we are studying the solar source region of the CME and its propagation through the interplanetary medium to Earth. We summarize the rather weak solar activity that apparently was associated with this CME, and contrast it with the strong surface and coronal activity associated with the 9-11 February 1997 magnetic cloud/storm. We present evidence that the solar sources of both of these events occurred over an area where the southern polar crown filament channel diverted sharply to the north and in the decaying remnants of the first large-scale active region to form during the new solar cycle. Our results also suggest that this region was the site of earlier CMEs; i.e., it was a key site of recurrent activity during 1996-97 which, when aimed toward Earth, produced recurrent magnetic clouds and storms. Title: Multi-wavelength Observations of Transient Microwave Brightenings in a Solar Active Region Authors: Zhang, Jie; Gopalswamy, N.; Kundu, M. R.; Schmahl, E. J.; Lemen, J. R. Bibcode: 1997SPD....28.0163Z Altcode: 1997BAAS...29..891Z We present multi-wavelength Very Large Array observations of two transient microwave brightenings (TMBs) in the solar active region 7135. The events were observed at 2 cm (spatial resolution ~ 2'') and 3.6 cm (spatial resolution ~ 3'') with a temporal resolution of 3.3 s in a time-sharing mode. Soft X-ray data (about 5'' spatial resolution) were available from the Soft X-ray Telescope on board the YOHKOH satellite. The 2 cm and 3.6 cm emission sources were very compact, located near the footpoint of the magnetic loops seen in the X-ray images. The TMBs traced out the three dimensional structure of the magnetic loops where the transient brightenings occurred. For the two events reported in this paper, the projected angular separation between the centroids of 2 and 3.6 cm source is about 2.3'' and 3.1'', respectively. We interpret the spatial and temporal distributions as implying that the 2 and 3.6 cm flux is mainly due to thermal gyro-resonance emmision. The 2 cm emission seems to be at the 3rd gyro-harmonic coming from the 1800 G gyro-resonance layer. The 3.6 cm emission seems to be at both the 2nd and 3rd harmonics, originating from gyro-resonance layers with a magnetic field of 1500 G and 1000 G, respectively. However, the two gyro-resonance layers for 3.6 cm emission are not resolved with the current spatial resolution. The estimated magnetic field gradient near the footpoint of the magnetic loop is about 0.17 G km(-1) and 0.22 G km(-1) for the two events. Title: Source Parameters for Impulsive Bursts Observed in the Range 18-23 GHz Authors: Sawant, H. S.; Rosa, R. R.; Cecatto, J. R.; Gopalswamy, N. Bibcode: 1997SoPh..171..155S Altcode: Here, we report on impulsive solar radio bursts observed for the first time with high time/spectral resolution in the range 18 to 23 GHz. Using observational parameters and assuming nonthermal gyrosynchrotron emission from energetic electrons in a loop structure, we have estimated the density of nonthermal electrons, magnetic field, and dimension of the source along the line of sight. Title: A Multi-Wavelength Analysis of the February 6/7, 1997 Coronal Mass Ejection Authors: Plunkett, S. P.; Gopalswamy, N.; Kundu, M. R.; Howard, R. A.; Thompson, B. J.; Gurman, J. B.; Lepping, R. P.; Hudson, H. S.; Nitta, N.; Hansoka, Y.; Kosugi, T.; Burkepile, J. T. Bibcode: 1997ESASP.404..615P Altcode: 1997cswn.conf..615P No abstract at ADS Title: Radio and X-Ray Studies of a Coronal Mass Ejection Associated with a Very Slow Prominence Eruption Authors: Gopalswamy, N.; Hanaoka, Y.; Kundu, M. R.; Enome, S.; Lemen, J. R.; Akioka, M.; Lara, A. Bibcode: 1997ApJ...475..348G Altcode: We report on the observations of an X-ray coronal mass ejection (CME) with its three part structure: frontal loop, coronal cavity, and the eruptive prominence core. The prominence core was observed in microwaves, and the frontal loop was observed in X-rays. A coronal volume much larger than that occupied by the prominence seems to be affected by the eruption. Formation of an arcade structure was also observed beneath the erupting prominence. X-ray enhancement at the arcade persisted for several hours similar to long decay events. At the apex of the arcade there was a bright knot, which we interpret as the reconnection region from which the filament gets detached. We determined the trajectories of the frontal loop and the prominence core and found them to have very different characteristics. The CME showed an extremely small acceleration, while the prominence had a linear motion in the beginning followed by an exponential rise. However, during the several hours of simultaneous observation, the prominence did not catch up with the frontal loop. We determined the evolution of the CME mass, which increased by a factor of 4 during our observations. We discuss the implications of the observations in the general context of coronal mass ejections. Title: A Giant Prominence Eruption Observed by Nobeyama Radioheliograph and YOHKOH Spacecraft Authors: Gopalswamy, N.; Hanaoka, Y.; Kundu, M. R.; Shibasaki, K.; Koshiishi, H.; Enome, S.; Lemen, J. R. Bibcode: 1997IAUJD..19E...4G Altcode: The results of an investigation of a giant prominence which erupted from the northwest limb of the Sun on 1994 April 05, will be reported. The event could be traced back to a large prominence of March 19, 1994 above the east limb. The filament was located in the north-south direction when it appeared on the disk. At about 23:00 UT on April 05, the filament started slowly rising and then accelerated. The speed of the prominence was was only 75 km s^{-1} when it reached a height of about 0.5 R_ odot above the surface. Preliminary examination shows that the eruption caused a geomagnetic storm on April 07 at 20:00 UT. We study the dynamical and physical properties of the erupting prominence and obtain physical parameters of the prominence plasma. In X-rays, the region of eruption was relatively faint. After the eruption, however, there was a large void at the previous location of the prominence and an arcade formed progressively spreading from south to north along the limb. Based on the X-ray and radio observations, we determine the characteristics of the pre- and post-eruption structures. Title: Yohkoh/SXT observations of a coronal mass ejection near the solar surface Authors: Gopalswamy, N.; Kundu, M. R.; Hanaoka, Y.; Enome, S.; Lemen, J. R.; Akioka, M. Bibcode: 1996NewA....1..207G Altcode: We report the observations of a coronal mass ejection (CME) using the Soft X-ray Telescope on board the Yohkoh Mission. The CME had the familiar three part structure (frontal loop, prominence core and a cavity). The erupting prominence was observed by the Nobeyama radioheliograph. We were able to determine the mass of the CME (2.6 × 1014 g) from X-ray observations which seems to be at the lower end of the range of CME masses reported before from white light observations. This is the first time the mass of a CME has been determined from X-ray observations. The height of onset of the CME was 0.3R⊙. The CME moved much faster than the erupting prominence while its acceleration was smaller than that of the erupting prominence. J. Leonard Culhane Title: Radio and X-ray manifestations of a bright point flare Authors: Gopalswamy, N.; Kundu, M. R.; Hanaoka, Y.; Enome, S.; Lemen, J. R. Bibcode: 1996AIPC..374..408G Altcode: 1996hesp.conf..408G We have found remarkably different manifestations of a bright point flare in X-ray and radio (microwave) wavelengths, unlike previous observations. In X-rays, the BP flare was relatively simple while in radio, the bright point flare had a large scale component and a transient moving component. The large scale structure may be the radio counterpart of large scale structures sometimes seen during X-ray BP flares. The transient component was also compact and moved away from the location of the X-ray BP flare with a speed of ∼60 km s-1. The compact source also showed fast time structure which suggests nonthermal emission mechanism for the transient sources. Title: Tracking Type III and Type II Solar Radio Bursts from Metric to Hectometric Wavelengths using Ground-based and Space-borne Observations Authors: Gopalswamy, N.; Kundu, M. R.; Kaiser, M. L.; Kahler, S. W.; Kondo, T.; Isobe, T.; Akioka, M. Bibcode: 1996AAS...188.1908G Altcode: 1996BAAS...28..851G There exists a controversy regarding the origin of coronal and interplanetary (IP) shocks. Present observations shows that coronal shocks are associated with flares while the IP shocks are associated with coronal mass ejections (CMEs). An important question in this connection is whether the IP shocks are extensions of the coronal shocks or they are independently driven by CMEs. The coronal shocks have traditionally been inferred from metric type II radio bursts. The ionospheric cut-off around 20 MHz had been a hurdle in arriving at a firm conclusion regarding the continuation of type II bursts to frequencies lower than the ionospheric cut off. The WAVES experiment on board the WIND spacecraft has essentially removed this hurdle so that we are able to track metric radio bursts to hectometric wavelengths. We have identified about two dozen type II bursts observed by the Hiraiso Radio Spectrograph (HiRAS) after the launch of the WIND satellite. Most of these type II bursts were accompanied by type III bursts. We have positively identified the solar flares associated with all the events. When we examined the WIND Radio and Plasma waves (WAVES) data, we found the following: (i) Most of the metric (Hiraiso) type III bursts have counterparts in the WAVES data; (ii) None of the metric type II bursts have counterparts in the WAVES data. This result suggest that coronal shocks responsible for metric type II bursts are blast waves which decay rapidly within the inner corona while the electron beams producing type III bursts continue to propagate to the IP medium. Title: Polarization of Microwaves Emitted From A Bipolar Active Region Authors: Lee, Jeongwoo; White, Stephen; Gopalswamy, N.; Kundu, M. R. Bibcode: 1996AAS...188.3603L Altcode: 1996BAAS...28R.873L High resolution microwave maps of a complex bipolar active region, AR6615, were obtained using the VLA on 1991 May 7 at three frequencies, 4.9 GHz, 8.4 GHz, and 15 GHz. Comparison of this microwave observation with Big Bear magnetogram suggests that inversion and depolarization of microwave emission must have occurred at different sites of the active region depending on frequency. For quantitative interpretation of the polarization data, we constructed the coronal magnetic fields above the active region using the potential field extrapolation. In the model, we identified the quasi-transverse (QT) surface across which change of the polarization may occur. It is found that the required topology of the QT surface to explain the observed polarization is correctly predicted by the potential field model, although the locations of the 15 GHz gyroresonance sources required a nonlinear force-free field extrapolation in part. With the calculation of the mode coupling coefficient along the QT surface, we were able to locate the region of depolarization above a strong sunspot, consistent with the observation. We also discuss the appropriate theoretical gyroresonant opacity for waves propagating perpendicular to the magnetic fields, as needed to understand the observed polarization across the magnetic neutral line. Applicability of the present results to study of the coronal magnetic structure above complex bipolar regions, in general, is briefly discussed. Title: A Multi Wavelength Study of Active Region Development Authors: Lara, A.; Gopalswamy, N.; Kundu, M. R.; Perez-Enriquez, R.; Koshiishi, H.; Enome, S. Bibcode: 1996AAS...188.3601L Altcode: 1996BAAS...28Q.873L We report on a study of the evolution of several active regions during 1993 April 17-28 using data obtained at multiple wavelengths that probe various heights of the active region corona. We use simultaneous microwave (1.5 and 17 GHz) and Soft X-ray images obtained by the Very Large Array (VLA), the Nobeyama Radio Heliograph (NRH) and the Soft X-ray Telescope (SXT) on board the Yohkoh spacecraft. We also use photospheric magnetograms from Kitt Peak National Observatory to study the development of Solar Active Regions. We have followed the development of various observed parameters such as brightness temperature and polarization using radio images. The X-ray data were used to track the development of density and temperature of active regions. Using the fact that the quiet active region radiation is thermal and adopting proper emission mechanism at each frequency domain, we construct a consistent picture for the three dimensional structure of the active regions. Particular attention has been paid to the mode coupling observed at 17 GHz while the active regions crossed the solar disk. Title: Coronal Disconnection Events and Metric Radio Emisison Authors: Gopalswamy, N. Bibcode: 1996Ap&SS.243..129G Altcode: 1996IAUCo.154..129G We review the existing literature on the coronal disconnection events (CDEs) and discuss the importance of these events in understanding coronal structures. We discuss the possible radio signatures of the CDEs and how they may be observed by radio instruments. Title: Detection of Large-Scale Radio Structure and Plasma Flow during a Solar Bright Point Flare Authors: Gopalswamy, N.; Kundu, M. R.; Hanaoka, Y.; Enome, S.; Lemen, J. R. Bibcode: 1996ApJ...457L.117G Altcode: We report on the detection of a large-scale radio structure and plasma flow associated with a bright point flare observed on 1993 July 11. The bright point (BP) flare was simultaneously imaged by the Nobeyama radioheliograph at 17 GHz and the Soft X-Ray Telescope on board the Yohkoh mission. The microwave emission consists of a large-scale structure and a compact moving source. The large-scale component seems to be the radio counterpart of large-scale loop structures sometimes observed in association with BP flares in X-rays. The compact source moved from the location of the X-ray BP flare with a speed of about 60 km s-1, which suggests a plasma flow. Spatial comparison between X-ray and radio data shows that the BP flare had different manifestations in the two wavelength domains. The emission peaks in the two wavelength domains did not coincide, which suggests cool plasma flow along the large-scale radio structure. We were able to determine the temperature and emission measure of the BP flare plasma from the X-ray data, and thus we computed the expected radio flux from the X-ray--emitting plasma. We found that the computed radio flux was much smaller than the total observed radio flux. Title: VLA Observations of a Solar Active Region at 6.2 and 3.5 CM Wavelength Compared with Model Calculations Authors: Hildebrandt, J.; Kruger, A.; Gopalswamy, N.; Raulin, J. -P.; Kundu, M. R. Bibcode: 1996ASPC...93..369H Altcode: 1996ress.conf..369H No abstract at ADS Title: Three Part Structure of a CME Revealed by X-Ray and Microwave Observations Authors: Gopalswamy, N.; Kundu, M. R.; Lara, A.; Hanaoka, Y.; Enome, S.; Lemen, J. R.; Akioka, M. Bibcode: 1996ASPC..111..393G Altcode: 1997ASPC..111..393G The authors present X-ray (Yohkoh/SXT) and microwave (17 GHz Nobeyama) observations of the 1993 July 10 - 11 CME. During this event, all the substructures of a classical CME are revealed: frontal loop in X-rays, prominence core in microwaves, dark cavity between prominence and frontal loop in X-rays, and arcade structure beneath the prominence in X-rays. Title: A Study of Active Region Magnetic Field Structure Using VLA-Radio YOHKOH X-Ray and Mess-Optical Observations Authors: Gopalswamy, N. Bibcode: 1995JApAS..16..381G Altcode: No abstract at ADS Title: VLA and YOHKOH Observations of an M1.5 Flare Authors: Gopalswamy, N.; Raulin, J. -P.; Kundu, M. R.; Nitta, N.; Lemen, J. R.; Herrmann, R.; Zarro, D.; Kosugi, T. Bibcode: 1995ApJ...455..715G Altcode: A major solar flare (X-ray importance M1.5 and optical importance SB) was fully observed by the Very Large Array and the Yohkoh mission on 1993 April 22. Both thermal and nonthermal emissions were observed in radio. In soft X-rays, the flare was confined to a compact region in an arcade. In hard X-rays, there were two prominent footpoints, coincident in projection with the soft X-ray footpoints and located on either side of the magnetic neutral line inferred from photospheric magnetograms The Yohkoh Bent Crystal Spectrometer (B CS) data provided important context information which was helpful in cross-checking the quantitative agreement between the radio and X-ray data. The microwave spectrum peaked around 10 GHz and showed Razin suppression in the beginning. Later on, the low-frequency spectral index dropped to a value of 2, suggesting thermal emission. The VLA images of the flare at 1.5 GHz show that the flare emission started as a single source above one footpoint; later on, the emission centroid moved toward the soft X-ray structure to finally become cospatial with the latter. The two locations of the 20 cm source corresponded to nonthermal (footpoint source) and thermal (source cospatial with the soft X-ray structure) emissions. We performed temperature and emission measure analysis of the X-ray data (SXT, BCS, and HXT) and used them as input to determine the expected radio emission. While there is morphological agreement between the radio and soft X-ray structures in the thermal phase, the 20 cm brightness temperature shows quantitative agreement with temperature derived from the BCS data. We were able to identify three emission mechanisms contributing to the 20 cm radio emission at different times without any ad hoc assumption regarding emission mechanisms. Razin-suppressed nonthermal gyroresonance emission, plasma emission, and thermal free-free emission seem to be operating and are found to be consistent with the plasma parameters derived from the X-ray data. The magnetic field structure in the flaring region showed differences before and after the flare as traced b soft X-ray structures in the flaring region and confirmed by 20 cm radio images. The superhot component with a temperature of 32 MK was observed in hard X-ray images and in light curves during the impulsive phase of the flare with possible radio signatures at 20 cm wavelength. We derived the physical parameters of the flaring plasma, the magnetic field, and the characteristics of nonthermal particles in the flaring region. Title: Radio Counterpart of an X-ray Bright Point Flare Authors: Gopalswamy, N.; Kundu, M. R.; Hanaoka, Y.; Enome, S.; Lemen, J. R. Bibcode: 1995SPD....26.1317G Altcode: 1995BAAS...27Q.991G No abstract at ADS Title: Surprises in the Radio Signatures of CMEs Authors: Gopalswamy, N.; Kundu, M. R. Bibcode: 1995LNP...444..223G Altcode: 1995cmer.conf..223G We discuss several results regarding the relationship between coronal mass ejections (CMEs) and metric radio emissions which have changed our understanding of these phenomena considerably. Imaging observations of metric radio emissions along with coronagraph observations have been used to obtain these results. We consider the following: (i) Why slow CMEs are associated with metric type IV radio emission contrary to the earlier belief, (ii) Why shocks piston driven by the CMEs are not seen in the solar corona, (iii) Thermal radio emission from the CMEs and their implications to CME-flare relationship and (iv) Radio signatures of coronas disconnection events. Title: Polarization Features of Solar Radio Emission and Possible Existence of Current Sheets in Active Regions Authors: Gopalswamy, N.; Zheleznyakov, V. V.; White, S. M.; Kundu, M. R. Bibcode: 1994SoPh..155..339G Altcode: We show that it is possible to account for the polarization features of solar radio emission provided the linear mode coupling theory is properly applied and the presence of current sheets in the corona is taken into account. We present a schematic model, including a current sheet that can explain the polarization features of both the low frequency slowly varying component and the bipolar noise storm radiation; the two radiations face similar propagation conditions through a current sheet and hence display similar polarization behavior. We discuss the applications of the linear mode coupling theory to the following types of solar radio emission: the slowly varying component, the microwave radio bursts, metric type U bursts, and bipolar noise storms. Title: Transient Microwave Brightenings in Solar Active Regions: Comparison between VLA and YOHKOH Observations Authors: Gopalswamy, N.; Payne, T. E. W.; Schmahl, E. J.; Kundu, M. R.; Lemen, J. R.; Strong, K. T.; Canfield, R. C.; de La Beaujardiere, J. Bibcode: 1994ApJ...437..522G Altcode: We report observations of transient microwave (2 cm) brightenings and their relationship with brightenings in soft X-rays. The peak flux of the microwave brightenings observed by the Very Large Array (VLA) is smaller than the previously reported fluxes by two orders of magnitude. The microwave sources were highly polarized (up to 100%) and were situated on the periphery of a sunspot umbra. Among the many transients observed in X-rays by Yohkoh, two were observed simultaneously in microwaves. The microwave sources were found to be closer to the umbra of the sunspot than were the X-ray loops. It seems that the microwave sources are located at the footpoints of the looplike X-ray transients. Using the combined VLA, Yohkoh, and Mees data set, we determine the physical parameters of the loop in which the brightenings occur. We find that an increase in emission measure accompanied by small-scale heating can account for the X-ray brightening. The microwave emission can be interpreted as thermal gyroresonance or nonthermal gyrosynchrotron processes during the X-ray brightening. The magnetic field in the microwave-source region is found to be 1200-1800 G. The observations also provide evidence for temperature gradient in the coronal loops. Title: Study of Active Region Magnetic Field Structures Using VLA Radio, YOHKOH X-ray and MEES Optical Observations Authors: Gopalswamy, N.; Schmahl, E. J.; Kundu, M. R.; Lemen, J. R.; Strong, K. T.; Canfield, R. C.; de La Beaujardiere, J. Bibcode: 1994kofu.symp..347G Altcode: We report on the observation of compact magnetic flux tubes from the boundary between the umbra and penumbra of a large sunspot in AR 7135 on April 24, 1992. The structure and geometry of one such flux tube was determined using the coordinated observations obtained by the Very Large Array, the Yohkoh Soft X-ray Telescope and the Mees Solar Observatory. From radio observations we infer that the magnetic field of the flux tube at the spot-side footpoint is ~ 1300-1800 G. Title: Nonthermal Radio Emission Associated with a Coronal Disconnection Event Authors: Gopalswamy, N.; Kundu, M. R.; St. Cyr, O. C. Bibcode: 1994ApJ...424L.135G Altcode: We have found possible radio signatures of a coronal disconnection event observed by the Solar Maximum Mission Coronagraph/Polarimeter. The radio emission seems to be produced by charged particles accelerated during the same reconnection process which is responsible for the disconnection event. We discuss the implications of the radio emission characteristics to the reconnection process. Title: Three dimensional coronal structures using clark lake observations Authors: Schmahl, E. J.; Gopalswamy, N.; Kundu, M. R. Bibcode: 1994AdSpR..14d..65S Altcode: 1994AdSpR..14...65S Throughout the quiet-Sun years 1982-1987, the Clark Lake Radioheliograph mapped the solar corona on a daily basis at frequencies from 30 to 100 MHz. The Clark Lake maps show a variety of features which we have analyzed quantitatively. Among the features are coronal streamers, which appear to cross the solar disk during a solar rotation. We have modeled the streamers with various geometrics and density profiles, and computed ray-tracing images for comparison with the CLRO maps. These models produced estimates of density and spatial scales in 3 dimensions for the streamers. We discuss the significance of these estimates and compare them with inferences made from optical observations. One of the possible conclusions we draw from these comparisons is that there are unresolved structures in stremers, not observable optically in the limb data. Title: Three Dimensional Coronal Structures Using Clark-Lake Observations Authors: Schmahl, E. J.; Gopalswamy, N.; Kundu, M. R. Bibcode: 1994SoPh..150..325S Altcode: We have undertaken a study of coronal features observed at meter-decameter wavelengths using the Clark Lake radioheliograph. Among the coronal structures we have studied are the radio manifestations of coronal streamers on the solar disk and above the solar limb. We have analyzed the radio data quantitatively, using ray-tracing models for comparison with the maps. Our study provides information about the streamers' three-dimensional shapes, scales, and density profiles, for comparison with related observations using white-light coronagraphs. Title: Non-radial magnetic field structures in the solar corona Authors: Gopalswamy, N.; Kundu, M. R.; Raoult, A.; Pick, M. Bibcode: 1994SoPh..150..317G Altcode: We report on the structure and geometry of coronal magnetic fields inferred from the observations of meter-decimeter type III and moving type IV radio bursts, associated with a Hα flare. This is the first report of type III radio bursts from the Nançay radioheliograph after it acquired the two-dimensional multifrequency capability. Dispersion of the radio source positions with frequency suggests that open and closed field lines are considerably inclined to the radial direction which is consistent with the connectivity observed in the magnetogram. We suggest that multiple arch systems are involved in the type IV emission. From the polarization and dispersion characteristics of the type IV source, we infer that the emission is due to fundamental plasma emission. Title: Solar Simple Bursts Observed with High Spectral Resolution in the 18--23 GHz Range Authors: Sawant, H. S.; Rosa, R. R.; Cecatto, J. R.; Gopalswamy, N. Bibcode: 1994ApJS...90..693S Altcode: 1994IAUCo.142..693S For the first time, solar bursts in the frequency range of (18-23) GHz have been observed with high-time (0.6-1.2 s) and high-frequency resolution (1 GHz), by using the Itapetinga 13.7 m diameter antenna. Here, we investigate the microwave type 'simple low level (less than 10 SFU) bursts' associated with the impulsive phase of solar flares. Observed properties of these simple bursts are: rise time tr approximately 3 s, decay time td approximately 5 s and spectral index ranging between -1 and -4. These bursts were found to be associated with SF or SN flares as seen in H(alpha). The above properties suggest that they are likely to be a microwave counterpart of elementary flare bursts. In the majority of the cases the spectral evolution is soft-hard-soft. This suggests a nonthermal gyrosynchrotron mechanism for generating these elementary flare bursts. Estimated parameters of these simple burst sources are height (h approximately 2400 km), electron density (Nepsilon is less than 8.8 x 109/cu cm.), and magnetic field (B approximately 300 G). Title: Millimeter, Microwave, Hard X-Ray, and Soft X-Ray Observations of Energetic Electron Populations in Solar Flares Authors: Kundu, M. R.; White, S. M.; Gopalswamy, N.; Lim, J. Bibcode: 1994ApJS...90..599K Altcode: 1994IAUCo.142..599K We present comparisons of multiwavelength data for a number of solar flares observed during the major campaign of 1991 June. The different wavelengths are diagnostics of energetic electrons in different energy ranges: soft X-rays are produced by electrons with energies typically below 10 keV, hard X-rays by electrons with energies in the range 10-200 keV, microwaves by electrons in the range 100 keV-1 MeV, and millimeter-wavelength emission by electrons with energies of 0.5 MeV and above. The flares in the 1991 June active period were remarkable in two ways: all have very high turnover frequencies in their microwave spectra, and very soft hard X-ray spectra. The sensitivity of the microwave and millimeter data permit us to study the more energetic (greater than 0.3 MeV) electrons even in small flares, where their high-energy bremsstrahlung is too weak for present detectors. The millimeter data show delays in the onset of emission with respect to the emissions associated with lower energy electrons and differences in time profiles, energy spectral indices incompatible with those implied by the hard X-ray data, and a range of variability of the peak flux in the impulsive phase when compared with the peak hard X-ray flux which is two orders of magnitude larger than the corresponding variability in the peak microwave flux. All these results suggest that the hard X-ray-emitting electrons and those at higher energies which produce millimeter emission must be regarded as separate populations. This has implications for the well-known 'number problem' found previously when comparing the numbers of non thermal electrons required to produce the hard X-ray and radio emissions. Title: A Study of Active Region Magnetic Fields Using Radio, X-ray and Optical Observations Authors: Gopalswamy, N. Bibcode: 1994ASPC...68..395G Altcode: 1994sare.conf..395G No abstract at ADS Title: Interferometry of Solar Flares at 3-mm Wavelength Authors: Kundu, M. R.; White, S. M.; Gopalswamy, N.; Lim, J. Bibcode: 1994IAUS..154..131K Altcode: No abstract at ADS Title: VLA Observations of a High Coronal Flare Authors: Raulin, J. P.; Gopalswamy, N.; Kundu, M. R.; Nitta, N. Bibcode: 1993AAS...183.0706R Altcode: 1993BAAS...25.1300R We present radio observations of a coronal flare which occurrred on 1993 April 22, in a weak magnetic field region to the west of AR 7477. The observations were made by the Very Large Array (VLA) at 20 and 90 cm. The event consists of bright (brightness temperature of 10(10) K) unpolarized bursts, followed by a longlasting unpolarized continuum with moderately high brightness temperature (2-3 10(9) K) in the high corona (90 cm observations). The low coronal counterpart of this flare is a weak and moderatly polarized 20 cm radio emission. Full disk Yohkoh images show that the corresponding radio emission is located in or above magnetic loops connecting AR 7477 and its neighborhood. The presence of permanent and non-varying noise storm associated with AR 7477 seems to indicate that the overall magnetic field structure of the active region is unaffected by the flare. The coronal radio source which is indicative of acceleration of electrons to nonthermal energies, is not associated with major Hα emissio n nor with bright X ray emission. The absence of any detectable circular polarization, as well as the high brightness temperature, seems to indicate that the 90 cm emission is second harmonic plasma emission. Title: Variability in Sunspot Associated Microwave Emission: Umbral Oscillations? Authors: Gopalswamy, N.; Schmahl, E. J.; Kundu, M. R. Bibcode: 1993AAS...183.6808G Altcode: 1993BAAS...25.1396G We report on microwave observations of sunspot associated emission that shows variability over a time scale of minutes. To our knowledge, this is the first time such rapid variability has been observed in microwave radiation from a sunspot. These observations were obtained by the Very Large Array (VLA) on April 24, 1992 at 2cm. The radio emission from the sunspot umbra was in the form of several compact sources with a size less than 4 arcsec. The time evolution of the peak flux of these sources showed significant time variations which were sometimes periodic. The period of these ocillations was approximately 3 min, similar to that of intensity and Doppler shift oscillations observed in optically thin, transition region lines such as C IV (1548.19 Angstroms) in sunspot umbrae. There were also morphological changes in the extended sunspot emission over which the compact sources were superposed. We also observed the appearance of new compact sources within the umbra where there was reduced emission before. The brightness temperatures of these compact sources were in the range (1-5)times 10(5) K. We explore possible interpretations of the time variability. Title: Structure of a fast coronal mass ejection from radio observations. Authors: Gopalswamy, N.; Kundu, M. R. Bibcode: 1993AdSpR..13i..75G Altcode: 1993AdSpR..13R..75G The authors investigate the thermal structure of a coronal mass ejection (CME) in meter-dekameter wavelengths and compare it with the optical evidence. The multifrequency observations enable us to infer the three dimensional structure of the CME. The authors estimated the mass of the CME and found to be in reasonable agreement with the range of values obtained from white light observations. Title: Interferometric observations of solar flares at 3 mm wavelength Authors: Kundu, M. R.; White, S. M.; Gopalswamy, N.; Lim, J. Bibcode: 1993AdSpR..13i.289K Altcode: 1993AdSpR..13..289K We report on the observations of a number of flares at a wavelength of 3.5 mm during the 1991 June solar campaign. Many flares, including small ones, show an impulsive phase at milllimeter wavelengths which indicates the presence of MeV electrons, and the millimeter observations are far more sensitive to such electrons than are current γ-ray detectors. However, these energetic electrons do not always show a good correlation with the lower-energy electrons which produce hard X-rays below 100 keV. The production efficiency of MeV electrons seems to vary considerably from flare to flare. An extended phase similar to the soft X-ray behaviour is also seen at millimeter wavelengths, which we attribute to dense hot material radiating thermal bremsstrahlung. In the impulsive onset the millimeter emission seems to be consistently delayed with respect to the hard X-rays. Title: Simultaneous Observations of Solar Plage with the Solar Extreme Ultraviolet Rocket Telescope and Spectrograph (SERTS), the VLA, and the Kitt Peak Magnetograph Authors: Brosius, Jeffrey W.; Davila, Joseph M.; Thompson, William T.; Thomas, Roger J.; Holman, Gordon D.; Gopalswamy, N.; White, Stephen M.; Kundu, Mukul R.; Jones, Harrison P. Bibcode: 1993ApJ...411..410B Altcode: We obtained simultaneous images of solar plage on 1991, May 7 with SERTS, the VLA,4 and the NASA/National Solar Observatory spectromagnetograph at the NSO/Kitt Peak Vacuum Telescope. Using intensity ratios of Fe XVI to Fe XV emission lines, we find that the coronal plasma temperature is (2.3-2.9) x 10 exp 6 K throughout the region. The column emission measure ranges from 2.5 x 10 exp 27 to l.3 x 10 exp 28 cm exp -5. The calculated structure and intensity of the 20 cm wavelength thermal bremsstrahlung emission from the hot plasma observed by SERTS is quite similar to the observed structure and intensity of the 20 cm microwave emission observed by the VLA. Using the Meyer (1991, 1992) revised coronal iron abundance, we find no evidence either for cool absorbing plasma or for contributions from thermal gyroemission. Using the observed microwave polarization and the SERTS plasma parameters, we calculate a map of the coronal longitudinal magnetic field. The resulting values, about 30-60 G, are comparable to extrapolated values of the potential field at heights of 5000 and 10,000 km. Title: A Study of the Solar Active Regions Using Simultaneous VLA and Yohkoh Soft X-ray Imaging: CoMStOC `92 Authors: Gopalswamy, N.; White, S. M.; Kundu, M. R.; Lemen, J. R.; Strong, K. T.; Schmelz, J. T. Bibcode: 1993BAAS...25R1213G Altcode: No abstract at ADS Title: Hard X-ray and Radio Spectra for Solar Flares from AR 6659 Authors: White, S. M.; Murphy, R.; Schwartz, R. A.; Kundu, M. R.; Gopalswamy, N.; Lim, J. Bibcode: 1993BAAS...25Q1222W Altcode: No abstract at ADS Title: VLA and Yohkoh Observations of an M1.5 Flare Authors: Gopalswamy, N.; Kundu, M. R.; Lemen, J. R.; Nitta, N.; Strong, K. T. Bibcode: 1993BAAS...25.1186G Altcode: No abstract at ADS Title: VLA, OVRO, Yohkoh and Optical Observations During CoMStOC Authors: Schmahl, E. J.; Gopalswamy, N.; Kundu, M. R.; Lemen, J.; Strong, K. T.; de La Beaujardiere, J. Bibcode: 1993BAAS...25.1213S Altcode: No abstract at ADS Title: Solar Coronal Plasma and Magnetic Field Diagnostics Using SERTS and Coordinated VLA Observations Authors: Brosius, J. W.; Davila, J. M.; Thompson, W. T.; Thomas, R. J.; Holman, G. D.; Gopalswamy, N.; White, S. M.; Kundu, M. R.; Jones, H. P. Bibcode: 1993BAAS...25.1224B Altcode: No abstract at ADS Title: A Multiwavelength Portrait of a Solar Active Region Authors: White, S. M.; Kundu, M. R.; Gopalswamy, N. Bibcode: 1993BAAS...25.1183W Altcode: No abstract at ADS Title: Thermal and nonthermal emissions during a coronal mass ejection Authors: Gopalswamy, N.; Kundu, M. R. Bibcode: 1993SoPh..143..327G Altcode: We report on the thermal and nonthermal radio emissions from a coronal mass ejection (CME) observed at meter-decameter wavelengths using the Clark Lake multifrequency radioheliograph. From white-light observations of the Solar Maximum Mission Coronagraph/Polarimeter instrument the CME was found to have a speed of ∼ 450 km s−1. Since there was no nonthermal radio emission in the beginning of the event and the one which occurred later was quite weak, we were able to observe the thermal structure of the CME in radio. Type III bursts and a nonthermal continuum started several minutes after the CME onset. We use the radio and optical observations to show that the CME was not driven by the flare. We investigate the thermal structure and geometry of the mass ejection in radio and compare it with the optical evidence. Finally we develop a schematic model of the event and point out that particle acceleration high in the corona is possible. Title: A new investigation of microbursts at meter-decameter wavelengths Authors: Subramanian, K. R.; Gopalswamy, N.; Sastry, Ch. V. Bibcode: 1993SoPh..143..301S Altcode: We report on a new investigation of microbursts at meter-decameter wavelengths observed using the Broad Band Array at Gauribidanur Radio Observatory. This is an independent set of observations of microbursts: previous observations had been obtained only by the Clark Lake multifrequency radioheliograph. We confirm several properties of microbursts reported earlier. In addition, we have studied some new properties of microbursts such as time profile characteristics, flux density and energy spectra for comparison with the corresponding properties of normal type III bursts. The present study supports the idea that the microbursts and the normal type III bursts are generated by electron beams of similar characteristics. We interpret the low brightness temperature of microbursts as follows: plasma waves generated by the electron beams through beam-plasma instability are quickly isotropized as they scatter on the density fluctuations in the corona. The resulting low levels of plasma waves are converted into transverse radiation of low brightness temperature. One important consequence of the isotropization is that the second harmonic plasma emission dominates the fundamental and hence the microbursts are expected to be predominantly a harmonic plasma emission. Title: Analysis of EUV, Microwave and Magnetic Field Observations of Solar Plage Authors: Brosius, J. W.; Davila, J. M.; Jones, H. P.; Thompson, W. T.; Thomas, R. J.; Holman, G. D.; White, S. W.; Gopalswamy, N.; Kundu, M. R. Bibcode: 1993ASPC...46..291B Altcode: 1993mvfs.conf..291B; 1993IAUCo.141..291B No abstract at ADS Title: Plasma Emission from Isotropic Langmuir Turbulence: Are Radio Microbursts Structureless? Authors: Gopalswamy, N. Bibcode: 1993ApJ...402..326G Altcode: The brightness temperature of radio emission through the fundamental and second harmonic plasma processes is determined for isotropic Langmuir waves of low-energy density in order to account for the microbursts at meter-dekameter wavelengths. The probable cause for low levels of Langmuir turbulence is the presence of isotropic density fluctuations in the corona which isotropize the beam-generated Langmuir waves. We determined the energy density of Langmuir waves attainable from the beam-plasma instability in the presence of isotropic density fluctuations. Since the electron density fluctuations isotropize the beam-generated plasma waves, the head-on collision of plasma waves becomes efficient to produce the second harmonic plasma emission. For reasonable beam parameters, the brightness temmperature of the fundamental never exceeds 10 exp 6 K, while the second harmonic covers the observed range of microburst brightness temperatures. Thus, the microbursts are predominantly at second harmonic. This leads to an important conclusion that the microbursts are structureless, similar to a population of normal type III bursts of low polarization with no fundamental-harmonic structure. Title: Are coronal type II shocks piston driven? Authors: Gopalswamy, N.; Kundu, M. R. Bibcode: 1992AIPC..264..257G Altcode: 1992pacp.work..257G Flare blast waves and shocks piston driven by coronal mass ejections (CMEs) have been proposed to be responsible for generating type II radio bursts in the solar corona. The idea for piston-driven shocks came primarily from temporal association of shocks and CMEs. Our compilation of CME events with simultaneous radio observations with positional information supports idea of flare blast waves. Title: Analysis of EUV, Microwave, and Magnetic Field Observations of a Solar Active Region Authors: Brosius, J. W.; Davila, J. M.; Jones, H. P.; Thompson, W. T.; White, S. M.; Gopalswamy, N.; Kundu, M. R. Bibcode: 1992AAS...180.4002B Altcode: 1992BAAS...24R.792B No abstract at ADS Title: Simultaneous Hard X-ray, Soft X-ray, Millimeter and Microwave Observations of a Solar Flare Authors: White, S. M.; Kundu, M. R.; Lim, J.; Gopalswamy, N. Bibcode: 1992AAS...180.4504W Altcode: 1992BAAS...24..802W We present non-imaging data across a wide range of wavelengths for a solar flare which occurred on 1991 June 13. This flare is of interest because it shows a spike in hard X-rays at the beginning of the event which had a relatively hard X-ray spectrum, and was followed by a much softer impulsive phase. We present the BATSE and OSSE observations (from the Gamma Ray Observatory): the former have good time resolution, while the latter provide well-resolved spectral information. These are contrasted with the GOES soft-X-ray data on the hot thermal component in the corona, and radio observations up to 86 GHz which are sensitive to both the nonthermal and thermal components of the flare. The 86 GHz data from the BIMA millimeter interferometer show a spike in the impulsive phase coincident with the hard X-ray spike above 100 keV, as well as a long-duration thermal phase which appears to be consistent with an origin in the same material seen by GOES. We discuss the implications of the observations for particle acceleration in this flare. Title: Estimation of the Mass of a Coronal Mass Ejection from Radio Observations Authors: Gopalswamy, N.; Kundu, M. R. Bibcode: 1992ApJ...390L..37G Altcode: The mass of a coronal mass ejection (CME) is estimated using meter-decametric observations obtained with the Clark Lake multifrequency radioheliograph. Mass estimates in the past were made using coronagraph and white-light photometer observations. Since the radiation at radio and optical wavelength regimes has different physical origins, the radio method can provide an independent check on the mass estimates. The estimate of the 1986 February 16 CME using the radio method is close to the average value of CME masses reported in the literature. Title: Are Microbursts Structureless? Authors: Gopalswamy, N. Bibcode: 1992AAS...180.5601G Altcode: 1992BAAS...24Q.820G Microbursts are of lowest brightness temperature of all the radio bursts in the meter-decameter wavelength regime. Since the low brightness temperature is a consequence of low level of Langmuir turbulence, it was thought that a nonlinear process such as the second harmonic plasma emission would be unimportant. The probable cause for low levels of Langmuir turbulence is the presence of isotropic density fluctuations in the corona which isotropize the beam-generated Langmuir waves. The isotropy of the Langmuir turbulence favors the head-on collision of plasma waves needed to satisfy the kinematic conditions of harmonic plasma emission. For reasonable beam parameters, we find that the second harmonic plasma emission always dominates; the fundamental brightness temperature never exceeds 10(6) K. Thus we conclude that the microbursts may be structureless. We also find that the microburst electron beams are no different from the normal type III electron beams. Title: High Dynamic Range Multifrequency Radio Observations of a Solar Active Region Authors: White, S. M.; Kundu, M. R.; Gopalswamy, N. Bibcode: 1992ApJS...78..599W Altcode: High-dynamic-range multifrequency radio observations of a solar active region are presented. The evolution of the region is followed at 5 GHz as it rotates from the limb to disk center, and when it is at disk center, observations at 0.33, 1.5, 5, 8.4, and 15 GHz are used to analyze the distribution of density and magnetic field within the active region. A dynamic range of up to 1500 (at 8.4 GHz) was achieved because these data were well suited to the self-calibration technique. The signatures of both optically thick gyroresonance emission are unambiguously identified, and magnetic fields and optically thin thermal free-free emission are outlined. Images are compared at 5 and 8.4 GHz in order to identify regions in the trailing part of the active region where optically thin four-harmonic gyroresonance emission is contributing to the observed brightness temperatures at 5 GHz, indicating the presence of 450 G fields. Title: Millimeter and hard X-ray/γ-ray observations of solar flares during the June 91 GRO campaign. Authors: Kundu, M. R.; White, S. M.; Gopalswamy, N.; Lim, J. Bibcode: 1992NASCP3137..502K Altcode: 1992como.work..502K We have carried out high-spatial-resolution millimeter observations of solar flares using the Berkeley-Illinois-Maryland Array (BIMA). At the present time, BIMA consists of only three elements, which is not adequate for mapping highly variable solar phenomena, but is excellent for studies of the temporal structure of flares at millimeter wavelengths at several different spatial scales. We present BIMA observations made during the Gamma Ray Observatories (GRO)/Solar Max 1991 campaign in Jun. 1991 when solar activity was unusually high. Our observations covered the period 8-9 Jun. 1991; this period overlapped the period 4-15 Jun. when the Compton Telescope made the Sun a target of opportunity because of the high level of solar activity. Title: Meter-decameter radio emission associated with a coronal mass ejection Authors: Kundu, M. R.; Gopalswamy, N. Bibcode: 1992LNP...399..268K Altcode: 1992esf..coll..268K; 1992LNP...399..268G; 1992IAUCo.133..268K A study of meter-dekameter radio emission associated with the 1986 Feb 10 coronal Mass ejection event is presented here. The event was accompanied by a major flare (optical importance 1B and X-ray importance C9.6), preceded by a filament disappearance. Changes in the intensity of a pre-existing noise storm was observed during the onset of the flare. A flare continuum, a moving type IV, and a type II occurred during the event. The event was also associated with a strong hard X-ray burst. The speeds of moving type IV burst and CME were of the same order of 1600 kms -1, while the type II shock speed was 1900 kms -1. The positional data indicate that the moving type IV burst and the inferred type II shock had different trajectories. The moving type IV burst was confined to one leg of the CME while the type II shock was far ahead of the CME leading edge. We discuss the inferred relation among different entities such as the CME, type II shock, type IV plasmoid and the erupting filament. Title: Largescale Structures Associated with Eruptive Flares and Radio Waves Authors: Gopalswamy, N.; Kundu, M. R. Bibcode: 1992LNP...399..207G Altcode: 1992esf..coll..207G; 1992IAUCo.133..207G We review some recent results obtained from 2-dimensional imaging observations of the Sun using the Clark Lake multifrequency radioheliograph. The radioheliograph produced images of the Sun's corona on a daily basis at several frequencies within the range 20-125 MHz during the period 1982-87. Using these images both large scale structures as well as transient phenomena such as bursts have been studied. In this paper we discuss the nature of radio emission associated with eruptive filaments and CMEs. It is possible to trace the structure of magnetic fields in the corona based on the multifrequency observations of moving type IV bursts at meter and decameter wavelengths. We illustrate this by discussing specific events. We discuss a rare case of the detection of thermal radio emission in association with a fast CME. We estimate the CME mass using spatially resolved radio data. Title: Large-Scale Features of the Sun at 20 Centimeter Wavelength Authors: Gopalswamy, N.; White, S. M.; Kundu, M. R. Bibcode: 1991ApJ...379..366G Altcode: Results are reported from an experimental study of the characteristics of large-scale coronal structures such as active regions, plages, filaments, and coronal holes using data obtained with the VLA at 1.5 GHz during the period September 11-17, 1988. The radio data were supplemented with He 10830- A, H-alpha, and Calcium-K spectroheliograms. A statistical analysis of some of the characteristics of the active regions is performed. Most of the active region sources were found to be about 100 arcsec in size, with bridges between regions common; lower brightness temperature regions showed a higher degree of polarization in general. The maximum polarization was found at the edge of active regions but well within the associated plages. The degree of polarization from bright active regions was small (not more than 20 percent), in agreement with previous results. Evidence was found for compression of preexisting flux by the emerging flux from a new region, which took place in the apparent absence of magnetic reconnection. Title: Simultaneous EUV, Microwave, and Magnetic Field Observations of Solar Active Regions Authors: Brosius, J. W.; Davila, J. M.; Thompson, W. T.; Gopalswamy, N.; White, S. M.; Jones, H. P.; Metcalf, T. R. Bibcode: 1991BAAS...23.1388B Altcode: No abstract at ADS Title: Coronal Magnetic Structures Observing Campaign. I. Simultaneous Microwave and Soft X-Ray Observations of Active Regions at the Solar Limb Authors: Nitta, N.; White, S. M.; Kundu, M. R.; Gopalswamy, N.; Holman, G. D.; Brosius, J. W.; Schmelz, J. T.; Saba, J. L. R.; Strong, K. T. Bibcode: 1991ApJ...374..374N Altcode: Using simultaneous microwave and soft X-ray measurements made with the Very Large Array (VLA) at 6 and 20 cm and the X-ray Polychromator (XRP) aboard the Solar Maximum Mission (SMM), we have studied two active regions near the solar limb. These observations were taken as part of the Coronal Magnetic Structures Observing Campaign (CoMStOC), a collaboration designed to study the magnetic field in the solar corona. The images in soft X-rays and at 20 cm wavelength are similar: both show peaks above the active regions and extended bridge of emission 200,000 km long connecting the two regions. The brightness temperature of the 20 cm emission is lower than that predicted from the X-ray emitting material, however; it can be attributed to free-free emission in cooler (<106 K) plasma not visible to XRP, with an optical depth ∼1. The 6 cm emission is concentrated at lower altitudes and in a ∼160,000 km long bundle of loops in the northern active region. Comparison of the 6 cm map with the potential magnetic field lines computed from photospheric magnetic fields (measured 2 days earlier) indicates that the 6 cm emission is associated with fields of less than ∼200 G. Such fields would be too weak to attribute the observed 6 cm emission to gyroresonance radiation. Analysis of the 6 cm loop bundle indicates that it is strongly asymmetric, with the magnetic field in the northern leg ∼2 times stronger than in the southern leg; the 6 cm emission most likely arises from a combination of hot ( ≥ 2 × 106 K) and cool plasmas, while the 20 cm emission becomes optically thick in the cooler (∼9 × 103 K) plasma. We estimate an Alfvén speed ∼7000 km s-1 and ratio of electron gyrofrequency to plasma frequency ∼1.0 in the northern leg of the 6 cm loop. Title: Global Streamer Evolution Authors: Thejappa, G.; Kundu, M. R.; Gopalswamy, N. Bibcode: 1991BAAS...23.1045T Altcode: No abstract at ADS Title: VLA Observations of Radio Filaments Authors: Gopalswamy, N.; White, S. M.; Kundu, M. R. Bibcode: 1991BAAS...23.1045G Altcode: No abstract at ADS Title: Strong Magnetic Fields and Inhomogeneity in the Solar Corona Authors: White, S. M.; Kundu, M. R.; Gopalswamy, N. Bibcode: 1991ApJ...366L..43W Altcode: It is shown that fields of 1800 G can exist in the corona based on observations of gyroresonance emission at 15 GHz at coronal temperatures. The strong fields occur in a small source radiating in the extraordinary (x) mode over the penumbra of a large symmetric sunspot. The optically-thin ordinary mode emission from the region shows a nearby peak at only 36,000 K which may be due to a sunspot plume, and a hole over the umbra consistent with the expected low-density material there. The x-mode source is highly asymmetric, despite the apparent symmetry of the sunspot, and its appearance and location imply that the strongest magnetic fields in the corona are localized in a compact flux tube. Title: VLA Observations of Active Region 5555 During the 1st Max'91 Campaign Authors: Schmahl, E. J.; Gopalswamy, N.; Kundu, M. R. Bibcode: 1991max..conf...23S Altcode: No abstract at ADS Title: Association of a Type IV Burst with a Slow CME Authors: Gopalswamy, N.; Kundu, M. R. Bibcode: 1991max..conf..139G Altcode: No abstract at ADS Title: The Observation of an Unusually Fast Type IV Plasmoid Authors: Gopalswamy, N.; Kundu, M. R. Bibcode: 1990ApJ...365L..31G Altcode: A moving type IV burst of the 'isolated source' type has been detected whose out-of-plane speed, at 1600 km/sec, becomes about 2800 km/sec upon assumption of radial motion; this is twice as high as previously reported speeds for bursts of this type. While shock waves are known to have such high speeds, and a shock wave is likely to form ahead of a high-speed plasmoid, no radio signature has been observed for such a shock. This lack of shock detection may, however, be primarily due to poor observing conditions. Energetic electrons, trapped in an about 1.4 G magnetic field of the plasmoid, can adequately account for the emission. Title: Filament Eruption and Storm Radiation at Meter / Decameter Wavelengths Authors: Kundu, M. R.; Gopalswamy, N. Bibcode: 1990SoPh..129..133K Altcode: We report the study of a weak noise storm observed by the Clark Lake multifrequency radioheliograph at four frequencies. The noise storm onset was associated with a filament eruption and a gradual rise and fall in soft X-rays. We compare the noise storm emission with related emissions in other wavelengths to develop a composite scenario of the event. Using the properties of the quiet corona inferred from the simultaneously observed quiet-Sun radiation, we estimate the brightness temperature of the storm continuum, which seems to be consistent with the observations reported in Solar Geophysical Data. Superthermal particles with a temperature that is ten times the coronal electron temperature and a density of ∼ 10−3 times the coronal density are adequate to explain the observed radiation. Since the noise storm observations were made at four frequencies, we were able to obtain a brightness temperature spectrum of the storm radiation. If the storm radiation is affected in the same way as the quiet-Sun emission by inhomogeneities, the observed spectrum can be interpreted as due to propagation effects. Since the Clark Lake instrument can observe both quiet Sun and weak bursts simultaneously, we were able to estimate the propagation effects from the quiet-Sun observations and use it to correct the brightness temperature of storm radiation. Title: Multiple Moving Magnetic Structures in the Solar Corona Authors: Gopalswamy, N.; Kundu, M. R. Bibcode: 1990SoPh..128..377G Altcode: 1990IAUCo.121P.377G We report the study of moving magnetic structures inferred from the observations of a moving type IV event with multiple sources. The ejection contains at least two moving radio emitting loops with different relative inclinations. The radio loops are located above multiple Hα flare loops in an active region near the limb. We investigate the relationship between the two systems of loops. The spatial, temporal and geometrical associations between the radio emission and near surface activities suggest a scenario similar to coronal mass ejection (CME) events, although no CME observations exist for the present event. From the observed characteristics, we find that the radio emission can be interpreted as Razin suppressed optically thin gyrosynchrotron emission from nonthermal particles of energy ∼ 100, keV and density ∼ 102-105 cm−3 in a magnetic field ≤ 2 G. Title: First High Spatial Resolution Interferometric Observations of Solar Flares at Millimeter Wavelengths Authors: Kundu, M. R.; White, S. M.; Gopalswamy, N.; Bieging, J. H.; Hurford, G. J. Bibcode: 1990ApJ...358L..69K Altcode: The first high spatial resolution interferometric observations of solar flares at millimeter wavelengths, carried out with the Berkeley-Illinois-Maryland Array are presented. The observations were made at 3.3 mm wavelength during the very active periods of March 1989, using one or three baselines with fringe spacings of 2-5 arcsec. The observations represent an improvement of an order of magnitude in both sensitivity and spatial resolution compared with previous solar observations at these wavelengths. It appears that millimeter burst sources are not much smaller than microwave sources. The most intense bursts imply brightness temperatures of over 10 to the 6th K and are due to nonthermal gyrosynchrotron emission or possibly thermal free-free emission. If the emission in the flash phase is predominantly due to gyrosynchrotron emission, thermal gyrosynchrotron models can be ruled out for the radio emission because the flux at millimeter wavelengths is too high. Title: Microbursts at Meter-Decameter Wavelengths Authors: Thejappa, G.; Gopalswamy, N.; Kundu, M. R. Bibcode: 1990SoPh..127..165T Altcode: We study the characteristics of microbursts using a large data base obtained with the multifrequency radioheliograph of the Clark Lake Radio Observatory. Most of the new observations were made during July 29, 1985 to August 2, 1985; we also include for statistical studies the microburst data used in our earlier studies. We perform a statistical analysis of many characteristics such as frequency drift, source size and brightness temperature and compare them with the properties of normal type III bursts. We investigate the coronal structures and surface activities associated with some of the events. We find that (i) the brightness temperature is in the range 6 × 105 K to 6 × 107 K; (ii) the drift rate of the microbursts is slightly smaller than that of normal type III bursts, implying electron beams with speeds ∼0.2c. Title: A Note on the Emission Mechanism of Storm Radiation Authors: Gopalswamy, N. Bibcode: 1990SoPh..126..367G Altcode: A new mechanism has been proposed for the continuum and burst components of solar storm radiation by Genkin, Erukhimov, and Levin (1989a, b). In this paper, we point out that while bursts can be explained by the proposed mechanism of scattering on plasma turbulence generated density fluctuations, the continuum cannot be explained by sattering on thermal ion density fluctuations. The reason is, under the same coronal conditions, second harmonic emissions will dominate over the fundamental emission due to scattering on thermal ion density fluctuations in contradiction to observations. We also note that the range of plasma wave densities needed for this mechanism may not be realistic for the case of plasma wave generation due to loss cone instability. It is further argued that coalescence of plasma waves with low-frequency waves still seems to be the plausible mechanism. Title: CoMStOCI: Physical Properties of an Active Region Loop Observed at the Solar Limb Authors: Holman, G. D.; Brosius, J. W.; Nitta, N.; White, S. M.; Kundu, M. R.; Gopalswamy, N.; Schmelz, J. T.; Saba, J. L. R.; Strong, K. T. Bibcode: 1990BAAS...22..899H Altcode: No abstract at ADS Title: Evolution of Active Regions at 20 cm Authors: Gopalswamy, N.; White, S. M.; Kundu, M. R. Bibcode: 1990BAAS...22..795G Altcode: No abstract at ADS Title: High-Dynamic-Range Multifrequency Radio Observations of a Solar Active Region Authors: White, S. M.; Kundu, M. R.; Gopalswamy, N. Bibcode: 1990BAAS...22R.794W Altcode: No abstract at ADS Title: Millimeter-Interferometer Observations of Solar Flares Authors: Kundu, M. R.; White, S. M.; Gopalswamy, N.; Bieging, J. H.; Hurford, G. J. Bibcode: 1990BAAS...22..823K Altcode: No abstract at ADS Title: New Observations of Storm Radiation at Decameter Wavelengths and Their Interpretation Authors: Thejappa, G.; Gopalswamy, N.; Kundu, M. R. Bibcode: 1990BAAS...22..794T Altcode: No abstract at ADS Title: Some Problems in Low Frequency Solar Radio Physics Authors: Gopalswamy, N.; Kundu, M. R. Bibcode: 1990LNP...362...97G Altcode: 1990lfas.work...97G Several important problems in solar radio physics can be attacked using the high spatial resolution observations from a low frequency space array, as the problem of ionospheric refraction does not exist. Noise storms are believed to occur in closed magnetic loops due to trapped superthermal particles. Recent radioheliograph observations suggest such a magnetic field topology up to altitudes of about 40 MHz emission. The problem of relative locations and sources of the storm continuum and bursts can be effectively studied by imaging them with higher spatial resolution. Interplanetary type II bursts are observed from heights above ~ 10 R while coronal type II bursts are observed from heights less than ~ 3 R. Observations filling this gap have important implications for the understanding of solar-terrestrial relations through shocks and mass ejections. Title: Microbursts at Meter-Decameter Wavelengths Authors: Thejappa, G.; Gopalswamy, N.; Kundu, M. R. Bibcode: 1990IAUS..142..521T Altcode: No abstract at ADS Title: Clark-Lake Radio Observations of Coronal Mass Ejections Authors: Gopalswamy, N. Bibcode: 1990IAUS..142..495G Altcode: Some recent studies of mass ejections from the sun are reviewed using 2D imaging observations of the Clark Lake multifrequency radioheliograph. Radio signatures of both fast and slow coronal mass ejections (CMEs) have been observed. Using temporal and positional analysis of moving type-IV and type-II bursts, and white light CMEs it is found that the type II bursts and CMEs need not have a direct cause and effect relationship. Instead, the type II burst seems to be generated by a 'decoupled shock', probably due to an associated flare. The moving type IV burst requires nonthermal particles trapped in magnetic structures associated with the CME. Since nonthermal particles can be generated independent of the speed of CMEs, moving type IV bursts need not be associated only with fast CMEs. Specific examples are presented to support these views. Title: The Sun at the Vla's Metric and Decimetric Wavelengths Authors: White, S. M.; Kundu, M. R.; Gopalswamy, N.; Schmahl, E. J. Bibcode: 1990IAUS..142..523W Altcode: Preliminary results of solar observations at 0.333 and 1.5 GHz made with the VLA during the September 11-17, 1988 period are presented. Generally, there are few structural changes in the active region sources from one day to the next, suggesting that structural evolution is relatively slow. Contour maps at 1.5 GHz are presented for each of the four days. Two noise storms were present at 0.33 GHz all week and were highly polarized. Title: The Radio Signatures of a Slow Coronal Mass Ejection: Electron Acceleration at Slow-Mode Shocks? Authors: Kundu, M.; Gopalswamy, N.; White, S.; Cargill, P.; Schmahl, E. J.; Hildner, E. Bibcode: 1989ApJ...347..505K Altcode: The evolution of a coronal mass ejection (CME) event observed on February 17, 1985 is studied using two-dimensional radio imaging observations along with simultaneously obtained coronagraph observations. This event shows that a slow CME can be associated with type II and type IV radio bursts. The implications of the spatial association of the radio bursts with the CME are discussed. It is argued that the CME is due to an instability of the large-scale magnetic field in a helmet streamer and that the radio bursts are some of the responses to this instability. The new feature of this event is the clear association of the moving type IV burst with a CME traveling slower than the coronal Alfven speed. The structure of slow shocks driven by such a CME is discussed, and it is shown that shock drift and diffusive acceleration are ineffective. An acceleration mechanism involving current-driven lower hybrid waves is proposed. Title: Evidence for Noise Storm Emission by Superthermal Particles During a Filament Eruption Authors: Gopalswamy, N.; Kundu, M. R. Bibcode: 1989BAAS...21.1146G Altcode: No abstract at ADS Title: Radio Observations of Coronal Changes Authors: Kundu, M. R.; Gopalswamy, N. Bibcode: 1989BAAS...21.1145K Altcode: No abstract at ADS Title: Microbursts at Meter-Decameter Wavelengths Authors: Thejappa, G.; Gopalswamy, N.; Kundu, M. R. Bibcode: 1989BAAS...21.1145T Altcode: No abstract at ADS Title: The First Interferometric Observations with Arc-Second Resolution of Solar Radio Bursts at Millimeter Wavelengths Authors: Kundu, M. R.; White, S. M.; Gopalswamy, N.; Bieging, J. H. Bibcode: 1989BAAS...21..861K Altcode: No abstract at ADS Title: Meter Wave Radio Signatures of Slow CME's and Coronal Streamer Evolution Authors: Kundu, M. R.; Gopalswamy, N. Bibcode: 1989BAAS...21R.857K Altcode: No abstract at ADS Title: Radioheliograph and White-Light Coronagraph Studies of a Coronal Mass Ejection Event Authors: Gopalswamy, N.; Kundu, M. R. Bibcode: 1989SoPh..122..145G Altcode: We analyze the radioheliograph and SMM-C/P observations of 1986 November 3 mass ejection event. The metric radio emissions are the only detected activity associated with the mass ejection, but are adequate to study the evolution of the event. The start time of the ejection seems to precede a possible flare behind the limb indicated by the early type III bursts. We discuss the physical relation between various types of bursts and the CME. We interpret moving type IV bursts as a plasma emission process. It is also shown using white-light coronagraph data that the density in the source region of the moving type IV is sufficient to support second harmonic plasma emission at the observed frequency of 50 MHz. Title: Interpretation of Multiwavelength Observations of Solar Active Regions Obtained During CoMStOC Authors: Brosius, J. W.; Holman, G. D.; Nitta, N.; White, S. M.; Kundu, M. R.; Gopalswamy, N.; Schmelz, J. T.; Saba, J. R. L.; Willson, R. Bibcode: 1989BAAS...21..838B Altcode: No abstract at ADS Title: Radio and Optical Observations of Moving Magnetic Structures in the Solar Corona Authors: Gopalswamy, N.; Kundu, M. R. Bibcode: 1989BAAS...21..857G Altcode: No abstract at ADS Title: Simultaneous Microwave and Soft X-ray Observations of Active Regions at the Solar Limb Authors: Nitta, N.; White, S.; Kundu, M.; Gopalswamy, N.; Holman, G.; Brosius, J.; Schmelz, J.; Saba, J.; Strong, K. Bibcode: 1989BAAS...21..828N Altcode: No abstract at ADS Title: The Sun at the VLA's Meter and Decimeter Wavelengths Authors: White, S. M.; Gopalswamy, N.; Kundu, M. R. Bibcode: 1989BAAS...21..861W Altcode: No abstract at ADS Title: A Slowly Moving Plasmoid Associated with a Filament Eruption Authors: Gopalswamy, N.; Kundu, M. R. Bibcode: 1989SoPh..122...91G Altcode: We report the imaging observations of a slowly moving type IV burst associated with a filament eruption. This event was preceded by weak type III burst activity and was accompanied by a quasi-stationary continuum that persisted for several hours. The starting times and speeds of moving type IV burst and the erupting filament are nearly the same, implying a close physical relation between the two. The moving type IV burst is interpreted as gyrosynchrotron emission from a plasmoid containing a magnetic field of ∼1-2 G and nonthermal electrons of density ∼105-106 cm−3 with a relatively low average energy of ∼50 keV. Title: Recent results of meter-decameter wave observations of solar flares. Authors: Gopalswamy, N.; Kundu, M. R. Bibcode: 1989sasf.confP.185G Altcode: 1989IAUCo.104P.185G; 1988sasf.conf..185G The authors present recent results from meter-decameter imaging of several classes of solar radio bursts: preflare activity in the form of type III bursts, correlated type IIIs from distant sources, and type II and moving type IV bursts associated with flares and CMEs. Title: Three dimensional structures of coronal streamers, holes and CME plasmoids from multifrequency imaging observations Authors: Kundu, M. R.; Schmahl, E. J.; Gopalswamy, N.; White, S. M. Bibcode: 1989AdSpR...9d..41K Altcode: 1989AdSpR...9R..41K Throughout the quiet Sun years 1982-1987, the Clark Lake Radioheliograph routinely mapped the solar corona on a daily basis at frequencies from 30 to 100 MHz. The Clark Lake maps show a variety of features which we have analyzed quantitatively, providing information about the three dimensional nature of large scale structures of the solar corona. Title: First interferometric observations with arc-sec. resolution of solar radio bursts at millimeter wavelengths Authors: Kundu, Mukul R.; White, S. M.; Gopalswamy, N.; Bieging, J. H. Bibcode: 1989dots.work..119K Altcode: The Berkeley-Maryland-Illinois Array (BIMA) is briefly described in the context of solar observations. Specific areas of research that could be performed using BIMA during the Solar Maximum Mission (SMM) in 1991 are outlined. Some preliminary results of flare observations during March 1989 are presented. Title: Millimeter wavelength observations of solar flares for Max 1991 Authors: Kundu, M. R.; Gopalswamy, N.; Nitta, N.; Schmahl, E. J.; White, S. M.; Welch, W. J. Bibcode: 1988fnsm.work..107K Altcode: The Hat Creek millimeter-wave interferometer (to be known as the Berkeley-Illinois-Maryland Array, BIMA) is being upgraded. The improved array will become available during the coming solar maximum, and will have guaranteed time for solar observing. The Hat Creek millimeter-wave interferometer is described along with the improvements. The scientific objectives are briefly discussed. Title: Millimeter Wavelength Observations of Solar Flares for Max'91 Authors: Kundu, M. R.; Gopalswamy, N.; Nitta, N.; Schmahl, E. J.; White, S. M. Bibcode: 1988BAAS...20..746K Altcode: No abstract at ADS Title: Moving Radio Loop Structure During a Fast CME Authors: Gopalswamy, N.; Kundu, M. R.; Hundhausen, A. Bibcode: 1988BAAS...20Q.682G Altcode: No abstract at ADS Title: Slowly-Varying Observed with the Clark Lake Radioheliograph Authors: Schmahl, E. J.; Kundu, M. R.; Gopalswamy, N.; Jackson, P. D. Bibcode: 1988BAAS...20..712S Altcode: No abstract at ADS Title: Imaging observations of the evolution of meter-decameter burst emission during a major flare. Authors: Gopalswamy, N.; Kundu, M. R. Bibcode: 1987SoPh..111..347G Altcode: We present the results of a study of the evolution of 3 February, 1986 flare at meter-decameter wavelengths using the two dimensional imaging observations made with the Clark Lake multifrequency radioheliograph. The flare was complex and produced various types of meter-decameter bursts. The preflare activity was observed in the form of type III bursts some tens of minutes prior to the impulsive onset. From the positional analysis of the preflare and impulsive phase type III bursts and other measured characteristics we discuss the characteristics of energy release and possible magnetic field configurations in the vicinity of energy release region. From positional and temporal studies of the flare continuum and type II burst in relation to the microwave and hard X-ray emissions, we discuss the possible magnetic field structures in which the accelerated particles are confined or along which they propagate. We develop a schematic model of the flaring region based upon our study. Title: A Study of Solar Preflare Activity Using Two-Dimensional Radio and Smm/xrp Observations Authors: Kundu, M. R.; Gopalswamy, N.; Saba, J. L. R.; Schmelz, J. T. S.; Strong, K. T. Bibcode: 1987SoPh..114..273K Altcode: We present a study of type III activity at meter- decameter wavelengths in the preflare phase of the 1986 February 3 flare using data obtained with the Clark Lake Multifrequency Radioheliograph. We compare this activity with similar type III burst activity during the impulsive phase and find that there is a displacement of burst sources between the onset and end times of the activity. A comparison of this displacement at three frequencies suggests that the type III emitting electrons gain access progressively to diverging and different field lines relative to the initial field lines. The energetics of the type III emitting electrons are inferred from observations and compared with those of the associated hard X-ray emitting electrons. The soft X-ray data from SMM-XRP shows enhanced emission measure, density and temperature in the region associated with the preflare type III activity. Title: Fine Structures in Solar Microwave Flares Authors: Gopalswamy, N. Bibcode: 1987SoPh..110..327G Altcode: The pulsed electron acceleration and release from the energy release volume in solar flares implies that there is a possibility of interaction between a group of electrons reflected from the foot of a bipolar flux tube with a newly injected beam. It is shown that interaction can lead to the stoppage of the synchrotron maser instability caused by the loss cone distribution and hence can produce further millisecond fine structures in the solar microwave bursts. Title: Simultaneous radio and white light observations of the 1984 June 27 coronal mass ejection event Authors: Gopalswamy, N.; Kundu, M. R. Bibcode: 1987SoPh..114..347G Altcode: We present the two-dimensional imaging observations of radio bursts in the frequency range 25-50 MHz made with the Clark Lake multifrequency radioheliograph during a coronal mass ejection event (CME) observed on 1984, June 27 by the SMM Coronagraph/Polarimeter and Mauna Loa K-coronameter. The event was spatially and temporally associated with precursors in the form of meter-decameter type III bursts, soft X-ray emission and a Hα flare spray. The observed type IV emission in association with the CME (and the Hα spray) could be interpreted as gyrosynchrotron emission from a plasmoid containing a magnetic field of ∼2.5 G and nonthermal electrons with a number density of ∼ 105 cm−3 and energy ≳350 keV. Title: Two dimensional imaging observations of meter-decameter bursts associated with the February 1986 flare activity Authors: Gopalswamy, N.; Kundu, M. R. Bibcode: 1987sici.symp...16G Altcode: An analysis is presented of the two dimensional imaging observations of a flare observed on 3 Feb. l986 using the Clark Lake Multifrequency Radioheliograph. The flare produced almost all types of Meter-decimeter radio emission: enhanced storm radiation, type III/V bursts, II and IV and flare continuum. The flare continuum had early (FCE) and late (FC II) components and the type II occurred during the period between these two components. Comparing the source positions of type III/V and FCE it was found that these bursts must have occurred along adjacent open and closed field lines, respectively. The positional analysis of type II and FC II implies that the nonthermal electrons responsible for FC II need not be accelerated by type II shock and this conclusion is further supported by the close association of FC II with a microwave peak. Using the positional and temporal analysis of all these bursts and the associated hard X-ray and microwave emissions, a schematic model is developed for the magnetic field configuration in the flaring region in which the nonthermal particles responsible for these bursts are confined or along which they propagate. Title: Propagation of Electrons Emitting Weak Type-Iii Bursts in Coronal Streamers Authors: Gopalswamy, N.; Kundu, M. R.; Szabo, A. Bibcode: 1987SoPh..108..333G Altcode: We report the observations of weak type III bursts at 73.8, 57.5, 50.0, and 38.5 MHz from Clark Lake Radio Observatory on four days and discuss their characteristics. In addition to Clark Lake data, the magnetogram and sunspot/active region data and the coronal streamer data obtained by HAO's Coronagraph/Polarimeter aboard SMM satellite are used to study the location of the burst sources with respect to the coronal streamers emanating from active regions. It is shown that the bursts occur within or close to the edge of dense coronal streamers implying that the coronal streamers contain open magnetic field lines along which the electrons generating the bursts propagate. The positional analysis of the bursts is used to estimate the variation of coronal electron density with radial distance. Title: Correlated Type-Iii Burst Emission from Distant Sources on the Sun Authors: Kundu, M. R.; Gopalswamy, N. Bibcode: 1987SoPh..112..133K Altcode: We report the observation and interpretation of a correlated type III burst emitted from distant sources on the Sun. The angular separation between the distant sources is as large as 26' or ∼ 106 km. There was an active region ∼ 30° behind the limb, and it is believed that the type III burst emission originated from activity in this region. The implications of the locations of the correlated sources with regard to the geometry of the magnetic structures involved in the flare process are discussed. Title: Propagation of Weak Type III Burst Electrons in Dense Coronal Streamers Authors: Gopalswamy, N.; Kundu, M. R.; Szabo, A. Bibcode: 1986BAAS...18R.900G Altcode: No abstract at ADS Title: Some interesting features in the drift pair phenomena of solar decametric radiation Authors: Thejappa, G.; Gopalswamy, N.; Sastry, C. N.; Aubier, M. G. Bibcode: 1986ESASP.251..121T Altcode: 1986plas.work..121T Observational results on drift pair (DP) chains and vertical DP bursts in the decametric solar corona are reported. As the magnetic field in this region is predominantly open, a free energy source propagating sunward most of the time cannot explain the predominant reverse drift pair chains. The appearance of the vertical chains and DPs rules out the possibility of an agency moving in the corona causing the observed drift. Observations support the idea that the resonance layer in which the radiation is generated is different at different instants of time so that one gets a slope in the frequency-time plane. If considerable fluctuations in macroscopic parameters are assumed, it is possible to have drifts of all directions as the drift rate depends upon the medium in which the fluctuations occur. It is shown that the magnetic field decreases steeply if the density of the medium is not affected by the DP activity when the frequency drift is very high. Title: A Theory of Jovian Shadow Bursts Authors: Gopalswamy, N. Bibcode: 1986EM&P...35...93G Altcode: The shadow events in the dynamic spectra of Jovian decametric emission are explained as the result of interaction between electron bunches responsible for S and L emissions. The relevant dispersion relation is derived for the fast extraordinary mode in the cold magnetospheric plasma in the presence of S and L electron bunches. The growth rate of the synchrotron maser instability is studied in the presence and absence of S-electrons. It is shown that the synchrotron maser instability responsible for L-emission can be temporarily quenched by the invasion of S-electrons, thereby stopping the L-emission. The theory accounts for various observed features of the shadow events. Title: Estimation of Coronal Magnetic Fields Using Type-I Emission Authors: Gopalswamy, N.; Thejappa, G.; Sastry, Ch. V.; Tlamicha, A. Bibcode: 1986BAICz..37..115G Altcode: The radial dependence of the coronal magnetic field above active regions is calculated using Type-I chain data existing in the literature. Assuming that Type-I emission is due to shock waves, the upstream shock velocity and the density jump across the shock are obtained respectively from the drift rate and the bandwidth of the Type-I chains. Making use of the shock velocity and the density jump in the Rankine-Hugoniot relation, the Alfvén velocity and hence the magnetic field in the corona is calculated. The results are compared with existing estimates. Title: Notes and News Authors: Gopalswamy, N.; Krishan, V.; Tarter, Jill C. Bibcode: 1986BASI...14...56G Altcode: No abstract at ADS Title: Type-I solar radio bursts. Authors: Gopalswamy, N. Bibcode: 1986KodOB...6...77G Altcode: A brief review of the recent work done on Type-I radio emission in the Indian Institute of Astrophysics is presented. The most plausible low frequency turbulence needed to generate the Type-I bursts is shown to be ion-sound turbulence. A method is presented to evaluate the coronal magnetic field using Type-I radio emission data. Title: Estimation of coronal magnetic fields using solar type I radio emission. Authors: Gopalswamy, N.; Thejappa, G.; Sastry, C. V. Bibcode: 1985BASI...13...81G Altcode: No abstract at ADS Title: Ion-sound turbulence due to shock gradients in collisionless plasmas. Authors: Gopalswamy, N.; Thejappa, G. Bibcode: 1985Prama..25..575G Altcode: No abstract at ADS Title: Second Indo-US workshop on solar-terrestrial physics. Authors: Gopalswamy, N. Bibcode: 1984BASI...12..324G Altcode: Report on the second Indo-US workshop on solar-terrestrial physics, held 1984 January 30 - February 3 at National Physical Laboratory, New Delhi. Title: Notes and News Authors: Padmanabhan, T.; Kembhavi, A.; Bhaysar, S. P.; Bhattacharya, D.; Gopalswamy, N. Bibcode: 1984BASI...12..319P Altcode: Report on the IAGRG XII meeting held at the University of Poona, 1983 November 9 - 12. Title: Narrow-band, short duration radio bursts at decameter wavelengths andtheir interpretation. Authors: Gopalswamy, N.; Thejappa, G.; Subramanian, K. R.; Sastry, C. V. Bibcode: 1984BASI...12...75G Altcode: No abstract at ADS Title: An interpretation of decametric absorption bursts Authors: Gopalswamy, N.; Thejappa, G.; Sastry, Ch. V. Bibcode: 1984stp..conf..197G Altcode: No abstract at ADS Title: Observations on the Fine Structures in Solar Decametric Radio Emission Authors: Gopalswamy, N.; Thejappa, G.; Sastry, C. V. Bibcode: 1984KodOB...4...47G Altcode: The solar decametric radio emission consists of a variety of fine structures. This reflects the complexity of the corona at this level. Two observations viz. absorption bursts and short duration narrow band bursts are presented. An interpretation of each of these observations is provided. Title: Fine structure in solar decametric radiation Authors: Thejappa, G.; Sastry, Ch. V.; Gopalswamy, N. Bibcode: 1984ntpp.proc..547T Altcode: Observations and interpretations of some of the fine structure in decametric solar radio emission - such as (1) the time structure of type III bursts, (2) absorption bursts, and (3) slowly drifting spikes - are presented. Physical parameters such as the electron temperature, the characteristics of collisionless shocks, and the coronal magnetic field - are estimated. Title: Observations and interpretation of solar decametric absorption bursts. Authors: Gopalswamy, N.; Thejappa, G.; Sastry, Ch. V. Bibcode: 1983JApA....4..215G Altcode: The observations of intensity reductions or absorption bursts in the solar decametric radio-continuum are reported. The reductions are interpreted as the absorption of continuum radiation by a shock-generated ion sound turbulence present in the layer above the continuum level. The duration of the absorption is attributed to the life-time of the ion-sound turbulence while the depth of absorption is determined by the level of Langmuir waves generated as a result of absorption. Title: Absorption of intense electromagnetic beams in a magnetoplasma. Authors: Gopalswamy, N.; Krishan, V. Bibcode: 1980Ap&SS..73..179G Altcode: The multiphoton inverse bremsstrahlung absorption of two intense electromagnetic beams passing through a magnetized plasma is studied. The rate of absorption of electromagnetic energy by the electrons is calculated by deriving a kinetic equation for the electrons. It is found that the absorption enhances when the frequency of one electromagnetic beam is more, and that of the other electromagnetic beam is less, than the electron-cyclotron frequency. A possible application to extragalactic radio sources is discussed.