Author name code: pesnell ADS astronomy entries on 2022-09-14 author:"Pesnell, William Dean" ------------------------------------------------------------------------ Title: Two New Methods for Counting and Tracking the Evolution of Polar Faculae Authors: Hovis-Afflerbach, B.; Pesnell, W. Dean Bibcode: 2022SoPh..297...48H Altcode: 2022arXiv220410863H Polar faculae are the footpoints of magnetic-field lines near the Sun's poles that are seen as bright regions along the edges of granules. The time variation in the number of polar faculae has been shown to correlate with the strength of the polar magnetic field and to be a predictor of the subsequent solar cycle. Due to the small size and transient nature of these features, combined with different techniques and observational factors, previous counts of polar faculae differ in magnitude. Further, there were no scalable techniques to measure the statistical properties of the faculae, such as the variation of the facular lifetime with time or solar activity. Using data from the Helioseismic and Magnetic Imager (HMI) onboard the Solar Dynamics Observatory (SDO), we present two new methods for tracking faculae and measuring their properties. In the first, we calculate the pixel-by-pixel standard deviation of the HMI continuum intensity images over one day, visualizing the faculae as streaks. The lifetime of the facula is found by dividing the angular length of the streaks by the latitude-dependent rotation rate. We apply this method to the more visible pole each day for a week every six months, from September 2010 to March 2021. Combining all of the measured facular lifetimes provides a statistical distribution with a mean of 6.0 hours, a FWHM of 5.4 hours, and a skew towards longer lifetimes, with some faculae lasting up to 1 day. In the second method, we overlay images of the progressive standard deviation with the HMI magnetogram to show the close relationship between the facular candidates and the magnetic field. The results of this method allow us to distinguish between motion due to the Sun's rotation and "proper motion" due to faculae moving across the Sun's surface, confirming that faculae participate in convective motions at the poles. Counts of polar faculae using both methods agree with previous counts in their variation with the solar cycle and the polar magnetic field. These methods can be extended to automate the identification and measurement of other properties of polar faculae, which would allow for daily measurements of all faculae since SDO began operation in 2010. Title: Comparing the Sun Watcher Using Active Pixel System Detector and Image Processing Instrument to the Atmosphere Imaging Assembly Instrument Through Measurements of Polar Coronal Holes Authors: Kirk, Michael S. F.; Pesnell, W. Dean; Arge, C. Nickolos; West, Matthew J.; Attié, Raphael Bibcode: 2022SoPh..297...42K Altcode: The PRoject for OnBoard Autonomy 2/Sun Watcher using Active pixel system detector and image Processing (PROBA2/SWAP) instrument images the full-disk extreme ultraviolet (EUV) Sun using a complementary metal-oxide semiconductor active-pixel sensor (CMOS-APS) detector with a filter centered on a 174 Å passband at a cadence of one to two minutes. In contrast, the Atmosphere Imaging Assembly (AIA) instrument onboard the Solar Dynamics Observatory (SDO) has a passband filter centered on 171 Å and uses a charge-coupled device (CCD) detector to make full-disk observations of the EUV corona. The images that these two telescope designs produce are visually quite similar in active regions, coronal loops, and the quiet corona. This work takes a deeper look at the stability of the most difficult coronal features to capture in an image: polar coronal holes. Polar coronal holes are the longest-lived features on the Sun and are critical to understand the global state of the solar corona, but because of an oblique viewing angle, obstruction due to the coronal plasma scale height and lack of ground-truth magnetic-field measurements make reliable segmentation of polar holes difficult. We use perimeter tracing to make consistent measurements of a polar-hole's perimeter and area in both SWAP 174 Å and AIA 171 Å images. The generated time series of coronal-hole parameters rarely agree with each other. Direct comparison of polar-hole measurements generated by these two imagers allows us to simultaneously analyze the physical properties of polar coronal holes and to identify systematic differences between the two different instruments. Title: Properties of Polar Faculae Authors: Pesnell, William; Hovis-Afflerbach, Beryl; Wampler, Paul Bibcode: 2021AGUFMSH34D..03P Altcode: Polar Faculae (PFe) are bright points at the edges of granules that illuminate where magnetic field lines intersect the solar surface near the Suns poles. We previously reported the average PF lifetime determined from the Helioseismic and Magnetic Imager (HMI) on Solar Dynamics Observatory (SDO) is 6.0 2.7 hours. We also showed that the number of PFe in Solar Cycle 24 is correlated with the strength of the polar magnetic field and anti-correlated with the sunspot number. Those correlations had been known before but, as with any solar activity variable, the time dependence is more complicated than a linear correlation. We report on our continuing analysis of HMI PF data, extending the time coverage of the number of PFe and measuring the magnetic field associated with a sample of those PFe. We will map the proper motion of those PF that appear to move in latitude. This proper motion confirms that faculae participate in convective motions at the poles. By measuring the presence, trajectory, and magnetic field strength of a large sample of faculae, we can better understand polar faculae and therefore the polar magnetic field and its evolution, as well as conditions and convective motions at the poles. These observations will help design space missions to observe the solar polar regions. Title: Solar Cycle 25 Spits and Sputters, but Fireworks are Predicted Authors: Pesnell, William Bibcode: 2021AGUFMSH43B..01P Altcode: Solar Cycle 25 has begun its rapid rise to solar maximum. The increase in EUV spectral irradiances will cause thermospheric densities to increase and create satellite drag. Ham radio operators look forward to improved propagation conditions. We have learned much about predicting solar activity in Solar Cycle 24, especially with the data provided by SDO, STEREO, and other missions and observatories. At least 54 predictions of the amplitude of activity in Solar Cycle 25 have been published. Some of these predictions were made long before solar minimum while others are still appearing. As with Solar Cycle 24, these predictions depend heavily on statistics and precursors. The next step in our attempts to predict solar activity is to produce accurate error bars that can be used in simulations of the thermosphere over the years of a space mission. An updated prediction of Solar Cycle 25 using the SODA polar field precursor method will be presented. This precursor has accurately predicted the last three cycles. I will also comment on the data needed to understand the polar regions of the Sun --- the seeds of the next cycle. Title: Using Hilbert curves to organize, sample, and sonify solar data Authors: Pesnell, W. Dean; Ingram-Johnson, Kyle; Addison, Kevin Bibcode: 2021AmJPh..89..943P Altcode: How many ways can we explore the Sun? We have images in many wavelengths and squiggly lines of many parameters that we can use to characterize the Sun. We know that while the Sun is blindingly bright to the naked eye, it also has regions that are dark in some wavelengths of light. All of those classifications are based on vision. Hearing is another sense that can be used to explore solar data. Some data, such as the sunspot number or the extreme ultraviolet spectral irradiance, can be readily sonified by converting the data values to musical pitches. Images are more difficult. Using a raster scan algorithm to convert a full-disk image of the Sun to a stream of pixel values creates variations that are dominated by the pattern of moving on and off the limb of the Sun. A sonification of such a raster scan will contain discontinuities at the limbs that mask the information contained in the image. As an alternative, Hilbert curves are continuous space-filling curves that map a linear variable onto the two-dimensional coordinates of an image. We have investigated using Hilbert curves as a way to sample and analyze solar images. Reading the image along a Hilbert curve keeps most neighborhoods close together as the resolution (i.e., the order of the Hilbert curve) increases. It also removes most of the detector size periodicities and may reveal larger-scale features. We present several examples of sonified solar data, including sunspot number, extreme ultraviolet (EUV) spectral irradiances, an EUV image, and a sequence of EUV images during a filament eruption. Title: Two new methods for counting and tracking the evolution of polar faculae Authors: Hovis-Afflerbach, B.; Pesnell, W. Bibcode: 2021AAS...23811302H Altcode: Polar Faculae are the unipolar footpoints of field lines near the sun's poles and are visible as bright points on the edges of granules. Their number has been shown to correlate with the strength of the polar magnetic field, and therefore better understanding polar faculae enables better understanding of the polar magnetic field and its evolution, as well as conditions and convective motions at the poles. We present two methods of tracking faculae. In one the standard deviation of HMI continuum intensity images is calculated over a day and the facular candidates identified by their trails. The other overlays images of the progressive standard deviation over the course of the day with individual HMI magnetograms to show the close relationship between the facular candidates and the magnetic field. We apply this method to one pole each day for a week every 6 months, beginning September 2010. Our results confirm that faculae track regions of unipolar magnetic field that match the polarity of the visible pole. We observe the motion of the faculae and distinguish between motion due to the sun's rotation and "proper motion" due to faculae moving on the sun's surface, confirming that faculae participate in convective motions at the poles. This method provides a larger daily count of faculae than previous studies, allowing for a valid statistical determination of the facular lifetime. We show that the lifetime has a mode of 1-3 hours, with some faculae lasting up to 10 hours. Title: FISHA: the science case for a fast solar imager Authors: Inglis, A.; Kirk, M.; Attie, R.; Pesnell, W. Bibcode: 2021AAS...23831305I Altcode: The modern era of high-resolution solar EUV imaging at multiple wavelengths has unlocked a wealth of scientific discovery. Despite this, there are two fundamental issues that limit our ability to understand bright, rapidly evolving events on the Sun. These are 1) temporal cadence, and 2) image saturation. The combination of these two issues means that the fast dynamics on the Sun, particularly during eruptive events, are difficult to resolve in both time and space. This is problematic because models predict and observations show that during flares reconnection and particle acceleration processes can occur on < 1s timescales. These processes lead to rapidly varying thermal responses in chromospheric and coronal plasma.

We present the science case for the FISHA concept, a fast imager for the solar atmosphere. FISHA would image the Sun at high spatial resolution and sub-second temporal cadence, providing targeted observations of bright, transient features. This can be achieved while avoiding saturation effects using a combination of short exposure times and rapid readout detector capabilities. FISHA would also employ situational exposure and cadence control to allow observations of a wide range of solar phenomena. Here, we explore the potential science that FISHA could achieve and discuss methods of implementation. Title: LORRI observations of waves in Pluto's atmosphere Authors: Jacobs, Adam D.; Summers, Michael E.; Cheng, Andrew F.; Gladstone, G. Randall; Lisse, Carey M.; Pesnell, W. Dean; Bertrand, Tanguy; Strobel, Darrell F.; Young, Leslie A.; Weaver, Harold A.; Kammer, Joshua; Gao, Peter Bibcode: 2021Icar..35613825J Altcode: Observations during the New Horizons (NH) spacecraft flyby of Pluto in July 2015 revealed that Pluto's atmosphere supports an extensive circumplanetary haze with embedded layers, suggesting several possible microphysical and/or dynamical excitation processes. The purpose of this paper is to build upon existing observations and analyses of Pluto's atmosphere-specifically of the complex haze layer structures-to identify wave structure in Pluto's atmosphere. Here three NH/Long Range Reconnaissance Imager (LORRI) image sequences from the flyby at high phase angles (148°-169°) and three different resolutions (0.093 km/pix, 0.96 km/pix, and 3.86 km/pix) are analyzed. Several haze layer characteristics were extracted, namely-slope, amplitude, waveform, and the associated power spectral densities (PSDs); and their variations with local geography. These are then explored in the context of possible wave types in Pluto's atmosphere, such as tidal and orographically driven inertia-gravity (buoyancy) waves. PSD peaks at 8-10 km and 18-22 km vertical wavelength are found in NH images, which is consistent with the perturbations seen in Earth-based stellar occultations of Pluto's atmosphere. The 8-10 km signals are localized to low-latitudes and equatorial regions and the 18-22 km signals are more globally distributed. Haze layer background relative amplitudes were found to be around 0.01-0.04. Slopes of layers were found to be correlated with the emergence and disappearance of a 25 km layer around 30°N. An amplitude increase of oscillations below 30 km altitude exists in the high-resolution image sequence. These findings indicate the possibility of waves in Pluto's atmosphere and motivate further studies of wave dynamics combining NH data with state-of-the-art models of Pluto's atmosphere. These results are important because they can provide strong constraints to models and to the type of waves that can be present in Pluto's atmosphere. Title: A Study of Equatorial Coronal Holes and Active regions during the Maximum Phase of four Solar Cycles Authors: Karna, Nishu; DeLuca, Edward; Pesnell, William; Saar, Steven; Karna, Mahendra Bibcode: 2021cosp...43E.920K Altcode: The 11-year Solar Cycle (SC) is characterized by periodic changes in solar activity indicators such as number of sunspots, coronal holes, active regions (ARs), as well as the occurrence rate of solar energetic events such as filament eruptions, flares and coronal mass ejections (CMEs). In this work we performed a statistical study of the equatorial coronal holes (ECHs) and ARs during the maximum phase of the last four solar cycles: SC 21 (1979--1982), SC 22 (1989--1992), SC 23 (1999--2002) and SC 24 (2012--2015). We compared the number of ECHs and ARs, separations between their centroids, solar wind speed, pressure and the number of intense geomagnetic storms (IGS) data over these four cycles. We note a strong anticorrelation between the number of ARs and ECHs. We found that the number of close ARs and ECHs, solar wind speed, and the number of IGS increases with average sunspot maximum number for even cycles and decreases with average sunspot maximum for odd cycles. These odd-even trends largely (though not entirely) disappear in the relation between the wind properties and the numbers of close AR and ECH. This suggests a possible link between ECH-AR interactions and the solar wind phenomena, though residual odd-even trends point to the importance of other effects (e.g., Sun-earth magnetic alignment) as well. Title: SunCET: The Sun Coronal Ejection Tracker Concept Authors: Mason, James Paul; Chamberlin, Phillip C.; Seaton, Daniel; Burkepile, Joan; Colaninno, Robin; Dissauer, Karin; Eparvier, Francis G.; Fan, Yuhong; Gibson, Sarah; Jones, Andrew R.; Kay, Christina; Kirk, Michael; Kohnert, Richard; Pesnell, W. Dean; Thompson, Barbara J.; Veronig, Astrid M.; West, Matthew J.; Windt, David; Woods, Thomas N. Bibcode: 2021JSWSC..11...20M Altcode: 2021arXiv210109215M The Sun Coronal Ejection Tracker (SunCET) is an extreme ultraviolet imager and spectrograph instrument concept for tracking coronal mass ejections through the region where they experience the majority of their acceleration: the difficult-to-observe middle corona. It contains a wide field of view (0-4 R⊙) imager and a 1 Å spectral-resolution-irradiance spectrograph spanning 170-340 Å. It leverages new detector technology to read out different areas of the detector with different integration times, resulting in what we call "simultaneous high dynamic range", as opposed to the traditional high dynamic range camera technique of subsequent full-frame images that are then combined in post-processing. This allows us to image the bright solar disk with short integration time, the middle corona with a long integration time, and the spectra with their own, independent integration time. Thus, SunCET does not require the use of an opaque or filtered occulter. SunCET is also compact - ~15 × 15 × 10 cm in volume - making it an ideal instrument for a CubeSat or a small, complementary addition to a larger mission. Indeed, SunCET is presently in a NASA-funded, competitive Phase A as a CubeSat and has also been proposed to NASA as an instrument onboard a 184 kg Mission of Opportunity. Title: Predicting Solar Cycle 25 with an Ap/F10.7 Geomagnetic Precursor Pair Authors: Pesnell, W. D. Bibcode: 2020AGUFMSH053..08P Altcode: Long-term predictions of solar activity indices are used in orbital prediction and mission planning. We describe using an Ap/F10.7 geomagnetic precursor pair to predict the amplitude of the just-started Solar Cycle 25. The method is an evolution of an earlier algorithm that now removes the baseline solar activity cycle-by-cycle. A recurrence index is used to determine the timing of the precursor peak used in the prediction. Unlike previous times, when the recurrence index showed well-defined peaks during the decline from solar maxima, the recurrence index in the decline of Solar Cycle 24 increases rapidly after solar maximum in 2014 and remains at a large value until 2020. The effect of this on the timing of the precursor value will be examined. We conclude that Solar Cycle 25 will be no stronger than average and could be much weaker than average. Title: Lessons learned from predictions of Solar Cycle 24 Authors: Pesnell, W. Dean Bibcode: 2020JSWSC..10...60P Altcode: Solar Cycle 24 has almost faded and the activity of Solar Cycle 25 is appearing. We have learned much about predicting solar activity in Solar Cycle 24, especially with the data provided by SDO and STEREO. Many advances have come in the short-term predictions of solar flares and coronal mass ejections, which have benefited from applying machine learning techniques to the new data. The arrival times of coronal mass ejections is a mid-range prediction whose accuracy has been improving, mostly due to a steady flow of data from SoHO, STEREO, and SDO. Longer term (greater than a year) predictions of solar activity have benefited from helioseismic studies of the plasma flows in the Sun. While these studies have complicated the dynamo models by introducing more complex internal flow patterns, the models should become more robust with the added information. But predictions made long before a sunspot cycle begins still rely on precursors. The success of some categories of the predictions of Solar Cycle 24 will be examined. The predictions in successful categories should be emphasized in future work. The SODA polar field precursor method, which has accurately predicted the last three cycles, is shown for Solar Cycle 25. Shape functions for the sunspot number and F10.7 are presented. What type of data is needed to better understand the polar regions of the Sun, the source of the most accurate precursor of long-term solar activity, will be discussed. Title: A Study of Equatorial Coronal Holes during the Maximum Phase of Four Solar Cycles Authors: Karna, Mahendra Lal; Karna, Nishu; Saar, Steven H.; Pesnell, W. Dean; DeLuca, Edward E. Bibcode: 2020ApJ...901..124K Altcode: The 11 yr solar cycle (SC) is characterized by periodic changes in solar activity indicators such as the number of sunspots, coronal holes, and active regions (ARs), as well as the occurrence rate of solar energetic events such as filament eruptions, flares, and coronal mass ejections. In this work we performed a statistical study of the equatorial coronal holes (ECHs) and ARs during the maximum phase of the last four SCs: SC 21 (1979-1982), SC 22 (1989-1992), SC 23 (1999-2002), and SC 24 (2012-2015). We compared the number of ECHs and ARs, separations between their centroids, solar wind speed, pressure, and the number of intense geomagnetic storm (IGS) data over these four cycles. We note a strong anticorrelation between the number of ARs and ECHs. We found that the number of close ARs and ECHs, solar wind speed, and the number of IGS increases with average sunspot maximum number for even cycles and decreases with average sunspot maximum for odd cycles. Also, we find strong odd-even trends in the relation between the wind properties and the numbers of close AR and ECH. These results obtained from the annual average data suggest a possible link between ECH and AR proximity and the solar wind phenomena, though odd-even trends point to the importance of other effects (e.g., Sun-Earth magnetic alignment) as well. Title: A Study of Equatorial Coronal Holes during the Maximum Phase of four Solar Cycles Authors: Karna, N.; Karna, M.; Saar, S.; Pesnell, W.; DeLuca, E. Bibcode: 2020SPD....5120903K Altcode: The 11-year Solar Cycle (SC) is characterized by periodic changes in solar activity indicators such as a number of sunspots, coronal holes, active regions (ARs), as well as the occurrence rate of solar energetic events such as filament eruptions, flares and coronal mass ejections (CMEs). In this work we performed a statistical study of the equatorial coronal holes (ECHs) and ARs during the maximum phase of the last four solar cycles: SC 21 (1979-1982), SC 22 (1989-1992), SC 23 (1999-2002) and SC 24 (2012-2015). We compared the number of ECHs and ARs, separations between their centroids, solar wind speed, pressure and the number of intense geomagnetic storms (IGS) data over these four cycles. We note a strong anticorrelation between the number of ARs and ECHs. We found that the number of close ARs and ECHs (which are potentially interacting), solar wind speed, and the number of IGS increases with average sunspot maximum number for even cycles and decreases with average sunspot maximum for odd cycles. Also, we find strong odd-even trends in the relation between the wind properties and the numbers of close AR and ECH. These results suggest a possible link between ECH-AR interactions and the solar wind phenomena, though odd-even trends point to the importance of other effects (e.g., Sun-earth magnetic alignment) as well. Title: Using Ephemeral Coronal Holes to Validate the SPOCA Database of Coronal Holes Authors: Pesnell, W. D.; Pant, N.; Kirk, M. S.; Inglis, A. R. Bibcode: 2019AGUFMSH11D3385P Altcode: Given the relatively few examples of ephemeral coronal holes found by direct examination of data from the Solar Dynamics Observatory (SDO), we looked to the Spatial Possibilistic Clustering Algorithm (SPOCA) feature-finding algorithm to identify more examples. The SPOCA results are stored at the Heliophysics Event Knowledgebase (HEK), which was interrogated for this research. Unlike the direct examination, SPOCA identifies many small candidates for ephemeral coronal holes. We will report several causes for this difference, such as many candidates near the limb. Several filaments are also included as coronal holes. A dipole moment algorithm was developed to automatically eliminate these candidates from consideration. The magnetic configuration around a polarity inversion line underlying a filament has a more organized appearance than does the random field line placement within a coronal hole. The algorithm will be described, test cases presented, and solar examples will be presented. Title: Probing the solar corona with Sun-grazing comets: comparing MHDsimulations with EUV observations Authors: Jia, Y. D.; Pesnell, W. D.; Liu, W.; Downs, C.; Bryans, P. Bibcode: 2019AGUFMSH13A..03J Altcode: Sun -grazing comets can dive within one solar radii of the Sun 's surface. The cometary materials expand along the comet's orbit, and undergo various stages of fierce thermal-chemical reactions on the scales of seconds to minutes. These reactions ionize cometary ions through successive charge states , which is revealed by certain emission lines in the AIA images. Such plasma reaction processes are significantly affected by the transient structures in the corona, and thus these structures are revealed by the structures and shapes of the comet tail. We combine three numerical models: a global corona model, particle transportation model, and cometary plasma interaction model into one framework to simulate the interaction of Sun -grazing comets in the low corona. In our framework, cometary ejecta are vaporized and then ionized via multiple channels, and then confined by the coronal magnetic field. Constrained by imaging observations of the and cometary interaction images, we apply our framework to trace back to the local condition of the ambient corona, and its spatiotemporal variation. Previously, our model confirmed the importance of the ambient magnetic field vector in shaping the tail. In this study, we use the C/2011 W3 (Lovejoy) perihelion to determine the local plasma and field conditions in the corona. Our framework is capable of resolving structures from thousands of meters to tens of million meters, so we can identify the fine spatial variations in plasma density and magnetic field intensity, which may be visible in future/on-going close-up coronal observations. Title: Tracking supergranulation near the poles with SDO/HMI Authors: Attié, R.; Kirk, M. S.; Tremblay, B.; Muglach, K.; Hess Webber, S. A.; Pesnell, W. D.; Thompson, B. J. Bibcode: 2019AGUFMSH13B..01A Altcode: Due to the spherical curvature of the Sun, solar observers suffer from an increasing loss of resolution as we move away from the solar equator. Thus knowledge of the photospheric flows near the poles has eluded the scope of traditional flow tracking algorithms that are using granules as tracers of the underlying flows. Using the new "Balltracking" framework which we adapted to the observations from SDO/HMI, we present an unprecedented analysis of the horizontal flow fields at latitudes beyond +/- 60 degrees. The flow fields are derived every 4 hours at a spatial resolution of 4 Mm. Using flow segmentation techniques, we extract geometric and spectral information on the supergranular cells and compare them with those of the supergranulation at lower latitude. The correlation with the dynamics of moving magnetic features is also investigated. Title: A Study of Equatorial Coronal Holes during the Maximum Phase of Four Solar Cycles Authors: Karna, N.; Karna, M. L.; Saar, S. H.; Pesnell, W. D.; DeLuca, E. Bibcode: 2019AGUFMSH44A..03K Altcode: The 11-year Solar Cycle (SC) is characterized by periodic changes in the solar activity such as sunspot numbers, coronal holes, active regions, eruptions such as prominence eruptions, flares and coronal mass ejections. In this work we performed a statistical study of the equatorial coronal holes and the active regions during the maximum phases of four solar cycles (SC 21 (1979, 1980, 1981 and 1982), SC 22 (1989, 1990, 1991 and 1992), SC 23 (1999, 2000, 2001 and 2002) and SC 24 (2012, 2013, 2014 and 2015)). We compared equatorial coronal hole and active region numbers, separations between equatorial coronal holes and active regions centroids, solar wind speed and the number of intense geomagnetic storms data over these four cycles. We found that the distance between equatorial coronal holes and active regions, the solar wind speed, and the the number of intense geomagnetic storms increases with average sunspot maximum number for even cycles and decreases with average sunspot maximum for odd cycles. We also noticed that the solar wind speeds, pressures, and the number of intense geomagnetic storms increase with the numbers of close equatorial coronal holes and active regions, suggesting a possible link between equatorial coronal holes--active regions interactions and the wind phenomena. Title: Comparing Polar Coronal Hole Size to Polar Magnetic Flux Authors: Kirk, M. S.; Pesnell, W. D.; Arge, C. N. Bibcode: 2019AGUFMSH41B..02K Altcode: Polar magnetic fields are a critical piece to understand the global state of the solar corona. However, measuring the solar polar magnetic fields are notoriously difficult because of the oblique viewing angle. Polar coronal holes are the longest-lived features on the sun and represent areas of open magnetic flux. We make comprehensive measurements of polar hole's perimeter and area in three EUV wavelengths between 1996 and 2018 using five different space-based imagers: SOHO EIT, STEREO A and B EUVI, PROBA2 SWAP, and SDO AIA. The generated time-series of coronal hole boundaries rarely agree with each other, which presents a difficult data problem: multi-band, multi-instrument, heteroscedastic measurements with periodic and systematic signals. We combine these measurements using a parametric bootstrap method to make an empirical estimation of the polar coronal hole's size and boundary. This technique allows us to accurately characterize the evolving area and boundary of the polar holes. From this timeseries of polar hole area, we infer the evolving polar field flux over the past 22 years. Title: A Time-Distance Helioseismology Method for Quasi-Linear Geometries Authors: Hess Webber, Shea A.; Pesnell, W. Dean Bibcode: 2019SoPh..294..151H Altcode: Helioseismology is the study of the solar interior, through which we extract flow and wave-speed information from Doppler velocity observations at the surface. Local helioseismology involves the study of small regions on the solar disk and is used to create a detailed picture of the interior in that particular region. Perturbations in the flow and wave-speed results indicate, e.g. magnetic-flux or temperature variations. There are multiple methods used in local-helioseismic research, but all current local-helioseismic techniques assume a point-source perturbation. For this study, we develop a new time-distance (TD) helioseismic methodology that can exploit the quasi-linear geometry of an elongated feature, allowing us to i) improve the signal-to-noise ratio of the TD results, and ii) greatly decrease the number of calculations required and therefore the computing time of the TD analysis. Ultimately, the new method will allow us to investigate solar features with magnetic-field configurations previously unexplored. We validate our new technique using a simple f -mode wave simulation, comparing results of point-source and linear perturbations. Results indicate that local-helioseismic analysis is dependent on the geometry of the system and can be improved by taking the magnetic-field configuration into account. Title: Characteristics of Ephemeral Coronal Holes Authors: Inglis, A. R.; O'Connor, R. E.; Pesnell, W. D.; Kirk, M. S.; Karna, N. Bibcode: 2019ApJ...880...98I Altcode: 2019arXiv190601757I Small-scale ephemeral coronal holes may be a recurring feature on the solar disk but have received comparatively little attention. These events are characterized by compact structures and short total lifetimes, which are substantially less than a solar disk crossing. We present a systematic search for these events, using Atmospheric Imaging Assembly extreme ultraviolet image data from the Solar Dynamics Observatory, covering the time period of 2010-2015. Following strict criteria, this search yielded four clear examples of the ephemeral coronal hole phenomenon. The properties of each event are characterized, including their total lifetime, growth and decay rates, and areas. The magnetic properties of these events are also determined using Helioseismic and Magnetic Imager data. Based on these four events, ephemeral coronal holes experience rapid initial growth of up to ∼3000 Mm2 hr-1, while the decay phases are typically more gradual. Like conventional coronal holes, the mean magnetic field in each ephemeral coronal hole displays a consistent polarity, with mean magnetic flux densities generally <10 G. No evidence of a corresponding signature is seen in solar wind data at 1 au. Further study is needed to determine whether ephemeral coronal holes are underreported events or are truly rare phenomena. Title: Orbits through polytropes Authors: Gjerløv, Amalia; Pesnell, W. Dean Bibcode: 2019AmJPh..87..452G Altcode: We describe how orbital tunnels could be used to transport payloads through the Earth. If you use a brachistochrone for the tunnel, the body forces in the tunnel become overwhelmingly large for small angular distances traveled. Projectiles move along an orbital tunnel faster than they would along a brachistochrone connecting the same points but the body force components cancel. We describe how parabolic Keplerian orbits outside the object merge onto quasi-Keplerian orbits inside the object. We use models of the interior of the Earth with three values of the polytropic index (n) to calculate interior orbits that travel between surface points. The n = 3 results are also scaled to the Sun. Numerical integrations of the equations describing polytropes were used to generate the initial models. Numerical integration of the equations of motion are then used to calculate the angular distance you can travel along the surface and the traversal time as a function of the parabolic periapsis distance for each model. Trajectories through objects of low central condensation show a focussing effect that decreases as the central condensation increases. Analytic solutions for the trajectories in a homogeneous sphere are derived and compared to the numeric results. The results can be scaled to other planets, stars, or even globular clusters. Title: Characteristics of ephemeral coronal holes Authors: Inglis, Andrew; O'Connor, Rachel; Pesnell, W. Dean; Kirk, Michael S.; Karna, Nishu Bibcode: 2019AAS...23410605I Altcode: Small-scale ephemeral coronal holes may be a recurring feature on the solar disk, but have received comparatively little attention. These events are characterized by compact structure and short total lifetimes, substantially less than a solar disk crossing. Following a search of the time period 2010 - 2015 using Atmospheric Imaging Assembly EUV image data from the Solar Dynamics Observatory, we present analysis of four of the clearest examples of the ephemeral coronal hole phenomenon. The properties of each event are characterized, including their total lifetime, growth and decay rates, and areas. The magnetic properties of these events are also determined using Heliospheric Magnetic Imager data. These ephemeral coronal holes possess common characteristics, experiencing rapid initial growth of up to 3000 Mm2 / hr, while the decay phases are typically more gradual. Like conventional coronal holes, the mean magnetic field in each ephemeral coronal hole displays a consistent polarity, with mean fields generally < 10 G. No evidence of a corresponding signature is seen in solar wind data at 1AU. Further study is needed to determine whether ephemeral coronal holes are under-reported events or a truly rare phenomenon. Title: A Comprehensive Assessment of EUV Polar Coronal Holes: 1996 - 2018 Authors: Kirk, Michael S.; Pesnell, W. Dean; Arge, Charles Bibcode: 2019AAS...23412501K Altcode: Polar Coronal Holes are the longest-lived features on the sun and are a critical piece to understand the global state of the solar corona. Because of the oblique viewing angle, obstruction due to the coronal plasma scale height, and lack of ground truth make segmentation of polar holes difficult. We make new measurements of polar hole's perimeter and area in three EUV wavelengths between 1996 and 2018 using five different space-based imagers: SOHO EIT, STEREO A and B EUVI, PROBA2 SWAP, and SDO AIA. The generated time-series of coronal hole parameters rarely agree with each other, which presents a difficult data problem: multi-band, multi-instrument, heteroscedastic measurements with periodic and systematic signals. We combine these measurements using a parametric bootstrap method to make an empirical estimation of the polar coronal hole's size, boundary, and center of mass. This technique allows us to simultaneously analyze the physical properties of polar coronal holes and identify regular periodicities in our data from other origins. We present a comprehensive view of the EUV polar coronal hole over the past 22 years. Title: Listening to the Sun Authors: Pesnell, W. Dean; Ingram-Johnson, Kyle Bibcode: 2019AAS...23410703P Altcode: How many ways can we explore the Sun? We have images in many wavelengths and squiggly lines of many parameters that we can use to characterize the Sun. We learn that the Sun is bright with regions that are dark in some wavelengths and bright in others. But those classifications are both based on vision. Sound is another sense to use in exploring solar data. Some data, such as the sunspot number or the extreme ultraviolet spectral irradiance, can be easily sonified. Images are more difficult. A simple raster scan is dominated by moving on and off the limb of the Sun. Any sonification of the raster scan will contain discontinuities at the limbs that mask the information contained in the image. We propose to sample the curves with Hilbert curves to reduce those discontinuities. Hilbert curves are continuous space-filling curves that map the two-dimensional coordinates of an image onto a linear variable. We have investigated using Hilbert curves as ways to sample and analyze solar images. Reading the image along a Hilbert curve keeps neighborhoods close together as the resolution (i.e., the length of the Hilbert curve) increases. It also removes most of the detector size periodicities and actually shows the presence of longer-scale features. We shall provide several examples of sonified solar data, including the sunspot number, a selection of EUV spectral irradiances, an AIA 171 image, and a series of images during a solar flare. Title: Fractal Dimensions of Solar and Geomagnetic Indices Authors: Pesnell, W. Dean Bibcode: 2019AAS...23411801P Altcode: Correlations between solar and geomagnetic indices are often used in space weather research. How sensitive are these correlations to pre-whitening of the data and auto-correlation within the data sets? Statistical and timeseries analyses of the sunspot number are often used to predict solar activity. These methods have not been completely successful as the solar dynamo changes over time and one cycle's sunspots are not a faithful predictor of the next cycle's activity. Can more accurate predictions be produced by partitioning the data into periods when it obeys certain statistical properties? The Hurst exponent and the related fractal dimension are two such ways to partition the data. We can use these measures of complexity to compare the sunspot number with other solar and geomagnetic indices. We use five algorithms to calculate the Hurst exponent or fractal dimension and examine what happens when the mean and a linear trend trends are removed. We find that some algorithms are robust and return similar or identical values for the original, mean-removed, and linear-trend-subtracted data. The behavior of the Fourier transform at low frequencies is the most sensitive to the type of pre-whitening applied to the data. The rescaled-range algorithm is robust but needs to be corrected for autocorrelation in the data. Title: Characteristics of Ephemeral Coronal Holes Authors: O'Connor, Rachel E.; Inglis, Andrew R.; Pesnell, W. Dean; Kirk, Michael S.; Karna, Nishu Bibcode: 2019shin.confE.202O Altcode: Small-scale ephemeral coronal holes may be a recurring feature on the solar disk, but have received comparatively little attention. These events are characterized by compact structure and short total lifetimes, substantially less than a solar disk crossing. We present a systematic search for these events, using Atmospheric Imaging Assembly EUV image data from the Solar Dynamics Observatory, covering the time period 2010 - 2015. Following strict criteria, this search yielded four clear examples of the ephemeral coronal hole phenomenon. The properties of each event are characterized, including their total lifetime, growth and decay rates, and areas. The magnetic properties of these events are also determined using Helioseismic and Magnetic Imager data. Based on these four events, ephemeral coronal holes experience rapid initial growth of up to 3000 Mm2/hr, while the decay phases are typically more gradual. Like conventional coronal holes, the mean magnetic field in each ephemeral coronal hole displays a consistent polarity, with mean magnetic flux densities generally < 10 G. No evidence of a corresponding signature is seen in solar wind data at 1 AU. Further study is needed to determine whether ephemeral coronal holes are under-reported events or a truly rare phenomenon. Title: Quantifying the Variability of Coronal Hole Boundaries Authors: Kirk, Michael S.; Pesnell, W. Dean; Arge, C. Nick Bibcode: 2019shin.confE..69K Altcode: Polar Coronal Holes are the longest-lived features on the sun and are a critical piece to understand the global state of the solar corona. Because of the oblique viewing angle, obstruction due to the coronal plasma scale height, and lack of ground truth make segmentation of polar holes difficult. We make comprehensive measurements of polar hole’s perimeter and area in three EUV wavelengths between 1996 and 2018 using five different space-based imagers: SOHO EIT, STEREO A and B EUVI, PROBA2 SWAP, and SDO AIA. The generated time-series of coronal hole boundaries rarely agree with each other, which presents a difficult data problem: multi-band, multi-instrument, heteroscedastic measurements with periodic and systematic signals. We combine these measurements using a parametric bootstrap method to make an empirical estimation of the polar coronal hole’s size, boundary, and center of mass. This technique allows us to accurately characterize the evolving boundary of the polar holes and identify the EUV band passes that best capture these structures. Title: Simulations of Observed Haze Layer Structure in Pluto's Atmosphere Authors: Jacobs, A. D.; Summers, M. E.; Gladstone, R.; Cheng, A. F.; Strobel, D. F.; Lisse, C. M.; Gao, P.; Young, L. A.; Pesnell, W. D.; Kammer, J.; Weaver, H. A., Jr. Bibcode: 2018AGUFM.P51F2949J Altcode: Observations during the New Horizons spacecraft flyby of Pluto in July 2015 revealed that Pluto's atmosphere has an extensive haze with embedded layers, suggesting several possible microphysical and/or dynamical processes operating in the atmosphere. Orographically driven gravity (buoyancy) waves are the main layering mechanism explored in this study. A single scattering model was implemented to simulate three LORRI image sequences at high phase angles (148˚-169°) and three different resolutions (0.093 km/pix: HIPHASE_HIRES, 0.96 km/pix: P_MULTI, and 3.5 km/pix: FULLFRAME). All scattering calculations were done for the LORRI pivot wavelength of 607.6 nm. A 2D gravity wave (GW) perturbation field created from an orographically-driven GW model was used to generate north/south and east/west oriented 3D layered structures. The two sets of GW perturbations were then applied to two types of background haze densities. Haze layer I/F simulations were further explored by applying LORRI's PSF to the simulated images. Some discrepancies between model results and observations still exist, including: (1) larger tilt/slope of modelled layers for both GW orientations than observed in the P_MULTI sequence, (2) smaller layer wavelength and larger layer distinctness/amplitude than observed at altitudes below 40 km in the HIPHASE_HIRES sequence, and (3) missing larger scale structure observed in the P_MULTI and FULLFRAME sequences where haze layering is geographically most distinct. These discrepancies may be accounted for by: (1) adjustments to the GW model wind speed over terrain and/or changing the assumed terrain/aspect ratio (i.e., by decreasing the assumed wind-aligned wavenumber), (2) the inclusion of mixing processes or consideration of faster layer dissipation processes for low altitude layers, and (3) the superposition of different wave types (i.e., Rossby waves) with orographically generated waves. Limitations on possible adjustments to the GW model perturbations intrinsic tilt/slope that still allow vertical propagation through Pluto's strong temperature inversion, as well as power spectra extracted from LORRI images, are evidence for the presence of other wave types that could cause haze layering through generation mechanisms not considered by the orographic gravity wave model. Title: Multi-wavelength Observations of Flare-Induced Acoustic Waves Around Active Regions with SDO AIA Authors: Monsue, Teresa; Pesnell, W. Dean; Hill, Frank; Kirk, Michael Bibcode: 2018csc..confE.111M Altcode: Active regions on the Sun are abundant with a variety of waves that are both acoustically helioseismic and magnetohydrodynamic in nature. The occurrence of a solar flare can disrupt these waves, through MHD mode-mixing or scattering by the excitation of these waves. We take a multi-wavelength observational approach to understand the source of these waves by studying active regions where flaring activity occurs. Utilizing a Fast Fourier Transform (FFT) algorithm, our approach is to search for signals within a time series of images by producing multi-frequency power map movies and spatially sampling the time series by radial sectors with constant area that minimizes the spatial variation of the acoustic power. With this application we are able to study the active region both spatially and temporally and correlate data over multiple wavelengths, allowing us to observe the behavior of the waves at different heights within the Solar atmosphere. We apply multi-wavelength measurements utilizing NASA's SDO AIA 1700 (lower photosphere), 1600 (upper photosphere) and 304 (chromosphere) passbands. When we run power map movies of the chromosphere we are able to see a subtle propagating feature moving outward from the center of the flare; this could be an MHD-wave propagating outward by the flaring event. With our sector sampling method we observe power variation around the flaring active region. This power variation corresponds to the flare induced enhancement of the oscillations around the active region. Furthermore, there seems to be absorptive properties observed within the chromospheric line of the AIA 304 Å passband. Title: The Solar Dynamics Observatory, Eight Years of Science Authors: Pesnell, W. Dean Bibcode: 2018csc..confE.110P Altcode: The Solar Dynamics Observatory has been producing science and science data since May 2010. I will describe some highlights of SDO results, including filament eruptions, flares, and comets. The status of the observatory hardware will also be discussed. The future of SDO will be a series of extended missions, each lasting three years. Our second extended mission started October 1, 2017. That gives us another year to study the data before writing another proposal! Title: Roadmap for Reliable Ensemble Forecasting of the Sun-Earth System Authors: Nita, Gelu; Angryk, Rafal; Aydin, Berkay; Banda, Juan; Bastian, Tim; Berger, Tom; Bindi, Veronica; Boucheron, Laura; Cao, Wenda; Christian, Eric; de Nolfo, Georgia; DeLuca, Edward; DeRosa, Marc; Downs, Cooper; Fleishman, Gregory; Fuentes, Olac; Gary, Dale; Hill, Frank; Hoeksema, Todd; Hu, Qiang; Ilie, Raluca; Ireland, Jack; Kamalabadi, Farzad; Korreck, Kelly; Kosovichev, Alexander; Lin, Jessica; Lugaz, Noe; Mannucci, Anthony; Mansour, Nagi; Martens, Petrus; Mays, Leila; McAteer, James; McIntosh, Scott W.; Oria, Vincent; Pan, David; Panesi, Marco; Pesnell, W. Dean; Pevtsov, Alexei; Pillet, Valentin; Rachmeler, Laurel; Ridley, Aaron; Scherliess, Ludger; Toth, Gabor; Velli, Marco; White, Stephen; Zhang, Jie; Zou, Shasha Bibcode: 2018arXiv181008728N Altcode: The authors of this report met on 28-30 March 2018 at the New Jersey Institute of Technology, Newark, New Jersey, for a 3-day workshop that brought together a group of data providers, expert modelers, and computer and data scientists, in the solar discipline. Their objective was to identify challenges in the path towards building an effective framework to achieve transformative advances in the understanding and forecasting of the Sun-Earth system from the upper convection zone of the Sun to the Earth's magnetosphere. The workshop aimed to develop a research roadmap that targets the scientific challenge of coupling observations and modeling with emerging data-science research to extract knowledge from the large volumes of data (observed and simulated) while stimulating computer science with new research applications. The desire among the attendees was to promote future trans-disciplinary collaborations and identify areas of convergence across disciplines. The workshop combined a set of plenary sessions featuring invited introductory talks and workshop progress reports, interleaved with a set of breakout sessions focused on specific topics of interest. Each breakout group generated short documents, listing the challenges identified during their discussions in addition to possible ways of attacking them collectively. These documents were combined into this report-wherein a list of prioritized activities have been collated, shared and endorsed. Title: An Early Prediction of the Amplitude of Solar Cycle 25 Authors: Pesnell, W. Dean; Schatten, Kenneth H. Bibcode: 2018SoPh..293..112P Altcode: A "Solar Dynamo" (SODA) Index prediction of the amplitude of Solar Cycle 25 is described. The SODA Index combines values of the solar polar magnetic field and the solar spectral irradiance at 10.7 cm to create a precursor of future solar activity. The result is an envelope of solar activity that minimizes the 11-year period of the sunspot cycle. We show that the variation in time of the SODA Index is similar to several wavelet transforms of the solar spectral irradiance at 10.7 cm. Polar field predictions for Solar Cycles 21 - 24 are used to show the success of the polar field precursor in previous sunspot cycles. Using the present value of the SODA index, we estimate that the next cycle's smoothed peak activity will be about 140 ±30 solar flux units for the 10.7 cm radio flux and a Version 2 sunspot number of 135 ±25 . This suggests that Solar Cycle 25 will be comparable to Solar Cycle 24. The estimated peak is expected to occur near 2025.2 ±1.5 year. Because the current approach uses data prior to solar minimum, these estimates may improve as the upcoming solar minimum draws closer. Title: Interaction between cool material from Sun-grazing comets and the low corona Authors: Jia, Yingdong; Pesnell, William; Liu, Wei; Downs, Cooper; Bryans, Paul Bibcode: 2018cosp...42E1613J Altcode: Sun-grazing comets dive into altitudes lower than 1 solar radius from the chromosphere. Cool materials of temperature lower than 10 ^{3}K explode from the comet into the 10 ^{6} K corona. These materials undergone various stages of rapid chemical reactions in scales of seconds to minutes. Such reactions Structures in such images of various wavelengths indicate strong variation in ambient conditions of the corona. We combine three numerical models: low corona model, particle transportation model, and cometary plasma interaction model into one framework to model the interaction of Sun-grazing comets in the low corona. In our framework, cometary vapor are ionized via multiple channels, and then detained by the coronal magnetic field. In seconds, these ions are further ionized into their highest charge state, which is revealed by certain emission lines. Constrained by coronal graphs and cometary interaction images, we apply our framework to trace back to the local condition of the ambient corona, and its spatial/time variation. Our frame work is able to resolve structures of sub-million meters to tens of million meters. Once trained by multiple stages of the comet's journey in the low corona, this framework can identify the fine spatial variations in plasma density and magnetic field intensity, which may be visible to future close-up observations. Title: Predicting the Sun: Black Swans or Dragon Kings? Authors: Pesnell, William Dean Bibcode: 2018tess.conf22405P Altcode: Our goal of predicting the Sun spans timescales from seconds to centuries and phenomena from flares to convective flows. We are faced with questions of what extremes to expect when predicting each phenomenon. Some extremes are obvious: What is the brightest flare, largest active region or fastest coronal mass ejection we can expect? Others are less so: What is the largest magnetic field strength? Or how often should we expect a Grand Minimum, an era of low to absent solar activity, and what happens to the irradiance of the Sun during that era? Most phenomena have a robust set of observations covering a wide range of possibilities that allows statistical methods to be used. Every so often, an exceptional event is seen, such as the X45 flare of November 2002 or the geomagnetic storm following the Carrington Event in September 1859, that sits outside of those statistics. Longer term examples include predicting sunspot cycles of unusually large or small amplitude. I will describe Black Swans and Dragon Kings and how they can be used to understand the predictions of extreme events in solar physics. Title: The Recalibrated Sunspot Number: What It Is and How Will It be Updated? Authors: Clette, Frederic; Pesnell, William Dean; Lefevre, Laure Bibcode: 2018tess.conf30288C Altcode: Recently, and for the first time since their creation, the definition of the sunspot number and group number series were revisited. A fully recalibrated version was officially released in July 2015 by the World Data Center SILSO (Brussels). Those long-term reference series are widely used as input data or as a calibration reference by many research projects in solar physics and space weather. To clarify the nature of the applied changes, we describe the different corrections applied to the sunspot and group number series, which affect extended time periods and can reach up to 40%. While some changes simply involve constant scale factors, other corrections vary with time or are modulated by the solar cycle. Depending on the research project and the selected time interval, this can lead to different responses and biases. For example, predictions of solar activity based on the sunspot number should be redone using the new sunspot series, and methods already used for predicting Solar Cycle 24 will require adaptations before attempting predictions of the next cycles. In addition, the revised sunspot series includes standard error estimates, which may help in deriving more accurate uncertainties for predicted activity indices. We conclude with the new round of recalibration that is now undertaken in the framework of a broad multi-team collaboration articulated around upcoming ISSI workshops. We outline the future corrections that can still be expected in the future, as part of a permanent upgrading process and quality control. From now on, future sunspot-based predictive models should thus be made more adaptable, and regular updates of such models should become common practice in order to track periodic upgrades of the sunspot number series, just like it is done when using other modern solar observational series. Title: Oscillations and Asymmetries in Polar Coronal Holes Authors: Kirk, Michael S.; Pesnell, William Dean Bibcode: 2018tess.conf30921K Altcode: Coronal holes are the origin of the fast solar wind and define the quiescent heliosphere. Polar coronal holes are prevalent during solar minimum, non-axisymmetric, and are stable. They also offer an indirect measurement of the polar magnetic flux. Polar holes are regularly observed capping the northern and southern solar poles in EUV images of the corona and are understood as the primary source of the fast solar wind. We make new measurements of polar hole's perimeter and area in three EUV wavelengths between 1996 and 2017 using five different space-based imagers: SOHO EIT, STEREO A and B EUVI, PROBA2 SWAP, and SDO AIA. The generated time-series of coronal hole parameters have significant oscillatory power in them - however this produces a difficult data problem: multi-band, multi-instrument, heteroscedastic measurements with periodic signals. To separate the oscillations associated with physical phenomena from systematic measurement errors, we employ a generalized Lomb-Scargle periodic analysis. This technique allows us to simultaneously analyze the physical properties of polar coronal holes and identify regular periodicities in our data from other origins. Title: Using the Solar Polar Magnetic Field for Longterm Predictions of Solar Activity, Solar Cycles 21-25 Authors: Pesnell, W. D.; Schatten, K. H. Bibcode: 2017AGUFMSH13A2473P Altcode: We briefly review the dynamo and geomagnetic precursor methods of long-term solar activity forecasting. These methods depend upon the most basic aspect of dynamo theory to predict future activity, future magnetic field arises directly from the amplification of pre-existing magnetic field. We then generalize the dynamo technique, allowing the method to be used at any phase of the solar cycle, to the Solar Dynamo Amplitude (SODA) index. This index is sensitive to the magnetic flux trapped within the Sun's convection zone but insensitive to the phase of the solar cycle. Since magnetic fields inside the Sun can become buoyant, one may think of the acronym SODA as describing the amount of buoyant flux. We will show how effective the SODA Index has been in predicting Solar Cycles 23 and 24, and present a unified picture of earlier estimates of the polar magnetic configuration in Solar Cycle 21 and 22. Using the present value of the SODA index, we estimate that the next cycle's smoothed peak activity will be about 125 ± 30 solar flux units for the 10.7 cm radio flux and a sunspot number of 70 ± 25. This suggests that Solar Cycle 25 will be comparable to Solar Cycle 24. Since the current approach uses data prior to solar minimum, these estimates may improve when the upcoming solar minimum is reached. Title: Digging into the corona: A modeling framework trained with Sun-grazing comet observations Authors: Jia, Y. D.; Pesnell, W. D.; Bryans, P.; Downs, C.; Liu, W.; Schwartz, S. J. Bibcode: 2017AGUFMSH11B2437J Altcode: Images of comets diving into the low corona have been captured a few times in the past decade. Structures visible at various wavelengths during these encounters indicate a strong variation of the ambient conditions of the corona. We combine three numerical models: a global coronal model, a particle transportation model, and a cometary plasma interaction model into one framework to model the interaction of such Sun-grazing comets with plasma in the low corona. In our framework, cometary vapors are ionized via multiple channels and then captured by the coronal magnetic field. In seconds, these ions are further ionized into their highest charge state, which is revealed by certain coronal emission lines. Constrained by observations, we apply our framework to trace back to the local conditions of the ambient corona, and their spatial/time variation over a broad range of scales. Once trained by multiple stages of the comet's journey in the low corona, we illustrate how this framework can leverage these unique observations to probe the structure of the solar corona and solar wind. Title: Acoustic Oscillation Properties of Active Region 12193 Authors: Monsue, Teresa; Pesnell, William D.; Hill, Frank Bibcode: 2017SPD....4810904M Altcode: Solar flares are dynamic objects occurring randomly and yet unannounced in nature. In order to find an efficient detection method, we require a greater breadth of knowledge of the system. One path to such a method is to observe the solar atmosphere in a region around a flare in different wavelengths of light and acoustic frequency bands. This provides information from different altitudes in the solar atmosphere and allows us to study the temporal evolution of each altitude through the flaring event. A more complete understanding of the time evolution may lead to yet undiscovered precursors of the flare. In this project, we study Active Region 12192 using acoustic observations near an X3 flare occurring on October 24, 2014 at 21:41UT. Our wavelet analysis utilizes time series data to create Fourier power spectra of individual pixels spatially resolved around the flare region, to study the frequency bands. In order to study the power distribution in regions around the flare and to search for any correlation we apply several methods. One method we partition sub-regions in our main flaring region and take a survey of the oscillations for each frequency band within power maps. Another method we average the FFT to take measurements within the p-modes (2-4 mHz) and chromospheric (4-6 mHz) frequencies. The application of these methods should be able to get us closer to tracking waveforms within power maps. Title: The Complexity of Solar and Geomagnetic Indices Authors: Pesnell, W. Dean Bibcode: 2017SPD....48.0703P Altcode: How far in advance can the sunspot number be predicted with any degree of confidence? Solar cycle predictions are needed to plan long-term space missions. Fleets of satellites circle the Earth collecting science data, protecting astronauts, and relaying information. All of these satellites are sensitive at some level to solar cycle effects. Statistical and timeseries analyses of the sunspot number are often used to predict solar activity. These methods have not been completely successful as the solar dynamo changes over time and one cycle's sunspots are not a faithful predictor of the next cycle's activity. In some ways, using these techniques is similar to asking whether the stock market can be predicted. It has been shown that the Dow Jones Industrial Average (DJIA) can be more accurately predicted during periods when it obeys certain statistical properties than at other times. The Hurst exponent is one such way to partition the data. Another measure of the complexity of a timeseries is the fractal dimension. We can use these measures of complexity to compare the sunspot number with other solar and geomagnetic indices. Our concentration is on how trends are removed by the various techniques, either internally or externally. Comparisons of the statistical properties of the various solar indices may guide us in understanding how the dynamo manifests in the various indices and the Sun. Title: The Formation and Maintenance of the Dominant Southern Polar Crown Cavity of Cycle 24 Authors: Karna, N.; Zhang, J.; Pesnell, W. D. Bibcode: 2017ApJ...835..135K Altcode: In this article, we report a study of the longest-lived polar crown cavity of Solar Cycle 24, using an observation from 2013, and propose a physical mechanism to explain its sustained existence. We used high temporal and spatial resolution observations from the Atmospheric Imaging Assembly (AIA) and the Helioseismic Magnetic Imager (HMI) instruments on board the Solar Dynamics Observatory (SDO) to explore the structure and evolution of the cavity. Although it existed for more than a year, we examined the circumpolar cavity in great detail from 2013 March 21 to 2013 October 31. Our study reinforces the existing theory of formation of polar crown filaments that involves two basic processes to form any polar crown cavity as well as the long-lived cavity that we studied here. First, the underlying polarity inversion line (PIL) of the circumpolar cavity is formed between (1) the trailing part of dozens of decayed active regions distributed in different longitudes and (2) the unipolar magnetic field in the polar coronal hole. Second, the long life of the cavity is sustained by the continuing flux cancellation along the PIL. The flux is persistently transported toward the polar region through surface meridional flow and diffusion. The continuing flux cancellation leads to the shrinking of the polar coronal hole. Title: Identifying Long-term Oscillations in Polar Coronal Holes Authors: Kirk, M. S.; Pesnell, W. D.; Young, C. A. Bibcode: 2016AGUFMSH11A2223K Altcode: Polar coronal holes offer an indirect measurement of the polar magnetic flux, which is a significant component to our understanding of the solar cycle. Polar holes are prevalent during solar minimum, non-axisymmetric, and are stable. They are regularly observed capping the northern and southern solar poles in EUV images of the corona and are understood as the primary source of the fast solar wind. We make measurements of polar hole area with three EUV wavelengths from 1996 through 2016 using five different space-based imagers: SOHO EIT, STEREO A and B EUVI, PROBA2 SWAP, and SDO AIA. Each time series of coronal hole parameters have significant oscillatory power in them, however this produces a difficult data problem: multi-band, multi-instrument, heteroscedastic measurements with periodic signals. To separate the oscillations associated with systematic measurement errors from physical phenomena, we employ a Tikhonov regularization scheme to generalize the conventional Lomb-Scargle method to a multi-band periodic analysis. This technique allows us to simultaneously analyze the physical properties of polar coronal holes and identify regular periodicities in our data from other origins. Title: Comparing Time-Distance Results within a Coronal Hole to the Quiet Sun Authors: Hess Webber, Shea A.; Pesnell, W. Dean; Duvall, Thomas, Jr.; Birch, Aaron; Cameron, Robert Bibcode: 2016usc..confE...1H Altcode: Time-distance helioseismology studies perturbations in solar wave modes. We use these techniques with SDO/HMI time-distance velocity-tracked dopplergram data to investigate differences between f -mode wave propagation within a coronal hole feature and without. We use symmetry arguments to enhance the signal-to-noise ratio of the cross-correlation results. We then look for phase and amplitude discrepancies between the coronal hole and quiet sun by comparing statistically significant differences between the regions. Title: Space Oddities: The Search For Ephemeral Coronal Holes Authors: O'Connor, Rachel E.; Pesnell, W. Dean; Kirk, Michael S.; Karna, Nishu Bibcode: 2016usc..confE...9O Altcode: Ephemeral coronal holes are short-lived, volatile counterparts to equatorial coronal holes. Very little is known about their characteristics and behavior aside from their definition: open, unipolar magnetic field lines resulting in darkened regions of the corona. The first exemplar of this phenomenon was observed by NASA's Solar Dynamics Observatory (SDO) on October 26, 2010, which spurred our search for other occurrences in order to understand the frequency and evolution of these phenomena. To accomplish this, we visually evaluated SDO 211 Å images on a 12-hour cadence between June 2010 and June 2016. Each compact and isolated dim region we encountered was flagged as a potential ephemeral coronal hole for further analysis. This preliminary effort resulted in 149 candidate holes. For further analysis of their characteristics, we applied a strict definition criterion of an ephemeral coronal hole. This criterion was a set of four factors that were created in order to ensure events being observed were isolated, individual events- the candidates had to be dark relative to the surrounding material, not influenced by a nearby eruption, not obviously connected to other coronal hole structures, and their lifetime had to occur completely within the disk crossing. This criterion was designed so that events could be completely analyzed, from beginning to end, to better understand the origins. Application of this criterion eliminated all candidates but 5 of the original 149. True ephemeral coronal holes are rare occurrences, appearing only five times in six years. Future research in this area is needed to both locate additional events and study the underlying driving forces behind these rare phenomena. Title: Estimating and Separating Noise from AIA Images Authors: Kirk, Michael S.; Ireland, Jack; Young, C. Alex; Pesnell, W. Dean Bibcode: 2016usc..confE..26K Altcode: All digital images are corrupted by noise and SDO AIA is no different. In most solar imaging, we have the luxury of high photon counts and low background contamination, which when combined with carful calibration, minimize much of the impact noise has on the measurement. Outside high-intensity regions, such as in coronal holes, the noise component can become significant and complicate feature recognition and segmentation. We create a practical estimate of noise in the high-resolution AIA images across the detector CCD in all seven EUV wavelengths. A mixture of Poisson and Gaussian noise is well suited in the digital imaging environment due to the statistical distributions of photons and the characteristics of the CCD. Using state-of-the-art noise estimation techniques, the publicly available solar images, and coronal loop simulations; we construct a maximum-a-posteriori assessment of the error in these images. The estimation and mitigation of noise not only provides a clearer view of large-scale solar structure in the solar corona, but also provides physical constraints on fleeting EUV features observed with AIA. Title: On the Formation Mechanism of A Long-lived Polar Crown Cavity Authors: Karna, Nishu; Pesnell, William D.; Zhang, Jie Bibcode: 2016usc..confE..22K Altcode: We report the study of the longest-lived polar crown cavity of Solar Cycle 24th observed in the year 2013 and propose a physical mechanism to explain the sustained existence. We used high temporal and spatial resolution observations from the Atmospheric Imaging Assembly (AIA) and the Helioseismic Magnetic Imager (HMI) instruments on board the Solar Dynamics Observatory (SDO) to explore the structure and evolution. We examined the circumpolar cavity in great detail from March 21, 2013, till October 31, 2013, while it existed for more than one year. Our study suggests two necessary conditions to form a long stable circumpolar cavity or any polar crown cavity. First, the underlying polarity inversion line (PIL) of the circumpolar cavity is formed between the trailing part of dozens of decayed active regions distributed in different longitudes and the unipolar magnetic field in the polar coronal hole. Second, the long life of the cavity is sustained by the continuing flux cancellation along the polarity inversion line. The flux is persistently transported toward the polar region through surface meridional flow and diffusion, which also leads to the shrinking of the polar coronal hole. Comparing with the existing theory of the formation of polarity inversion lines, we introduce a new category named as "Diffused trailing flux and polar coronal hole interaction region" to explain the polar crown cavity. The existence of such region also helps explain the process of polar reversal, which provides insight into the solar cycle. Title: The Solar Dynamics Observatory, Six Years of Science Authors: Pesnell, W. Dean Bibcode: 2016usc..confE..57P Altcode: The Solar Dynamics Observatory has been producing science and science data since May 2010. I will describe some highlights of SDO results, including filament eruptions, flares, and comets. The status of the observatory hardware will also be discussed. The future of SDO will be a series of extended missions, each lasting two years. Our next extended mission proposal will be due early next year and I will discuss part of that process. Title: SDO 2016: Unraveling the Suns Complexity Authors: Pesnell, W. Dean; Thompson, Barbara Bibcode: 2016usc..conf.....P Altcode: Living With a Star Solar Dynamics Observatory research connects to many areas of solar physics and many other solar missions. Tracing these connections allows us to build a more accurate understanding of the Sun and solar activity. The workshop will focus on our improved knowledge and understanding of the Suns magnetic field that have come from the SDO data, and what will come in the future. Scientific sessions will feature a broad spectrum of science topics fundamental to SDO science investigations: Atmospheric Imaging Assembly (AIA), EUV Variability Experiment (EVE), and Helioseismic and Magnetic Imager (HMI), as well as the overlap between SDO and other scientific missions and activities. We invite you to celebrate the breadth of research topics enabled by SDO during its Prime Mission and the First Extended Mission. Title: Solar Acoustic Oscillations Observations in SDO AIA and HMI around AR 12192 Authors: Monsue, Teresa; Pesnell, W. Dean; Hill, Frank Bibcode: 2016usc..confE..89M Altcode: Solar flares are dynamic objects occurring randomly and yet unannounced in nature. In order to find an efficient detection method, we require a greater breadth of knowledge of the system. One such mode is to observe flares in different frequency bands at different depths and study their temporal evolution through the flaring event. In this project we obtain acoustic observations of an X3 flare occurring on October 24, 2014 at 21:41UT. We employ the study of active regions, near sunspots, in which flaring activity is taking place. Our wavelet analysis utilizes time series data to create Fourier power spectra of individual pixels spatially resolved around the flare region, to study the frequency bands. In order to study the power distribution in regions around the flare and compare the measurements to magnetograms to search for any correlation, we combine observations of oscillations in three SDO AIA wavelengths: the 1600Å, 1700 Å and 304Å, and combine them with HMI data. We then study how the frequency distribution evolves temporally by constructing a Power Map Movie (PMM) of the regions. From these PMMs we can partition sub-regions in our main flaring region and take a survey of the oscillations for each frequency band. Title: Watching the Sun from space Authors: Pesnell, W. Dean Bibcode: 2016AsJPh..25..233P Altcode: Space-based solar observatories have made fundamental discoveries about the lifecycle of the solar magnetic field and how that field affects the solar system. Observing the Sun from space provides access to all wavelengths of light and eliminates the smearing of atmospheric seeing. Being in space means the emissions from the highly-ionized material that are the natural emissions of the corona can be measured. Continuous observations of the Sun can be made from a single satellite in certain orbits. This leads to unexpected discoveries, such as orbiting coronagraphs showing that sun grazing comets are the most common class of observed comets. Or when the coronal holes discovered with the solar X-ray telescopes on Skylab explained long-noticed correlations in particle fluxes from the Sun with solar longitudes. Space-based coronagraphs and heliospheric imagers are able to track coronal mass ejections from when they leave the Sun until they hit the Earth or another planet. In a more practical point, as humans have become more entwined in the use of technology, the magnetic field of the Sun has become more intrusive. Energetic particles and high-energy photons from solar fares can compromise humans and electronics in space. As a coronal mass ejection passes by and interacts with the Earth's magnetosphere, it generates large currents at the Earth's surface that can disrupt power distribution systems. The measurements of Sun made possible by being in space will be described, along with some highlights of the observatories that make them. Title: On the Formation Mechanism of A Long-lasting Polar Crown Cavity Authors: Karna, Nishu; Pesnell, William Dean; Zhang, Jie Bibcode: 2016shin.confE.140K Altcode: We report the observation of the longest-lived polar crown cavity of Solar Cycle 24th observed in the year 2013 and propose a physical mechanism to explain the sustained existence. We used high temporal and spatial resolution observations from the Atmospheric Imaging Assembly (AIA) and the Helioseismic Magnetic Imager (HMI) instruments on board the Solar Dynamics Observatory (SDO) to explore the structure and evolution. We examined the circumpolar cavity in great detail from March 21, 2013, till October 31, 2013., while it existed for more than one year. Our study suggests two necessary conditions to form a long stable circumpolar cavity or any polar crown cavity. First, the underlying polarity inversion line (PIL) of the circumpolar cavity is formed between the trailing part of dozens of decayed active regions distributed in different longitudes and the unipolar magnetic field in the polar coronal hole. Second, the long lasting of the cavity is sustained by the continuing flux cancellation along the polarity inversion line. The flux is persistently transported toward the polar region through surface meridional flow and diffusion, which also leads to the shrinking of the polar coronal hole. Comparing with the existing theory of the formation of polarity inversion lines, we introduce a new category named as "Diffused bipole and polar coronal hole interaction region" to explain the polar crown cavity. The existence of such region also helps explain the process of polar reversal, which provides insight into the solar cycle. Title: A Comprehensive study of Cavities on the Sun: Structure, Formation, and Evolution Authors: Karna, Nishu; Zhang, Jie; Pesnell, William D. Bibcode: 2016SPD....4710302K Altcode: Coronal cavities are large-scale structures in the Sun's corona that are closely related with the long-term evolution of the magnetic field in the photosphere as well as associated with the energetic solar activity such as prominence eruptions and coronal mass ejections. They are observed as circular or elliptical-shaped relatively low-density dark regions above the solar limb in EUV, X-ray, and white-light coronal images. We used SDO/AIA limb synoptic maps, constructed from annuli above the solar limb, to systematically identify cavities. We observed 429 coronal prominence cavities between May 20, 2010 and Feb 1, 2015. We examined correlations between height, width, and length of the cavities. Based on the fitting of the shape of the cross section, we classified cavities in three types: prolate (38%), oblate (27%) and circular (35%). We found that the cavities of all shapes are common in shorter length while circular and oblate cavities are more common in the longer length. In general, we found that the overall 3-D topology of long stable cavities can be characterized as a long tube with an elliptical cross-section. Next, we investigated the pattern of cavity location and found that cavity systematically drifts towards the pole. We found that cavities form a belt by making a plot using SDO/HMI surface magnetogram similar to classical buttery diagram of sunspots, we call that the cavity belt. Our analysis showed that the cavity belts migrated towards higher latitude with time and the cavity belts disappeared after the polar magnetic field reversal. This result shows that cavity evolution provides new insight into the solar cycle. Moreover, we studied the underlying magnetic field of a circumpolar crown cavity (Mar 21, 2013- Oct 25, 2013) that was observed for several Carrington Rotations. Our results showed that the underlying polarity inversion line of cavities is formed between the trailing part of decayed active regions and the unipolar magnetic field in the pole. The long life of cavities was due to continuous and sustained adding of trailing flux from multiple active regions as their remnants diffused toward the pole. Title: Statistical Differences in Time-Distance Helioseismology Results Authors: Hess Webber, Shea A.; Pesnell, William D.; Duvall, Thomas; Cameron, Robert; Birch, A. C. Bibcode: 2016SPD....4720301H Altcode: Time-distance helioseismology studies phase correlations in solar wave modes. We use these techniques to investigate the phase differences in f-mode wave propagation within a coronal hole feature and without. We isolate the coronal hole boundary location using edge detection techniques on SDO AIA data. We then use this location information to inform the analysis of the corresponding HMI time-distance velocity tracked data product, provided by Stanford's JSOC archive. We look at time-distance results inside the coronal hole, outside the coronal hole, the coronal hole data as a whole, and an independent quiet sun region. We use Student's t-Test to evaluate the significance of the differences between the various regions. Title: On the Absence of EUV Emission from Comet C/2012 S1 (ISON) Authors: Bryans, Paul; Pesnell, W. Dean Bibcode: 2016ApJ...822...77B Altcode: When the sungrazing comet C/2012 S1 (ISON) made its perihelion passage within two solar radii of the Sun’s surface, it was expected to be a bright emitter at extreme ultraviolet (EUV) wavelengths. However, despite solar EUV telescopes repointing to track the orbit of the comet, no emission was detected. This “null result” is interesting in its own right, offering the possibility of placing limits on the size and composition of the nucleus. We explain the lack of detection by considering the properties of the comet and the solar atmosphere that determine the intensity of EUV emission from sungrazing comets. By comparing these properties with those of sungrazing comet C/2011 W3 (Lovejoy), which did emit in the EUV, we conclude that the primary factor resulting in non-detectable EUV emission from C/2012 S1 (ISON) was an insufficiently large nucleus. We conclude that the radius of C/2012 S1 (ISON) was at least a factor of four less than that of C/2011 W3 (Lovejoy). This is consistent with white-light observations in the days before perihelion that suggested the comet was dramatically reducing in size on approach. Title: The Unusual Event of October 26, 2010: An "Almost" Coronal Hole Authors: Pesnell, W. D.; O'Connor, R. Bibcode: 2015AGUFMSH52A..04P Altcode: Coronal holes are dark regions in the solar corona that develop where open magnetic field lines are found. They come in many different shapes, sizes, and forms. Ephemeral coronal holes are a short-lived form of the phenomena, sometimes lasting only a few rotations. On October 26, 2010, NASA's Solar Dynamics Observatory (SDO) observed what was first thought to be an unusual ephemeral coronal hole, appearing for less than 48 hours and surrounded by a filament. We present an analysis of the area and magnetic signatures of the filament and suspected hole, as well as solar wind data. Multiple EUV channels from SDO/AIA are combined with magnetograms from SDO/HMI and the GONG network to quantify the evolution of this event. Another ephemeral coronal hole from June 2015 is used a comparison. Results from this analysis show that the 2010 event was not an ephemeral coronal hole, but rather a solar 'hiccup' - the attempted, and failed, formation of a small coronal hole. While the reasons behind the failure remain speculative, these findings show that a lot of potential lies in future research of this event - in observing the interactions between the hole and the filament, and our continued understanding of the formation and characteristics of coronal holes. Title: The Solar Non-activity Cycle of Polar Coronal Holes Authors: Kirk, M. S.; Pesnell, W. D.; Young, C. A. Bibcode: 2015AGUFMSH33D..07K Altcode: After the unusually extended minimum in 2008 and 2009, solar cycle 24 continues to be an exceptionally weak cycle both in sunspot number and number of large magnetic storms. Coronal holes offer a direct measurement of the non-activity solar cycle, a missing link in our understanding of solar cycle progression. They are prevalent during solar minimum, non-axisymmetric, and are stable. Polar coronal holes are regularly observed capping the northern and southern solar poles in EUV images of the corona and are understood as the primary source of the fast solar wind. We make measurements of these features from 1996 through 2015 using four different NASA imagers: SOHO EIT, STEREO A and B EUVI, and SDO AIA. A measurement of the axial symmetry of the polar holes is seen to have clear solar cycle dependence. Polar coronal holes are aligned with the solar rotation axis during minimum and have a maximum asymmetry between holes of about 14 degrees in the declining phase of the current solar cycle. Title: A comprehensive study of cavities on the Sun: Structures and Evolution Authors: Karna, N.; Pesnell, W. D.; Zhang, J. Bibcode: 2015AGUFMSH54B..03K Altcode: Coronal cavities are often observed as circular or elliptical-shaped, darkned regions above the solar limb in EUV coronal images. They are believed to be regions of lower density relative to the surrounding corona. The cavity surrounds the prominence: prior to the eruption and as an aspect of CMEs. We used SDO/AIA limb synoptic maps, constructed from annuli above the solar limb; best show cavities in the 211Å, 193Å and 171Å passbands. The prominence associated with each cavity is best seen in the 304Å synoptic maps. We observed 429 cavities between May 2010 - Feb 2015. We examined correlations between each cavity's height, width and length. Our findings showed that around 38% of cavities were prolate, 27% oblate and 35% circular in shape. The lengths of the cavities ranged from 0.06-2.9 R¤. When a cavity is longer than 1.5 R¤ it has a narrower height range (0.1-0.3 R¤), whereas when the cavity was shorter than 1.5 R¤, it had a wider height range (0.07-0.5 R¤). We find that the overall 3-D topology of the long stable cavities can be characterized as a long tube with an elliptical cross section. We also noticed that the circular and oblate cavities are longer in length than prolate cavities. We also studied the physical mechanisms behind the cavity drift towards the pole and found it to be tied to the meridional flow. Finally, by observing the evolution cavity regions using SDO/HMI surface magnetic field observations, we found cavity belt formed near the polar coronal hole boundary. Results showed that the cavity belt migrated towards higher latitude with time and the cavity belt disappeared after the polar magnetic field reversal. This result shows that cavity evolution provides new insight into the solar cycle. Moreover, we selected 30 random cavities from our catalog and studied their morphology, thermal properties, linear polarization signatures, precursors of eruption, and underlying magnetic field and tried to interpret the shapes and stability of the cavities. Title: Study of the 3D Geometric Structure and Temperature of a Coronal Cavity Using the Limb Synoptic Map Method Authors: Karna, N.; Zhang, J.; Pesnell, W. Dean; Hess Webber, S. A. Bibcode: 2015ApJ...810..124K Altcode: We present the three-dimensional geometric structure and thermal properties of a coronal cavity deduced from limb synoptic maps. The observations are extreme ultraviolet images from the Atmospheric Imager Assembly (AIA) and magnetic images from the Helioseismic Magnetic Imager instruments on board the Solar Dynamics Observatory. We describe a limb synoptic-map method used to effectively identify and measure cavities from annuli of radiance above the solar limb. We find that cavities are best seen in the 211, 193, and 171 Å passbands. The prominence associated with each cavity is best seen in the 304 Å synoptic maps. We also estimate the thermal properties of the cavity and surrounding plasma by combining the AIA radiances with a differential emission measure analysis. This paper focuses on one long cavity from a catalog of coronal cavities that we are developing. Cavities in this catalog are designated by a coded name using the Carrington Rotation number and position. Cavity C211347177N was observed during Carrington Rotation 2113 at the northwestern limb of the solar disk with an average latitude of 47° N and a central longitude of 177°. We showed the following. (1) The cavity is a long tube with an elliptical cross-section with ratios of the length to width and the length to height of 11:1 and 7:1, respectively. (2) The cavity is about 1360 Mm long, or 170° in longitude. (3) It is tilted in latitude. (4) And it is slightly hotter than its surroundings. Title: Appearances and Statistics of Coronal Cavities During the Ascending Phase of Solar Cycle 24 Authors: Karna, N.; Pesnell, W. D.; Zhang, J. Bibcode: 2015ApJ...810..123K Altcode: We present a survey of 429 coronal prominence cavities found between 2010 May and 2015 February using the Solar Dynamics Observatory (SDO)/Atmospheric Imaging Assembly limb synoptic maps. We examined correlations between each cavity’s height, width, and length. Our findings showed that around 38% of the cavities were prolate, 27% oblate, and 35% circular in shape. The lengths of the cavities ranged from 0.06 to 2.9 {R}⊙ . When a cavity is longer than 1.5 {R}⊙ , it has a narrower height range (0.1-0.3 {R}⊙ ), whereas when the cavity was shorter than 1.5 {R}⊙ , it had a wider height range (0.07-0.5 {R}⊙ ). We find that the overall three-dimensional topology of the long, stable cavities can be characterized as a long tube with an elliptical cross section. We also noted that the circular and oblate cavities are longer in length than the prolate cavities. We also studied the physical mechanisms behind the cavity drift toward the pole and found it to be tied to the meridional flow. Finally, by observing the evolution of the cavity regions using SDO/Helioseismic Magnetic Imager (HMI) surface magnetic field observations, we found that the cavities formed a belt near the polar coronal hole boundary; we call this the cavity belt. Our results showed that the cavity belt migrated toward higher latitude over time and the cavity belt disappeared after the polar magnetic field reversal. This result shows that cavity evolution provides new insight into the solar cycle. Title: Appearances and Statistics of Coronal Cavities During the Ascending Phase of Solar Cycle 24 Authors: Karna, Nishu; Pesnell, William Dean; Zhang, Jie Bibcode: 2015shin.confE..72K Altcode: We present a survey of 429 coronal prominence cavities found between May 2010-Feb 2015 using SDO/AIA limb synoptic maps. We examined correlations between each cavity's height, width and length. Our findings showed that around 38% of cavities were prolate, 27% oblate and 35% circular in shape. The lengths of the cavities ranged from 0.06 - 2.9 R⊙ When a cavity is longer than 1.5 R⊙, it has a narrower height range (0.1 - 0.3 R⊙), whereas when the cavity was shorter than 1.5 R⊙, it had a wider height range (0.07 - 0.5 R). We find that the overall 3-D topology of the long stable cavities can be characterized as a long tube with an elliptical cross section. We also noticed that the circular and oblate cavities are longer in length than prolate cavities. We also studied the physical mechanisms behind the cavity drift towards the pole and found it to be tied to the meridional flow. Finally, by observing the evolution cavity regions using SDO/HMI surface magnetic field observations, we found that cavities formed a belt near the polar coronal hole boundary; we call this the cavity belt. Results showed that the cavity belt migrated towards higher latitude with time and the cavity belt disappeared after the polar magnetic field reversal. This result shows that cavity evolution provides new insight into the solar cycle. Title: Connecting the Evolution of Polar Coronal Holes to the Heliosphere Authors: Kirk, Michael S.; Pesnell, W. Dean; Hess-Webber, Shea Bibcode: 2015shin.confE.123K Altcode: Polar coronal holes are regularly observed capping the northern and southern solar poles in EUV images of the corona and are understood as the primary source of the fast solar wind. Polar holes are also the longest-lived solar magnetic features and observed to have strong solar cycle dependence - becoming more stable and prominent in solar minimum and disappearing at solar maximum. We make measurements of these features from 1996 through 2015 using four different NASA imagers: SOHO EIT, STEREO A and B EUVI, and SDO AIA. This dataset reveals several long-term trends in the corona. A measurement of the axial symmetry of the polar holes is seen to have clear solar cycle dependence. Polar coronal holes are aligned with the solar rotation axis during minimum and have a maximum off-axial perturbation of about 8 degrees in the declining phase of the solar cycle. With nearly 20 years of coronal hole measurements, we are able correlate the evolution of the polar holes to complementary measurements of the solar wind. Title: Solar Cycle 24 up to Now: Flying Over Peaks and Through Streams Authors: Pesnell, W. Dean Bibcode: 2015TESS....130804P Altcode: Solar Cycle 24 has been a below-average sunspot cycle. There were peaks in the daily and monthly-averaged sunspot number in the Northern hemisphere in 2011 and in the Southern hemisphere in 2014. Now that sunspot activity appears to be on the decline, another part of the solar cycle becomes important. Energetic events from high-speed streams flowing from the Sun can produce crippling radiation storms in the magnetosphere. Predicting those events that will affect our assets in space requires a different kind of solar prediction and some idea of how the radiation will propagate through the solar system. With the rapid increase in solar data and capability of numerical models of the solar convection zone we are developing the ability to forecast the level of the next solar cycle. But no prediction based only on sunspot number will be usable for predicting the variation of the decline of a sunspot cycle. I will describe the status of Solar Cycle 24, our need for solar activity predictions at all phases of the solar cycle, and anticipate how those predictions could be made more accurate in the future. Title: Trends Of The Void: Solar Cycles Observed Through Polar Coronal Holes Authors: Kirk, Michael S.; Hess Webber, Shea; Pesnell, W. Dean Bibcode: 2015TESS....130802K Altcode: Coronal holes are defined by their open magnetic field configuration and lack of emitting plasma. Holes that cap the northern and southern solar poles are the longest-lived features observed on the Sun - persisting for nearly an entire solar cycle. Polar holes disappear briefly at solar maximum for about a year before returning. The size and evolution of the polar holes are also strongly anti-correlated with the solar activity cycle. Their longevity combined with this solar activity relationship makes polar coronal holes an ideal proxy for measuring the long-term evolution of the solar magnetic field. We use a perimeter tracking technique to measure the size and location of the polar coronal holes for 19 years starting in 1996. Utilizing the SOHO EIT archive and current SDO AIA images, we present a comprehensive look at how polar coronal holes evolve and what they can tell us about our current and unusual solar cycle. Title: Statistical Studies of Coronal Cavities Since the Launch of SDO Authors: Karna, Nishu; Zhang, Jie; Pesnell, W. Dean Bibcode: 2015TESS....140905K Altcode: We present a survey of 409 coronal prominence cavities found between May 2010- Sep 2014 using SDO/AIA limb synoptic maps. We examined correlations between cavity’s height, width and length. Our finding showed that around 50% of cavities were taller than wider, 40% wider and 10% circular in shape. The length of the cavity ranged from 0.09-2.9 R⊙. When the cavity length is greater than 1.5 R⊙, cavity had a narrow height range (0.1-0.3 R⊙), whereas when the cavity length was smaller than 1.5 R⊙, cavity had wider height range (0.07-0.5 R⊙). We find that the overall 3-D topology of the long stable cavities can be characterized as a long tube with an elliptical cross section. We also studied the physical mechanisms behind the cavity drift towards the pole and found it to be tied to the polar reversal. Finally, by observing the evolution of the cavity region using SDO/HMI surface magnetic field observations, we found that cavities formed a belt between the polar coronal hole boundary and the active region belt; we call this new belt the cavity belt. Results showed that the cavity belt migrated towards higher and higher latitude with time and the cavity belt disappeared after the polar magnetic field reversal. This result shows that cavity evolution provides another dimension of knowledge of studying the solar cycle. Title: Solar Dynamics Observatory (SDO) Authors: Pesnell, W. Dean Bibcode: 2015hchp.book..179P Altcode: No abstract at ADS Title: Pushing the Envelope of Extreme Space Weather Authors: Pesnell, W. D. Bibcode: 2014AGUFMSH21C4129P Altcode: Extreme Space Weather events are large solar flares or geomagnetic storms, which can cost billions of dollars to recover from. We have few examples of such events; the Carrington Event (the solar superstorm) is one of the few that had superlatives in three categories: size of solar flare, drop in Dst, and amplitude of aa. Kepler observations show that stars similar to the Sun can have flares releasing millions of times more energy than an X-class flare. These flares and the accompanying coronal mass ejections could strongly affect the atmosphere surrounding a planet. What level of solar activity would be necessary to strongly affect the atmosphere of the Earth? Can we map out the envelope of space weather along the evolution of the Sun? What would space weather look like if the Sun stopped producing a magnetic field? To what extreme should Space Weather go? These are the extremes of Space Weather explored in this talk. Title: Areas of Polar Coronal Holes from 1996 Through 2010 Authors: Hess Webber, S. A.; Karna, N.; Pesnell, W. D.; Kirk, M. S. Bibcode: 2014SoPh..289.4047H Altcode: 2014SoPh..tmp..103H Polar coronal holes (PCHs) trace the magnetic variability of the Sun throughout the solar cycle. Their size and evolution have been studied as proxies for the global magnetic field. We present measurements of the PCH areas from 1996 through 2010, derived from an updated perimeter-tracing method and two synoptic-map methods. The perimeter-tracing method detects PCH boundaries along the solar limb, using full-disk images from the SOlar and Heliospheric Observatory/Extreme ultraviolet Imaging Telescope (SOHO/EIT). One synoptic-map method uses the line-of-sight magnetic field from the SOHO/Michelson Doppler Imager (MDI) to determine the unipolarity boundaries near the poles. The other method applies thresholding techniques to synoptic maps created from EUV image data from EIT. The results from all three methods suggest that the solar maxima and minima of the two hemispheres are out of phase. The maximum PCH area, averaged over the methods in each hemisphere, is approximately 6 % during both solar minima spanned by the data (between Solar Cycles 22/23 and 23/24). The northern PCH area began a declining trend in 2010, suggesting a downturn toward the maximum of Solar Cycle 24 in that hemisphere, while the southern hole remained large throughout 2010. Title: Evolving Solar Activity and Its Influence on Space and Earth Authors: Pesnell, W. Dean; Thompson, Barbara Bibcode: 2014esai.conf.....P Altcode: The 2014 Living with a Star (LWS) Science Meeting will focus on advancing the understanding of the integral system coupling the Sun to the Earth. An important part of this meeting is the inclusion of the Hinode-8 and IRIS-2 meetings with complementary objectives towards improved understanding of the evolving solar activity. Title: Deciphering Solar Magnetic Activity. I. On the Relationship between the Sunspot Cycle and the Evolution of Small Magnetic Features Authors: McIntosh, Scott W.; Wang, Xin; Leamon, Robert J.; Davey, Alisdair R.; Howe, Rachel; Krista, Larisza D.; Malanushenko, Anna V.; Markel, Robert S.; Cirtain, Jonathan W.; Gurman, Joseph B.; Pesnell, William D.; Thompson, Michael J. Bibcode: 2014ApJ...792...12M Altcode: 2014arXiv1403.3071M Sunspots are a canonical marker of the Sun's internal magnetic field which flips polarity every ~22 yr. The principal variation of sunspots, an ~11 yr variation, modulates the amount of the magnetic field that pierces the solar surface and drives significant variations in our star's radiative, particulate, and eruptive output over that period. This paper presents observations from the Solar and Heliospheric Observatory and Solar Dynamics Observatory indicating that the 11 yr sunspot variation is intrinsically tied to the spatio-temporal overlap of the activity bands belonging to the 22 yr magnetic activity cycle. Using a systematic analysis of ubiquitous coronal brightpoints and the magnetic scale on which they appear to form, we show that the landmarks of sunspot cycle 23 can be explained by considering the evolution and interaction of the overlapping activity bands of the longer-scale variability. Title: Using Polar Coronal Hole Area Measurements to Determine the Solar Polar Magnetic Field Reversal in Solar Cycle 24 Authors: Karna, N.; Hess Webber, S. A.; Pesnell, W. D. Bibcode: 2014SoPh..289.3381K Altcode: 2014SoPh..tmp...80K An analysis of solar polar coronal hole (PCH) areas since the launch of the Solar Dynamics Observatory (SDO) shows how the polar regions have evolved during Solar Cycle 24. We present PCH areas from mid-2010 through 2013 using data from the Atmospheric Imager Assembly (AIA) and Helioseismic and Magnetic Imager (HMI) instruments onboard SDO. Our analysis shows that both the northern and southern PCH areas have decreased significantly in size since 2010. Linear fits to the areas derived from the magnetic-field properties indicate that, although the northern hemisphere went through polar-field reversal and reached solar-maximum conditions in mid-2012, the southern hemisphere had not reached solar-maximum conditions in the polar regions by the end of 2013. Our results show that solar-maximum conditions in each hemisphere, as measured by the area of the polar coronal holes and polar magnetic field, will be offset in time. Title: Predicting Solar Cycle 24 Using a Geomagnetic Precursor Pair Authors: Pesnell, W. Dean Bibcode: 2014SoPh..289.2317P Altcode: 2014SoPh..tmp...18P We describe using Ap and F10.7 as a geomagnetic-precursor pair to predict the amplitude of Solar Cycle 24. The precursor is created by using F10.7 to remove the direct solar-activity component of Ap. Four peaks are seen in the precursor function during the decline of Solar Cycle 23. A recurrence index that is generated by a local correlation of Ap is then used to determine which peak is the correct precursor. The earliest peak is the most prominent but coincides with high levels of non-recurrent solar activity associated with the intense solar activity of October and November 2003. The second and third peaks coincide with some recurrent activity on the Sun and show that a weak cycle precursor closely following a period of strong solar activity may be difficult to resolve. A fourth peak, which appears in early 2008 and has recurrent activity similar to precursors of earlier solar cycles, appears to be the "true" precursor peak for Solar Cycle 24 and predicts the smallest amplitude for Solar Cycle 24. To determine the timing of peak activity it is noted that the average time between the precursor peak and the following maximum is ≈ 6.4 years. Hence, Solar Cycle 24 would peak during 2014. Several effects contribute to the smaller prediction when compared with other geomagnetic-precursor predictions. During Solar Cycle 23 the correlation between sunspot number and F10.7 shows that F10.7 is higher than the equivalent sunspot number over most of the cycle, implying that the sunspot number underestimates the solar-activity component described by F10.7. During 2003 the correlation between aa and Ap shows that aa is 10 % higher than the value predicted from Ap, leading to an overestimate of the aa precursor for that year. However, the most important difference is the lack of recurrent activity in the first three peaks and the presence of significant recurrent activity in the fourth. While the prediction is for an amplitude of Solar Cycle 24 of 65±20 in smoothed sunspot number, a below-average amplitude for Solar Cycle 24, with maximum at 2014.5±0.5, we conclude that Solar Cycle 24 will be no stronger than average and could be much weaker than average. Title: Coronal Cavity Catalog from SDO Observations Authors: Karna, Nishu; Zhang, Jie; Pesnell, William D; Hess Webber, Shea A. Bibcode: 2014AAS...22432355K Altcode: We present a catalog of coronal cavities and prominences associated with cavities since the launch of Solar Dynamics Observatory (SDO). Coronal cavities are dark, circular regions observed above the solar limb in white light and EUV coronal images. They are believed to be regions of lower density relative to the surrounding corona. We use synoptic maps made from EUV images from the Atmospheric Imager Assembly (AIA) instrument on board SDO to study coronal cavities. The synoptic maps, constructed from annuli above the solar limb, best show cavities in 211 A (Fe XIV, 2.0 MK) and 193 A (Fe XII, 1.6 MK) and 171 A (Fe IX, 0.6 MK) passbands. Moreover, 304 A (He II, 0.05 MK) synoptic maps best show the evolution of any prominences associated with a cavity. The catalog lists the number of cavities seen in each Carrington rotation starting from CR 2097, the cavity’s size, shape, and the heliographic longitudes and latitudes of the appearance and disappearance of the cavity. Our goal is to provide a consistent set of the cavity structures for broad scientific use. Title: Coronal Diagnostics from Cometary Emission Authors: Bryans, Paul; Pesnell, William D; Seaton, Daniel B; West, Matthew J Bibcode: 2014AAS...22442203B Altcode: The extreme ultraviolet (EUV) emission observed from sungrazing comets as they pass through the solar atmosphere can be used to infer the properties of the corona. In this paper we will discuss several of these properties that can be estimated from the EUV observations of Comet Lovejoy from AIA/SDO and SWAP/PROBA2. The longevity of the emission allows us to constrain the coronal electron density through which the comet passes. We will also discuss how dispersion of the emitting cometary material we can be used to estimate the local Alfven speed in the corona. Finally, measuring the deformation of the magnetic field as it is impacted by the comet can be used to estimate the magnetic field strength in this location. In the absence of the comet, none of these parameters are directly measurable in the corona. Sungrazing comets are thus unique probes of the solar atmosphere. Title: Asymmetries and the Off-Axial Wandering of Polar Coronal Holes Authors: Kirk, Michael S.; Hess-Webber, Shea; Pesnell, W. Dean; Karna, Nishu Bibcode: 2014shin.confE..23K Altcode: Polar coronal holes are regularly observed capping the northern and southern solar poles in EUV images of the corona and are understood as the primary source of the fast solar wind. Polar holes are also observed to have strong solar cycle dependence: becoming more stable and prominent in solar minimum and disappearing at solar maximum. We extend the perimeter tracking methods of Kirk et al. (2009) and Hess-Webber et al. (2014, submitted) to examine the centroid of identified polar coronal holes during solar cycle 24 by utilizing the entirety of the EIT image archive on SOHO. We demonstrate that the centroids of the polar holes have clear solar cycle dependence. Polar coronal holes are symmetrically aligned during minimum and have a maximum asymmetry at solar maximum of about 17 degrees. Title: Taking Extreme Space Weather to the Milky Way Authors: Pesnell, W. Dean Bibcode: 2014AAS...22432359P Altcode: Extreme Space Weather events are large solar flares or geomagnetic storms, which can cause economic damage that cost billions of dollars to recover from. We have few examples of such events; only the Carrington Event (the solar superstorm) has superlatives in three categories: size of solar flare, drop in Dst, and amplitude of aa. Kepler observations show that stars similar to the Sun can have flares releasing thousands of times more energy than an X-class flare. These flares would strongly affect the atmosphere surrounding a planet orbiting such a star. Particle and magnetic field outflows from these stars could also be present. We are investigating the level of solar activity that is necessary to strongly affect the atmosphere of terrestrial planets. We assume that a habitable planet requires an atmosphere with a temperature and composition that is stable in time. Can we then extrapolate results from our solar system to determine a space of stellar parameters in which habitable planets can exist? Title: Time-Series Analysis of Supergranule Characteristics at Solar Minimum Authors: Williams, Peter E.; Pesnell, W. Dean Bibcode: 2014SoPh..289.1101W Altcode: Sixty days of Doppler images from the Solar and Heliospheric Observatory (SOHO) / Michelson Doppler Imager (MDI) investigation during the 1996 and 2008 solar minima have been analyzed to show that certain supergranule characteristics (size, size range, and horizontal velocity) exhibit fluctuations of three to five days. Cross-correlating parameters showed a good, positive correlation between supergranulation size and size range, and a moderate, negative correlation between size range and velocity. The size and velocity do exhibit a moderate, negative correlation, but with a small time lag (less than 12 hours). Supergranule sizes during five days of co-temporal data from MDI and the Solar Dynamics Observatory (SDO) / Helioseismic Magnetic Imager (HMI) exhibit similar fluctuations with a high level of correlation between them. This verifies the solar origin of the fluctuations, which cannot be caused by instrumental artifacts according to these observations. Similar fluctuations are also observed in data simulations that model the evolution of the MDI Doppler pattern over a 60-day period. Correlations between the supergranule size and size range time-series derived from the simulated data are similar to those seen in MDI data. A simple toy-model using cumulative, uncorrelated exponential growth and decay patterns at random emergence times produces a time-series similar to the data simulations. The qualitative similarities between the simulated and the observed time-series suggest that the fluctuations arise from stochastic processes occurring within the solar convection zone. This behavior, propagating to surface manifestations of supergranulation, may assist our understanding of magnetic-field-line advection, evolution, and interaction. Title: The Time-dependent Chemistry of Cometary Debris in the Solar Corona Authors: Pesnell, W. D.; Bryans, P. Bibcode: 2014ApJ...785...50P Altcode: Recent improvements in solar observations have greatly progressed the study of sungrazing comets. They can now be imaged along the entirety of their perihelion passage through the solar atmosphere, revealing details of their composition and structure not measurable through previous observations in the less volatile region of the orbit further from the solar surface. Such comets are also unique probes of the solar atmosphere. The debris deposited by sungrazers is rapidly ionized and subsequently influenced by the ambient magnetic field. Measuring the spectral signature of the deposited material highlights the topology of the magnetic field and can reveal plasma parameters such as the electron temperature and density. Recovering these variables from the observable data requires a model of the interaction of the cometary species with the atmosphere through which they pass. The present paper offers such a model by considering the time-dependent chemistry of sublimated cometary species as they interact with the solar radiation field and coronal plasma. We expand on a previous simplified model by considering the fully time-dependent solutions of the emitting species' densities. To compare with observations, we consider a spherically symmetric expansion of the sublimated material into the corona and convert the time-dependent ion densities to radial profiles. Using emissivities from the CHIANTI database and plasma parameters derived from a magnetohydrodynamic simulation leads to a spatially dependent emission spectrum that can be directly compared with observations. We find our simulated spectra to be consistent with observation. Title: Analysis of Supergranule Sizes and Velocities Using Solar Dynamics Observatory (SDO)/ Helioseismic Magnetic Imager (HMI) and Solar and Heliospheric Observatory (SOHO)/ Michelson Doppler Imager (MDI) Dopplergrams Authors: Williams, Peter E.; Pesnell, W. Dean; Beck, John G.; Lee, Shannon Bibcode: 2014SoPh..289...11W Altcode: Co-temporal Doppler images from Solar and Heliospheric Observatory (SOHO)/Michelson Doppler Imager (MDI) and Solar Dynamics Observatory (SDO)/Helioseismic Magnetic Imager (HMI) have been analyzed to extract quantitative information about global properties of the spatial and temporal characteristics of solar supergranulation. Preliminary comparisons show that supergranules appear to be smaller and have stronger horizontal velocity flows within HMI data than was measured with MDI. There appears to be no difference in their evolutionary timescales. Supergranule sizes and velocities were analyzed over a ten-day time period at a 15-minute cadence. While the averages of the time-series retain the aforementioned differences, fluctuations of these parameters first observed in MDI data were seen in both MDI and HMI time-series, exhibiting a strong cross-correlation. This verifies that these fluctuations are not instrumental, but are solar in origin. The observed discrepancies between the averaged values from the two sets of data are a consequence of instrument resolution. The lower spatial resolution of MDI results in larger observed structures with lower velocities than is seen in HMI. While these results offer a further constraint on the physical nature of supergranules, they also provide a level of calibration between the two instruments. Title: The Perihelion Passage of Comet ISON as seen by SDO Authors: Pesnell, W. D.; Schrijver, C. J.; Boerner, P.; DeRosa, M. L.; Liu, W.; Thompson, B. J. Bibcode: 2013AGUFM.P24A..10P Altcode: Comet ISON will fly through perihelion on November 28, 2013. It is one of the largest sungrazing comets to be seen in the Space Age. The Solar Dynamics Observatory (SDO) has seen two previous sungrazing comets in the extreme ultraviolet channels of the Atmospheric Imaging Assembly (AIA). Comet ISON will fly farther from the Sun (perihelion distance of 2.7 Rsun compared to 1.15 for Comet Lovejoy), meaning it probes a different part of the solar corona, but its larger size should provide enough mass to illuminate the path of the nucleus. Based on the latest ephemeris, SDO will be able to track Comet ISON through the entire perihelion passage by a series of off-point maneuvers. We will present the AIA data obtained from the Comet ISON perihelion, discussing the differences between Comets ISON and Lovejoy. We will then summarize what we have learned from the observations and offer some thoughts on what sungrazing comets may reveal about comets, the Sun, and their interaction. Title: What EUV Observations of Comet ISON Reveal About the Solar Corona Authors: Bryans, P.; Pesnell, W. D. Bibcode: 2013AGUFM.P31A1787B Altcode: Recent advances in space-based solar observations have greatly progressed the study of sungrazing comets. They can now be imaged along the entirety of their perihelion passage, revealing details of their composition, structure, and size. Such comets are also unique probes of the solar corona. The debris deposited by sungrazers is rapidly ionized and subsequently forced to follow the ambient magnetic field. In this paper we present preliminary results from EUV observations of Comet ISON. We estimate the size of the comet nucleus based on the EUV radiance and compare with independent estimates. The variation of the EUV emission with wavelength provides limits on the density of the ambient corona, and the motion of ionized debris will be used to infer the coronal magnetic field structure. Title: Inter-hemispheric coupling during northern polar summer periods of 2002-2010 using TIMED/SABER measurements Authors: Goldberg, R. A.; Feofilov, A. G.; Pesnell, W. D.; Kutepov, A. A. Bibcode: 2013JASTP.104..277G Altcode: It has been found that for more than one polar summer season between 2002 and 2010, the northern polar mesospheric region near and above about 80 km was warmer than normal. The strongest warming effect of this type was observed to occur during northern summer 2002. Observational and theoretical studies imply that these “anomalies” were preceded by unusual dynamical processes in the southern hemisphere. We have analyzed temperature distributions measured by the SABER limb scanning infrared radiometer aboard the NASA TIMED satellite between 2002 and 2010 at altitudes from 15 to 110 km and for latitudes between 83°S and 83°N. We describe the approach to trace the spatial extent of inter-hemispheric temperature correlations demonstrating the global features that were unique for the “anomalous” northern polar summers. From our analysis of SABER data from 2002 to 2010, the anomalous heating for the northern mesopause region during northern summer was accompanied by stratospheric heating in the equatorial region. In the winter hemisphere it is accompanied by heating in the lower stratosphere and mesopause region, and cooling in the stratopause region. Also, all the elements of the temperature anomaly structure appear to develop and fade away nearly simultaneously, thereby suggesting either a global influence or a short lagging period (less than 7 days). Title: Time-dependent chemisty of outgassed cometary detritus in the solar corona Authors: Bryans, Paul; Pesnell, W. D. Bibcode: 2013SPD....44...32B Altcode: Recent observations of sungrazing comets have opened an exciting novel methof of probing the solar atmosphere. As well as providing valuable insight on the magnetic field of the lower corona, sungrazing comets also promise the potential of measuring the solar wind as their detritus follows the open field lines of the corona. In this work, we model the chemisty of the material sublimated from comets as they skim across the Sun. This material, largely water ice, is rapidly dissociated and ionized by the solar radiation field and coronal electrons. We track the evolution of the ionizing material as it expands into the corona using a generalized Haser-like model. Based on these results, we have predicted the emission resulting from these ions in different regions of the corona and compared the results with SDO/AIA observations. Title: What Will Comet ISON Debris Teach Us About the Sun? Authors: Pesnell, W. D.; Bryans, P. Bibcode: 2013SPD....44...34P Altcode: Comet ISON is a large sun-grazing comet due to pass perihelion on November 28, 2013. It will go through the corona 2.7 Rsun above the surface, much higher than earlier EUV comets. We will use our time-dependent models of cometary debris to discuss how the trail of Comet ISON can be used to probe the solar corona. The debris trail left behind as a sun-grazing comet passes by the Sun undergoes different chemical processes at different distances from the Sun. Near the Sun the material is rapidly converted to atomic ions and becomes part of the solar corona. Far from the Sun the evaporated material can remain in molecular form for a long time, while the grains of asteroidal material can exist long enough to become meteors in planetary atmospheres. The larger fragments may survive as independent comets, until the next perihelion passage. In between those limits the material moves in the solar wind acceleration region. The debris could become entrained in the solar wind and be measured by satellites far from the Sun. This material would be observed as abundance anomalies in the solar wind. We will describe the fate of the cometary debris trail left by Comet ISON and what the trail can tell us about the solar corona and solar wind. Title: The study of the cavity’s morphology, density, thermal and magnetic properties from the SDO observations Authors: Karna, Nishu; Zhang, J.; Pesnell, W. D.; Hess Webber, S. A. Bibcode: 2013SPD....44...47K Altcode: Coronal cavities are circular darkened regions observed above the solar limb in white light and EUV coronal images. It is a region of low density relative to the surrounding corona. In this study, we are using synoptic maps made from EUV images from the Atmospheric Imager Assembly (AIA) instrument and vector magnetogram images from Helioseismic and Magnetic Imager (HMI) on the SDO to determine the structure and evolution of cavities. The EUV synoptic maps, constructed from circular rings above the limb, are found to best show cavities in 211Å (Fe XIV, ~2.0 MK) and 193 Å (Fe XII, ~1.6 MK) and171 Å (Fe IX, ~0.6 MK) pass bands. Moreover, 304Å (He II, ~0.05 MK) synoptic map best shows the evolution of prominence associated with cavity. Magnetogram synoptic map constructed from the central meridian, shows the underlying magnetic structure of the cavity and prominence. We have also used EUV synoptic map to construct the polar view of the cavities. DEM analysis was used to calculate the temperature and density of the cavities. The high spatial and time resolution combined with the broad temperature coverage provides a consistent picture of the cavity material and the dynamics of the structure.Abstract (2,250 Maximum Characters): Coronal cavities are circular darkened regions observed above the solar limb in white light and EUV coronal images. It is a region of low density relative to the surrounding corona. In this study, we are using synoptic maps made from EUV images from the Atmospheric Imager Assembly (AIA) instrument and vector magnetogram images from Helioseismic and Magnetic Imager (HMI) on the SDO to determine the structure and evolution of cavities. The EUV synoptic maps, constructed from circular rings above the limb, are found to best show cavities in 211Å (Fe XIV, ~2.0 MK) and 193 Å (Fe XII, ~1.6 MK) and171 Å (Fe IX, ~0.6 MK) pass bands. Moreover, 304Å (He II, ~0.05 MK) synoptic map best shows the evolution of prominence associated with cavity. Magnetogram synoptic map constructed from the central meridian, shows the underlying magnetic structure of the cavity and prominence. We have also used EUV synoptic map to construct the polar view of the cavities. DEM analysis was used to calculate the temperature and density of the cavities. The high spatial and time resolution combined with the broad temperature coverage provides a consistent picture of the cavity material and the dynamics of the structure. Title: Coronal Cavities from SDO Observations Authors: Karna, Nishu; Zhang, J.; Pesnell, W. D.; Hess Webber, S. A. Bibcode: 2013shin.confE.101K Altcode: Coronal cavities are circular darkened regions observed above the solar limb in white light and EUV coronal images. It is a region of low density relative to the surrounding corona. In this study, we are using synoptic maps made from EUV images from the Atmospheric Imager Assembly (AIA) instrument and vector magnetogram images from Helioseismic and Magnetic Imager (HMI) on the SDO to determine the structure and evolution of cavities. The EUV synoptic maps, constructed from circular rings above the limb, are found to best show cavities in 211Å (Fe XIV, 2.0 MK) and 193Å (Fe XII, 1.6 MK) and171Å (Fe IX, 0.6 MK) pass bands. Moreover, 304Å (He II, 0.05 MK) synoptic map best shows the evolution of prominence associated with cavity. Magnetogram synoptic map constructed from the central meridian, shows the underlying magnetic structure of the cavity and prominence. We have also used EUV synoptic map to construct the polar view of the cavities. The high spatial and time resolution combined with the broad temperature coverage provides a consistent picture of the cavity material and the dynamics of the structure. Title: Exploring the Network of SDO Science Authors: Pesnell, W. Dean; Thompson, Barbara Bibcode: 2013enss.conf.....P Altcode: Living With a Star's Solar Dynamics Observatory invites you to its 2013 Science Workshop to be held March 3-8, 2013 at the Hyatt Regency Chesapeake Bay in Cambridge, MD (http://chesapeakebay.hyatt.com/). The workshop is a follow-on to the "Many Spectra of Solar Activity" workshop held May 1-5, 2011 in Squaw Valley, CA.

Scientific sessions will feature a broad spectrum of science topics fundamental to SDO's science investigations: Atmospheric Imaging Assembly (AIA), EUV Variability Experiment (EVE), and Helioseismic and Magnetic Imager (HMI), as well as the overlap between SDO and other scientific missions and activities. Title: Polar Coronal Hole Areas from 1996 through Present Authors: Hess Webber, S. A.; Karna, N.; Pesnell, W. D. Bibcode: 2013enss.confE..20H Altcode: The evolutionary analysis of the polar coronal hole (PCH) areas from the beginning of solar cycle 23 through the cycle 24 minimum has introduced several new scientific results regarding changes in the magnetic field configuration during the past solar cycle. Observations show that the PCH sizes peak at discrete times in the two hemispheres, suggesting that the two poles reach solar minimum (magnetic maximum) up to three years apart. The northern polar hole has also decreased significantly in size since 2010, while the southern hole has remained stable. This indicates that the northern hemisphere has already reached solar maximum even though the southern hemisphere has yet to peak. Title: EUV Emission from Sungrazing Comets Authors: Bryans, Paul; Pesnell, W. Dean Bibcode: 2013enss.confE..33B Altcode: The EUV emission resulting from comets' passage through the solar atmosphere has opened many exciting avenues of study. The observations show the sublimated cometary material to interact with ambient magnetic field and highlight magnetic features that are not normally visible with EUV telescopes. The first step, however, is to explain why the comet produces the EUV emission. In this talk, I will outline a model that describes the interaction of the cometary atmosphere with the quiescent solar background and results in such emission. In particular, the model accurately predicts the temporal and wavelength response of the emission detected by SDO/AIA. After describing the emission process, I will go on to discuss what we can learn about the corona from these observations. Title: Coronal Cavities from SDO Observations Authors: Karna, N.; Zhang, J.; Pesnell, W. D.; Hess Webber, S. A. Bibcode: 2013enss.confE.134K Altcode: Coronal cavities are circular darkened regions observed above the solar limb in white light and EUV coronal images. It is believed a region of low density relative to the surrounding corona. In this study, we are using synoptic maps made from EUV images from the Atmospheric Imager Assembly (AIA) instrument on the SDO to determine the structure and evolution of cavities. The synoptic maps, constructed from circular rings above the limb, are found to best show cavities in 211Å (Fe XIV, 2.0 MK) and 193 Å (Fe XII, 1.6 MK) and171 Å (Fe IX, 0.6 MK) pass bands. Moreover, 304Å (He II, 0.05 MK) synoptic map best shows the evolution of prominence associated with cavity. The high spatial and time resolution combined with the broad temperature coverage provides a consistent picture of the cavity material and the dynamics of the structure. Our goal in this work is to study the cavity's sizes (height, diameter and length), density and temperature properties. Title: The Solar Dynamics Observatory after three years in orbit Authors: Poland, D.; Ekinci, F. M.; Fink, D.; Pesnell, W. D. Bibcode: 2013aero.confE.183P Altcode: There are three instruments aboard the Solar Dynamics Observatory (SDO): EVE, which measures the extreme ultraviolet irradiance of the Sun; AIA, which images the Sun at high cadence in ten wavelengths; and HMI, which measures the solar magnetic field and velocity of the solar surface. These instruments have returned roughly 1.5 Tbytes of solar data per day nearly continuously since the beginning of SDO's science operations in May 2010, which has been facilitated by a continuous downlink from geosynchronous orbit to SDO's dedicated pair of 18-m antennas in White Sands, New Mexico. Science data returned from SDO is continually advancing knowledge of and research in prominence and filament eruptions, late phase flares, and the solar vector magnetic field, amongst other areas. Additionally, observations made during orbit maintenance, collision avoidance, and ground system operations have yielded lessons learned about the need to account for extreme weather in antenna design and the importance of clear, direct communication channels with other satellite operators. These observations and lessons are being used to improve the SDO ground system and operations approach and may prove useful for future mission design. Title: Investigating Coronal Activity by Release Using Sublimation Authors: Moore, T. E.; Bryans, P.; Pesnell, W. D.; Thompson, B. J. Bibcode: 2012AGUFMSH21D..05M Altcode: Plasma tails left by sun-grazing comets are visible in EUV, expanding their traditional role as "windsocks" into the low corona and serving as natural "chemical release" experiments. SDO obtained spectrally resolved video imagery of passages as close as 0.15 Rs to the solar photosphere at 12 sec frame cadence. Vaporized cometary materials form sublimation trails or "subtrails" that persist as long as 20 min. in 13.1 and 17.1 nm channels. Striation along local magnetic flux tubes implies filamentation of the visible plasma, and the subtrails exhibit substantial deviations from the comet orbital track. These reveal coronal winds and shears with velocities that are comparable to the comet velocity of up to 600 km/s. We analyze the likely origins and directionality of these winds and their implications for coronal heating in the altitude range where ion-neutral collision mean free paths are longer than the gyro radius but shorter than the atmospheric scale height, that is, the solar transition region. With active impact or photo-ionization, and charge exchange, the inferred super-thermal, sub-Alfvenic ion-neutral relative velocities will lead to ion pick-up distributions that decay or relax into "kappa" distributions with super-thermal power law tails that are relevant to the formation of the corona. Title: Time-dependent Chemistry of Detritus from Sun-grazing Comets Authors: Pesnell, W. D.; Bryans, P. Bibcode: 2012AGUFMSH13B2253P Altcode: As a sun-grazing comet passes the Sun at perihelion it leaves behind a trail of water vapor and detritus. The latter are grains of stony material that rapidly heat and vaporize in the intense radiation field of the solar photosphere. A large amount of O is produced from both the water and the stony material. The atomic material does not continue along the comet's orbital path but appears to move along the ambient magnetic field. This requires an ionization mechanism that rapidly converts the neutral atoms into ions. We propose two models of the time-dependent chemistry that can be used to calculate the ionization balance of O and Fe. One is an extension of the Haser model to include many stages of ionization but without recombination. The advantage is that an analytic solution can be derived for an arbitrary numbers of ionization stages. Once the time dependence is known it can be converted to the radial profile in either spherical or cylindrical symmetry. The other model integrates in time the equations describing ionization/recombination balance. Both types of solutions can be numerically inverted to estimate the radiance profiles. The models give the same sequence to the ionization stages, but the time dependence and radial profiles are shown to differ. Although we concentrate on the O and Fe chemistry because it is observed from SDO/AIA, any atom can be considered. Title: Solar Cycle Predictions (Invited Review) Authors: Pesnell, W. Dean Bibcode: 2012SoPh..281..507P Altcode: 2012SoPh..tmp..135P; 2012SoPh..tmp..105P Solar cycle predictions are needed to plan long-term space missions, just as weather predictions are needed to plan the launch. Fleets of satellites circle the Earth collecting many types of science data, protecting astronauts, and relaying information. All of these satellites are sensitive at some level to solar cycle effects. Predictions of drag on low-Earth orbit spacecraft are one of the most important. Launching a satellite with less propellant can mean a higher orbit, but unanticipated solar activity and increased drag can make that a Pyrrhic victory as the reduced propellant load is consumed more rapidly. Energetic events at the Sun can produce crippling radiation storms that endanger all assets in space. Solar cycle predictions also anticipate the shortwave emissions that cause degradation of solar panels. Testing solar dynamo theories by quantitative predictions of what will happen in 5 - 20 years is the next arena for solar cycle predictions. A summary and analysis of 75 predictions of the amplitude of the upcoming Solar Cycle 24 is presented. The current state of solar cycle predictions and some anticipations of how those predictions could be made more accurate in the future are discussed. Title: The Extreme-ultraviolet Emission from Sun-grazing Comets Authors: Bryans, P.; Pesnell, W. D. Bibcode: 2012ApJ...760...18B Altcode: 2012arXiv1209.5708B The Atmospheric Imaging Assembly (AIA) on the Solar Dynamics Observatory has observed two Sun-grazing comets as they passed through the solar atmosphere. Both passages resulted in a measurable enhancement of extreme-ultraviolet (EUV) radiance in several of the AIA bandpasses. We explain this EUV emission by considering the evolution of the cometary atmosphere as it interacts with the ambient solar atmosphere. Molecules in the comet rapidly sublimate as it approaches the Sun. They are then photodissociated by the solar radiation field to create atomic species. Subsequent ionization of these atoms produces a higher abundance of ions than normally present in the corona and results in EUV emission in the wavelength ranges of the AIA telescope passbands. Title: Coronal Cavities from SDO Observations Authors: Karna, Nishu; Hess Webber, Shea A.; Pesnell, W. Dean; Zhang, Jie; Kirk, M. S. Bibcode: 2012shin.confE.207K Altcode: Coronal cavities are circular darkened regions observed above the solar limb in white light and EUV coronal images. It is a region of low density relative to the surrounding corona. In this study, we are using synoptic maps made from EUV images from the Atmospheric Imager Assembly (AIA) instrument on the SDO to determine the structure and evolution of cavities. The synoptic maps, constructed from circular rings above the limb, are found to best show cavities in 211Å (Fe XIV, 2.0 MK) and 193 Å (Fe XII, 1.6 MK) pass bands. The high spatial and time resolution combined with the broad temperature coverage provides a consistent picture of the cavity material and the dynamics of the structure. Our goal is to study the cavity"s sizes (height, diameter and length), density and temperature properties. Moreover, we will examine the correlation between cavity morphology and underlying magnetic field distribution using Heliosesmic and Magnetic imager (HMI) instrument on SDO. This study will shed light on the origin, evolution and dynamics of coronal cavities. Title: Solar Cycle 23/24 Polar Coronal Hole Areas: Scientific Results Authors: Hess Webber, Shea A.; Karna, Nishu; Pesnell, W. Dean Bibcode: 2012shin.confE.118H Altcode: The evolutionary analysis of the polar coronal hole (PCH) areas from the beginning of solar cycle 23 through the cycle 24 minimum has introduced several new scientific results regarding changes in the magnetic field configuration during the past solar cycle. Observations show that the PCH sizes peak at discrete times in the two hemispheres, suggesting that the two poles reach solar minimum (magnetic maximum) up to three years apart. The northern polar hole has also decreased significantly in size since 2010, while the southern hole has remained stable. This indicates that the northern hemisphere has already reached solar maximum even though the southern hemisphere has yet to peak. The relationship between the temporal difference of the PCH area peaks at solar minimum and that of the area drop-offs during solar maximum are under investigation. Title: The Journey of Sungrazing Comet Lovejoy Authors: Bryans, Paul; A'Hearn, M.; Battams, K.; Biesecker, D.; Bodewits, D.; Boice, D.; Brown, J.; Caspi, A.; Chodas, P.; Hudson, H.; Jia, Y.; Jones, G.; Keller, H. U.; Knight, M.; Linker, J.; Lisse, C.; Liu, W.; McIntosh, S.; Pesnell, W. D.; Raymond, J.; Saar, S.; Saint-Hilaire, P.; Schrijver, C.; Snow, M.; Tarbell, T.; Thompson, W.; Weissman, P.; Comet Lovejoy Collaboration Team Bibcode: 2012AAS...22052507B Altcode: Comet Lovejoy (C/2011 W3) was the first sungrazing comet, observed by space-based instruments, to survive perihelion passage. First observed by ground-based telescopes several weeks prior to perihelion, its journey towards the Sun was subsequently recorded by several solar observatories, before being observed in the weeks after perihelion by a further array of space- and ground-based instruments. Such a surfeit of wide-ranging observations provides an unprecedented insight into both sungrazing comets themselves, and the solar atmosphere through which they pass. This paper will summarize what we have learnt from the observations thus far and offer some thoughts on what future sungrazing comets may reveal about comets, the Sun, and their interaction. Title: The Solar Polar Coronal Holes in Solar Cycle 24 Authors: Hess Webber, Shea; Karna, N.; Pesnell, W. D.; Kirk, M. S. Bibcode: 2012AAS...22020201H Altcode: We have measured the area of the solar polar coronal holes in both hemispheres. One data series uses synoptic maps from two instruments on SOHO and the AIA instrument on SDO. The other used the perimeter tracking method on data from SoHO EIT. This allows us to calculate the areas of the solar polar coronal holes from the beginning of Solar Cycle 23 up to late 2010. This method used synoptic maps constructed from 170 Carrington Rotations of the 171, 195, and 304 Å channels of the Extreme-ultraviolet Imaging Telescope (EIT) on SoHO. Our second method used synoptic maps constructed from the Michelson Doppler Imager (MDI) for 187 Carrington Rotations from mid 1996 through 2010. In this method, polar coronal holes are easily distinguished from the equatorial coronal hole regions. The north and south polar hole areas were noticeably smaller in the recent minimum than they were at the beginning of Solar Cycle 23. We compared these polar hole areas with the polar coronal hole area found using a perimeter tracking to analyze a series of 171, 195, and 304 Å full disk images from EIT to measure the perimeter of polar coronal holes as they appear on the limbs. It is found that both the Northern and Southern polar coronal hole areas obtained from the perimeter tracking method similar to those from the synoptic maps. The coronal hole areas will be compared with the polar magnetic fields to estimate what phase of the solar cycle the hemispheres have reached. Title: The EUV Emission from Sun-Grazing Comets Authors: Bryans, Paul; Pesnell, W. D. Bibcode: 2012AAS...22042305B Altcode: The Atmospheric Imaging Assembly (AIA) on the Solar Dynamics Observatory (SDO) has, to date, viewed two Sun-grazing comets as they passed through the solar corona. Both passages resulted in the significant enhancement of Extreme Ultraviolet (EUV) emission in several of the AIA bandpasses. We explain this EUV emission by considering the evolution of the cometary atmosphere as it interacts with the ambient solar atmosphere. Water ice in the comet rapidly sublimates as it approaches the Sun. This water vapor is then photodissociated by the solar radiation field to create atomic H and O. Other molecules present in the comet also evaporate and dissociate to give atomic Fe and other metals. Subsequent ionization of these atoms produces a high abundance of ions not normally present at the temperature of the corona and results in EUV emission in the wavelength ranges of the AIA telescopes. Understanding the EUV emission places constraints on the cometary composition and provides valuable insight to the nature of the upper solar atmosphere. Title: Coronal Cavities from SDO Observations Authors: Karna, Nishu; Hess Webber, S. A.; Pesnell, W. D.; Zhang, J.; Kirk, M. S. Bibcode: 2012AAS...22020204K Altcode: Coronal cavities are circular darkened regions observed above the solar limb in white light and EUV coronal images. It is a region of low density relative to the surrounding corona. In this study, we are using synoptic maps made from EUV images from the Atmospheric Imager Assembly (AIA) instrument on the SDO to determine the structure and evolution of cavities. The synoptic maps, constructed from circular rings above the limb, are found to best show cavities in 211Å (Fe XIV, 2.0 MK) and 193 Å (Fe XII, 1.6 MK) pass bands. The high spatial and time resolution combined with the broad temperature coverage provides a consistent picture of the cavity material and the dynamics of the structure. Our goal is to study the cavity’s sizes (height, diameter and length), density and temperature properties. Moreover, we will examine the correlation between cavity morphology and underlying magnetic field distribution using Heliosesmic and Magnetic imager (HMI) instrument on SDO. This study will shed light on the origin, evolution and dynamics of coronal cavities. Title: The Solar Dynamics Observatory (SDO) Education and Outreach (E/PO) Program: Changing Perceptions One Program at a Time Authors: Drobnes, E.; Littleton, A.; Pesnell, W. D.; Beck, K.; Buhr, S.; Durscher, R.; Hill, S.; McCaffrey, M.; McKenzie, D. E.; Myers, D.; Scherrer, D.; Wawro, M.; Wolt, A. Bibcode: 2012SoPh..275..391D Altcode: 2011SoPh..tmp..420D; 2011SoPh..tmp..424D; 2011SoPh..tmp..367P We outline the context and overall philosophy for the combined Solar Dynamics Observatory (SDO) Education and Public Outreach (E/PO) program, present a brief overview of all SDO E/PO programs along with more detailed highlights of a few key programs, followed by a review of our results to date, conclude a summary of the successes, failures, and lessons learned, which future missions can use as a guide, while incorporating their own content to enhance the public's knowledge and appreciation of science and technology as well as its benefit to society. Title: Destruction of Sun-Grazing Comet C/2011 N3 (SOHO) Within the Low Solar Corona Authors: Schrijver, C. J.; Brown, J. C.; Battams, K.; Saint-Hilaire, P.; Liu, W.; Hudson, H.; Pesnell, W. D. Bibcode: 2012Sci...335..324S Altcode: Observations of comets in Sun-grazing orbits that survive solar insolation long enough to penetrate into the Sun's inner corona provide information on the solar atmosphere and magnetic field as well as on the makeup of the comet. On 6 July 2011, the Solar Dynamics Observatory (SDO) observed the demise of comet C/2011 N3 (SOHO) within the low solar corona in five wavelength bands in the extreme ultraviolet (EUV). The comet penetrated to within 0.146 solar radius (~100,000 kilometers) of the solar surface before its EUV signal disappeared. Before that, material released into the coma - at first seen in absorption - formed a variable EUV-bright tail. During the final 10 minutes of observation by SDO's Atmospheric Imaging Assembly, ~6 × 10^8 to 6 × 10^10 grams of total mass was lost (corresponding to an effective nucleus diameter of ~10 to 50 meters), as estimated from the tail's deceleration due to interaction with the surrounding coronal material; the EUV absorption by the comet and the brightness of the tail suggest that the mass was at the high end of this range. These observations provide evidence that the nucleus had broken up into a family of fragments, resulting in accelerated sublimation in the Sun's intense radiation field. Title: The Solar Dynamics Observatory (SDO) Authors: Pesnell, W. Dean; Thompson, B. J.; Chamberlin, P. C. Bibcode: 2012SoPh..275....3P Altcode: The Solar Dynamics Observatory (SDO) was launched on 11 February 2010 at 15:23 UT from Kennedy Space Center aboard an Atlas V 401 (AV-021) launch vehicle. A series of apogee-motor firings lifted SDO from an initial geosynchronous transfer orbit into a circular geosynchronous orbit inclined by 28° about the longitude of the SDO-dedicated ground station in New Mexico. SDO began returning science data on 1 May 2010. SDO is the first space-weather mission in NASA's Living With a Star (LWS) Program. SDO's main goal is to understand, driving toward a predictive capability, those solar variations that influence life on Earth and humanity's technological systems. The SDO science investigations will determine how the Sun's magnetic field is generated and structured, how this stored magnetic energy is released into the heliosphere and geospace as the solar wind, energetic particles, and variations in the solar irradiance. Insights gained from SDO investigations will also lead to an increased understanding of the role that solar variability plays in changes in Earth's atmospheric chemistry and climate. The SDO mission includes three scientific investigations (the Atmospheric Imaging Assembly (AIA), Extreme Ultraviolet Variability Experiment (EVE), and Helioseismic and Magnetic Imager (HMI)), a spacecraft bus, and a dedicated ground station to handle the telemetry. The Goddard Space Flight Center built and will operate the spacecraft during its planned five-year mission life; this includes: commanding the spacecraft, receiving the science data, and forwarding that data to the science teams. The science investigations teams at Stanford University, Lockheed Martin Solar Astrophysics Laboratory (LMSAL), and University of Colorado Laboratory for Atmospheric and Space Physics (LASP) will process, analyze, distribute, and archive the science data. We will describe the building of SDO and the science that it will provide to NASA. Title: The EUV Emission in Comet-Solar Corona Interactions Authors: Bryans, P.; Pesnell, W. D.; Schrijver, C. J.; Brown, J. C.; Battams, K.; Saint-Hilaire, P.; Liu, W.; Hudson, H. S. Bibcode: 2011AGUFMSH34B..05B Altcode: The Atmospheric Imaging Assembly (AIA) on the Solar Dynamics Observatory (SDO) viewed a comet as it passed through the solar corona on 2011 July 5. This was the first sighting of a comet by a EUV telescope. For 20 minutes, enhanced emission in several of the AIA wavelength bands marked the path of the comet. We explain this EUV emission by considering the evolution of the cometary atmosphere as it interacts with the ambient solar atmosphere. Water ice in the comet rapidly sublimates as it approaches the Sun. This water vapor is then photodissociated, primarily by Ly-α, by the solar radiation field to create atomic H and O. Other molecules present in the comet also evaporate and dissociate to give atomic Fe and other metals. Subsequent ionization of these atoms can be achieved by a number of means, including photoionization, electron impact, and charge exchange with coronal protons and other highly-charged species. Finally, particles from the cometary atmosphere are thermalized to the background temperature of the corona. Each step could cause emission in the AIA bandpasses. We will report here on their relative contribution to the emission seen in the AIA telescopes. Title: Time-Series Analyses of Supergranule Characteristics Compared Between SDO/HMI, SOHO/MDI and Simulated Datasets Authors: Williams, P. E.; Pesnell, W. D. Bibcode: 2011AGUFMSH23D..03W Altcode: Supergranulation is a well-observed solar phenomenon despite its underlying mechanisms remaining a mystery. Originally considered to arise due to convective motions, alternative mechanisms have been suggested such as the cumulative downdrafts of granules as well as displaying wave-like properties. Supergranule characteristics are well documented, however. Supergranule cells are approximately 35 Mm across, have lifetimes on the order of a day and have divergent horizontal velocities of around 300 m/s, a factor of 10 higher than their central radial components. While they have been observed using Doppler methods for more than half a century, their existence is also observed in other datasets such as magnetograms and Ca II K images. These datasets clearly show the influence of supergranulation on solar magnetism and how the local field is organized by the flows of supergranule cells. The Heliospheric and Magnetic Imager (HMI) aboard the Solar Dynamics Observatory (SDO) continues to produce Doppler images enabling the continuation of supergranulation studies made with SOHO/MDI, but with superior temporal and spatial resolution. The size-distribution of divergent cellular flows observed on the photosphere now reaches down to granular scales, allowing contemporaneous comparisons between the two flow components. SOHO/MDI Doppler observations made during the minima of cycles 22/23 and 23/24 exhibit fluctuations of supergranule characteristics (global averages of the supergranule size, size-range and horizontal velocity) with periods of 3-5 days. Similar fluctuations have been observed in SDO/HMI Dopplergrams and the high correlation between co-temporal HMI & MDI suggest a solar origin. Their nature has been probed by invoking data simulations that produce realistic Dopplergrams based on MDI data. Title: Using the EUV to Weigh a Sun-grazing Comet as it Disappears in the Solar Corona Authors: Pesnell, W. D.; Schrijver, C. J.; Brown, J. C.; Battams, K.; Saint-Hilaire, P.; Hudson, H. S.; Lui, W. Bibcode: 2011AGUFMSH33A2040P Altcode: On July 6, 2011, the Atmospheric Imaging Assembly (AIA) on the Solar Dynamics Observatory (SDO) observed a comet in most of its EUV passbands. The comet disappeared while moving through the solar corona. The comet penetrated to 0.146 solar radii ( ∼~100,000 km) above the photosphere before its EUV faded. Before then, the comet's coma and a tail were observed in absorption and emission, respectively. The material in the variable tail quickly fell behind the nucleus. An estimate of the comet's mass based on this effect, one derived from insolation, and one using the tail's EUV brightness, all yield ∼ 50 giga-grams some 10 minutes prior to the end of its visibility. These unique first observations herald a new era in the study of Sun-grazing comets close to their perihelia and of the conditions in the solar corona and solar wind. We will discuss the observations and interpretation of the comet by SDO as well as the coronagraph observations from SOHO and STEREO. A search of the SOHO comet archive for other comets that could be observed in the SDO/AIA EUV channels will be described. Title: A Comparison of Solar Polar Coronal Hole Areas Between Solar Cycles 23 and 24 Authors: Hess Webber, Shea A.; Karna, Nishu; Pesnell, W. Dean; Kirk, Michael S. Bibcode: 2011mfpc.confE...1H Altcode: We have used the perimeter tracing algorithm and analysis of EUV and magnetic field synoptic maps to extend our time series of polar coronal hole areas through solar minimum between cycles 23 and 24 (through 2010). Both EUV algorithms use 171, 195, and 304 Å images from the Extreme ultraviolet Imaging Telescope (EIT) on SOHO. The perimeter tracing algorithm measures the polar coronal hole boundaries as they appear on the limbs over each polar rotation and calculates the enclosed area, while the synoptic method calculates the area of the polar coronal holes from the meridional boundary through each Carrington rotation. Line-of-sight magnetic field synoptic maps from SOHO's Michelson Doppler Imager (MDI) instrument are used to estimate the polar coronal hole areas via polarity signatures. We remain convinced that the northern polar hole area is measurably smaller in the recent minimum than it was at the beginning of cycle 23, while the southern polar hole area is roughly the same. Title: Solar Dynamics and Magnetism from the Interior to the Atmosphere Authors: Pesnell, W. Dean; Thompson, Barbara Bibcode: 2011sdmi.conf.....P Altcode: The goal of the workshop is to discuss recent advances and new problems in the exploration of the Sun's interior structure, solar dynamics and dynamo, mechanisms of sunspot and active regions formation, sources of solar irradiance variations, and links between the subsurface dynamics, flaring and CME activity.

NASA's Solar Dynamics Observatory (SDO) mission is providing a large amount of new data on solar dynamics and magnetic activities during the rising phase of the current and highly unusual solar cycle. These data are complemented by the continuing SOHO mission, and by ground-based observatories that include the GONG helioseismology network and the New Solar Telescope. This unprecedented amount of data provides a unique opportunity for multi-instrument investigations that address fundamental problems of the origin of solar magnetic activity at various spatial and temporal scales.

The data is being used to develop new methods for forecasting solar cycles, emergence and evolution of active regions and their flaring and CME activity.

The scientific program will begin on Monday, October 31 at 9 AM, and conclude on Friday, November 4 at 1PM. Abstracts are solicited on the following topics:

- "Local and Global Helioseismology" - "Large-Scale Dynamics, Magnetism and Dynamo" - "Emerging Magnetic Flux and Subsurface Dynamics" - "Formation, Structure and Evolution of Sunspots and Active Regions" - "Numerical Simulations and Laboratory Experiments" - "Observations of the Solar Dynamics and Magnetism" - "Links between the Solar Interior and Atmosphere" - "Sources of Spectral and Total Irradiance Variations" - "Dynamics and Magnetic Topology of Flares and CMEs"

The workshop program will include invited and contributed talks, as well as poster sessions. On the last day, 4 splinter working group meetings will be organized:

1. Helioseismology (organizers R. Bogart, R. Komm, A. Kosovichev) 2. Vector Magnetometry (organizer T. Hoeksema and A. Pevtsov) 3. Feature Recognition, and Data Distribution and Access (organizers P. Martens and N. Hurlburt) 4. Numerical Simulations and Modeling (organizers N. Mansour and I. Kitiashvili) Title: An Error Analysis of Oscillations in Solar Polar Coronal Hole Areas Authors: Hess Webber, Shea A.; Pesnell, W. Dean; Karna, Nishu Bibcode: 2011shin.confE.169H Altcode: The results obtained from our polar coronal hole (PCH) area analysis of EUV images from the Extreme ultraviolet Imaging Telescope (EIT) on SOHO show an annual periodicity propagating through the data set. Investigations into the cause of this variability have been inconclusive. However, the frequency of the oscillation suggests that the uncertainty comes from orbital effects. We discuss the relevant orbital variations of the SOHO spacecraft and analytically determine the potential error due to those variations. These effects include the variations in solar B0 and L0 angles within the working coordinate system, and B0 projection effects of coronal material. Our goal in conducting this error analysis is to gain a better understanding of how SOHO's orbital variations affect the determination of solar coordinates, particularly at the limb and poles. This work is supported by the Solar Dynamics Observatory. Title: An Error Analysis of Oscillations in Solar Polar Coronal Hole Areas Authors: Hess Webber, Shea A.; Karna, Nishu; Pesnell, W. Dean Bibcode: 2011shin.confE...1H Altcode: The results obtained from our polar coronal hole (PCH) area analysis of EUV images from the Extreme ultraviolet Imaging Telescope (EIT) on SOHO show an annual periodicity propagating through the data set. Investigations into the cause of this variability have been inconclusive. However, the frequency of the oscillation suggests that the uncertainty comes from orbital effects. We discuss the relevant orbital variations of the SOHO spacecraft and analytically determine the potential error due to those variations. These effects include the variations in solar B0 and L0 angles within the working coordinate system, and B0 projection effects of coronal material. Our goal in conducting this error analysis is to gain a better understanding of how SOHO's orbital variations affect the determination of solar coordinates, particularly at the limb and poles. This work is supported by the Solar Dynamics Observatory. Title: The evolution of the Polar Coronal Hole During Solar Cycles 23 and 24 Authors: Karna, Nishu; Hess Webber, Shea A.; Pesnell, W. Dean; Kirk, M. S. Bibcode: 2011shin.confE.168K Altcode: Synoptic maps made from two instruments on SOHO are analyzed to track the size of the solar polar coronal holes (PCH) over Solar Cycles 23 and 24. The first method uses 171 Å, 195 Å, and 304 Å synoptic maps constructed from the Extreme-ultraviolet Imaging Telescope (EIT) on SOHO for 145 Carrington Rotations from mid 1996 through mid 2007 from archive. After this time, we have created the synoptic maps for 42 Carrington Rotation to compare the fractional PCH area between two solar minima and extending our time series up to 2010. Our second method used line-of-sight magnetic field synoptic maps from SOHO's Michelson Doppler Imager (MDI) instrument to estimate the polar coronal hole area via polarity signatures for 187 Carrington Rotations from mid 1996 through 2010. There is a good correlation between the estimated PCH extracted form EIT and MDI. This work was supported by the Solar Dynamics Observatory. Title: Solar Polar Coronal Hole Areas Through the Past Solar Minimum Authors: Hess Webber, Shea A.; Karna, Nishu; Pesnell, W. Dean; Kirk, Michael S. Bibcode: 2011lws..workE...1H Altcode: We have used the perimeter tracking algorithm and analysis of EIT synoptic maps to extend our time series of polar coronal hole areas through solar minimum (through 2010). Both algorithms use 171, 195, and 304 Å images from the Extreme ultraviolet Imaging Telescope (EIT) on SOHO, the first to measure the perimeter of polar coronal holes as they appear on the limbs and the second the area of the polar coronal hole during each Carrington rotation. Line-of-sight magnetic field synoptic maps are also used to estimate the polar coronal hole area. We have updated the time series and we are analyzing uncertainties in EIT ephemeris data. We remain convinced that the northern polar hole area is measurably smaller in the recent minimum than it was at the beginning of cycle 23, while the southern polar hole area is roughly the same. Polar hole areas found via perimeter tracking agree within uncertainty with those determined using EIT synoptic map analysis. Title: Solar Polar Coronal Hole Areas Through the Past Solar Minimum Authors: Hess Webber, Shea; Karna, N.; Pesnell, W. D.; Kirk, M. Bibcode: 2011SPD....42.1825H Altcode: 2011BAAS..43S.1825H We have used the perimeter tracking algorithm and analysis of EIT synoptic maps to extend our timeseries of polar coronal hole areas through solar minimum (through 2010). Both algorithms use 171, 195, and 304 Å images from the Extreme ultraviolet Imaging Telescope (EIT) on SOHO, the first to measure the perimeter of polar coronal holes as they appear on the limbs and the second the area of the polar coronal hole during each Carrington rotation. Line-of-sight magnetic field synoptic maps are also used to estimate the polar coronal hole area. We have updated the time series and we are analyzing uncertainties in EIT ephemeris data. We remain convinced that the northern polar hole area is measurably smaller in the recent minimum than it was at the beginning of cycle 23, while the southern polar hole area is roughly the same. Polar hole areas found via perimeter tracking agree within uncertainty with those determined using EIT synoptic map analysis. This work was supported by the Solar Dynamics Observatory. Title: Time-Series Analysis of Supergranule Characteristics Derived from SOHO/MDI Dopplergrams. Authors: Williams, Peter E.; Pesnell, W. D. Bibcode: 2011SPD....42.1725W Altcode: 2011BAAS..43S.1725W Supergranulation exhibits both radial and horizontal velocity components within Doppler data. The weak, radial flows drag magnetic field lines to the surface while their strong, divergent, horizontal counterparts advect the field to the edges of the supergranulation cells. Field congregation at supergranule boundaries is observed in magnetic filed images and via Ca II K observations of the chromospheric network.

Supergranulation characteristics, such as typical sizes and velocities, have been studied using MDI Doppler data and tracked over 60-days of observations made in 1996 and 2008, relating to periods of solar minimum. Time-series of these characteristics exhibit regular fluctuations on the order of 3-5 days. These time-series are analyzed to extract frequency information and cross-correlated to investigate any temporal link between the characteristics.

Whether the fluctuations are an instrumental artifact is studied by comparing contemporaneous time series produced from SOHO/MDI and SDO/HMI Dopplergrams. There exists a high correlation between the two time-series showing that the fluctuations are solar in origin. Title: Comparisons of Supergranule Characteristics During the Solar Minima of Cycles 22/23 and 23/24 Authors: Williams, Peter E.; Pesnell, W. Dean Bibcode: 2011SoPh..270..125W Altcode: 2011SoPh..tmp...28W; 2011arXiv1103.1696W Supergranulation is a component of solar convection that manifests itself on the photosphere as a cellular network of around 35 Mm across, with a turnover lifetime of 1 - 2 days. It is strongly linked to the structure of the magnetic field. The horizontal, divergent flows within supergranule cells carry local field lines to the cell boundaries, while the rotational properties of supergranule upflows may contribute to the restoration of the poloidal field as part of the dynamo mechanism, which controls the solar cycle. The solar minimum at the transition from cycle 23 to 24 was notable for its low level of activity and its extended length. It is of interest to study whether the convective phenomena that influence the solar magnetic field during this time differed in character from periods of previous minima. This study investigates three characteristics (velocity components, sizes and lifetimes) of solar supergranulation. Comparisons of these characteristics are made between the minima of cycles 22/23 and 23/24 using MDI Doppler data from 1996 and 2008, respectively. It is found that whereas the lifetimes are equal during both epochs (around 18 h), the sizes are larger in 1996 (35.9 ± 0.3 Mm) than in 2008 (35.0 ± 0.3 Mm), while the dominant horizontal velocity flows are weaker (139 ± 1 m s−1 in 1996; 141 ± 1 m s−1 in 2008). Although numerical differences are seen, they are not conclusive proof of the most recent minimum being inherently unusual. Title: Comparison of Vector Magnetograms from the Solenoidal and Irrotational Components of the Magnetic Field Authors: Bryans, Paul; Pesnell, W. D. Bibcode: 2011SPD....42.2108B Altcode: 2011BAAS..43S.2108B According to the Helmholtz Theorem, the solar magnetic field can be defined in terms of an irrotational and a solenoidal component. We will discuss the partitioning of the field into these components as a means of attributing elements of the magnetic field to its vorticity and divergence. We will then discuss the advantages of this decomposition as a metric for comparing vector magnetograms of varying spatial and temporal resolution. Title: Properties of Supergranulation During the Solar Minima of Cycles 22/23 and 23/24 Authors: Williams, Peter E.; Pesnell, W. Dean Bibcode: 2011JPhCS.271a2082W Altcode: The solar minimum at the transition from cycle 23 to 24 was notable for its low level of activity and its extended duration. Among the various fields of study, the evolution of the solar convection zone may provide insight into the causes and consequences of this recent minimum. This study continues previous investigations of the characteristics of solar supergranulation, a convection component strongly linked to the structure of the magnetic field, namely the time-evolution of the global mean of supergranule cell size, determined from spectral analysis of MDI Dopplergrams from the two previous solar minima. Analyses of the global mean of supergranule sizes show a quasi-oscillatory nature to the evolution of this particular supergranule characteristic. Performing similar analyses on realistic, synthetic Doppler images show similar time-dependent characteristics. We conclude that the observed fluctuations are not observational artifacts, and that an underlying trend exists within the evolution of the supergranulation network. Title: Analysis of Photospheric Convection Cells with SDO/HMI Authors: Williams, P. E.; Pesnell, W. D. Bibcode: 2010AGUFMSH14A..06W Altcode: Supergranulation is a component of solar convection that assists in the outward transportation of internal energy. Supergranule cells are approximately 35 Mm across, have lifetimes on the order of a day and have divergent horizontal velocities of around 300 m/s, a factor of 10 higher than their central radial components. While they have been observed using Doppler methods for around half a century, their existence is also observed in other datasets such as magnetograms and Ca II K images. These datasets clearly show the influence of supergranulation on solar magnetism and how the local field is organized by the flows of supergranule cells. The Heliospheric and Magnetic Imager (HMI) aboard SDO is making fresh observations of convection phenomena at a higher cadence and a higher resolution that should make granular features visible. Granulation and supergranulation characteristics can now be compared within the same datasets, which may lead to further understanding of any mutual influences. The temporal and spatial enhancements of HMI will also reduce the noise level within studies of convection so that more detailed studies of their characteristics may be made. We present analyses of SDO/HMI Dopplergrams that provide new estimates of convection cell sizes, lifetimes, and velocity flows, as well as the rotation rates of the convection patterns across the solar disk. We make comparisons with previous data produced by MDI, as well as from data simulations. Title: Comparisons of Supergranule Properties from SDO/HMI with Other Datasets Authors: Pesnell, W. D.; Williams, P. E. Bibcode: 2010AGUFMSH21C..02P Altcode: While supergranules, a component of solar convection, have been well studied through the use of Dopplergrams, other datasets also exhibit these features. Quiet Sun magnetograms show local magnetic field elements distributed around the boundaries of supergranule cells, notably clustering at the common apex points of adjacent cells, while more solid cellular features are seen near active regions. Ca II K images are notable for exhibiting the chromospheric network representing a cellular distribution of local magnetic field lines across the solar disk that coincides with supergranulation boundaries. Measurements at 304 Å further above the solar surface also show a similar pattern to the chromospheric network, but the boundaries are more nebulous in nature. While previous observations of these different solar features were obtained with a variety of instruments, SDO provides a single platform, from which the relevant data products at a high cadence and high-definition image quality are delivered. The images may also be cross-referenced due to their coincidental time of observation. We present images of these different solar features from HMI & AIA and use them to make composite images of supergranules at different atmospheric layers in which they manifest. We also compare each data product to equivalent data from previous observations, for example HMI magnetograms with those from MDI. Title: ``ALTITUDE Variation'' of the CO2(V2)-O Quenching Rate Coefficient in Mesosphere and Lower Thermosphere Authors: Feofilov, A.; Kutepov, A.; She, C.; Smith, A. K.; Pesnell, W. D.; Goldberg, R. A. Bibcode: 2010AGUFMSA52A..07F Altcode: Among the processes governing the energy balance in the mesosphere and lower thermosphere (MLT), the quenching of CO2(ν2) vibrational levels by collisions with oxygen atoms plays an important role. However, the k(CO2-O) values measured in the lab and retrieved from atmospheric measurements vary from 1.5 x 10-12 cm3 s-1 through 9.0 x 10-12 cm3 s-1 that requires further studying. In this work we used synergistic data from a ground based lidar and a satellite infrared radiometer to estimate k(CO2-O). We used the night- and daytime temperatures between 80 and 110 km measured by the Colorado State University narrow-band sodium (Na) lidar located at Fort Collins, Colorado (41N, 255E) as ground truth of the SABER/TIMED nearly simultaneous (±10 minutes ) and common volume (within ±1 degree in latitude, ±2 degrees in longitude) observations. For each altitude in 80-110 km interval we estimate an “optimal” value of k(CO2-O) needed to minimize the discrepancy between the simulated 15 μm CO2 radiance and that measured by the SABER/TIMED instrument. The k(CO2-O) obtained in this way varies in altitude from 3.5 x 10-12 cm3 s-1 at 80 km to 5.2 x 10-12 cm3 s-1 for altitudes above 95 km. We discuss this variation of the rate constant and its impact on temperature retrievals from 15 μm radiance measurements and on the energy budget of MLT. Title: An Update of the Automatic Detection of Polar Coronal Holes in the EUV Authors: Hess Webber, Shea A.; Karna, Nishu; Pesnell, W. Dean; Kirk, Michael S. Bibcode: 2010eddy.confE...1H Altcode: An automated detection method of polar coronal holes was presented by Kirk et al. in 2009. This method, called perimeter tracking, uses a series of 171, 195, and 304 Å full disk images from the Extreme ultraviolet Imaging Telescope (EIT) on SOHO to measure the perimeter of polar coronal holes as they appear on the limbs. We have updated the previous time series, which ranged from mid 1996 through 2007, up to the most recently available EIT data in 2010, and refined the detection parameters, adjusting them to fit the data more precisely and accurately. Additionally, we increased our analysis to utilize all available EIT images rather than one image per day in the previous work. We find the wavelength average of the northern hole is about 5.5% of the solar surface area while the southern hole average measures about 4.5% during 1996 in the revised data set. These values are somewhat larger then we previously reported due to the improvements in the algorithm. We also find that in 2010, the northern and southern hole areas are about 3.0% and 3.5% of the total solar surface, respectively. The north and south polar hole areas are now noticeably smaller in the recent minimum than they were at the beginning of cycle 23. This is especially true in the northern hemisphere. We will compare these polar hole areas with the total coronal hole area found using EIT synoptic maps over the same time series and wavelengths. Title: An Update of the Automatic Detection of Polar Coronal Holes in the EUV Authors: Hess Webber, Shea A.; Karna, Nishu; Pesnell, W. Dean; Kirk, Michael S. Bibcode: 2010shin.confE...1H Altcode: An automated detection method of polar coronal holes was presented by Kirk et al. in 2009. This method, called perimeter tracking, uses a series of 171, 195, and 304 Å full disk images from the Extreme ultraviolet Imaging Telescope (EIT) on SOHO to measure the perimeter of polar coronal holes as they appear on the limbs. We have updated the previous time series, which ranged from mid 1996 through 2007, up to the most recently available EIT data in 2010, and refined the detection parameters, adjusting them to fit the data more precisely and accurately. Additionally, we increased our analysis to utilize all available EIT images rather than one image per day in the previous work. We had observed the area of the northern polar hole in 1996, at the beginning of solar cycle 23, to be about 4.2% of the total solar surface area. The area of the southern polar hole was observed to be about 4.0% in 1996. These numbers are slightly larger in the revised data set, the northern hole at about 5.5% of the solar surface area in 1996 and the southern hole measuring about 4.5%. We further find that in 2010, the northern and southern hole areas are about 2.8% and 3.0% of the total solar surface, respectively. The north and south polar hole areas are no more than 1/3 smaller now than they were at the beginning of cycle 23. We will compare these polar hole areas with the total coronal hole area found using EIT synoptic maps over the same time series and wavelengths Title: Automated Detection of Polar Coronal Holes in EUV Authors: Pesnell, W. Dean; Hess Webber, Shea A.; Karna, Nishu; Kirk, Michael S. Bibcode: 2010shin.confE.158P Altcode: Perimeter tracking is an automated detection method of polar coronal holes that uses full-disk images to measure the perimeter of polar coronal holes as they appear on the limbs. We applied this technique to images at three wavelengths (171, 195, and 304 Å) from the Extreme ultraviolet Imaging Telescope (EIT) on SOHO. We have updated the previous time series to the most recently available EIT data in 2010, and refined the detection parameters, adjusting them to more accurately fit the data. We also modified the analysis to use all available EIT images rather than the one image per day used in the previous work. With these changes, the northern polar hole area in the 304 channel is observed to be about 4.4% of the solar surface area in the previous solar minimum (1996/1997) while the southern hole measures about 4%. We also find that the northern polar hole reached a maximum area of about 3.7% in 2007/2008 while the southern hole area reached a maximum of about 4% in mid-2009. We will compare these polar hole areas with the areas found using EIT synoptic maps over the same time period and wavelengths. Title: Photospheric Manifestations of Supergranules during the Last Two Solar Minima Authors: Williams, P. E.; Pesnell, W. D. Bibcode: 2010ASPC..428..127W Altcode: 2010arXiv1004.0936W Solar supergranulation plays an important role in generating and structuring the solar magnetic field and as a mechanism responsible for the 11-year solar cycle. It is clearly detected within SOHO/MDI Dopplergrams, from which a variety of properties may be derived. Techniques that extract spatial, temporal, and kinematic characteristics and provide comparisons for the two most recent solar minima are described. Although supergranule lifetimes are comparable between these minima, their sizes may be slightly smaller during the recent minimum. Title: Comparisons of Photospheric Convection Cell Characteristics During the Solar Minima of Cycles 22-23 and 23-24 Authors: Williams, Peter E.; Pesnell, W. D. Bibcode: 2010AAS...21631702W Altcode: 2010BAAS...41..898W With its elongated tail and extended periods of zero activity, the period marking the transition from solar cycle 23 to 24 has seemed peculiar when compared to other minima. Among the various phenomena studied, the evolution of the solar convection zone may provide insight into the causes and consequences of this recent minimum.

Convection in the Sun plays an important role in generating and structuring the solar magnetic field and as a mechanism responsible for the 11-year solar cycle. The observed phenomena are strongly linked within both observational and physical regimes.

This study uses SOHO/MDI Dopplergrams to highlight supergranulation within the line-of-sight velocity data. Suites of analysis methods are applied to time-series of Doppler images to quantitatively describe supergranule flow velocities, spatial scales and temporal lifetimes.

The results show similarities in supergranule evolution (1/e lifetimes of 18 hours), while their sizes are smaller and their flows stronger during the 23-24 minimum compared to 22-23. We also present provisional results of statistical analyses performed both within and between the various data sets, some of which tend to show a quasi-oscillatory nature.

Future studies to place this work in the wider context of the solar cycle are discussed, as a whole as well as investigations of supergranule characteristics found in various other data such as magnetograms and CaIIK images. Observed hemispheric asymmetries will be presented and how our methods may be applied to further these enquiries. Title: The Solar Dynamics Observatory: Your eye on the Sun Authors: Pesnell, William Bibcode: 2010cosp...38.4183P Altcode: 2010cosp.meet.4183P The Solar Dynamics Observatory (SDO) was launched on February 11, 2010 into partly cloudy skies over Cape Canaveral, Florida. SDO has since moved into a 28 degree inclined geosyn-chronous orbit over the longitude of the ground station in New Mexico. SDO is the first Space Weather Mission in NASA's Living With a Star Program. SDO's main goal is to understand and predict those solar variations that influence life on Earth and our technological systems. The SDO science investigations will determine how the Sun's magnetic field is generated and structured, how this stored magnetic energy is released into the heliosphere and geospace as the solar wind, energetic particles, and variations in the solar irradiance. The SDO mission consists of three scientific investigations (AIA, EVE, and HMI), a spacecraft bus, and a ded-icated Ka-band ground station to handle the 150 Mbps data flow. Science teams at LMSAL, LASP, and Stanford are responsible for processing, analyzing, distributing, and archiving the science data. We will talk about the building of SDO, its launch, and the data and science it will provide to NASA. Title: Conditions for PMC formation in 2002-2008 estimated from TIMED/SABER measurements Authors: Feofilov, Artem; Goldberg, Richard A.; Kutepov, Alexander; Pesnell, William Bibcode: 2010cosp...38.1232F Altcode: 2010cosp.meet.1232F In this work, mesospheric temperature, pressure, and water vapor concentration measured by the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument on board the Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) satel-lite are used to estimate the probability of the polar mesospheric ice clouds (PMC) formation for the summer periods of 2002-2008. We show the zonal averages of the PMC probability distri-butions and estimated PMC heights for both hemispheres and compare them to ground-based and satellite observations. 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: Comparisons of Photospheric Convection Cell Characteristics Authors: Pesnell, W. D.; Wiliams, P. E. Bibcode: 2009AGUFMSH11A1500P Altcode: Solar convection plays an important role in generating and structuring the solar magnetic field as well as a mechanism responsible for the 11-year solar cycle. The observed phenomena are strongly linked within both observational and physical regimes. Our main focus is the study of supergranulation from SOHO/MDI Dopplergrams. Suites of analysis methods are applied to time-series of Doppler images to quantitatively describe supergranule flow velocities, spatial scales and temporal lifetimes. SOHO/MDI magnetograms also show cellular structures, which trace the clustering of magnetic field lines around supergranule boundaries. These boundaries are extrapolated into the chromosphere where they are observed as a cellular network. We present preliminary results of applying methods similar to those applied to the Dopplergrams for estimating the spatial and temporal characteristics of this network. We extend our study to above the photosphere to the chromosphere where another cellular network is seen. Once again the responsibility lies with supergranulation. Spatial analysis on CaIIK data from the Precision Solar Photometric Telescope (PSPT) provides typical size scales for the network that can be compared to both the magnetogram network and supergranulation itself. Data comparisons over time can be made, notably between Doppler data received during the current (2008) and previous (1996) solar minima. Our provisional findings show that horizontal and radial velocity flows within supergranules are stronger during the current minimum, while the supergranules themselves appear larger during the previous minimum. However, comparable results are found for the 1/e lifetimes derived from each data set. We extend these provisional results by performing statistical analyses both within and between the various data sets. Title: CO2(ν2)-O Quenching Rate Coefficient Derived From Coincidental Fort Collins Lidar and SABER Measurements Authors: Feofilov, A.; Kutepov, A.; She, C.; Smith, A. K.; Pesnell, W. D.; Goldberg, R. A. Bibcode: 2009AGUFMSA53A1238F Altcode: Among the processes governing the energy balance in the mesosphere and lower thermosphere (MLT), the quenching of CO2(ν2) vibrational levels in collisions with oxygen atoms plays an important role. However, neither the rate coefficient of this process (k(CO2-O)) nor the atomic oxygen concentrations ([O]) in the MLT are well known. The discrepancy between k(CO2-O) measured in the lab and retrieved from atmospheric measurements is of about factor of 2.5. At the same time, the discrepancy between [O] in the MLT measured by different instruments is of the same order of magnitude. In this work we combine temperature data from a ground based lidar with limb radiances from a satellite infrared radiometer to estimate k(CO2-O). We used the night- and daytime temperatures between 80 and 110 km measured by the Colorado State University narrow-band sodium (Na) lidar located at Fort Collins, Colorado (41N, 255E) as ground truth of the SABER/TIMED nearly simultaneous (±10 minutes ) and common volume (within ±1 degree in latitude, ±2 degrees in longitude) observations. We used ALI-ARMS non-LTE research code designed to calculate the non-equilibrium radiance in planetary atmospheres to retrieve the product of k(CO2-O) x [O] from 15 μm CO2 limb radiance measured by SABER. The values retrieved for all overlapping measurements were then used to estimate the k(CO2-O) rate coefficient and its possible variation range by utilizing the [O] values measured by the SABER and other instruments. Title: What is an Extreme Solar Minimum? Authors: Pesnell, William Dean Bibcode: 2009shin.confE.143P Altcode: The study of solar minimum has been a poor cousin to solar maximum due to the large variations seen in the Sun during maximum. Solar activity is low or absent during solar minimum and all of the phenomena that follow the sunspot number are also smaller in frequency and strength. Even the definition of solar minimum is difficult because the main indicator of solar activity is zero for an extended period of time. But the Sun presents a different face at minimum. The magnetic field is weaker but far more symmetric, almost a dipole for the few minimum that have been measured. A similar behavior is seen in the corona measured by coronagraphs and magnetic fields measured in the heliosphere. Particle fluxes in the solar wind are smaller. As a result the scattering of galactic cosmic rays is reduced and a larger flux of GCRs is be seen at Earth. The current solar minimum has been extreme in having weaker surface fields than previous measurements, few spots for longer than average, and an interesting signature in Earth's magnetic field. We shall discuss these magnetic signatures and the implications for Space Weather and climate of a time with weak solar activity. Title: Automated detection of EUV Polar Coronal Holes during Solar Cycle 23 Authors: Kirk, M. S.; Pesnell, W. D.; Young, C. A.; Hess Webber, S. A. Bibcode: 2009SoPh..257...99K Altcode: 2009arXiv0901.1158K A new method for automated detection of polar coronal holes is presented. This method, called perimeter tracing, uses a series of 171, 195, and 304 Å full disk images from the Extreme ultraviolet Imaging Telescope (EIT) on SOHO over solar cycle 23 to measure the perimeter of polar coronal holes as they appear on the limbs. Perimeter tracing minimizes line-of-sight obscurations caused by the emitting plasma of the various wavelengths by taking measurements at the solar limb. Perimeter tracing also allows for the polar rotation period to emerge organically from the data as 33 days. We have called this the Harvey rotation rate and count Harvey rotations starting 4 January 1900. From the measured perimeter, we are then able to fit a curve to the data and derive an area within the line of best fit. We observe the area of the northern polar hole area in 1996, at the beginning of solar cycle 23, to be about 4.2% of the total solar surface area and about 3.6% in 2007. The area of the southern polar hole is observed to be about 4.0% in 1996 and about 3.4% in 2007. Thus, both the north and south polar hole areas are no more than 15% smaller now than they were at the beginning of cycle 23. This compares to the polar magnetic field measured to be about 40% less now than it was a cycle ago. Title: Automated Detection of Polar Coronal Holes in the EUV Authors: Kirk, Michael S.; Pesnell, W. D. Bibcode: 2009SPD....40.1407K Altcode: A new method for automatically detecting and measuring Polar Coronal Holes in the EUV is presented. We use a series of full solar disk images over solar cycle 23 to measure the perimeter of polar coronal holes as they appear on the limbs. This method utilizes 171, 195, and 304 Å solar images from the Extreme ultraviolet Imaging Telescope (EIT) on SOHO. We are able to more accurately define the size and shape of the polar hole by taking measurements on the limb and making two measurements per image rather than the one used to construct synoptic maps. This method also minimizes line-of-sight obscurations caused by the emitting plasma of the various wavelengths. Perimeter tracking allows for the polar coronal rotation period to emerge organically from the data as 33 days. We have called this the Harvey Rotation rate and count Harvey Rotations starting January 4, 1900. From the measured perimeter we are then able to fit a curve to the data and derive an area within the line of best fit. This method can be adapted to work with any extended data set of full disk solar images. Extending our data set to past NSO full disk spectroheliograms creates a base line of more than three solar cycles. In the future, SDO images will be added to further expand polar hole measurements. Title: Predicting Solar Cycle 24 With Geomagnetic Precursors Authors: Pesnell, W. Dean Bibcode: 2009SPD....40.1105P Altcode: We describe using a geomagnetic precursor to predict the amplitude of the upcoming solar cycle. The amplitude prediction for Solar Cycle 24 is 65 +/- 20 in smoothed sunspot number, indicating a below-average amplitude for Solar Cycle 24. Four precursor peaks are seen in the decline of Solar Cycle 23. The earliest is the most prominent but coincides with large levels of non-recurrent geomagnetic activity associated with the Halloween storms. The second and third peaks are for smaller amplitudes and show that a weak cycle precursor closely following a period of strong solar activity may be difficult to resolve. A fourth peak, in early 2008, which has recurrent activity similar to precursors of earlier solar cycles and appears to be the ``true" precursor peak for Solar Cycle 24, predicts the smallest amplitude for Solar Cycle 24. Several effects contribute to the smaller prediction when compared to other geomagnetic precursor predictions. During Solar Cycle 23 the correlation between sunspot number and F10.7 shows that F10.7 is greater than the equivalent sunspot number over most of the cycle, implying the sunspot number underestimates the solar activity component. During 2003 the correlation between aa and Ap shows that aa is much greater than the value predicted from Ap, leading to an overestimate of the aa precursor for that year. But the most important effect is the lack of recurrent geomagnetic activity until 2008. We conclude that Solar Cycle 24 will be no stronger than average and could be much weaker than average. Title: Analysis of Photospheric Convection Flows Over a Solar Cycle Authors: Williams, Peter E.; Pesnell, W. D. Bibcode: 2009SPD....40.0919W Altcode: Convection in the Sun plays an important role as a mechanism responsible for the 11-year solar cycle. Magnetic field phenomena are thus inextricably linked to the convective process, an example being the gathering of magnetic field lines around supergranule boundaries observed as the chromospheric network.

Our research asks to what extent variations in the global magnetic field affect particular characteristics of photospheric convection features, using Dopplergrams derived from SOHO/MDI data during the course of Solar Cycle 23.

We look ahead to the higher resolution data that SDO/HMI will provide and any further insight such data may provide. Title: Temperature Trends in the Polar Mesosphere between 2002--2007 using TIMED/SABER Data Authors: Goldberg, R. A.; Feofilov, A. G.; Kutepov, A. A.; Pesnell, W. D.; Latteck, R.; Russell, J. M. Bibcode: 2008AGUFMSA43A1574G Altcode: The TIMED Satellite was launched on December 7, 2001 to study the dynamics and energy of the mesosphere and lower thermosphere. The TIMED/SABER instrument is a limb scanning infrared radiometer designed to measure a large number of minor constituents as well as the temperature of the region. In this study, we have concentrated on the polar mesosphere, to investigate the temperature characteristics as a function of spatial and temporal considerations. We used the recently revised SABER dataset (1.07) that contains improved temperature retrievals in the Earth polar summer regions. Weekly averages are used to make comparisons between the winter and summer, as well as to study the variability in different quadrants of each hemisphere. For each year studied, the duration of polar summer based on temperature measurements compares favorably with the PMSE (Polar Mesospheric Summer Echoes) season measured by radar at the ALOMAR Observatory in Norway (69°N). The PMSE period should also define the summer period suitable for the occurrence of polar mesospheric clouds. The unusual short and relatively warm polar summer in the northern hemisphere during 2002 is also clearly defined in this analysis and shown to be unique for the period analyzed. Title: Temperature and water vapor measured by SABER/TIMED and implications for mesospheric ice clouds Authors: Feofilov, A. G.; Kutepov, A. A.; Marshall, B. T.; Pesnell, W. D.; Goldberg, R. A.; Gordley, L. L.; Russell, J. M. Bibcode: 2008AGUFMSA43A1575F Altcode: The SABER instrument on board the TIMED Satellite is a limb scanning infrared radiometer designed to measure temperature and minor constituent vertical profiles and energetics parameters in the mesosphere and lower thermosphere. We applied an updated non-LTE model for the interpretation of the 6.3 micron H2O radiance measured by SABER. The obtained meridional and seasonal distributions of the H2O density in the mesosphere are discussed. The conditions for the mesospheric ice particle formation are estimated using the combination of SABER H2O and temperature (V1.07) profiles. Title: Recent studies of the behavior of the Sun's white-light corona over time Authors: St. Cyr, O. C.; Young, D.; Pesnell, W. D.; Lecinski, A.; Eddy, J. Bibcode: 2008AGUFMSH44A..06S Altcode: Predictions of upcoming solar cycles are often related to the nature and dynamics of the Sun's polar magnetic field and its influence on the corona. For the past 30 years we have a more-or-less continuous record of the Sun's white-light corona from groundbased and spacebased coronagraphs. Over that interval, the large scale features of the corona have varied in what we now consider a "predictable" fashion--complex, showing multiple streamers at all latitudes during solar activity maximum; and a simple dipolar shape aligned with the rotational pole during solar minimum. Over the past three decades the white-light corona appears to be a better indicator of "true" solar minimum than sunspot number since sunspots disappear for months (even years) at solar minimum. Since almost all predictions of the timing of the next solar maximum depend on the timing of solar minimum, the white-light corona is a potentially important observational discriminator for future predictors. In this contribution we describe recent work quantifying the large-scale appearance of the Sun's corona to correlate it with the sunspot record, especially around solar minimum. These three decades can be expanded with the HAO archive of eclipse photographs which, although sparse compared to the coronagraphic coverage, extends back to 1869. A more extensive understanding of this proxy would give researchers confidence in using the white-light corona as an indicator of solar minimum conditions. Title: Predictions of Solar Cycle 24 Authors: Pesnell, William Dean Bibcode: 2008SoPh..252..209P Altcode: 2008SoPh..tmp..152P A summary and analysis of more than 50 predictions of the amplitude of the upcoming Solar Cycle 24 is presented. All of the predictions were published before solar minimum and represent our efforts to anticipate solar maximum at ever-earlier epochs. The consistency of the predictions within their assigned categories is discussed. Estimates of the significance of the predictions, compared to the climatological average, are presented. Title: SABER/TIMED Mesospheric Water Vapor and Temperature Authors: Feofilov, A. G.; Kutepov, A. A.; Garci­A-Comas, M.; Lopez-Puertas, M.; Marshall, B. T.; Gordley, L. L.; Manuilova, R. O.; Yankovsky, V. A.; Pesnell, W. D.; Goldberg, R. A.; Petelina, S.; Russell, J. M. Bibcode: 2008AGUSMSA41D..09F Altcode: Low temperatures and abundant water vapor are the necessary components for the mesospheric water ice forming. The SABER instrument on board the TIMED Satellite is a limb scanning infrared radiometer designed to measure temperature and minor constituent vertical profiles and energetics parameters in the mesosphere and lower thermosphere. This paper describes the methodology of the water vapor retrieval from the broadband 6.3μm non-LTE emissions and discusses some aspects of the temperature retrieval from the 15μm non-LTE CO2 emissions measured by SABER. The non-LTE models of H2O and CO2 are validated using the comparisons with the ACE-FTS occultation measurement and lidar temperature measurements, respectively. The seasonal and latitudinal distributions of water vapor and temperatures retrieved from the SABER measurements are shown and the conditions for ice clouds forming are discussed. Title: Seasonal variations of magnesium atoms in the mesosphere-thermosphere Authors: Correira, J.; Aikin, A. C.; Grebowsky, J. M.; Pesnell, W. D.; Burrows, J. P. Bibcode: 2008GeoRL..35.6103C Altcode: UV radiances from the Global Ozone Monitoring Experiment (GOME) spectrometer on the ERS-2 satellite are used to determine long-term dayside temporal variations of the total vertical column density below 795 km of the meteoric metal species Mg and Mg+ in the upper atmosphere. The GOME instrument has the ability to observe the ground state transition lines of Mg I at 285.2 nm and resolve the Mg II at 280 nm. A retrieval algorithm has been developed to determine column densities and applied to the years 1996-1997. Results show the middle latitude dayside Mg+ peaks in total vertical content during the summer, while neutral Mg demonstrates a much more subtle maximum in summer. Dayside trends are opposite previous midlatitude nighttime lidar observations, with the exception of calcium. The Mg+/Mg ratio has a seasonal variation, reaching a maximum in the summer. The total content of Mg+ is twice that of neutral Mg. Title: The Solar Dynamics Observatory: Your eye on the Sun Authors: Pesnell, William Bibcode: 2008cosp...37.2412P Altcode: 2008cosp.meet.2412P The Sun hiccups and satellites die. That is what NASA's Living With a Star Program is all about. The Solar Dynamics Observatory (SDO) is the first Space Weather Mission in LWS. SDO's main goal is to understand, driving towards a predictive capability, those solar variations that influence life on Earth and humanity's technological systems. The past decade has seen an increasing emphasis on understanding the entire Sun, from the nuclear reactions at the core to the development and loss of magnetic loops in the corona. SDO's three science investigations (HMI, AIA, and EVE) will determine how the Sun's magnetic field is generated and structured, how this stored magnetic energy is released into the heliosphere and geospace as the solar wind, energetic particles, and variations in the solar irradiance. SDO will return fulldisk Dopplergrams, full-disk vector magnetograms, full-disk images at seven EUV wavelengths, and EUV spectral irradiances, all taken at a rapid cadence. This means you can "observe the database" to study events, but we can also move forward in producing quantitative models of what the Sun is doing today. SDO is scheduled to launch in 2008 on an Atlas V rocket from the Kennedy Space Center, Cape Canaveral, Florida. The satellite will fly in a 28 degree inclined geosynchronous orbit about the longitude of New Mexico, where a dedicated Ka-band ground station will receive the 150 Mbps data flow. How SDO data will transform the study of the Sun and its affect on Space Weather studies will be discussed. Title: Chromospheric Lines as Diagnostics of Stellar Oscillations Authors: Paulson, Diane B.; Pesnell, W. Dean; Deming, L. Drake; Snow, Martin; Metcalfe, Travis S.; Woods, Tom; Hesman, Brigette Bibcode: 2008psa..conf..311P Altcode: Gravitational waves in the chromosphere, theorized as early as 1963 [10], are thoroughly explored in the more recent papers by [7, 8]. Theory predicts that the convective overshoot in the upper photosphere and low chromosphere will readily excite gravity waves. [9] note that these waves are not easily detected because of the long periods, short wavelengths required and slanted propagation angles of the waves themselves (causing small velocity shifts and short duration on individual detector pixels). Recently, [9] find evidence for gravity waves manifested in the f 700Å chromospheric line with frequencies <1 mHz. Title: SDO in Virtual Reality: A New Spacecraft Interactive Authors: Drobnes, Emilie; Pesnell, W. D. Bibcode: 2007AAS...211.9408D Altcode: 2007BAAS...39..893D Have you ever dreamed of rocketing into space as an astronaut? Or wished you could just float out among the stars and satellites? Well, now you can! With the new Solar Dynamics Observatory (SDO) Spacecraft Interactive you can spin, rotate, and explore the various parts of a spacecraft as if you were in space, without leaving the comforts and gravity of our home planet. This new and innovative interactive is a great cross-cutting tool with applications from project management to Education and Public Outreach (EPO). The current model allows users to explore the spacecraft and all of its various components creating a user-unique experience. When adapted to an immersive technology environment, users will be able to experience this exploration as if actually floating in space with the star field projected all around you. In either form, this interactive could also be used by program managers to navigate a photograph and video archive. Title: Variability of Solar Irradiances Using Wavelet Analysis Authors: Pesnell, W. D. Bibcode: 2007AGUFMSH13A1100P Altcode: We have used wavelets to analyze the sunspot number, F10.7 (the solar irradiance at a wavelength of 10.7~cm), and Ap (a geomagnetic activity index). Three different wavelets are compared, showing how each selects either temporal or scale resolution. Our goal is an envelope of solar activity that better bounds the large amplitude fluctuations form solar minimum to maximum. We show how the 11-year cycle does not disappear at solar minimum, that minimum is only the other part of the solar cycle. Power in the fluctuations of solar-activity-related indices may peak during solar maximum but the solar cycle itself is always present. The Ap index has a peak after solar maximum that appears to be better correlated with the current solar cycle than with the following cycle. Title: Self-consistent Non-LTE Model of Infrared Molecular Emissions and Oxygen Dayglows in the Mesosphere and Lower Thermosphere Authors: Kutepov, A. A.; Feofilov, A. G.; Yankovsky, V. A.; Manuilova, R. O.; Pesnell, W. D.; Goldberg, R. A. Bibcode: 2007AGUFMSA41A0293K Altcode: We describe the new version of the ALI-ARMS (for Accelerated Lambda Iterations for Atmospheric Radiation and Molecular Spectra) model. The model allows simultaneous, self-consistent calculations of the non-LTE populations of the electronic- vibrational levels of ozone and O2 photolysis products and the vibrational level populations of CO2, N2, O2, O3, H2O, CO, and other molecules with a detailed accounting of electronic-vibrational, vibrational-vibrational and vibrational-translational energy exchange processes. The model is used as the reference for modeling O2 dayglow experiments and for the infrared molecular emissions measured by the multi-channel observations of MLT in the SABER experiment on TIMED. It also permits the re-evaluation of the thermalization efficiency of absorbed solar ultraviolet energy and infrared radiative cooling/heating of MLT through a detailed accounting of the electronic-vibrational relaxation of excited photolysis products via a complex chain of collisional energy conversion processes down to the vibrational energy of optically active trace gas molecules. Title: Mesospheric Water Vapor Retrieved From SABER/TIMED Measurements Authors: Feofilov, A. G.; Marshall, B. T.; Garci-A-Comas, M.; Kutepov, A. A.; Lopez-Puertas, M.; Manuilova, R. O.; Yankovsky, V. A.; Pesnell, W. D.; Goldberg, R. A.; Gordley, L. L.; Petelina, S.; Russell, J. M. Bibcode: 2007AGUFMSA41A0291F Altcode: The SABER instrument on board the TIMED Satellite is a limb scanning infrared radiometer designed to measure temperature and minor constituent vertical profiles and energetics parameters in the mesosphere and lower thermosphere (MLT). The H2O concentrations are retrieved from 6.3 micron band radiances. The interpretation of this radiance requires developing a non-LTE H2O model that includes energy exchange processes with the system of O3 and O2 vibrational levels populated at the daytime through a number of photoabsorption and photodissociation processes. We developed a research model based on an extended H2O non-LTE model of Manuilova et al, 2001 coupled with the novel model of the electronic-vibrational kinetics of the O2 and O3 photolysis products suggested by Yankovsky and Manuilova, 2006. The performed study of this model helped us to develop and test an optimized operational model for interpretation of SABER 6.3 micron band radiances. The sensitivity of retrievals to the parameters of the model is discussed. The H2O retrievals are compared to other measurements for different seasons and locations. Title: Methods of Detecting Polar Coronal Holes in the EUV Authors: Kirk, M. S.; Pesnell, W. D. Bibcode: 2007AGUFMSH13A1099K Altcode: One method of forecasting the peak amplitude of future solar cycles uses the polar magnetic field strength at solar minimum to predict the value of the upcoming maximum. Because the polar field is closely related to the polar coronal hole, we would like to consider the size and shape of the polar hole on the prediction. We measure the perimeter of polar coronal holes over solar cycle 23 as they appear on the limb of the sun in 171, 195, and 304 Å\ solar images from the Extreme ultraviolet Imaging Telescope (EIT) on SOHO. The area within the perimeter can easily be determined. Taking measurements on the limb minimizes the effects of differences in scale height between the material emitting the various wavelengths. Perimeter tracking also allows for the coronal rotation rate to emerge organically from the data rather than forcing a period on the data. This method should help to improve our estimates of the size and shape of the polar coronal holes. Title: Getting Something from Nothing: Polar Coronal Holes in Cycles 22 and 23 Authors: Hess Webber, Shea A.; Kirk, Michael S.; Pesnell, W. Dean Bibcode: 2007fste.conf...38H Altcode: Methods of predicting the peak amplitude of solar cycles currently disagree as to whether Solar Cycle 24 will have a high or low level activity. One method uses the polar magnetic field lines at minimum to predict the value of the upcoming maximum. Because it uses the polar field, we would like to assess the impact of the size and shape of the polar coronal hole on the prediction. We will measure the area of the polar coronal holes during solar cycles 22 and 23 by measuring the opening angle of the hole as it appears on the limb of the sun. A correlation of coronal hole parameters from Kitt Peak 10,830Å solar images with 171, 195, and 304Å solar images from the Extreme ultraviolet Imaging Telescope (EIT) on the SoHO satellite taken during the ascending phase of Solar Cycle 23 will be used to produce a continuous set of coronal holes during Cycles 22 and 23. This will also provide a smooth transition between the current EIT images and the Kitt Peak data. Using multiple wavelengths will allow a more consistent definition of the boundaries of the polar coronal holes. To accomplish these tasks, an automatic detection method is employed. This method should help to refine our understanding of the polar field precursor of solar activity. Title: SDO Asks: What's The Sun Doing Now? Authors: Pesnell, W. D. Bibcode: 2007AAS...21010101P Altcode: 2007BAAS...39..228P Solar observations have tended to emphasize events like flares and CMEs, and what leads to these events. The past decade has seen an increasing emphasis on understanding the entire Sun, from the nuclear reactions at the core to the development and loss of magnetic loops in the corona. The Solar Dynamics Observatory (SDO) will return synoptic data, taken at a regular cadence and covering the entire Sun. This means you can still study events, but can also move forward to producing a quantitative model of what the Sun is doing today. The science investigations of SDO will determine how the Sun's magnetic field is generated and structured, how this stored magnetic energy is released into the heliosphere and geospace as the solar wind, energetic particles, and variations in the solar irradiance. How SDO data will transform the study of the Sun and the affect on stellar astrophysics will be discussed. Title: Solar Cycle 24 and the Solar Dynamo Authors: Pesnell, W. D.; Schatten, K. Bibcode: 2007AAS...210.9204P Altcode: 2007BAAS...39..209P We will discuss the polar field precursor method for solar activity prediction, which predicts cycle 24 will be significantly lower than recent activity cycles, and some new ideas rejuvenating Babcock's shallow surface dynamo. The polar field precursor method is based on Babcock and Leighton's dynamo models wherein the polar field at solar minimum plays a major role in generating the next cycle's toroidal field and sunspots. Thus, by examining the polar fields of the Sun near solar minimum, a forecast for the next cycle's activity is obtained. With the current low value for the Sun's polar fields, this method predicts solar cycle 24 will be one of the lowest in recent times, with smoothed F10.7 radio flux values peaking near 135 ± 35 (2 σ), in the 2012-2013 timeframe (equivalent to smoothed Rz near 80 ± 35 [2 σ]). One may have to consider solar activity as far back as the early 20th century to find a cycle of comparable magnitude. We discuss unusual behavior in the Sun's polar fields that support this prediction. Normally, the solar precursor method is consistent with the geomagnetic precursor method, wherein geomagnetic variations are thought to be a good measure of the Sun's polar field strength. Because of the unusual polar field, the Earth does not appear to be currently bathed in the Sun's extended polar field (the interplanetary field), hence negating the primal cause behind the geomagnetic precursor technique. We also discuss how percolation may support Babcock's original shallow solar dynamo. In this process ephemeral regions from the solar magnetic carpet, guided by shallow surface fields, may collect to form pores and sunspots. Title: Family Science Night: Changing Perceptions One Family at a Time Authors: Pesnell, W. D.; Drobnes, E.; Mitchell, S.; Colina-Trujillo, M. Bibcode: 2007AAS...210.0503P Altcode: 2007BAAS...39Q.100P If students are not encouraged to succeed in science, mathematics, and technology classes at school, efforts to improve the quality of content and teaching in these subjects may be futile. Parents and families are in a unique position to encourage children to enroll and achieve in these classes. The NASA Goddard Space Flight Center Family Science Night program invites middle school students and their families to explore the importance of science and technology in our daily lives by providing a venue for families to comfortably engage in learning activities that change their perception and understanding of science - making it more practical and approachable for participants of all ages. Family Science Night strives to change the way that students and their families participate in science, within the program and beyond. Title: The Polar Summer MLT Plasma Environment as Seen by the DROPPS Sounding Rockets Authors: Assis, M. P.; Goldberg, R. A.; Webb, P. A.; Pesnell, W. D.; Voss, H. D. Bibcode: 2006AGUFMSA21A0240A Altcode: During early July, 1999, the DROPPS (Distribution and Role of Particles in the Polar Summer Mesosphere) campaign launched two rocket payloads whose purpose was to study the polar summer MLT (mesosphere and lower thermosphere), particularly PMSEs (polar mesospheric summer echoes) and PMCs (polar mesospheric clouds). The rockets were launched from the Andøya Rocket Range in Norway the nights of the 5th and 14th of July. Both payloads included a front-mounted PID (Particle Impact Detector) consisting of charge and mass telescopes to measure aerosol and dust mass distributions. Ice particles of nanometer size are believed to be responsible for PMSEs through the process of electron scavenging. Evidence for this process is suggested, for example, by the presence of an electron "biteout" simultaneously measured by several instruments at an altitude of ~82-87 km during the first DROPPS launch. This presentation will characterize similarities and differences between both flights as seen by the charge and mass telescopes, starting at launch until the loss of data on the downleg of each flight. Various stages of the flights will be considered in detail, such as the PMSE layer and the apogee at 117 km, as well as the calibration of the data before launch. Title: Revised correlation between Odin/OSIRIS PMC properties and coincident TIMED/SABER mesospheric temperatures Authors: Feofilov, A.; Petelina, S. V.; Kutepov, A. A.; Pesnell, W. D.; Goldberg, R. A.; Llewellyn, E. J.; Russell, J. M. Bibcode: 2006AGUFMSA21A0243F Altcode: The Optical Spectrograph and Infrared Imaging System (OSIRIS) instrument on board the Odin satellite detects Polar Mesospheric Clouds (PMCs) through the enhancement in the limb-scattered solar radiance. The Sounding of the Atmosphere using the Broadband Emission Radiometry (SABER) instrument on board the TIMED satellite is a limb scanning infrared radiometer that measures temperature and vertical profiles and energetic parameters for minor constituents in the mesosphere and lower thermosphere. The combination of OSIRIS and SABER data has been previously used to statistically derive thermal conditions for PMC existence [Petelina et al., 2005]. In this work, we employ the simultaneous common volume measurements of PMCs by OSIRIS and temperature profiles measured by SABER for the Northern Hemisphere summers of 2002--2005 and corrected in the polar region by accounting for the vibrational-vibrational energy exchange among the CO2 isotopes [Kutepov et al., 2006]. For each coincidence identified within ±1 degree latitude, ±2 degrees longitude and ≤1 hour time the frost point temperatures were calculated using the corresponding SABER temperature profile and water vapor densities of 1, 3, and 10 ppmv. We found that the PMC presence and brightness correlated only with the temperature threshold that corresponds to the frost point. The absolute value of the temperature below the frost point, however, didn't play a significant role in the intensity of PMC signal for the majority of selected coincidences. The presence of several bright clouds at temperatures above the frost point is obviously related to the limitation of the limb geometry when some near- or far-field PMCs, actually located at higher (and colder) altitudes are detected at lower altitudes. S.V. Petelina, D.A. Degenstein, E.J. Llewellyn, N.D. Lloyd, C.J. Mertens, M.G. Mlynczak, and J.M. Russell III, "Thermal conditions for PMC existence derived from Odin/OSIRIS and TIMED/SABER data", Geophys. Res. Lett., 32, L17813, doi: 10.1029/2005GL023099, (2005) A.A. Kutepov, A.G. Feofilov, B.T. Marshall, L.L. Gordley, W. D. Pesnell, R.A. Goldberg, and J.M. Russell III, "SABER temperature observations in the summer polar mesosphere and lower thermosphere: importance of accounting for the CO2 ν_2 quanta V -V exchange", accepted for publication in Geophys. Res. Lett., (2006) Title: Sources, Propagators, and Sinks of Space Weather Authors: Pesnell, W. D. Bibcode: 2006AGUFMSA53A1371P Altcode: Space Weather is a complex web of sources, propagators, and sinks of energy, mass, and momentum. A complete understanding of Space Weather requires specifying, and an ability to predict, each link in this web. One important problem in Space Weather is ranking the importance of a particular measurement or model in a research program. One way to do this ranking is to examine the simplest linked diagram of the sources, propagators, and sinks and produce. By analyzing only those components that contribute to a particular area the individual contributions can be better appreciated. Several such diagrams will be shown and used to discuss how long-term effects of Space Weather can be separated from the impulsive effects. Title: SABER temperature observations in the summer polar mesosphere and lower thermosphere: Importance of accounting for the CO2 ν2 quanta V-V exchange Authors: Kutepov, Alexander A.; Feofilov, Artem G.; Marshall, Benjamin T.; Gordley, Larry L.; Pesnell, W. Dean; Goldberg, Richard A.; Russell, James M. Bibcode: 2006GeoRL..3321809K Altcode: The polar summer thermal structure, with its cold mesopause and steep temperature gradients, both below and above the mesopause, produces the largest non-LTE effects in the CO2 ν2 mode manifold states. In this paper we focus on validating the non-LTE model applied for operational temperature retrievals from the SABER 15 μm limb radiance observations for these extreme conditions. We demonstrate that accounting for the redistribution of ν2 quanta among various CO2 isotopes shifts the retrieved summer 2002 polar mesopause altitude upwards by 2 to 4 km. It brings the SABER temperature measurements into a better agreement with those of falling sphere experiments, lidar observations, as well as with climatological data. Title: Sensitivity of IR Temperature Retrievals in the Polar Summer MLT to NLTE considerations Authors: Kutepov, A.; Feofilov, A.; Marshall, B. T.; Gordley, L. L.; Pesnell, W. D.; Goldberg, R. A.; Russell, J. M. Bibcode: 2006AGUSMSA53A..07K Altcode: Adequate retrieval of kinetic temperature and other parameters in the summer polar mesosphere and lower thermosphere (MLT) from limb infrared radiances requires detailed accounting for the breakdown of local thermodynamic equilibrium (NLTE). A large fraction of the limb radiance is formed by resonant scattering of the upwelling radiation from the stratosphere and therefore, does not have links to the local thermal radiation sources. Moreover, in case of CO2, this scattering depends strongly on the V-V rate of the ν2 quanta exchange between isotopes. As a result, both the temperature values and the position of the retrieved mesopause depend on the rate coefficient of this process. On the other hand, the lower boundary of a noctilucent cloud (NLC) lies near the lower crossing point of the temperature profile and the frost point curve. This suggests that NLC observations may provide an important tool for validating temperature and water vapor density retrievals as well as the NLTE model describing the formation of infrared radiance in the MLT. This paper will describe these considerations including examples using the TIMED-SABER data for the polar summer mesosphere. Title: Particulate and plasma variations in NLC and PMSE during DROPPS 1 and 2 flights Authors: Voss, H. D.; Webb, P. A.; Pesnell, W. D.; Gumbel, J.; Assiss, M. P.; Goldberg, R. A. Bibcode: 2006cosp...36.3336V Altcode: 2006cosp.meet.3336V High-time resolution rocket measurements have been made of charged particulates under polar summer mesospheric conditions on 5 and 14 July 1999 during the DROPPS campaign at And o ya Rocket Range Norway Each rocket carried a Particle Impact Detector PID composed of two telescopes with three biased grids and which were pointed into the rocket ram during both up- and downleg On the first night the rocket DROPPS 1 was flown into a strong PMSE polar mesospheric summer echo condition with a weak NLC noctilucent cloud located at the base of the PMSE The second flight DROPPS 2 was launched into a bright NLC with no PMSE present For DROPPS 1 large amounts of negatively charged particulates were observed in the PMSE region with relatively small size distributions 1 nm radius Net positive charge particulates were measured in the NLC regions for both flights Ions and charged particulates have been simulated using a finite difference code SIMION 3D to trace particle paths and resulting grid currents For the simulations the thermal effects through the shock and within the sensor cause the ice rocky particulates to sublimate and lose mass In addition the particulates are observed to decelerate due to the ram pressure and electric fields for subsequent charge collection on the grids The background current on grid 2 -4 volt is consistent with the altitude variation and flux expected for UV photoionization Consistent effects were observed on another instrument PAT particle trap during the same flights Title: Non-LTE effects in the polar summer mesosphere and lower thermosphere and TIMED SABER temperature retrievals Authors: Feofilov, A. G.; Kutepov, A. A.; Marshall, B. T.; Gordley, L. L.; Pesnell, W. D.; Goldberg, R. A.; Russell, J. M., III Bibcode: 2006cosp...36.2516F Altcode: 2006cosp.meet.2516F The mesosphere lower thermosphere MLT is one of the most intriguing regions of Earth s atmosphere In past decades a large number of rocket and lidar experiments have been performed to explore catalogue and explain the thermal structure of MLT However the description of this region is sophisticated due to the large number of processes which govern the vibrational molecular levels populations The frequency of inelastic molecular collisions in MLT becomes low and one has to take into account various other processes which populate and de-populate the levels absorption and emission of radiation in molecular bands redistribution of excitation between colliding molecules chemical excitation The populations must be found by solving the system of rate equations expressing the balance of all these processes non-LTE Therefore the interpretation of radiance measurements in MLT depends on accuracy of non-LTE model Non-LTE effects for the CO 2 nu 2 manifold levels responsible for the 15 mu m CO 2 emission are more pronounced in the polar summer MLT than in other regions due to the cold mesopause and high vertical temperature gradients both below and above the mesopause region This case provides an example of a very strong infrared radiative coupling between warm stratosphere and cold mesosphere The SABER a instrument on board the TIMED b satellite is a limb scanning infrared radiometer designed to measure temperature and minor constituent vertical profiles and energetics parameters in the MLT Temperatures in the MLT are retrieved from the Title: Refinement of the DROPPS Polar Summer Mesosphere Particle Data Authors: Webb, P.; Goldberg, R.; Pesnell, W.; Voss, H.; Assis, M. Bibcode: 2006cosp...36.3413W Altcode: 2006cosp.meet.3413W The two Black Brant payloads flown during the DROPPS Distribution and Role of Particles in the Polar Summer Mesosphere rocket program were launched during early July 1999 from And o ya Rocket Range ARR Norway The purpose was to investigate the polar summer mesosphere particularly polar mesospheric summer echoes PMSE Both DROPPS payloads included front mounted side by side Particle Impact Detector PID charge and mass telescopes Computer simulations have shown that the PID telescopes have the potential to detect atmospheric ice particles within the mesosphere having dimensions of a few nanometers Ice particles of nanometer size are believed to be responsible for PMSEs through the process of scavenging Evidence for this process is suggested by the presence of an electron biteout observed in the same region as the observation of nanometer size particles at an altitude of sim 82-87 km over And o ya during the first DROPPS launch sequence Evidence for this dusty plasma was observed independently by several instruments aboard the DROPPS payload By comparing PID observations with the computer simulations we can obtain information concerning the properties of the PMSE particles including their rocky core size ice mantle thickness and distribution We have previously presented results from an analysis of the two detectors that suggested on the first flight particles with radius of approximately 2 nm were present in the PMSE layer We have recently realised that our interpretation of the PID data required further refinement For example we have now Title: Sources, Propagators, and Sinks of Space Weather Authors: Pesnell, W. D. Bibcode: 2006cosp...36.2994P Altcode: 2006cosp.meet.2994P Space Weather is a complex web of sources propagators and sinks of energy mass and momentum A complete understanding of Space Weather would require specifying and an ability to predict each link in this web One important problem in Space Weather is ranking the importance of a particular measurement or model in a research program One way to do this ranking is to identify the sources propagators and sinks and produce the simplest linked diagram of the components Such a diagram will be shown and used to discuss how longterm effects of Space Weather can be separated from the impulsive effects Title: Using the Far-Infrared to Understand the Thermosphere Authors: Pesnell, W. D.; Arnett, K. Bibcode: 2005AGUFMSA51B1140P Altcode: Atomic oxygen is the dominant constituent of the thermospheres of the Earth, Venus, and Mars. It is formed by photodissociation of a major molecular species from the lower atmosphere of each planet. Remote sensing of O greatly increases the amount of data available from each atmosphere. Several parts of the electromagnetic spectrum can be used to sense O, but the far-infrared line at 63~μm has several advantages, which we will discuss. The greatest advantage to using this line is the ability to resolve the tidal structure of the thermosphere. Using broadband radiometry to measure the limb radiance of this spectral feature will be discussed in the context of the OPIE (Oxygen Profiling Infrared Experiment) instrument. Some thoughts on the optimal orbit for these instruments with be presented. Title: The Temperature Climatology of the Polar Mesosphere in 2002-2004 Using SABER/TIMED Data Authors: Feofilov, A.; Kutepov, A.; Goldberg, R. A.; Pesnell, W. D.; Russell, J. M.; Mlynczak, M. G. Bibcode: 2005AGUFMSA43A1086F Altcode: The TIMED Satellite was launched on December 7, 2001 to study the dynamics and energy of the mesosphere and lower thermosphere. The SABER instrument is a limb scanning infrared telescope designed to measure minor atmospheric constituents as well as temperature and pressure of the region. In this study we have concentrated on data retrieved for the polar mesosphere, to investigate spatial and temporal temperature characteristics of this region. We made the comparisons between the winter and summer, and studied both short- and long-term variability in different quadrants of each hemisphere. The sharp transition between summer and winter, first demonstrated using falling-sphere meteorological rocket data, will be described for each hemisphere with a data base including variations in many geophysical parameters. Differences in this climatological base between 2002-2004 will also be discussed. Title: The Nature of Icy Dust Particles in the Polar Summer Mesosphere From Rocket Measurements During DROPPS Authors: Goldberg, R. A.; Webb, P. A.; Pesnell, W. D.; Voss, H. D. Bibcode: 2005AGUFMSA22A..08G Altcode: The two Black Brant payloads flown during the DROPPS (Distribution and Role of Particles in the Polar Summer Mesosphere) rocket program were launched during early July, 1999 from Andoya Rocket Range (ARR), Norway. Both payloads included front mounted side by side Particle Impact Detector (PID) charge and mass telescopes. Computer simulations have shown that the PID telescopes have the potential to detect atmospheric ice particles within the mesosphere, having dimensions of a few nanometers. Ice particles of nanometer size are believed to be responsible for polar mesospheric summer echoes (PMSEs), such as those observed at an altitude of ~82-87 km over Andoya during the first DROPPS launch sequence. We have previously presented results from the longer PID charge telescope that indicated two possible particle distributions differing by mean particle size. Due to the different geometries of the PID telescopes (primarily, that the charge telescope is longer than the mass telescope) each PID telescope collects a different portion of the nanometer sized PMSE particles distribution. When compared to the previous PID charge telescope results, the PID mass telescope results allow the true PMSE particle size distribution to be estimated. This talk will introduce the new observations from the shorter PID mass telescope and the comparison to the previous PID charge telescope. By then comparing PID observations with the computer simulations provides information concerning the properties of the PMSE particles, including their "rocky" core size, ice mantle thickness and distribution. Title: Venus Metal ion and Metal Neutral Species Distributions and Meteor Magnitudes Authors: Webb, P. A.; Grebowsky, J. M.; Pesnell, W. D. Bibcode: 2005AGUFM.P33A0237W Altcode: The lower ionospheres of all planetary atmospheres and any of those satellites that hold substantial atmospheres have a high likelihood of containing complex layers of metallic ions and their neutral species. These metal species arise from the ablation and subsequent ionization of small particles from the solar system cloud of meteoroids impacting their atmospheres. Venus is no exception and is unique in that it has the highest upper limit for incoming meteoroid velocities in the solar system and its extremely slow atmosphere revolution makes a one-dimensional modeling a better approximation than for other faster rotating bodies in the solar system. Previous modeling of one of the major meteoroid species, Mg, showed that indeed a prominent metallic layer expected with ion concentrations comparable to those seen at Earth. However the modeled Mg+ peak altitude was lower than any total electron density peak observed by spacecraft radio occultation measurements at Venus. A further analysis adding the contributions of other metal species and their chemistry has now shown that each metal ion species layers at a different altitude. Indeed the metal species Fe has its counterpart ion layer above 120 km in a region where there are sometimes traces of occultation electron density structures. Also, the new analysis includes estimates of the visual magnitudes of typical meteors as they would be observed from a satellite above the atmosphere. Title: Temporal evolution of the vertical content of metallic ion and neutral species Authors: Aikin, A. C.; Grebowsky, J. M.; Burrows, J. P.; Correira, J.; Pesnell, W. D. Bibcode: 2005JASTP..67.1238A Altcode: 2005JATP...67.1238A Temporal changes in the vertical column contents of the meteoric metals Mg+, Mg, Fe+, and Fe have been measured at ∼1030 LT for all longitudes in the latitude zone of 10°N 30°N during November 1996, encompassing the period of the Leonid meteor shower. The column contents were obtained using UV radiances measured by the GOME instrument on the ERS-2 satellite. Throughout the month there are several interesting prominent content enhancements of all species. After the Leonid shower peak on 17 November the ion species contents increase before the contents of the neutrals. However, it is difficult to confirm that this is a shower effect given the other similar variations seen earlier in the contents and in the sporadic meteor flux enhancements. The peaks in visual meteors on 17 November are not observed in the total metal column amounts. The GOME instrument has been in continuous operation since April 1995 and is an excellent resource for studying the temporal behavior of meteoric metals on a global scale. Title: The Physical Properties of PMSE Ice Particles as Determined During DROPPS by Measurements With the Particle Impact Detector Authors: Webb, P. A.; Goldberg, R. A.; Pesnell, W. D.; Voss, H. D. Bibcode: 2005AGUSMSA43A..07W Altcode: The two Black Brant payloads flown during the DROPPS (Distribution and Role of Particles in the Polar Summer Mesosphere) rocket program were launched during early July, 1999 from Andoya Rocket Range (ARR), Norway. Both payloads included a Particle Impact Detector (PID) charge telescope onboard. Computer simulations have shown that the PID instrument had the potential to detect atmospheric ice particles within the mesosphere, having dimensions of a few nanometers. Ice particles of nanometer size are believed to be responsible for polar mesospheric summer echoes (PMSEs), such as those observed at an altitude of ~82-87 km over Andoya during the first DROPPS launch sequence. This talk will discuss the analysis of the PID data obtained from the DROPPS campaign and comparison of these data to the results obtained from the nanometer scale ice particle computer simulations. Intercomparison of the PID observations with the computer simulations provides information concerning the properties of the PMSE particles, including their "rocky" core size, ice mantle thickness and distribution. Title: Non-LTE Analysis of SABER 15 μm Limb Observations of the Summer 2002 Polar Mesopause Region Authors: Kutepov, A. A.; Feofilov, A. G.; Pesnell, W. D.; Goldberg, R. A.; Gusev, O. A.; Marshall, T. Bibcode: 2005AGUSMSA43A..13K Altcode: The SABER instrument on TIMED measures the limb radiance in ten broadband infrared channels for an altitude range that includes the mesosphere and lower thermosphere. In this altitude range the effects of non-local thermal equilibrium (non-LTE) must be included to understand the measurements. The non-LTE algorithms and computer code package developed to analyze CRISTA infrared spectral limb radiances were adapted for this purpose. We retrieved temperature profiles from the 15 μm limb radiances measured in the summer 2002 polar mesopause. The retrieved temperature profiles will be compared with other retrievals, the coincident falling sphere experiments of the MaCWAVE campaign, and climatological data. Sources of the discrepancies between the various results are discussed. Title: From the Sun to You at the Speed of Light: The SDO Data System Authors: Pesnell, W. D. Bibcode: 2005AGUSMSH42A..06P Altcode: The Solar Dynamics Observatory (SDO) is on track to launch in April 2008. Solar images in the extreme ultraviolet, the EUV spectral irradiance, magnetic field maps, and Dopplergrams are the primary data products of this mission. Each primary data product is produced on a rapid cadence. For example, some space weather products, suitable for use in ionosphere-thermosphere models, should be produced every 10--20 seconds with a 5--10 minute delay between observation and appearance in the data system. Derived data products, including helioseismic properties and active region tracked in various wavelengths, will also be available from the data system. As part of NASA's Living With a Star Program, SDO will release data to the public as soon as possible after receipt from the satellite. The science teams will make the data available through Web-oriented interfaces, such as the Virtual Solar Observatory, allowing external people to make inquiries and have data delivered to their site. We will present an overview of the SDO data system and philosophy. Title: Meteoric Ions in Venus' Atmosphere Authors: Pesnell, W. D.; Grebowsky, J.; Webb, P. A. Bibcode: 2004AGUFM.P23A0238P Altcode: From a thorough modeling of the altitude profile of meteoric ionization in the cytherean atmosphere we have deduced that layers of magnesium, iron, and sodium ions should exist between altitudes between 115 and 120~km. Based on the estimated meteoroid mass flux density, a peak ion density of several 103 ions cm{}-3 is predicted. Allowing for the uncertainties in all of the model parameters, this value is probably within an order of magnitude of the correct density. The peak density is most sensitive to the meteoroid mass flux density, which determines the source function for Mg from the ablating meteoroids, the eddy viscosity coefficient, which determines the effectiveness of mixing the meteoric input downwards, and the presence of sulfuric acid droplets, which is an efficient sink of metallic compunds. We examine the effect of the aerosol layers in the upper mesosphere of Venus' atmosphere on the metallic layers. Title: Comparisons of PMSE Ice Particle Simulations With Observations From the DROPPS Rocket Campaign Authors: Goldberg, R. A.; Webb, P. A.; Pesnell, W. D. Bibcode: 2004AGUFMSA24A..01G Altcode: The origin of polar mesospheric summer echoes (PMSEs) and their proposed relationship to dust and aerosol particles and to noctilucent clouds (NLCs) are among the most pressing questions governing the physics of the polar summer mesosphere. Recent studies show increasing evidence for the presence of these particles, and their importance particularly in a charged state. One theory for the formation of the PMSE particles is that they are composed of a rocky core of meteoritic origin, which acts as a seed about which an ice mantle forms. Computer simulations have been conducted to model the flight trajectory and sublimation of spherical ice/rock particles with radius of 0.5 - 6.0 nm through the Particle Impact Detector (PID) charge telescope onboard two rockets that were part of the DROPPS (Distribution and Role of Particles in the Polar Summer Mesosphere) campaign. DROPPS involved two rocket sequences in July, 1999 launched from Andoya, Norway. The first launch sequence was nighttime (July 5-6) during the presence of a strong PMSE and a weak NLC. The second sequence (July 13-14) occurred during a bright NLC, but with no PMSE present. By comparing the PID observations from these two flights with the computer simulations, information about the properties of the PMSE particles, including their core size, ice mantle thickness and distribution, can be deduced. Title: Watching meteors on Triton Authors: Pesnell, W. Dean; Grebowsky, J. M.; Weisman, Andrew L. Bibcode: 2004Icar..169..482P Altcode: 2004Icar..169..482D The thin atmosphere of Neptune's moon Triton is dense enough to ablate micrometeoroids as they pass through. A combination of Triton's orbital velocity around Neptune and its orbital velocity around the Sun gives a maximum meteoroid impact velocity of approximately 19 km s -1, sufficient to heat the micrometeoroids to visibility as they enter. The ablation profiles of icy and stony micrometeoroids were calculated, along with the estimated brightness of the meteors. In contrast to the terrestrial case, visible meteors would extend very close to the surface of Triton. In addition, the variation in the meteoroid impact velocity as Triton orbits Neptune produces a large variation in the brightness of meteors with orbital phase, a unique Solar System phenomenon. Title: SABER observations of mesospheric temperatures and comparisons with falling sphere measurements taken during the 2002 summer MaCWAVE campaign Authors: Mertens, Christopher J.; Schmidlin, Francis J.; Goldberg, Richard A.; Remsberg, Ellis E.; Pesnell, W. Dean; Russell, James M.; Mlynczak, Martin G.; López-Puertas, Manuel; Wintersteiner, Peter P.; Picard, Richard H.; Winick, Jeremy R.; Gordley, Larry L. Bibcode: 2004GeoRL..31.3105M Altcode: 2004GeoRL..3103105M The SABER instrument was launched onboard the TIMED satellite in December 2001. Vertical profiles of kinetic temperature (Tk) are derived from broadband measurements of CO2 15 μm limb emission, in combination with measurements of CO2 4.3 μm limb emission used to derive CO2 volume mixing ratio (vmr). Infrared emission from the CO2 ro-vibrational bands are in non-local thermodynamic equilibrium (non-LTE) in the mesosphere and lower thermosphere (MLT), requiring new radiation transfer and retrieval methods. In this paper we focus on Tk and show some of the first SABER observations of MLT Tk and compare SABER Tk profiles with rocket falling sphere (FS) measurements taken during the 2002 summer MaCWAVE campaign at Andøya, Norway (69°N, 16°E). The comparisons are very encouraging and demonstrate a significant advance in satellite remote sensing of MLT limb emission and the ability to retrieve Tk under extreme non-LTE conditions. Title: Global measurements of atmospheric content of metallic ion and neutral species Authors: Aikin, A. C.; Grebowsky, J. M.; Pesnell, W. D.; Burrows, J. P. Bibcode: 2004cosp...35..371A Altcode: 2004cosp.meet..371A Changes in the ion and neutral composition of the persistent atmospheric metal layers associated with the Leonid showers are determined using solar-induced resonant radiation measurements from the European Remote Sensing Satellite (ERS-2) platform. The nadir-viewing Global Ozone Measuring Experiment (GOME) UV/VIS spectrometer on ERS-2 is utilized to measure vertical column densities of meteoric metals including, Mg, Mg^+, Fe, Fe^+, and Si. The satellite orbits the Earth 14 times per day at 795 km with an equatorial crossing time of 10:30 AM. The spectral range of GOME is 237 to 793 nm with a wavelength resolution of 0.2 nm between 237 to 316 nm - the region in which the metal species lines we analyze are observed. The instrument measures all wavelengths simultaneously during a scan through the satellite nadir every 1.5 seconds. The spectral range is divided into 5 channels. The 2 channels comprising the 237 to 316 nm range are integrated for 12 seconds giving a spatial resolution of 100 by 960 km. Metal data are examined for periods bracketing several Leonid meteor showers to isolate changes in the mesospheric and thermospheric abundances of meteoric material due to the showers. Since the Leonids occur annually in mid-November, global data from the entire month of November are analyzed for the years 1996 through 2002. Title: Experimental evidence for dusty plasmas in the polar summer mesosphere using rocket, lidar, and radar measurements Authors: Goldberg, R. A.; Pesnell, W. D. Bibcode: 2004cosp...35..321G Altcode: 2004cosp.meet..321G The origin of PMSEs (polar mesospheric summer echoes)and their proposed relationship to dust and aerosol particles and to NLCs (noctilucent clouds) are among the most important questions governing the physics of the polar summer mesosphere. Recent studies show increasing evidence for the presence of these particles, and their importance particularly in a charged state. Several recent experimental programs have concentrated on detection of these particles in the MLT (mesosphere and lower thermosphere) region, with an attempt to determine their role in the structure, dynamics and chemistry of the MLT. Here, we concentrate on results of the DROPPS program (Andøya, Norway,1999) and the MaCWAVE program (Andoya, 2002), both of which were designed to study problems relating to this issue. DROPPS involved two rocket sequences in July, 1999. The first launch sequence was nighttime (July 5-6) during the presence of a strong PMSE and a weak NLC. The second sequence (July 13-14) occurred during a bright NLC, but with no PMSE present. MaCWAVE also involved two summertime launch sequences, with emphasis on the influence of gravity waves on the MLT region, but with adequate instrumentation to search for charged dust or aerosols. In this case, launch sequences occurred on the nights of July 1-2, and 4-5, each during the presence of PMSE events. By combining results from the rocket instruments with radar and lidar soundings from ALOMAR Observatory (also at Andøya), it has been possible to analyze each event in sufficient detail to gain an improved understanding of the polar summer MLT and it's response to a dusty plasma environment. Title: SABER Observations of Polar Summer/Winter Mesospheric and Lower Thermospheric Temperatures and Comparisons With Correlative Measurements Taken During the MaCWAVE Campaign Authors: Remsberg, E. E.; Mertens, C. J.; Schmidlin, F. J.; Goldberg, R. A.; She, C.; Williams, B. P.; Pesnell, W. D.; Russell, J. M.; Mlynczak, M. G.; Gordley, L. L.; Lopez-Puertas, M.; Picard, R. H.; Winick, J. R.; Wintersteiner, P. P. Bibcode: 2003AGUFMSA41B0439R Altcode: The Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) experiment was launched onboard the TIMED satellite in December 2001. SABER derives kinetic temperature (Tk) in the mesosphere and lower thermosphere (MLT) from broadband measurements of CO2 15 um limb emission, in combination with measurements of CO2 4.3 um limb emission used to derive CO2 volume mixing ratio. Infrared emissions from the CO2 ro-vibrational bands are in non-local thermodynamic equilibrium (non-LTE) in the MLT, requiring non-LTE processes to be accurately modeled in the retrieval algorithm. In this paper we focus on Tk and show results derived from the non-LTE retrieval algorithm. We demonstrate the ability to retrieve Tk in an extreme non-LTE environment by comparing SABER MLT Tk with rocket falling sphere (FS) and sodium lidar measurements taken during the 2002 summer MaCWAVE campaign. The summer Tk profiles show that the SABER non-LTE retrieval algorithm improves upper mesospheric Tk retrievals by 35 K to 45 K, as compared to SABER LTE Tk retrievals. Combined measurements from SABER and MaCWAVE show a mesopause region that is highly variable in space and time. SABER data also show a mesopause altitude that changes with latitude and season, consistent with the bimodal character of the mesopause height. We also show preliminary comparisons with the recently available FS and sodium lidar measurements taken during the 2003 winter MaCWAVE campaign. Title: Occultation of π Arietis by asteroid (828) Lindemannia on November 10 2002 Authors: Sada, Pedro V.; Nugent, Richard; Maley, Paul; Frankenberger, Rick; Preston, Steve; Dunham, David; Pesnell, W. Dean Bibcode: 2003OccN....9d...9S Altcode: The occultation of the bright star π Arietis (HIP 13165) by the asteroid (828) Lindemannia was recorded by 10 observers in Texas on November 10, 2002. Clouds hampered many more potential observers. Nine disappearances, ten reappearances, and 2 near misses are reported. A least-squares fit to the data results in a 52.6 km × 50.8 km ellipse with the major axis oriented at a PA of 90.0o. However, deviations from a perfect ellipse were observed. Title: Evolution of relativistic electrons during a magnetic storm as seen in low-earth orbit Authors: Pesnell, W. Dean; Goldberg, Richard A.; Chenette, D. L.; Schulz, M.; Gaines, E. E. Bibcode: 2003AdSpR..31.1059P Altcode: Highly relativistic electron events (HREs) are periods of intense, long-lived, energetic electron fluxes in the outer radiation zone. We are using measurements from the High Energy Particle Spectrometer (HEPS) on the Upper Atmosphere Research Satellite (UARS) to develop a database of the pitch-angle and energy-resolved electron fluxes with energies between 30 keV and 5 MeV. The data acquired by HEPS have overlapped with the declining phase of solar cycle 22 making these data very important, since HREs are thought to peak in frequency and intensity during this phase of the solar cycle. We find a consistent scenario of electrons being injected into the radiation belts by a magnetic storm (deduced from Dst) and being slowly accelerated to ever higher energies over days to weeks. The energy dependence of the flux is an essential part of the analysis. Electrons with energies greater than 300 keV are the last to appear following an injection and also linger longer than electrons with lower energies. Title: Meteoric Material-An Important Component of Planetary Atmospheres Authors: Grebowsky, Joseph M.; Moses, Julianne I.; Pesnell, W. Dean Bibcode: 2002GMS...130..235G Altcode: 2002assc.book..235G Interplanetary dust particles (IDPs) interact with all planetary atmospheres and leave their imprint as perturbations of the background atmospheric chemistry and structure. They lead to layers of metal ions that can become the dominant positively charged species in lower ionospheric regions. Theoretical models and radio occultation measurements provide compelling evidence that such layers exist in all planetary atmospheres. In addition IDP ablation products can affect neutral atmospheric chemistry, particularly at the outer planets where the IDPs supply oxygen compounds like water and carbon dioxide to the upper atmospheres. Aerosol or smoke particles from incomplete ablation or recondensation of ablated IDP vapors may also have a significant impact on atmospheric properties. Title: Growth and decay of relativistic electrons during a magnetic storm as seen in low-Earth orbit Authors: Pesnell, W. Dean; Goldberg, Richard A.; Chenette, D. L.; Gaines, E. E.; Schulz, M. Bibcode: 2001JGR...10630039P Altcode: Highly relativistic electron events (HREs) are periods of intense, long-lived, energetic electron fluxes in the outer radiation zone. We are using measurements from the High Energy Particle Spectrometer (HEPS) on the Upper Atmosphere Research Satellite (UARS) to develop a database of the pitch-angle-resolved and energy-resolved electron fluxes with energies between 30 keV and 5 MeV. The data acquired by HEPS have overlapped with the declining phase of solar cycle 22, making these data very important, since HREs are thought to peak in frequency and intensity during this phase of the solar cycle. We find a consistent scenario of electrons being injected into the radiation belts by a magnetic storm (deduced from Dst) and being slowly accelerated to ever higher energies over days to weeks. The energy dependence of the flux is an essential part of the analysis. Above 700 keV the most energetic electrons are the last to appear and the slowest to fade following an injection event. Title: Meteoric Material - One of the Least Explored Components of Planetary Atmospheres Authors: Moses, J. I.; Grebowsky, J. M.; Pesnell, W. D.; Weisman, A. L. Bibcode: 2001AGUFMSA42A..09M Altcode: Interplanetary dust particles (IDPs) continuously impact all the planets and their satellites in the solar system. In all planetary atmospheres IDPs leave their imprint as aerosols or smoke particles that are left behind when the IDPs do not ablate completely or when the ablated vapors recondense. In addition, in all atmospheres they produce ionization layers comprised of metallic ions, predominantly Mg+ and Fe+. On Earth the metal ions are frequently measured to be the dominant positively charged species in low-latitude ionospheric layers. Theoretical models provide evidence that such layers exist at Venus, Mars, Jupiter, Saturn, Neptune and Saturn's moon Titan. Even the sparse atmosphere of Triton may be lit up by meteors. Spacecraft radio occultation measurements reveal low altitude, narrow ionosphere layers at each of the giant planets. These narrow features appear to be consistent with the presence of metallic ions that have been compressed by electrodynamic processes as on Earth. Observations at Mars and Venus do not show clear evidence of such layers. The IDPs also deposit nonmetal neutral species in the ablation process. For the inner planets these species blend unnoticed into the atmosphere, but for the outer planets they can lead to persistent amounts of water vapor and carbon dioxide. Although many measurements are available for the Earth, measurements of the IDP distributions and their atmospheric signatures at other planets are in their initial stages at the present time. Modeling efforts are still qualitative as the chemical reaction rates for many of the ablated gases are not established. Most of our knowledge of long lasting IDP atmospheric effects is derived from what we know about Earth, for which our understanding is still far from complete. This component of all atmospheres must be treated as a key factor in all planetary atmospheric aeronomy systems. Title: Ionospheric Dynamics Effects on the Ionospheric Magnesium-Iron Ion Concentration Ratios Authors: Grebowsky, J. M.; Pesnell, W. D.; Aikin, A. C. Bibcode: 2001AGUSM..SA31A04G Altcode: Sounding rocket and satellite ion composition measurements show that the meteoric Fe+ concentration typically exceeds that of Mg + in the main meteor ionization layer and above. This is a puzzle because the assumed source of the metal ions is the sporadic background of infalling meteoroids, which are on average chondritic in nature and hence should deposit a higher portion of Mg in the atmosphere than Fe. A more detailed investigation the ionosphere measurements revealed that the ratio varies from measurement to measurement with Mg + and Fe + often switching dominance roles, although on average Fe + dominates. Possible sources for the relative variations between the two species include differential ablation, species-dependent ion-neutral chemical processes, non-isotropic interplanetary particle populations and neutral wind and electrodynamic influences. We will discuss the observations and show that ionospheric dynamics and electrodynamic processes can play an important role. Title: Meteoric Ions in the Ionosphere of Jupiter Authors: Kim, Y. H.; Pesnell, W. Dean; Grebowsky, J. M.; Fox, J. L. Bibcode: 2001Icar..150..261K Altcode: A reanalysis of the Voyager 2 radio occultation data has recently revealed a low-altitude layer in the jovian ionosphere (Hinson et al. 1998, J. Geophys. Res. 103, 9505-9520). The peak electron density of the layer measured on egress, which was at 93° solar zenith angle near the morning terminator, was inferred to be of the order of 10 4 cm -3. A substantial low-altitude layer of hydrocarbon ions in the jovian ionosphere was predicted by Kim and Fox (1994), but the peak total ion density at predawn was about 10 2 cm -3, two orders of magnitude smaller than the noon values, due to the efficient recombination of molecular ions during the night. The existence of large electron densities in the jovian ionospheric E region at predawn suggests the presence of ions with long lifetimes and/or those produced by a source that exhibits little local time dependence, such as ions originating from meteoroid ablation in Jupiter's atmosphere. We have modeled the production rates and subsequent chemistry of seven meteoric ions, including O +, C +, Si +, Fe +, Mg +, Na +, and S +, their compounds with H, H 2, and hydrocarbons, and the corresponding neutral species. The models predict a layer of meteoric ions in the altitude region of 350-450 km above the 1-bar level, with peak total ion densities of several times 10 4 cm -3, which are comparable to the observed values. The peak of the meteoric atomic ion layer is most apparent at predawn and is located higher than that of the hydrocarbon ion layer during the daytime and higher than the altitude of peak production of ions by meteor ablation. At the altitude of peak ablation, about 350 km, meteoric ions are mainly removed by reactions with hydrocarbons in either two-body or three-body reactions, and the molecular ions produced are neutralized efficiently by dissociative recombination. Meteoric ions may also form adduct ions by termolecular reactions with hydrogen molecules, but metallic ions, such as Na +, Mg +, and Fe +, may be reformed from the adduct ions by a series of reactions with H atoms. Thus the net ion loss process at the metal ion peak may be dominated by rediative recombination, and the meteoric ion density profiles show little diurnal variation. The predicted peak electron density and altitude and the relative densities of the ions are dependent on the rate coefficients assumed for many of the reactions involved, and measurements of key rate coefficients are needed to further constrain the models. Title: Meteoric ions in planetary ionospheres Authors: Pesnell, W. Dean; Grebowsky, J. M. Bibcode: 2001AdSpR..27.1807P Altcode: 2001AdSpR..27.1807D Solar system debris, in the form of meteoroids, impacts every planet. The flux, relative composition and speed of the debris at each planet depends on the planet's size and location in the solar system. Ablation of this debris by the atmosphere leaves behind metal atoms. During the ablation process metallic ions are formed by impact ionization. For small inner solar system planets, including Earth, this source of ionization is typically small compared to either photoionization or charge exchange with ambient molecular ions. For Earth, the atmosphere above the main deposition region absorbs the spectral lines capable of ionizing the major metallic atoms (Fe and Mg) so that charge exchange with ambient ions is the dominant cause of ionization. Within the carbon dioxide atmosphere of Mars (and possibly Venus), photoionization is important in determining the ion density. For a heavy planet like Jupiter, far from the sun, impact ionization of ablated neutral atoms by impacts with molecules becomes a prominent source of ionization due to the gravitational acceleration to high incident speeds. We will describe the processes and location and extent of metal ion layers for Mars, Earth and Jupiter, concentrating on flagging the uncertainties in the models at the present time. This is an important problem, because low altitude ionosphere layers for the planets, particularly at night, probably consist predominantly of metallic ions. Comparisons with Earth will be used to illustrate the differing processes in the three planetary atmospheres. Title: Variation of mesospheric ozone during the highly relativistic electron event in May 1992 as measured by the High Resolution Doppler Imager instrument on UARS Authors: Pesnell, W. Dean; Goldberg, Richard A.; Jackman, Charles H.; Chenette, D. L.; Gaines, E. E. Bibcode: 2000JGR...10522943P Altcode: Highly relativistic electron precipitation events (HREs) include long-lived enhancements of the flux of electrons with E>1MeV into the Earth's atmosphere. HREs also contain increased fluxes of electrons with energies above 100 keV that have been predicted to cause large depletions of mesospheric ozone. For some of the measured instantaneous values of the electron fluxes during the HRE of May 1992, relative depletions greater than 22% were predicted to occur between altitudes of 55 and 80 km, where HOx reactions cause local minima in both the ozone number density and mixing ratio altitude profiles. These ozone depletions should follow the horizontal distribution of the electron precipitation, having a distinct boundary equatorward of the L=3 magnetic shell. To search for these effects, we have analyzed ozone data from the High Resolution Doppler Imager (HRDI) instrument on UARS. Owing to the multiple, off-track viewing angles of HRDI, observations in the region affected by the electrons are taken at similar local solar times before, during, and after the electron flux increase. Our analysis limits the relative ozone depletion to values <10% during the very intense May 1992 HRE. We do observe decreases in the ozone mixing ratio at several points in the diurnal cycle that may be associated with the transport of water vapor into the mesosphere during May 1992. This masking of the precipitating electron effects by the seasonal variations in water vapor can complicate the detection of those effects. Title: Meteoric magnesium ions in the Martian atmosphere Authors: Pesnell, William Dean; Grebowsky, Joseph Bibcode: 2000JGR...105.1695P Altcode: From a thorough modeling of the altitude profile of meteoric ionization in the Martian atmosphere we deduce that a persistent layer of magnesium ions should exist around an altitude of 70 km. On the basis of the estimated meteoroid mass flux density, a peak ion density of ~104ionscm-3 is predicted. Allowing for the uncertainties in all of the model parameters, this value is probably within an order of magnitude of the correct density. Of these parameters, the peak density is most sensitive to the meteoroid mass flux density which determines the source function for Mg from the ablating meteoroids. Unlike the terrestrial case, where the metallic ion production is dominated by charge-exchange of the deposited neutral Mg with the ambient ions, Mg+ in the Martian atmosphere is produced predominantly by photoionization. The low ultraviolet absorption of the Martian atmosphere makes Mars an excellent laboratory in which to study meteoric ablation. Resonance lines in the ultraviolet that cannot be seen in the spectra of terrestrial meteors may be visible to a surface observatory in the Martian highlands. Title: Theoretical Stellar Evolution Authors: Cox, Arthur N.; Becker, Stephen A.; Pesnell, W. Dean Bibcode: 2000asqu.book..499C Altcode: No abstract at ADS Title: A search of UARS data for ozone depletions caused by the highly relativistic electron precipitation events of May 1992 Authors: Pesnell, W. Dean; Goldberg, Richard A.; Jackman, Charles H.; Chenette, D. L.; Gaines, E. E. Bibcode: 1999JGR...104..165P Altcode: Highly relativistic electron precipitation (HRE) events containing significant fluxes of electrons with E>1MeV have been predicted by models to deplete mesospheric ozone. For the electron fluxes measured during the great HRE of May 1992, depletions were predicted to occur between altitudes of 55 and 80 km, where HOx reactions cause a local minimum in the ozone number density and mixing ratio. Measurements of the precipitating electron fluxes by the particle environment monitor (PEM) tend to underestimate their intensity; thus the predictions of ozone depletion should be considered an estimate of a lower limit. Since the horizontal distribution of the electron precipitation follows the terrestrial magnetic field, it would show a distinct boundary equatorward of the L=3 magnetic shell and be readily distinguished from material that was not affected by the HRE precipitation. To search for possible ozone depletion effects, we have analyzed data from the cryogenic limb array etalon spectrometer and microwave limb sounder instruments on UARS for the above HRE. A simplified diurnal model is proposed to understand the ozone data from UARS, also illustrating the limitations of the UARS instruments for seeing the ozone depletions caused by the HRE events. This diurnal analysis limits the relative ozone depletion at around 60 km altitude to values of <10% during the very intense May 1992 event, consistent with our prediction using an improved Goddard Space Flight Center two-dimensional model. Title: Uptake coefficient of charged aerosols—implications for atmospheric chemistry Authors: Aikin, Arthur C.; Pesnell, W. Dean Bibcode: 1998GeoRL..25.1309A Altcode: Gas uptake onto liquid particles is influenced by the electrical charge on the particle. This charge rearranges the spatial distribution of the dissolved reactant ions, modifying the solute-solvent reaction at the surface and for some distance into the liquid. This results in a modification of the uptake coefficient. A general expression, applicable to laboratory and atmospheric conditions, is presented. The change in the uptake coefficient is proportional to particle charge and the square of the Debye length within the liquid. It is inversely proportional to the square of the particle radius. Title: Do meteor showers significantly perturb the ionosphere? Authors: Grebowsky, J. M.; Goldberg, R. A.; Pesnell, W. D. Bibcode: 1998JASTP..60..607G Altcode: 1998JATP...60..607G More than 40 rocket flights through the main meteoric ionization layer, which peaks near 95 km, have sampled the meteoric metallic ion concentrations. Five of these flights were conducted during or near the peak times of a meteor shower. In each of the latter studies the observed meteoric ion concentrations were assumed to be a consequence of the shower. These measurements were not complemented by baseline observations made for similar ionospheric conditions immediately before the shower and no rigorous quantitative comparisons were made using average non-shower distributions. In order to further investigate the impact of the shower on the ionosphere, all published ion concentration altitude profiles obtained from sounding rockets in the meteoric ionization regime have been scanned to develop a digital data base of meteoric ion concentrations. These data are used to provide the first empirical altitude profile of the metallic ions. The average observed Mg+ concentrations are lower than those yielded by the most comprehensive model to date. This compiled ensemble of data provides supporting evidence that meteor showers do have a significant impact on the average ionosphere composition. Although there is much variability in the observed meteoric layers, the peaks in the total metallic ion concentrations at mid-latitudes, on the dayside, observed during meteor showers had concentrations comparable to, or exceeding, the highest concentrations measured in the same altitude regions during non-shower periods. Title: Pioneer Venus Orbiter Measurements of Solar EUV Flux During Solar Cycles 21 and 22 Authors: Mahajan, K. K.; Upadhyay, Hari Om; Sethi, N. K.; Hoegy, W. R.; Pesnell, W. D.; Brace, L. H. Bibcode: 1998SoPh..177..203M Altcode: The Pioneer Venus Orbiter (PVO) had on board the electron temperature probe experiment which measured temperature and concentration of electrons in the ionosphere of Venus. When the probe was outside the Venus ionosphere and was in the solar wind, the probe current was entirely due to solar photons striking the probe surface. This probe thus measured integrated solar EUV flux (Ipe) over a 13-year period from January 1979 to December 1991, thereby covering the declining phase of solar cycle 21 and the rising phase of solar cycle 22. In this paper, we examine the behavior of Ipe translated to the solar longitude of Earth (to be called EIpe) during the two solar cycles. We find that total EUV flux changed by about 60% during solar cycle 21 and by about 100% in solar cycle 22. We also compare this flux with other solar activity indicators such as F_10.7 , Lα, and the solar magnetic field. We find that while the daily values of EIpe are highly correlated with F_10.7 (correlation coefficient 0.87), there is a large scatter in EIpe for any value of this Earth-based index. A comparison of EIpe with SME and UARS SOLSTICE Lα measurements taken during the same period shows that EIpe tracks Lα quite faithfully with a correlation coefficient of 0.94. Similar comparison with the solar magnetic field (Bs) shows that EIpe correlates better with Bs than with F_10.7 . We also compare EIpe with total solar irradiance measured during the same period. Title: A New Graphical Interface for the Paczynski Stellar Evolution Code Authors: Odell, A. P.; Pesnell, W. D. Bibcode: 1998ASPC..135...69O Altcode: 1998hcsp.conf...69O The output of stellar structure and evolution codes has traditionally been in enormous tabular form. We have extensively modified the public-domain Paczynski Code to provide real-time screen-graphical output for use in undergraduate and graduate courses at the college level. Thus anyone studying the structure and evolution of stars can compute such models of varying mass and composition, and see the results (run of composition, energy generation, and gas properties with mass) presented visually as the evolution through core carbon burning proceeds.It is possible to determine the structure of the gray atmosphere of a star assuming the mixing length theory of convection, including the effects of different mixing length. One can watch as the main- sequence homogeneous model converges. A summary program is included which, at the end of an evolution sequence, will show the various model characteristics as a function of time, and also an H- R Diagram for comparison to real stars. We are currently working on a pulsation code which will allow the user to generate and display eigenfunctions for various modes. Title: Pioneer Venus Orbiter Measurements of Solar EUV Flux during Solar Cycles 21 and 22 Authors: Mahajan, K. K.; Upadhyay, Hari Om; Sethi, N. K.; Hoegy, W. R.; Pesnell, W. D.; Brace, L. H. Bibcode: 1998sers.conf..203M Altcode: No abstract at ADS Title: The Evolutionary and Pulsational Characteristics of Alpha Virginis Including Turbulent Diffusive Mixing Authors: Pesnell, W. D.; Odell, A. P. Bibcode: 1998ASPC..135...22P Altcode: 1998hcsp.conf...22P The best-observed star (besides the sun) for comparison to stellar evolution and pulsation theory is Alpha Virginis, a double-line spectroscopic and "visual" binary which shows apsidal motion and Beta Cephei-type pulsation. Unfortunately, it is impossible to fit simultaneously all of the observed properties of this star with one model that also exhibits an unstable pulsation mode of the correct period (see Odell and Pesnell, 32nd Liege Colloquium 1995 procedings), even with new opacities computed by the OPAL group of Rogers and Iglesias (Ap. J. Suppl. 79, 507, 1992).Lyubimkov et al. (Astronomicheskii Zhurnal 72, 212, 1995) have observed that the composition of Alpha Vir A differs from Alpha Vir B in that the helium abundance in the atmosphere of the primary star is significantly higher than the secondary, by approximately a factor of two. Denissenkov (A&A 287, 113, 1994) has suggested that this and other abundance anomolies (CN-cycle processed material) can be explained by Turbulent Diffusive Mixing in early B-stars near the main sequence. Thus it is of interest to determine the effects of this helium abundance change on the properties and stability of models of Alpha Virginis. Title: Meteoric Ionization Layers in the Martian Atmosphere Authors: Pesnell, W. D.; Grebowsky, J. M. Bibcode: 1997AAS...191.2703P Altcode: 1997BAAS...29.1254P Mars, like the other planets, is bombarded by meteorites. At least two families of particles impact the planets: sporadic and shower. In the terrestrial atmosphere both families cause sporadic-E layers when the introduced material is ionized by charge-exchange, photoionization, or impact ionization. Narrow layers of ionized material are produced when the long-lived metallic ions are compressed by tidal or gravity wave motions in the atmosphere. We will examine how the ion-neutral chemistry and dynamics of the Martian atmosphere affect the deposited meteoric material. Our emphasis is on magnesium, an easily ionized species that is a major component of the meteoric debris. The parameters that affect the meteoric ionization differ between Earth and Mars. In particular, the atmospheric compositions and ionospheric densities differ. Further, the lower atmospheric pressure on Mars means lower altitudes for the bulk of the atmospheric ablation of the meteorites. However, the range of atmospheric density variation at high altitudes is greater at Mars than at Earth, so that sputtering of high speed shower streams which occurs at high altitudes may be relatively more important at Mars than Earth. Title: A Student-Oriented Graphical Interface for the Paczynski Stellar Evolution Code Authors: Odell, A. P.; Pesnell, W. D. Bibcode: 1997AAS...191.1202O Altcode: 1997BAAS...29.1227O The output of stellar structure and evolution codes has traditionally been in enormous tabular form. We have extensively modified the public-domain Paczynski Code to provide real-time screen-graphical output for use in undergraduate and graduate college courses. Thus anyone studying the structure and evolution of stars can compute models of chosen mass and composition, and see the results (run of composition, energy generation, and gas properties with mass) presented visually as the evolution through core carbon burning proceeds. Programs are included to generate gray stellar envelopes with mixing-length convection, converge homogeneous main-sequence models, integrate evolution sequences, and create summaries of model characteristics as a function of time, such as a theoretical H-R diagram. Title: A comparison of solar EUV flux from langmuir probe photoelectron measurements on the pioneer venus orbiter with other solar activity indicators Authors: Mahajan, K. K.; Hoegy, W. R.; Pesnell, W. D.; Brace, L. H.; Sethi, N. K. Bibcode: 1997AdSpR..20..187M Altcode: The electron temperature probe acted as a photo-diode on the Pioneer Venus Orbiter (PVO) and measured the integrated solar EUV flux (I_pe) over a 13 year period from January 1979 to December 1991, thus covering the declining phase of solar cycle 21 and the rising phase of solar cycle 22. Gross features in the solar activity variations of this flux during the 13 year period have earlier been studied by Brace et al. (1988) and Hoegy et al. (1993). In this paper, we study the fine features by translating the observed I_pe to the solar longitude of Earth (to be called as EI_pe) and comparing it with other solar activity indicators like F_10.7, Lyman alpha and the solar magnetic field. We find that while the daily values of EI_pe are highly correlated with F10.7 (correlation coefficient 0.87), there is a large scatter in EI_pe for any value of this earth based index. Comparison of EI_pe with SME and UARS-SOLSTICE Lyman-alpha measurements taken during the same period indicates that EI_pe tracks Lyman-alpha quite faithfully. Similar comparison with the solar magnetic field (B_s) shows that EI_pe correlates better with B_s than with F10.7. Title: High-speed correction factor to the O(+)-O resonance charge exchange collision frequency Authors: Omidvar, K.; Pesnell, W. D. Bibcode: 1995AnGeo..13..253O Altcode: The high-speed correction factor to the O+-O collision frequency, resulting from drift velocities between ions and neutrals, is calculated by solving the integral expression in this factor both numerically and analytically. Although the analytic solution is valid for either small or large drift velocities between ions and neutrals, for temperatures of interest and all drift velocities considered, agreement is found between analytic and detailed numerical integration results within less than 1% error. Let Tr designate the average of the ion and neutral temperatures in K, and u=vd/<alpha>, where vd is the relative drift velocity in cm s-1, and <alpha>=4.56×103sqrtTr cm s-1 is the thermal velocity of the O+-O system. Then, as u ranges from 0 to 2, the correction factor multiplying the collision frequency increases monotonically from 1 to about 1.5. An interesting result emerging from this calculation is that the correction factor for temperatures of aeronomical interest is to a good approximation independent of the temperature, depending only on the scaled velocity u. Title: Alpha Virginis : A Test of Upper Main Sequence Stellar Structure and Evolution Authors: Odell, A. P.; Pesnell, W. D. Bibcode: 1995LIACo..32..417O Altcode: 1995sews.book..417O No abstract at ADS Title: O+-O collision frequency in high-speed flows Authors: Pesnell, William Dean; Omidvar, Kazem; Hoegy, Walter R.; Wharton, Larry E. Bibcode: 1994JGR....9921375P Altcode: Throughout much of the terrestrial thermosphere and ionosphere, the motions of the neutral and ionized constituents are closely coupled and relative velocities are small, of the order of 100 ms-1 or less. This is particularly true at midlatitudes to low latitudes where typical velocities in the neutral gas due to tidal forcing are only 20-50 ms-1. However, the solar wind-magnetosphere interaction drives a large-scale convection pattern in the polar ionosphere. When the rapid adjustment of the plasma to changes in the solar wind is combined with the slower response of the more massive neutral gas, large relative velocities on the order of 1 kms-1 can exist for substantial lengths of time. This will be more common during periods of high geomagnetic activity, as a result of the greater number of magnetic substorms and other particle precipitation events. When a significant relative velociy is present, the calculation of interaction parameters of the two gases passing through each other, such as collision frequency, must include that velocity. These effects are usually neglected when interpreting wind and ion drift observations. We show how the collision frequency is affected by a directed relative velocity between any two gases interacting with a power law or exponential potential energy curves. The directed velocity increases the collision frequency at all temperatures for most ion-neutral interactions. For certain power law potentials, such as the charge quadrupole, the collision frequency is decreased. We present an analytic solution for the high-speed collision integral using the resonance charge exchange cross section. Title: Accuracy of O+-O collision cross-section deduced from ionosphere-thermosphere observations Authors: Reddy, C. A.; Hoegy, W. R.; Pesnell, W. D.; Mayr, H. G.; Hines, C. O. Bibcode: 1994GeoRL..21.2429R Altcode: Aeronomic observations applied to the empirical derivation of the ion-neutral collision cross-section—a basic parameter governing the mutual interactions between the neutral and plasma components in the Earth's upper atmosphere—have given values considerably larger than those derived from theory. The empirical scheme uses the plasma velocities obtained with the Incoherent Scatter Radar and the neutral winds obtained with the Fabry-Perot Interferometer. It is shown here that such an analysis overestimates the collision cross-section due to the effects of errors in the observables. The effect may be sufficiently large to bring about agreement with theory, and calls for a re-analysis of the aeronomic data using methods which minimize the bias caused by measurement errors. Title: A Solar Dynamo Pediction: Cycle 23-Cycle 22 Authors: Schatten, K. H.; Pesnell, W. D. Bibcode: 1993AAS...183.2507S Altcode: 1993BAAS...25.1332S No abstract at ADS Title: The Solar Cycle in the Extreme Ultraviolet Authors: Pesnell, W. D.; Hoegy, W. R. Bibcode: 1993AAS...183.2506P Altcode: 1993BAAS...25.1331P We present Pioneer Venus Orbiter observations of the solar EUV flux. The 13 years of measurements cover the last part of Solar Cycle 21 and the majority of Solar Cycle 22. The Ipe flux is a direct measure of the solar EUV flux that correlated extremely well with earth based measurements until the onset of Solar Cycle 22. We demonstrate this correlation with the 10.7 cm. radio flux and ionospheric conditions. Our measurements show that Solar Cycle 22 was one of the most active ever recorded. The Ipe flux is a yield-weighted integration over wavelengths from 100 Angstroms to 1300 Angstroms. It is dominated by emission in L_alpha lambda 1216, with roughly 50% of the flux coming from the remaining wavelengths. Other EUV proxy measurements are compared to the Ipe flux. Title: An Early Solar Dynamo Prediction: Cycle 23 ∼ Cycle 22 Authors: Schatten, Kenneth H.; Pesnell, W. Dean Bibcode: 1993GeoRL..20.2275S Altcode: In this paper, we briefly review the “dynamo” and “geomagnetic precursor” methods of long-term solar activity forecasting. These methods depend upon the most basic aspect of dynamo theory to predict future activity, future magnetic field arises directly from the magnification of pre-existing magnetic field. We then generalize the dynamo technique, allowing the method to be used at any phase of the solar cycle, through the development of the “Solar Dynamo Amplitude” (SODA) index. This index is sensitive to the magnetic flux trapped within the Sun's convection zone but insensitive to the phase of the solar cycle. Since magnetic fields inside the Sun can become buoyant, one may think of the acronym SODA as describing the amount of buoyant flux. Using the present value of the SODA index, we estimate that the next cycle's smoothed peak activity will be about 210 ± 30 solar flux units for the 10.7 cm radio flux and a sunspot number of 170 ± 25. This suggests that solar cycle #23 will be large, comparable to cycle #22. The estimated peak is expected to occur near 1999.7 ± 1 year. Since the current approach is novel (using data prior to solar minimum), these estimates may improve when the upcoming solar minimum is reached. Title: Momentum transfer collision frequency of O+-O Authors: Pesnell, W. D.; Omidvar, Kazem; Hoegy, Walter R. Bibcode: 1993GeoRL..20.1343P Altcode: The interaction of the thermosphere and ionosphere is largely governed by collisions between ions and neutral particles. On Venus and the Earth, O+ is a dominant ion, and atomic O dominates throughout much of the thermosphere; therefore an accurate O+-O cross section is an important prerequisite for understanding the dynamics of planetary upper atmospheres. The cross section and momentum, transfer collision frequency are calculated with a quantum mechanical code which includes resonance charge exchange, polarization, and charge-quadrupole effects. Our results agree well with earlier calculations of Stubbe [1968] and Stallcop et al [1991]. Title: How active was solar cycle 22? Authors: Hoegy, W. R.; Pesnell, W. D.; Woods, T. N.; Rottman, G. J. Bibcode: 1993GeoRL..20.1335H Altcode: Solar EUV observations from the Langmuir probe on Pioneer Venus Orbiter suggest that at EUV wavelengths solar cycle 22 was more active than solar cycle 21. The Langmuir probe, acting as a photodiode, measured the integrated solar EUV flux over a 13 1/2 year period from January 1979 to June 1992, the longest continuous solar EUV measurement. The Ipe EUV flux correlated very well with the SME measurement of Lα during the lifetime of SME and with the UARS SOLSTICE Lα from October 1991 to June 1992 when the Ipe measurement ceased. Starting with the peak of solar cycle 21, there was good general agreement of Ipe EUV with the 10.7 cm, Ca K, and He 10830 solar indices, until the onset of solar cycle 22. From 1989 to the start of 1992, the 10.7 cm flux exhibited a broad maximum consisting of two peaks of nearly equal magnitude, whereas Ipe EUV exhibited a strong increase during this time period making the second peak significantly higher than the first. The only solar index that exhibits the same increase in solar activity as Ipe EUV and Lα during the cycle 22 peak is the total magnetic flux. The case for high activity during this peak is also supported by the presence of very high solar flare intensity. Title: Dynamical interactions between the middle atmosphere and thermosphere Authors: Mayr, H. G.; Harris, I.; Pesnell, W. D. Bibcode: 1992AdSpR..12j.335M Altcode: 1992AdSpR..12..335M Based on modeling, we discuss some interactions between the middle atmosphere and thermosphere: (1) Upward propagating tides affect the wind field and the temperature (and density) variations of the thermosphere at higher altitudes. (2) The thermospheric circulations driven by radiative and auroral heating affect the O concentration and temperature of the upper mesosphere through the exchange of chemical energy. (3) Gravity waves excited by auroral processes are ducted through the lower atmosphere and leak back into the thermosphere, permitting them to propagate large distances away from the source. Title: Properties of thermospheric gravity waves on Earth, Venus and Mars. Authors: Mayr, H. G.; Harris, I.; Pesnell, W. D. Bibcode: 1992GMS....66...91M Altcode: The authors review a spectral model with sherical harmonics and Fourier components that can simulate atmospheric perturbations in the global geometry of a multiconstituent atmosphere. The boundaries are the planetary surface where the transport velocities vanish and the exobase where molecular heat conduction and viscosity dominate. The time consuming integration of the conservation equations is reduced to computing the transfer function (TF) which describes the dynamic properties of the medium divorced from the complexities in the temporal and horizontal variations of the excitation source. Given the TF, the atmospheric response to a chosen source distribution is then obtained in short order. Theoretical studies are presented to illuminate some properties of gravity waves on Earth, Venus and Mars. Title: Thermospheric Gravity Waves - Observations and Interpretation Using the Transfer Function Model / Ftm Authors: Mayr, H. G.; Harris, I.; Herrero, F. A.; Spencer, N. W.; Varosi, F.; Pesnell, W. D. Bibcode: 1990SSRv...54..297M Altcode: Gravity waves are prominent in the polar region of the terrestiral thermosphere, and can be excited by perturbations in Joule heating and Lorents force due to magnetospheric processes. We show observations from the Dynamics Explorer-2 satellite to illustrate the complexity of the phenomenon and review the transfer function model (TFM) which has guided our interpretation. On a statistical basis, the observed atmospheric perturbations decrease from the poles toward the equator and tend to correlate with the magnetic activity index, Ap, although individual measurements indicate that the magnetic index is often a poor measure of gravity wave excitation. The theoretical models devised to describe gravity waves are multifaceted. On one end are fully analytical, linear models which are based on the work of Hines. On the other end are fully numerical, thermospheric general circulation models (TGCMs) which incorporate non-linear processes and wave mean flow interactions. The transfer function model (TFM) discussed in this paper is between these two approaches. It is less restrictive than the analytical approach and relates the global propagation of gravity waves to their excitation. Compared with TGCMs, the TFM is simplified by its linear approximation; but it is not limited in spatial and temporal resolution, and the TFM describes the wave propagation through the lower atmosphere. Moreover, the TFM is semianalytical which helps in delineating the wave components. Using expansions in terms of spherical harmonics and Fourier components, the transfer function is obtained from numerical height integration. This is time consuming computationally but needs to be done only once. Once such a transfer function is computed, the wave response to arbitrary source distributions on the globe can then be constructed in very short order. In this review, we discuss some numerical experiments performed with the TFM, to study the various wave components excited in the auroral regions which propagate through the thermosphere and lower atmosphere, and to elucidate the properties of realistic source geometries. The model is applied to the interpretation of satellite measurements. Gravity waves observed in the thermosphere of Venus are also discussed. Title: Nonradial, Nonadiabatic Stellar Pulsations Authors: Pesnell, W. Dean Bibcode: 1990ApJ...363..227P Altcode: This paper describes how nonradial stellar pulsations can be modeled using a Lagrangian formulation. The adiabatic eigenvalues of this operator are compared to previously published results, using simple stellar models to show the equivalence of this method and other techniques. Nonadiabatic effects are included by appending the thermal equation to the adiabatic operator. At this point, it becomes necessary to include variations in the convective energy transport. Several ways of doing this by 'freezing' the convection are examined. Title: Line Profile Variations in BW Vulpeculae Authors: Pesnell, W. D.; Odell, A. P. Bibcode: 1990BAAS...22.1209P Altcode: No abstract at ADS Title: Transfer Function Model for Thermospheric Gravity Waves Authors: Mayr, Hans G.; Harris, Isadore; Pesnell, W. Dean Bibcode: 1990rete.conf...49M Altcode: No abstract at ADS Title: Properties of Eoetvoes Spheres Authors: Pesnell, W. Dean Bibcode: 1989ApJ...344..851P Altcode: Derivations of the equations governing Eotvos spheres and degenerate Eotvos objects are presented. These simplified stellar models incorporate a short-range component in their gravitational potential. A Yukawa formulation to agree with other workers in this field is used, although any form that multiplies the normal inverse square law would be acceptable. Both polytropic and completely degenerate equations of state are used and separate equations governing the density distribution derived. Various global relationships are obeyed by these objects, much like the polytropes to which they are similar. A discussion of whether the simplified potential is accurate enough for astrophysics is included, along with a more accurate integral equation for the potential. Title: Some Thoughts on the Rapidly Oscillating AP Stars Authors: Pesnell, W. Dean Bibcode: 1989ApJ...339.1038P Altcode: The effects of combining a weak, axisymmetric magnetic field and slow rotation on the adiabatic pulsation frequencies of Ap stars are discussed. It is shown that standing wave patterns on the surface of the star are produced when the magnetic field dominates the rotation. When rotation is more important than the magnetic field, the standing waves are split into the usual running waves. It is shown how the standing waves affect the line profiles of the star during a pulsation cycle. When compared to the line profile variations of a running wave, distinct differences are seen. The standing waves resemble a radial pulsation at some rotation phases and almost disappear one-quarter of a rotation cycle later. Title: On the Possibility of Detecting Weak Magnetic Fields in Variable White Dwarfs Authors: Jones, Philip W.; Pesnell, W. Dean; Hansen, Carl J.; Kawaler, Steven D. Bibcode: 1989ApJ...336..403J Altcode: It is suggested that 'weak' magnetic fields of strengths less than 10 to the 6th G may be detectable in some variable white dwarfs. Weak fields can cause subtle changes in the Fourier power spectra of these stars in the form of 'splitting' in frequency of otherwise degenerate signals. Present-day observational and analysis techniques are capable of detecting these changes. It is suggested suggested, by listing some well-studied candidate stars, that perhaps the magnetic signature of splitting has already been observed in at least one object and that the difficult task of intensive measurements of weak fields should now be undertaken of those candidates. Title: Pulsation Induced HeI Line Profile Variations Authors: Pesnell, W. Dean Bibcode: 1989BAAS...21..714P Altcode: No abstract at ADS Title: Pulsations of EÖTVÖS Spheres Authors: Pesnell, W. Dean Bibcode: 1989upsf.conf..282P Altcode: 1989IAUCo.111..282P No abstract at ADS Title: A Catalogue of Line Profile Variations Due to Nonradial Pulsations Authors: Jones, P. W.; Pesnell, W. D.; Hansen, C. J.; Smith, M. A. Bibcode: 1988BAAS...20..673J Altcode: No abstract at ADS Title: Pulsations of White Dwarf Stars with Thick Hydrogen or Helium Surface Layers Authors: Cox, A. N.; Starrfield, S. G.; Kidman, R. B.; Pesnell, W. D. Bibcode: 1988IAUS..123..333C Altcode: In order to see if there could be agreement between results of stellar evolution theory and those of nonradial pulsation theory, calculations of white dwarf models have been made for hydrogen surface masses of 10-4M_sun;. Earlier results by Winget et al. (1982) indicated that surface masses greater than 10-8M_sun; would not allow nonradial pulsations, even though all the driving and damping is in surface layers only 10-12 of the mass thick. The authors show that the surface mass of hydrogen in the pulsating white dwarfs (ZZ Ceti variables) can be any value as long as it is thick enough to contain the surface convection zone. Title: Weight functions in adiabatic stellar pulsations. I - Radially symmetric motion Authors: Pesnell, W. Dean Bibcode: 1987PASP...99..975P Altcode: Through the use of two classes of simple stellar models, the author illustrates a weight function for radial pulsations that can be interpreted in terms of two types of potential energy. The traditional weight function is related to the present one via an integration by parts, and it is argued that both formulations should be examined to minimize possible errors that can arise from neglecting several surface terms. The present form provides a different interpretation of radial oscillations of stars with small central condensations. The author also follows the radial fundamental of a highly centrally condensed polytrope through the dynamic instability at γ = 4/3 and demonstrates that the envelope is not involved in the instability. Title: Angular Standing Waves in Stellar Pulsations Authors: Pesnell, W. D. Bibcode: 1987BAAS...19.1052P Altcode: No abstract at ADS Title: Pulsations of White Dwarf Stars with Thick Hydrogen or Helium Surface Layers Authors: Cox, Arthur N.; Starrfield, Sumner G.; Kidman, Russell B.; Pesnell, W. Dean Bibcode: 1987ApJ...317..303C Altcode: Models for DA white dwarf stars with effective temperatures between 9000 and 12,000 K and models for DB white dwarfs with effective temperatures of 25,000 K and 27,000 K have been tested for stability against both radial and nonradial pulsations. The construction of the models is discussed, and linear nonadiabatic nonradial pulsation results for these models are given assuming frozen-in convection. The time variation of convection is simulated in a crude way, and it is shown that many unstable modes can be completely stabilized. The results show that thick hydrogen shells can produce nonradial pulsations and that the existence of convection blocking exists for both radial and nonradial modes in DA and DB white dwarf stars. It is found that convection at the surface of white dwarfs must be very efficient in order for the theoretical nonradial instability strip to have a blue edge hot enough to agree with observations. Title: A New Driving Mechanism for Stellar Pulsations Authors: Pesnell, W. Dean Bibcode: 1987ApJ...314..598P Altcode: A new driving mechanism termed "convective blocking", a variation of the normal κ- and γ-mechanisms in Cepheids, is demonstrated using two models of hydrogen white dwarf stars. This mechanism is shown to be physically reasonable in the limit of frozen convection (implying the time scale for convective readjustment is long compared to a pulsation period). Some qualitative effects are given for when the two time scales are not as disparate. Title: Ensampling White Dwarf g-Modes Authors: Pesnell, W. Dean Bibcode: 1987LNP...274..363P Altcode: 1987stpu.conf..363P We examine the pulsation spectrum of zero temperature models as a first approximation to white dwarf stars. The g-mode spectrum of such objects is found by using a constant adiabatic exponent and we have found that the core is an important region for the determination of the eigenvalue. A comparison to an evolutionary model is given. Title: Pulsations in Completely Degenerate Objects Authors: Pesnell, W. D. Bibcode: 1986BAAS...18..951P Altcode: No abstract at ADS Title: Pulsations of white dwarf stars with thick hydrogen or helium surface layers Authors: Cox, A. N.; Starrfield, S. G.; Kidman, R. B.; Pesnell, W. D. Bibcode: 1986STIN...8721774C Altcode: In order to see if there could be agreement between results of stellar evolution theory and those of nonradial pulsation theory, calculations of white dwarf models have been made for hydrogen surface masses of 10 to the -4 solar masses. Earlier results indicated that surface masses greater than 10 to the -8 solar masses would not allow nonradial pulsations, even though all the driving and damping is in surface layers only 10 to the -12 of the mass thick. It is shown that the surface mass of hydrogen in the pulsating white dwarfs (ZZ Ceti variables) can be any value as long as it is thick enough to contain the surface convection zone. Title: The Structure of the Thermal Modes in Pulsating Stars Authors: Pesnell, W. D.; Buchler, J. R. Bibcode: 1986ApJ...303..740P Altcode: The eigenvectors and eigenvalues of the linearized thermal diffusion operator are studied and their effect on the thermal structure of radial stellar pulsations is examined. It is shown on the basis of two specific cases that the difference between these eigenvectors may explain the lack of pulsational instability of radial modes in the Beta Cephei stars. A rigorous definition of the thermal response time of a model is attempted and the location of the transition from adiabatic to highly nonadiabatic motion is discussed. Title: Brunt-Vaeisaelae Frequency and Semiconvection Authors: Pesnell, W. D. Bibcode: 1986ApJ...301..204P Altcode: A derivation of the Brunt-Väisälä frequency, valid in regions of a star where both partial ionization and a varying nuclear composition are present, is given. The final result shows that even in regions where the total ionization approximation is valid, a reduction of the Brunt-Väisälä when compared to the Ledoux criterion is necessary. Areas where this function is important are discussed, and examples are presented using different forms of equations of state. Title: The Connection Between Nonradial Pulsations and Stellar Winds in Massive Stars Authors: Abbott, D. C.; Garmany, C. D.; Hansen, C. J.; Henrichs, H. F.; Pesnell, W. D. Bibcode: 1986PASP...98...29A Altcode: No abstract at ADS Title: On one-zone models of stellar pulsation Authors: Pesnell, W. D. Bibcode: 1985ApJ...299..161P Altcode: A version of the one-zone model, the weakly coupled monomode model, is derived, showing that the small parameter in stellar pulsation is the coupling term in the momentum equation. A crude model of similar derivation is found that describes a portion of the convection-pulsation interaction. The latter model shows that the time dependence of the perturbation in the convection variables can be an important part of the convection-pulsation interaction. With the assumptions made, the pulsation is stabilized when the convection field is unstable and vice versa. Title: Ionization Driving Mechanisms in Pulsating Stars Authors: Pesnell, W. D. Bibcode: 1985BAAS...17..894P Altcode: No abstract at ADS Title: Observable quantities of nonradial pulsations in the presence of slowrotation. Authors: Pesnell, W. D. Bibcode: 1985ApJ...292..238P Altcode: Theoretical power spectra of both light and radial velocity variations of a nonradially pulsating star that include the effects of rotation are presented. Three classes of motion are defined, depending on the symmetry of the mode of interest and its orientation with respect to the rotating axis. The use of tabulated model atmospheres to predict color variations is compared to the blackbody approximation for two cases, a hydrogen white dwarf (DA) and a main-sequence B Star. Title: Rotational mode splitting about an inclined axis Authors: Aizenman, M. L.; Hansen, C. J.; Pesnell, W. D.; Cox, J. P. Bibcode: 1984ApJ...286L..43A Altcode: The authors have derived the "m-splitting" formula for the frequencies of nonradial oscillations of stars due to slow rotation about an axis which is inclined with respect to the pulsation axis. They obtain the simple result that the usual formula applies, except that only the component of the angular rotation velocity along the pulsation axis, rather than the full angular rotation velocity, is to be used in this formula. Title: Thermal response of stellar envelopes during nonradial pulsations Authors: Pesnell, W. D. Bibcode: 1984ApJ...285..778P Altcode: The response of spherical stellar envelopes in hydrostatic and thermal balance to nonradial thermal distributions is outlined. Because of the nature of the initial model, the governing equations yield an operator that is almost identical to the radial case. The use of propagation velocities to estimate the nonadiabatic effects in a pulsation is demonstrated. Title: An Analysis of the Nonradial Oscillations of the Central Star of the Planetary Nebula K1-16 Authors: Starrfield, S.; Cox, A. N.; Kidman, R. B.; Pesnell, W. D. Bibcode: 1984BAAS...16R.975S Altcode: No abstract at ADS Title: A Simple Model of the Convection-Pulsation Interaction Authors: Pesnell, W. D. Bibcode: 1984BAAS...16.1012P Altcode: No abstract at ADS Title: Critique of the iterative theory of stellar pulsations Authors: Buchler, J. R.; Pesnell, W. D. Bibcode: 1984ApJ...283..316B Altcode: An attempt to define a mathematical formalism for computing the periodic or multiperiodic oscillations of a weakly nonlinear oscillator is presented. Attention is focused on iterative theory (IT), i.e., the method of harmonic balances, applied to radial pulsators. The IT is shown capable of predicting adiabatic oscillations correctly, provided modifications are introduced to avoid divergences due to internal resonance. Chaotic solutions are, however, not amenable to IT asymptotic perturbation models. The IT is also extended to the nonadiabatic case through the addition of a work integral. The technique is demonstrated to be effective in the case of two incommensurate resonance modes in a stellar evolutionary scenario. Title: Nonradial instability strips based on carbon and oxygen partial ionization in hot, evolved stars. Authors: Starrfield, S.; Cox, A. N.; Kidman, R. B.; Pesnell, W. D. Bibcode: 1984ApJ...281..800S Altcode: The authors have calculated periods and growth rates for a new class of nonradially pulsating variable stars in the linear, nonradial, nonadiabatic theory. The best observed member of this class is PG 1159-035 which is observed to be pulsating in a number of periods around 500 s and may well have an effective temperature exceeding 105K. Stellar envelopes constructed for a 0.6 M_sun; star are in the effective temperature range 7×104K ≤ Te ≤ 1.5×105K following the white dwarf cooling track at radii 0.016 - 0.030 R_sun;. These envelopes have compositions of half carbon and half oxygen by mass. The authors present their nonradial results and discuss the newly discovered instability strip in some detail. All unstable nonradial modes in the period range from ≡25 s to ≡1200 s and their growth rates are described. The implications of these results for stellar evolution studies are examined. Title: Qualitative Aspects of the Convection-Pulsation Interaction Authors: Pesnell, W. D. Bibcode: 1984LIACo..25..294P Altcode: 1984tpss.conf..294P; 1984trss.conf..294P No abstract at ADS Title: Lagrangian, Non-Radial Stellar Pulsations Authors: Pesnell, W. Dean Bibcode: 1984BAAS...16..409P Altcode: No abstract at ADS Title: The discovery of nonradial instability strips for hot,evolved stars. Authors: Starrfield, S. G.; Cox, A. N.; Hodson, S. W.; Pesnell, W. D. Bibcode: 1983ApJ...268L..27S Altcode: Three different interior compositions are used in the present radial and nonradial, linear, nonadiabatic pulsation analyses of model stellar envelopes in the effective temperature range of 80,000-150,000 K, with total masses of 0.6 solar masses and radii chosen so that they line up along a prewhite dwarf cooling curve: (1) 100 percent C; (2) 50 percent C-12 and 50 percent O-16 by mass; and (3) 10 percent C-12 and 90 percent O-16 by mass. Radial and nonradial instability strips are found for each composition, caused the partial ionization of C, or O, or both. Attention is given to the cause of the pulsations of the hot, evolved star PG 1159-035, which, although perhaps too hot to lie within the proposed instability strips, is in some measure of agreement with models having significant amounts of O-16 near the stellar surface. This implies a greater production of O-16 through He burning than previously supposed. Title: Thermal Effects in Stellar Pulsations. Authors: Pesnell, W. D. Bibcode: 1983PhDT........14P Altcode: 1984DiAbI..45.1218P A Sturm-Liouville operator, embedded in the linearized radial pulsation equations, is used to analyze the thermal effects of stellar pulsations. Asymptotic expansions are utilized to demonstrate the nature of these eigenfunctions and to define the thermal response time of a stellar model. The eigenvalues and eigenvectors for models of a Cepheid and Beta Cephei variable are given showing the differences in the two classes of variables. The time scales introduced agree with earlier ones in their common use of predicting the location of possible driving zones. In addition, a way of displaying the temperature variations in the hydrogen ionization zone without the customary "spike" is demonstrated, and a new class of pulsations, called "sudden" modes, is introduced. Title: Thermal effects in stellar pulsations Authors: Pesnell, William Dean Bibcode: 1983PhDT.......114P Altcode: No abstract at ADS Title: The Non-Radial Pulsation Properties of Hot Hydrogen-Poor, Evolved Stars Authors: Starrfield, S.; Cox, A. N.; Hodson, S. N.; Pesnell, W. D. Bibcode: 1982BAAS...14..901S Altcode: No abstract at ADS Title: Linear theory radial and nonradial pulsations of DA dwarf stars Authors: Starrfield, S.; Cox, A. N.; Hodson, S.; Pesnell, W. D. Bibcode: 1982pccv.conf...78S Altcode: The stellar envelope and radial linear nonadiabatic computer code, along with a nonradial code are used to investigate the total hydrogen mass necessary to produce the nonradial instability of DA dwarfs. Opacities and equations of state are obtained for pure mixtures of hydrogen, helium, and carbon. In some cases, a small amount of metals are included in the composition in order to have a variety of mixtures available to make gradual changes in composition from hydrogen to helium. The presence of metals in these mixtures has no effect on the results. Title: Application of Two-Time Methods in Stellar Pulsations Authors: Pesnell, W. D.; Regev, O.; Buchler, J. R. Bibcode: 1982pccv.conf..216P Altcode: No abstract at ADS Title: Stability analysis of slow spherical motion for a gravitating fluid Authors: Livio, M.; Buchler, J. R.; Pesnell, W. D. Bibcode: 1981ApJ...243..617L Altcode: The stability of equations governing the spherical motion of a gravitating compressible fluid against adiabatic perturbations is analyzed. Assuming that the perturbation of the gravitational potential can be neglected and that motion is slow, a perturbative approach is used to obtain first-order corrections to the hydrostatic eigenvalues. The expression for this correction may be used to study the effect of velocity and acceleration fields on both stable and unstable hydrostatic modes. When applied to the homogeneous compressible case the correction gives the expected results, and stability criteria can be obtained for specific modes. Possible implications for the study of stellar collapse are noted. Title: The Light and Velocity Curve Bumps for Bw-Vulpeculae Authors: Pesnell, W. D.; Cox, A. N. Bibcode: 1980SSRv...27..337P Altcode: 1980IAUCo..58..337P BW Vulpeculae (HD 199140) is a well known Beta Cephei star, with several unusual characteristics. It possesses the largest amplitude in both light and radial velocity variations of any star in this classification. The most outstanding feature of the observations is a standstill, or bump, on the light curve, accompanied by doubled lines in the radial velocity observations. In this paper, an attempt has been made to explain these phenomena with two different models: firstly, the resonance mechanism, from Simon and Schmidt (1976), and secondly, a nonlinear calculation. Title: Spherical oscillation patterns Authors: Pesnell, W. Dean; Coggins, James M. Bibcode: 1980SSRv...27..473P Altcode: 1980IAUCo..58..473P Spherical harmonics are an integral part of the study of stellar pulsations. To gain an understanding of how the star is affected by non-radial pulsations, the radial part of the oscillation is plotted, with an assumed sinusoidal time variation. The amplitude of the motion is arbitrarily set at 20% of the radius.