Author name code: bothmer
ADS astronomy entries on 2022-09-14
author:"Bothmer, Volker"
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Title: Near-Sun Observations of CMEs with WSIPR on Parker Solar
Probe in April 2021
Authors: Bothmer, Volker; Chifu, Iulia
Bibcode: 2022cosp...44.1461B
Altcode:
During the pre-encounter days from April 20 to 27, 2021, more than
20 CMEs have been identified in observations made by the WISPR inner
telescope onboard the Parker Solar Probe (PSP) spacecraft. The WISPR
CME observations reveal unprecedented fine structures compared to
previous observations from near-Earth orbit. The PSP trajectory
during the 8th encounter with a perihelion of below 15,7 solar radii
on April 29, following its 4th Venus flyby in February 2021, was
ideally suited to compare the WISPR observations with simultaneous
STEREO/SECCHI/COR2A/HI1A and SOHO/LASCO/C2/C3 observations from
near-Earth orbit and with observations of the low corona made in EUV
wavelengths by SDO and STEREO/SECCHI/EUVI A. Here we present a summary
of the physics characteristics of the observed CMEs, their near-Sun
evolution and interactions seen in white-light. The identification
of their solar origins in SDO/AIA and STEREO/EUVIA, and the results
derived from the multipoint studies have important implications for a
better understanding of the heliospheric manifestations of the solar
photospheric and coronal magnetic fields.
Title: On modeling ICME cross sections as static MHD columns
Authors: Bhattacharjee, Debesh; Nieves-Chinchilla, Teresa; Bothmer,
Volker; Subramanian, Prasad; Vourlidas, Angelos
Bibcode: 2022cosp...44.1376B
Altcode:
Solar coronal mass ejections (CMEs) are observed to expand during
their propagation through the solar wind. However, their cross-sections
are usually modeled as static plasma columns within the framework of
magnetohydrodynamics (MHD). In this study, we test the validity of
this approach using in-situ plasma data from 151 magnetic clouds
(MCs) observed by the WIND spacecraft and 45 observed by the
Helios spacecrafts. We find that the most probable cross-section
expansion speeds for the WIND events are only $\approx 0.06$ times
the Alfvén speed inside the MCs while the most probable cross-section
expansion speeds for the Helios MCs is $\approx 0.03$. Hence, the MC
cross-sections can be considered approximately static over an Alfvén
crossing timescale. Using estimates of electrical conductivity arising
from Coulomb collisions, we find that the Lundquist number inside MCs is
high ( $\approx 10^{13}$), suggesting that the MHD description is well
justified. The Joule heating rates using our conductivity estimates
are several orders of magnitude lower than the requirement for plasma
heating inside MCs at 1 AU. The low heating rates are consistent
with the MHD description which assumes no dissipation. However, the
discrepancy with the heating requirement suggests possible departures
from MHD and the need for a better understanding of plasma heating
inside MCs.
Title: Multi-spacecraft analysis of multi-CME events observed by
WISPR on Parker Solar Probe in April 2021
Authors: Chifu, Iulia; Bothmer, Volker
Bibcode: 2022cosp...44.1466C
Altcode:
One week before Parker Solar Probe's (PSP) 8th perihelion, from 20
to 27 April 2021, the Sun showed increased activity as manifested
in the release of multiple CMEs into interplanetary space. Among
these, we selected a series of three interacting CMEs identified
in the observations of the WISPR-I telescope on 26 April and in the
coronagraph images of STEREO-A/SECCHI/COR2 and HI and SOHO/LASCO/C2/C3
on 25 April. We applied different methods for the 3D reconstruction of
the CMEs in order to derive their physical properties and kinematics
and to investigate potential in-situ crossings of the PSP trajectory. In
one CME event, WISPR imaged details of a small flux rope that could be
traced back to the Sun as identified from SDO and STEREO-A/SECCHI/EUVI
observations. In this study, we present the results of the 3D
reconstruction methods for these CME events.
Title: Evolution of ICME sheath and leading-edge structure in the
inner heliosphere
Authors: Temmer, Manuela; Bothmer, Volker
Bibcode: 2022cosp...44.1439T
Altcode:
We investigate a data sample of 40 interplanetary CME (ICME) events
from Helios 1 and 2 data that cover the distance range 0.3-1au. For
comparison, we add a sample of 5 ICMEs observed with Parker Solar
Probe during 2018-2021. From the solar wind plasma and magnetic field
measurements, we extract the ICME sub-structures sheath, leading-edge,
and magnetic ejecta. We analyze their characteristic parameters as
function of distance and present the main findings of this study: a)
the average starting distance for actual sheath formation appears to
be located at a distance of about 13 Rs; b) the sheath density becomes
dominant over the magnetic ejecta density beyond 38 Rs; c) the sheath
size could be related to the ambient solar wind density and magnetic
ejecta characteristics; d) a local linear relation between sheath
density and ambient solar wind speed was found; e) the leading-edge
does not increase in size over distance and might be an isolated
structure wedged in between sheath and magnetic ejecta. With Parker
Solar Probe approaching the Sun as close as 10Rs, we will certainly
detect more CME events to obtain measurements that might re-affirm
the presented results. The current findings can be applied to help
improve CME propagation models.
Title: On Modeling ICME Cross-Sections as Static MHD Columns
Authors: Bhattacharjee, Debesh; Subramanian, Prasad; Bothmer, Volker;
Nieves-Chinchilla, Teresa; Vourlidas, Angelos
Bibcode: 2022SoPh..297...45B
Altcode: 2022arXiv220306996B
Solar coronal mass ejections are well-known to expand as they propagate
through the heliosphere. Despite this, their cross-sections are usually
modeled as static plasma columns within the magnetohydrodynamics
(MHD) framework. We test the validity of this approach using
in-situ plasma data from 151 magnetic clouds (MCs) observed by
the WIND spacecraft and 45 observed by the Helios spacecraft. We
find that the most probable cross-section expansion speeds for the
WIND events are only ≈0.06 times the Alfvén speed inside the MCs,
while the most probable cross-section expansion speeds for the Helios
events is ≈0.03 . MC cross-sections can thus be considered to be
nearly static over an Alfvén crossing timescale. Using estimates
of electrical conductivity arising from Coulomb collisions, we find
that the Lundquist number inside MCs is high (≈1013),
suggesting that the MHD description is well justified. The Joule
heating rates using our conductivity estimates are several orders
of magnitude lower than the requirement for plasma heating inside
MCs near the Earth. While the (low) heating rates we compute are
consistent with the MHD description, the discrepancy with the heating
requirement points to possible departures from MHD and the need for
a better understanding of plasma heating in MCs.
Title: HiRISE - High-Resolution Imaging and Spectroscopy Explorer
- Ultrahigh resolution, interferometric and external occulting
coronagraphic science
Authors: Erdélyi, Robertus; Damé, Luc; Fludra, Andrzej; Mathioudakis,
Mihalis; Amari, T.; Belucz, B.; Berrilli, F.; Bogachev, S.; Bolsée,
D.; Bothmer, V.; Brun, S.; Dewitte, S.; de Wit, T. Dudok; Faurobert,
M.; Gizon, L.; Gyenge, N.; Korsós, M. B.; Labrosse, N.; Matthews,
S.; Meftah, M.; Morgan, H.; Pallé, P.; Rochus, P.; Rozanov, E.;
Schmieder, B.; Tsinganos, K.; Verwichte, E.; Zharkov, S.; Zuccarello,
F.; Wimmer-Schweingruber, R.
Bibcode: 2022ExA...tmp...21E
Altcode:
Recent solar physics missions have shown the definite role of waves and
magnetic fields deep in the inner corona, at the chromosphere-corona
interface, where dramatic and physically dominant changes occur. HiRISE
(High Resolution Imaging and Spectroscopy Explorer), the ambitious new
generation ultra-high resolution, interferometric, and coronagraphic,
solar physics mission, proposed in response to the ESA Voyage 2050
Call, would address these issues and provide the best-ever and most
complete solar observatory, capable of ultra-high spatial, spectral,
and temporal resolution observations of the solar atmosphere, from the
photosphere to the corona, and of new insights of the solar interior
from the core to the photosphere. HiRISE, at the L1 Lagrangian
point, would provide meter class FUV imaging and spectro-imaging,
EUV and XUV imaging and spectroscopy, magnetic fields measurements,
and ambitious and comprehensive coronagraphy by a remote external
occulter (two satellites formation flying 375 m apart, with a
coronagraph on a chaser satellite). This major and state-of-the-art
payload would allow us to characterize temperatures, densities, and
velocities in the solar upper chromosphere, transition zone, and inner
corona with, in particular, 2D very high resolution multi-spectral
imaging-spectroscopy, and, direct coronal magnetic field measurement,
thus providing a unique set of tools to understand the structure and
onset of coronal heating. HiRISE's objectives are natural complements
to the Parker Solar Probe and Solar Orbiter-type missions. We present
the science case for HiRISE which will address: i) the fine structure
of the chromosphere-corona interface by 2D spectroscopy in FUV at
very high resolution; ii) coronal heating roots in the inner corona by
ambitious externally-occulted coronagraphy; iii) resolved and global
helioseismology thanks to continuity and stability of observing at the
L1 Lagrange point; and iv) solar variability and space climate with,
in addition, a global comprehensive view of UV variability.
Title: Characteristics and evolution of sheath and leading edge
structures of interplanetary coronal mass ejections in the inner
heliosphere based on Helios and Parker Solar Probe observations
Authors: Temmer, Manuela; Bothmer, Volker
Bibcode: 2022arXiv220204391T
Altcode:
Aims: We statistically investigate the plasma and magnetic field
characteristics of the upstream regions of interplanetary coronal mass
ejections (ICMEs) and their evolution as function of distance to the Sun
in the inner heliosphere. We use a sample of 40 well-observed ICMEs from
Helios 1/2 (0.3-1au) and 5 from Parker Solar Probe (0.32-0.75au). For
each event we identify four main density structures, namely shock,
sheath, leading edge (LE), and magnetic ejecta (ME) itself. Methods:
We derive separately for each structure averaged plasma and magnetic
field parameter values as well as duration and place the results
into comparison with the upstream solar wind (SW) to investigate the
interrelation between the different density structures. Results:
The sheath structure presumably consists of compressed plasma due
to the turbulent SW material following the shock. The sheath lies
ahead of a region of compressed ambient SW, the LE, which is typically
found directly in front of the magnetic driver and seems to match the
bright leading edge commonly observed in remote sensing observations of
CMEs. The sheath becomes denser than the ambient SW at about 0.06au,
which we interpret as the average starting distance for actual sheath
formation. Between 0.09-0.28au the sheath structure density starts to
dominate over the density within the ME. The ME density seems to fall
below the ambient SW density over 0.45-1.07au. Besides the well-known
expansion of the ME, the sheath size shows a weak positive correlation
with distance, while the LE seems not to expand with distance from the
Sun. We further find a moderate anti-correlation between sheath density
and local SW plasma speed upstream of the ICME shock. An empirical
relation is derived connecting the ambient SW speed with sheath and LE
density that can be used for modeling of ICME evolution. Constraints
to those results are given.
Title: Comparing the Heliospheric Cataloging, Analysis, and Techniques
Service (HELCATS) Manual and Automatic Catalogues of Coronal Mass
Ejections Using Solar Terrestrial Relations Observatory/Heliospheric
Imager (STEREO/HI) Data
Authors: Rodriguez, L.; Barnes, D.; Hosteaux, S.; Davies, J. A.;
Willems, S.; Pant, V.; Harrison, R. A.; Berghmans, D.; Bothmer, V.;
Eastwood, J. P.; Gallagher, P. T.; Kilpua, E. K. J.; Magdalenic, J.;
Mierla, M.; Möstl, C.; Rouillard, A. P.; Odstrčil, D.; Poedts, S.
Bibcode: 2022SoPh..297...23R
Altcode:
We present the results of a comparative study between automatic
and manually compiled coronal mass ejection (CME) catalogues based
on observations from the Heliospheric Imagers (HIs) onboard NASA's
Solar Terrestrial Relations Observatory (STEREO) spacecraft. Using
the Computer Aided CME Tracking software(CACTus), CMEs are identified
in HI data using an automatic feature-detection algorithm, while
the Heliospheric Imagers Catalogue(HICAT) includes CMEs that are
detected by visual inspection of HI images. Both catalogues were
compiled as part of the EU FP7 Heliospheric Cataloguing, Analysis and
Techniques Service (HELCATS) project (www.helcats-fp7.eu). We compare
observational parameters of the CMEs from CACTus to those listed in
HICAT, such as CME frequency, position angle (PA), and PA-width. We
also compare CACTus-derived speeds to speeds derived from applying
geometric modelling to the majority of the HICAT CMEs, the results
of which are listed in the HELCATS Heliospheric Imagers Geometric
Catalogue(HIGeoCAT). We find that both CACTus and HICAT catalogues
contain a similar number of events when we exclude events narrower than
20∘, which are not included in the HICAT catalogue but are
found to be identified by CACTus. PA-distributions are strongly peaked
around 90∘ and 270∘, with a slightly larger
CME frequency northwards of the equatorial plane (particularly for the
STEREO-A versions of both catalogues). The CME PA-widths in both HICAT
and CACTus catalogues peak at approximately 60∘. Manually
derived speeds from HIGeoCAT and automatically derived speeds by
CACTus correlate well for values lower than 1000 km s−1,
in particular when CMEs are propagating close to the plane of the sky.
Title: The magnetic flux rope structure of coronal mass ejections -
2021 Julius Bartels Medal Lecture at vEGU
Authors: Bothmer, Volker
Bibcode: 2021EGUGA..2311152B
Altcode:
Magnetic clouds are transient solar wind flows in the interplanetary
medium with smooth rotations of the magnetic field vector and low
plasma beta values. The analysis of magnetic clouds identified in the
data of the two Helios spacecraft between 0.3 and 1 AU showed that
they can be interpreted to first order by force-free, large-scale,
cylindrical magnetic flux tubes. A close correlation of their
occurrences was found with disappearing filaments at the Sun. The
magnetic clouds that originated from the northern solar hemisphere
showed predominantly left-handed magnetic helicities and the ones from
the southern hemisphere predominantly right-handed ones. They were
often preceded by an interplanetary shock wave and some were found
to be directly following a coronal mass ejection towards the Helios
spacecraft as detected by the Solwind coronagraph on board the P78-1
satellite. With the SOHO mission unprecedented long-term observations of
coronal mass ejections (CMEs) were taken with the LASCO coronagraphs,
with a spatial and time resolution that allowed to investigate their
internal white-light fine structure. With complementary photospheric and
EUV observations from SOHO, CMEs were found to arise from pre-existing
small scale loop systems, overlying regions of opposite magnetic
polarities. From the characteristic pattern of their source regions in
both solar hemispheres, a generic scheme was presented in which their
projected white-light topology depends primarily on the orientation and
position of the source region"s neutral line on the solar disk. Based
on this interpretation the graduated cylindrical shell method was
developed, which allowed to model the electron density distribution of
CMEs as 3D flux ropes. This concept was validated through stereoscopic
observations of CMEs taken by the coronagraphs of the SECCHI remote
sensing suite on board the twin STEREO spacecraft. The observations
further revealed that the dynamic near-Sun evolution of CMEs often
leads to distortions of their flux rope structure. However, the
magnetic flux rope concept of CMEs is today one of the fundamental
methods in space weather forecasts. With the Parker Solar Probe we
currently observe for the first time CMEs in-situ and remotely at
their birthplaces in the solar corona and can further unravel their
origin and evolution from the corona into the heliosphere. This lecture
provides a state-of-the-art overview on the magnetic structure of CMEs
and includes latest observations from the Parker Solar Probe mission.
Title: Analysis of signal to noise ratio in coronagraph observations
of coronal mass ejections
Authors: Hinrichs, Johannes; Davies, Jackie A.; West, Matthew J.;
Bothmer, Volker; Bourgoignie, Bram; Eyles, Chris J.; Huke, Philipp;
Jiggens, Piers; Nicula, Bogdan; Tappin, James
Bibcode: 2021JSWSC..11...11H
Altcode:
We establish a baseline signal-to-noise ratio (SNR) requirement for the
European Space Agency (ESA)-funded Solar Coronagraph for OPErations
(SCOPE) instrument in its field of view of 2.5-30 solar radii based
on existing observations by the Solar and Heliospheric Observatory
(SOHO). Using automatic detection of coronal mass ejections (CMEs),
we anaylse the impacts when SNR deviates significantly from our
previously established baseline. For our analysis, SNR values are
estimated from observations made by the C3 coronagraph on the Solar and
Heliospheric Observatory (SOHO) spacecraft for a number of different
CMEs. Additionally, we generate a series of artificial coronagraph
images, each consisting of a modelled coronal background and a CME,
the latter simulated using the graduated cylindrical shell (GCS)
model together with the SCRaytrace code available in the Interactive
Data Language (IDL) SolarSoft library. Images are created with CME
SNR levels between 0.5 and 10 at the outer edge of the field of view
(FOV), generated by adding Poisson noise, and velocities between 700
km s-1 and 2800 km s-1. The images are analysed
for the detectability of the CME above the noise with the automatic
CME detection tool CACTus. We find in the analysed C3 images that CMEs
near the outer edge of the field of view are typically 2% of the total
brightness and have an SNR between 1 and 4 at their leading edge. An SNR
of 4 is defined as the baseline SNR for SCOPE. The automated detection
of CMEs in our simulated images by CACTus succeeded well down to SNR =
1 and for CME velocities up to 1400 km s-1. At lower SNR
and higher velocity of ≥ 2100 km s-1 the detection started
to break down. For SCOPE, the results from the two approaches confirm
that the initial design goal of SNR = 4 would, if achieved, deliver a
comparable performance to established data used in operations today,
with a more compact instrument design, and a margin in SNR before
existing automatic detection produces significant false positives.
Title: CMEs in the Heliosphere: III. A Statistical Analysis of the
Kinematic Properties Derived from Stereoscopic Geometrical Modelling
Techniques Applied to CMEs Detected in the Heliosphere from 2008 to
2014 by STEREO/HI-1
Authors: Barnes, D.; Davies, J. A.; Harrison, R. A.; Byrne, J. P.;
Perry, C. H.; Bothmer, V.; Eastwood, J. P.; Gallagher, P. T.; Kilpua,
E. K. J.; Möstl, C.; Rodriguez, L.; Rouillard, A. P.; Odstrčil, D.
Bibcode: 2020SoPh..295..150B
Altcode: 2020arXiv200614879B
We present an analysis of coronal mass ejections (CMEs) observed
by the Heliospheric Imagers (HIs) onboard NASA's Solar Terrestrial
Relations Observatory (STEREO) spacecraft. Between August 2008 and
April 2014 we identify 273 CMEs that are observed simultaneously,
by the HIs on both spacecraft. For each CME, we track the observed
leading edge, as a function of time, from both vantage points,
and apply the Stereoscopic Self-Similar Expansion (SSSE) technique
to infer their propagation throughout the inner heliosphere. The
technique is unable to accurately locate CMEs when their observed
leading edge passes between the spacecraft; however, we are able to
successfully apply the technique to 151, most of which occur once the
spacecraft-separation angle exceeds 180∘, during solar
maximum. We find that using a small half-width to fit the CME can
result in inferred acceleration to unphysically high velocities and that
using a larger half-width can fail to accurately locate the CMEs close
to the Sun because the method does not account for CME over-expansion
in this region. Observed velocities from SSSE are found to agree well
with single-spacecraft (SSEF) analysis techniques applied to the same
events. CME propagation directions derived from SSSE and SSEF analysis
agree poorly because of known limitations present in the latter.
Title: The Solar Orbiter Heliospheric Imager (SoloHI)
Authors: Howard, R. A.; Vourlidas, A.; Colaninno, R. C.; Korendyke,
C. M.; Plunkett, S. P.; Carter, M. T.; Wang, D.; Rich, N.; Lynch,
S.; Thurn, A.; Socker, D. G.; Thernisien, A. F.; Chua, D.; Linton,
M. G.; Koss, S.; Tun-Beltran, S.; Dennison, H.; Stenborg, G.; McMullin,
D. R.; Hunt, T.; Baugh, R.; Clifford, G.; Keller, D.; Janesick, J. R.;
Tower, J.; Grygon, M.; Farkas, R.; Hagood, R.; Eisenhauer, K.; Uhl,
A.; Yerushalmi, S.; Smith, L.; Liewer, P. C.; Velli, M. C.; Linker,
J.; Bothmer, V.; Rochus, P.; Halain, J. -P.; Lamy, P. L.; Auchère,
F.; Harrison, R. A.; Rouillard, A.; Patsourakos, S.; St. Cyr, O. C.;
Gilbert, H.; Maldonado, H.; Mariano, C.; Cerullo, J.
Bibcode: 2020A&A...642A..13H
Altcode:
Aims: We present the design and pre-launch performance of
the Solar Orbiter Heliospheric Imager (SoloHI) which is an instrument
prepared for inclusion in the ESA/NASA Solar Orbiter mission, currently
scheduled for launch in 2020.
Methods: The goal of this paper
is to provide details of the SoloHI instrument concept, design, and
pre-flight performance to give the potential user of the data a better
understanding of how the observations are collected and the sources
that contribute to the signal.
Results: The paper discusses
the science objectives, including the SoloHI-specific aspects, before
presenting the design concepts, which include the optics, mechanical,
thermal, electrical, and ground processing. Finally, a list of planned
data products is also presented.
Conclusions: The performance
measurements of the various instrument parameters meet or exceed the
requirements derived from the mission science objectives. SoloHI is
poised to take its place as a vital contributor to the science success
of the Solar Orbiter mission.
Title: High resolution multi-viewpoint observations of CME kinematics
and dynamics
Authors: Mrotzek, Niclas; Bothmer, Volker
Bibcode: 2020EGUGA..2222532M
Altcode:
Coronal mass ejections (CMEs) are impulsive outbursts of coronal
plasma bound in magnetic structures. Their initiation and evolution
into the heliosphere covers several orders of magnitude of temporal and
spatial scales that can be observed with space-borne extreme ultraviolet
imagers, coronagraphs and heliospheric imagers. In this work we present
a systematic investigation of the early dynamics of CMEs including their
kinematics, orientation and geometrical evolution. For this purpose, a
dedicated set of 21 Earth-directed CMEs between July 2011 and November
2012 was selected and analyzed. The CME parametrization is obtained
by applying a 3D modelling method, the Graduated Cylindrical Shell
(GCS) model, to simultaneous multi-viewpoint observations taken with
the SECCHI instrument suite onboard the twin STEREO spacecraft and
with the LASCO coronagraphs onboard the SOHO satellite. By using
these instruments, the CME dynamics including the kinematics and
geometry, are covered in high detail over a wide spatial range. For
the majority of events it started in the field of view of EUVI below 2
solar radii and extended into the field of view of HI1 up to 100 solar
radii. The results reveal interactions of the CMEs with the ambient
solar wind. CME deflections of up to 31° in longitude and 18° in
latitude were measured within the first 30 solar radii. Furthermore,
evidence of CME oscillations with periods between 29 and 93 minutes
were found. The analysis provides important implications for more
reliable space weather forecasts and further analysis through the new
observations from Parker Solar Probe and Solar Orbiter.
Title: Simulating White-Light Images of Coronal Structures for Parker
Solar Probe/WISPR: Study of the Total Brightness Profiles
Authors: Nisticò, Giuseppe; Bothmer, Volker; Vourlidas, Angelos;
Liewer, Paulett C.; Thernisien, Arnaud F.; Stenborg, Guillermo;
Howard, Russell A.
Bibcode: 2020SoPh..295...63N
Altcode: 2020arXiv200405447N
The Wide-field Imager for Parker Solar Probe (WISPR) captures
unprecedented white-light images of the solar corona and inner
heliosphere. Thanks to the uniqueness of the Parker Solar Probe's
(PSP) orbit, WISPR is able to image "locally" coronal structures at
high spatial and time resolutions. The observed plane of sky, however,
rapidly changes because of the PSP's high orbital speed. Therefore,
the interpretation of the dynamics of the coronal structures recorded
by WISPR is not straightforward. A first study, undertaken by Liewer et
al. (Solar Phys.294, 93, 2019), shows how different coronal features
(e.g., streamers, flux ropes) appear in the field-of-view of WISPR
by means of raytracing simulations. In particular, they analyze
the effects of the spatial resolution changes on both the images
and the associated height-time maps, and introduce the fundamentals
for geometric triangulation. In this follow-up paper, we focus on
the study of the total brightness of a simple, spherical, plasma
density structure, to understand how the analysis of Thomson-scattered
emission by the electrons in a coronal feature can shed light into the
determination of its kinematic properties. We investigate two cases:
(i) a density sphere at a constant distance from the Sun for different
heliographic longitudes; (ii) a density sphere moving outwardly with
constant speed. The study allows us to characterize the effects of
the varying heliocentric distance of the observer and scattering angle
on the total brightness observed, which we exploit to contribute to a
better determination of the position and speed of the coronal features
observed by WISPR.
Title: Imaging the Solar Corona From Within
Authors: Hess, P.; Howard, R.; Vourlidas, A.; Bothmer, V.; Colaninno,
R.; DeForest, C.; Gallagher, B.; Hall, J. R.; Higginson, A.; Korendyke,
C.; Kouloumvakos, A.; Lamy, P.; Liewer, P.; Linker, J.; Linton, M.;
Penteado, P.; Plunkett, S.; Poirer, N.; Raouafi, N.; Rich, N.; Rochus,
P.; Rouillard, A.; Socker, D.; Stenborg, G.; Thernisien, A.; Viall, N.
Bibcode: 2020AAS...23514907H
Altcode:
Parker Solar Probe (PSP), launched, in August 2018 is humanity's
first probe of a stellar atmosphere. It will make measurements of
the near-Sun plasma from 'within' the outer corona with gradually
reduced perihelia from its first perihelia of 35 Rs in 2018-19 to 9.8
Rs in 2025. Here we report the results from the imaging observations
of the electron and dust corona, whe PSP was 35-54 Rs from the solar
surface, taken by the Wide-field Imager for Solar Probe (WISPR). The
spacecraft was near-corotating with the solar corona throughout the
observing window, which is an unprecedented situation for any type of
coronal imaging. Our initial analysis uncovers a long-hypothesized
depletion of the primordial dust orbiting near the Sun, reveals the
plasma structure of small-scale ejections, and provides a strict test
for validating model predictions of the large-scale configuration of
the coronal plasma. Thus, WISPR imaging allows the study of near-Sun
dust dynamics as the mission progresses. The high-resolution images
of small transients, largely unresolved from 1 AU orbits, unravel
the sub-structures of small magnetic flux ropes and show that the
Sun continually releases helical magnetic fields in the background
wind. Finally, WISPR's observations of the coronal streamer evolution
confirm the large-scale topology of the solar corona but they also
reveal that, as recently predicted, streamers are composed of yet
smaller sub-streamers channeling continual density fluctuations at
all visible scales.
Title: Imaging the Solar Corona from Within: First Results from the
Parker Solar Probe Telescope
Authors: Howard, R. A.; Vourlidas, A.; Bothmer, V.; Colaninno, R. C.;
DeForest, C.; Gallagher, B.; Hall, J. R.; Hess, P.; Higginson, A. K.;
Korendyke, C.; Kouloumvakos, A.; Lamy, P.; Liewer, P. C.; Linker, J.;
Linton, M.; Penteado, P. F.; Plunkett, S. P.; Poirier, N.; Raouafi,
N.; Rich, N.; Rochus, P. L.; Rouillard, A. P.; Socker, D. G.; Stenborg,
G.; Thernisien, A.; Viall, N. M.
Bibcode: 2019AGUFMSH11A..04H
Altcode:
Parker Solar Probe (PSP) launched in August 2018 is humanity's
first probe of a stellar atmosphere. It will make measurements of
the near-Sun plasma from 'within' the outer corona with gradually
reduced perihelia from its first perihelia of 35 Rs in 2018-19 to 9.8
Rs in 2025. Here we report the results from the imaging observations
of the electron and dust corona, whe PSP was 35-54 Rs from the solar
surface, taken by the Wide-field Imager for Solar Probe (WISPR). The
spacecraft was near-corotating with the solar corona throughout the
observing window, which is an unprecedented situation for any type of
coronal imaging. Our initial analysis uncovers a long-hypothesized
depletion of the primordial dust orbiting near the Sun, reveals the
plasma structure of small-scale ejections, and provides a strict test
for validating model predictions of the large-scale configuration of
the coronal plasma. Thus, WISPR imaging allows the study of near-Sun
dust dynamics as the mission progresses. The high-resolution images
of small transients, largely unresolved from 1 AU orbits, unravel
the sub-structures of small magnetic flux ropes and show that the
Sun continually releases helical magnetic fields in the background
wind. Finally, WISPR's observations of the coronal streamer evolution
confirm the large-scale topology of the solar corona but they also
reveal that, as recently predicted, streamers are composed of yet
smaller sub-streamers channeling continual density fluctuations at
all visible scales.
Title: The Solar Orbiter Heliospheric Imager (SoloHI) for the Solar
Orbiter Mission: Science and Instrument Status
Authors: Vourlidas, A.; Howard, R. A.; Colaninno, R. C.; Korendyke,
C.; Thernisien, A.; Linton, M.; Tun Beltran, S.; Liewer, P. C.; Velli,
M.; Linker, J.; Bothmer, V.; Rochus, P. L.; Lamy, P. L.
Bibcode: 2019AGUFMSH24A..08V
Altcode:
The SoloHI instrument has completed its development effort and has been
integrated onto the Solar Orbiter spacecraft. The mission, scheduled
for launch in February 2020, will undergo gravity assist maneuvers
around Venus to change both the perihelion distance as well as the
plane of the orbit to ultimately achieve a minimum perihelion of 0.28
AU and an orbital inclination of about 35° relative to the ecliptic
plane. The remote sensing instruments will operate for three 10-day
periods out of the nominal 6-month orbit. SoloHI detects sunlight
scattered by free electrons in the corona and solar wind from 5° to
45° elongation in visible wavelengths, providing linkage between solar
and solar wind observations. The science investigation focuses mainly on
the solar wind, including streamers, small-scale intensity and density
fluctuations, jets, and Coronal Mass Ejections (CMEs). SoloHI is very
similar to the HI-1 instrument on STEREO/SECCHI but with double the FOV
of HI-1. In this paper, we present our preparations for the mission
including the instrument status, our science planning strategy, our
observing plans for cruise phase, calibrations, early science and our
low-latency and science data products This work has been supported
by NASA.
Title: Challenges in the Analysis of Images from the Wide-field Imager
(WISPR) on Parker Solar Probe
Authors: Liewer, P. C.; Hall, J. R.; Penteado, P.; Vourlidas, A.;
Thernisien, A.; Howard, R. A.; Qiu, J.; Nistico, G.; Bothmer, V.
Bibcode: 2019AGUFMSH23A..09L
Altcode:
The three-to-five-month highly elliptical orbit of Parker Solar Probe
(PSP), approaching within 10 solar radii of the Sun, will allow the
Wide-field Imager for Solar Probe (WISPR) to view the corona with
unprecedented spatial resolution from multiple viewpoints. WISPR,
located on the ram side of PSP, will image and fly through structures
sample by the in situ instruments. WISPR has a wide fixed angular
field-of-view (FOV), extending radially from 13.5° to 108° from
the Sun and approximately 50° in the transverse direction, but the
physical extent of the imaged coronal region varies directly with the
distance of the spacecraft from the Sun. Challenges to interpreting
the motion of density features seen in the WISPR images come from the
wide and changing field-of-view and the unknown extent of the region
of the coronal that co-rotates with the Sun. To relate and compare
features seen in the images to observation by other instruments and
spacecraft with other locations and viewpoints, it is necessary to
relate the field-of-view of the WISPR telescopes at any given time
to other frames of reference, such as the various Heliographic and
Heliocentric coordinate systems. Here we discuss re-projections of
WISPR images into several frames, made utilizing the World Coordinate
System, which relies on information in the images' FITS headers
(see W. T. Thompson, 2006, DOI: 10.1051/0004 6361:20054262). We will
present methods for creating elongation vs. time images (J-maps)
for WISPR images and also a technique for tracking observed density
features to determine their 3D trajectories. These methods will be
illustrated using data from WISPR's first encounters with the Sun.
Title: Near-Sun observations of an F-corona decrease and K-corona
fine structure
Authors: Howard, R. A.; Vourlidas, A.; Bothmer, V.; Colaninno, R. C.;
DeForest, C. E.; Gallagher, B.; Hall, J. R.; Hess, P.; Higginson,
A. K.; Korendyke, C. M.; Kouloumvakos, A.; Lamy, P. L.; Liewer, P. C.;
Linker, J.; Linton, M.; Penteado, P.; Plunkett, S. P.; Poirier, N.;
Raouafi, N. E.; Rich, N.; Rochus, P.; Rouillard, A. P.; Socker, D. G.;
Stenborg, G.; Thernisien, A. F.; Viall, N. M.
Bibcode: 2019Natur.576..232H
Altcode:
Remote observations of the solar photospheric light scattered by
electrons (the K-corona) and dust (the F-corona or zodiacal light)
have been made from the ground during eclipses1 and from
space at distances as small as 0.3 astronomical units2-5 to
the Sun. Previous observations6-8 of dust scattering have
not confirmed the existence of the theoretically predicted dust-free
zone near the Sun9-11. The transient nature of the corona
has been well characterized for large events, but questions still
remain (for example, about the initiation of the corona12
and the production of solar energetic particles13) and
for small events even its structure is uncertain14. Here
we report imaging of the solar corona15 during the first
two perihelion passes (0.16-0.25 astronomical units) of the Parker
Solar Probe spacecraft13, each lasting ten days. The view
from these distances is qualitatively similar to the historical views
from ground and space, but there are some notable differences. At
short elongations, we observe a decrease in the intensity of the
F-coronal intensity, which is suggestive of the long-sought dust
free zone9-11. We also resolve the fine-scale plasma
structure of very small eruptions, which are frequently ejected from
the Sun. These take two forms: the frequently observed magnetic flux
ropes12,16 and the predicted, but not yet observed, magnetic
islands17,18 arising from the tearing-mode instability in
the current sheet. Our observations of the coronal streamer evolution
confirm the large-scale topology of the solar corona, but also reveal
that, as recently predicted19, streamers are composed of
yet smaller substreamers channelling continual density fluctuations
at all visible scales.
Title: SCOPE: a coronagraph for operational space weather prediction:
phase A/B1 design and breadboarding
Authors: Middleton, Kevin F.; Anwand, Heiko; Bothmer, Volker; Davies,
Jackie A.; Earle, Andrew; Ergenzinger, Klaus; Eyles, Chris J.; Hardie,
Robert; Hellin, Marie-Laure; Hinrichs, Johannes; Huke, Philipp;
Jiggens, Piers; Kirschner, Volker; Mazy, Emmanuel; McCarron, Thomas;
Nicula, Bogdan; Stopfkuchen, Lars; Tappin, S. James; Tosh, Ian A. J.;
Waltham, Nick R.; West, Matthew J.
Bibcode: 2019SPIE11180E..3AM
Altcode:
Accurate prediction of the arrival of solar wind phenomena, in
particular coronal mass ejections (CMEs), is becoming more important
given our ever-increasing reliance on technology. SCOPE is a coronagraph
specifically optimised for operational space weather prediction,
designed to provide early evidence of Earth-bound CMEs. In this paper,
we present results from phase A/B1 of the instrument's development,
which included conceptual design and a program of breadboard testing. We
describe the conceptual design of the instrument. In particular, we
explain the design and analysis of the straylight rejection baffles and
occulter needed to block the image of the solar disc, in order to render
the much fainter corona visible. We discuss the development of in-house
analysis code to predict the straylight diffraction effects that limit
the instrument's performance, and present results, which we compare
against commercially available analysis tools and the results from
breadboard testing. In particular, we discuss some of the challenges
of predicting straylight effects in this type of instrument and the
methods we have developed for overcoming them. We present the test
results from an optical breadboard, designed to verify the end-to-end
straylight rejection of the instrument. The design and development
of both the breadboard and the test facility is presented. We discuss
some of the challenges of measuring very low levels of straylight and
how these drive the breadboard and test facility design. We discuss
the test and analysis procedures developed to ensure a representative,
complete characterisation of the instrument's straylight response.
Title: Simulating White Light Images of Coronal Structures for WISPR/
Parker Solar Probe: Effects of the Near-Sun Elliptical Orbit
Authors: Liewer, P.; Vourlidas, A.; Thernisien, A.; Qiu, J.; Penteado,
P.; Nisticò, G.; Howard, R.; Bothmer, V.
Bibcode: 2019SoPh..294...93L
Altcode:
The three-to-five-month elliptical orbit of Parker Solar Probe
(PSP), approaching within 10 solar radii of the Sun, will allow the
Wide-field Imager for Solar Probe (WISPR) to view the corona with
unprecedented spatial resolution from multiple viewpoints. WISPR has
a wide fixed angular field of view, extending from 13.5∘
to 108∘ from the Sun and approximately 50∘
in the transverse direction, but the physical extent of the imaged
coronal region varies directly with the distance of the spacecraft from
the Sun. In a solar encounter period of approximately 10 days around
perihelion, PSP covers over 100 - 200° of heliographic longitude and
the distance from the Sun varies by a factor of two to five. In this
paper, we use synthetic white-light images to study the effects of the
rapid elliptical orbit on the images that can be anticipated for WISPR's
observations. We find that sequences of images can help identify coronal
density features that will be sampled by in-situ instruments. We also
find that the multiple viewpoints, provided by the rapid motion near
perihelion, can be used to obtain three-dimensional information on
the coronal density features.
Title: CMEs in the Heliosphere: II. A Statistical Analysis of the
Kinematic Properties Derived from Single-Spacecraft Geometrical
Modelling Techniques Applied to CMEs Detected in the Heliosphere
from 2007 to 2017 by STEREO/HI-1
Authors: Barnes, D.; Davies, J. A.; Harrison, R. A.; Byrne, J. P.;
Perry, C. H.; Bothmer, V.; Eastwood, J. P.; Gallagher, P. T.; Kilpua,
E. K. J.; Möstl, C.; Rodriguez, L.; Rouillard, A. P.; Odstrčil, D.
Bibcode: 2019SoPh..294...57B
Altcode:
Recent observations with the Heliospheric Imagers (HIs) onboard the twin
NASA Solar Terrestrial Relations Observatory (STEREO) spacecraft have
provided unprecedented observations of a large number of coronal mass
ejections (CMEs) in the inner heliosphere. In this article we discuss
the generation of the HIGeoCAT CME catalogue and perform a statistical
analysis of its events. The catalogue was generated as part of the
EU FP7 HELCATS (Heliospheric Cataloguing, Analysis and Techniques
Service) project (www.helcats-fp7.eu/). It is created by generating
time/elongation maps for CMEs using observations from the inner (HI-1)
and outer (HI-2) cameras along a position angle close to the CME
apex. Next, we apply single-spacecraft geometric-fitting techniques
to determine the kinematic properties of these CMEs, including their
speeds, propagation directions, and launch times. The catalogue contains
a total of 1455 events (801 from STEREO-A and 654 from STEREO-B)
from April 2007 to the end of August 2017. We perform a statistical
analysis of the properties of CMEs in HIGeoCAT and compare the results
with those from the Large Angle Spectrometric Coronagraph (LASCO) CDAW
catalogues (Yashiro et al.J. Geophys. Res. Space Phys.109, A07105,
2004) and the COR-2 catalogue of Vourlidas et al. (Astrophys. J.838,
141, 2004) during the same period. We find that the distributions of
both speeds and latitudes for the HIGeoCAT CMEs correlate with the
sunspot number over the solar cycle. We also find that the HI-derived
CME speed distributions are generally consistent with coronagraph
catalogues over the solar cycle, albeit with greater absolute speeds
due to the differing methods with which each is derived.
Title: What we know and don't know about coronal mass ejections -
The answer is blowing in my presentation
Authors: Bothmer, Volker
Bibcode: 2019EGUGA..2110529B
Altcode:
In the same year the first interplanetary shock waves were discovered
in the solar wind through in-situ measurements the famous song "Blowing
in the Wind" was released by Bob Dylan. From that time on more and more
advanced space observations of the Sun and the interplanetary medium
have provided fundamental insights into the physics of coronal mass
ejections (CMEs) and their heliospheric evolution. I will review our
current understanding of CMEs, which is of extreme importance today to
help facilitate reliable space weather predictions in the near future. I
will also point out challenging remaining questions that need to be
answered by future investigations. My historical walkthrough of key
CME research will be presented from the watchtower of a space scientist
in the context of Dylan's famous lyrics since we know "the times they
are a-changin".
Title: Raytracing simulations of Parker Solar Probe/WISPR images
Authors: Nisticò, Giuseppe; Liewer, Paulett; Vourlidas, Angelos;
Thernisien, Arnaud; Howard, Russell; Bothmer, Volker
Bibcode: 2019EGUGA..2114202N
Altcode:
The Wide-field Imager for Parker Solar Probe (WISPR) provides
unprecedented white-light images of the solar corona and inner
heliosphere from unconventional viewpoints thanks to the close
perihelion transits of Parker Solar Probe. WISPR images coronal
structures at high spatial and time resolutions, but the data
analysis needs to consider the continuous change of the observation's
plane-of-sky and hence of the projection due to PSP's fast orbital
speed and high orbital eccentricity. Therefore, it is important to
understand how these factors affect the images. Here, we present an
analysis of simulated WISPR images and discuss how WISPR data can
be analyzed to study the physical conditions of the corona and the
near-Sun environment.
Title: Combined geometrical modelling and white-light mass
determination of coronal mass ejections
Authors: Pluta, Adam; Mrotzek, Niclas; Vourlidas, Angelos; Bothmer,
Volker; Savani, Neel
Bibcode: 2019A&A...623A.139P
Altcode:
Context. We use forward modelling on multi-viewpoint coronagraph
observations to estimate the 3-dimensional morphology, initial speed
and deprojected masses of Coronal Mass Ejections (CMEs). The CME
structure is described via the Graduated Cylindrical Shell (GCS) model,
which enables the measurement of CME parameters in a consistent and
comparable manner.
Aims: This is the first large-scale use of the
GCS model to estimate CME masses, so we discuss inherent peculiarities
and implications for the mass determination with a special focus on CME
events emerging from close to the observer's central meridian. Further,
we analyse the CME characteristics best suited to estimate the CME mass
in a timely manner to make it available to CME arrival predictions.
Methods: We apply the method to a set of 122 bright events observed
simultaneously from two vantage points with the COR2 coronagraphs
onboard of the twin NASA STEREO spacecraft. The events occurred between
January 2007 and December 2013 and are compiled in an online catalogue
within the EU FP7 project HELCATS. We statistically analyse the derived
CME parameters, their mutual connection and their relation to the solar
cycle.
Results: We show that the derived morphology of intense
disk events is still systematically overestimated by up to a factor of
2 with stereoscopic modelling, which is the same order of magnitude as
for observations from only one vantage point. The overestimation is very
likely a combination of projection effects as well as the increased
complexity of separating CME shocks and streamers from CME fronts
for such events. We further show that CME mass determination of disk
events can lead to overestimation of the mass by about a factor of 10
or more, in case of overlapping bright structures.
Conclusions:
We conclude that for stereoscopic measurements of disk events, the
measurement of the initial CME speed is the most reliable one. We
further suggest that our presented CME speed-mass correlation is most
suited to estimate the CME mass early from coronagraph observations.
Title: Observing the corona and inner heliosphere with Parker
Solar Probe
Authors: Nisticò, G.; Bothmer, V.; Liewer, P.; Vourlidas, , A.;
Thernisien, A.
Bibcode: 2019NCimC..42...21N
Altcode:
The recently launched Parker Solar Probe (PSP) mission is expected
to provide unprecedented views of the solar corona and inner
heliosphere. In addition to instruments devoted to taking measurements
of the local solar wind, the spacecraft carries a visible imager: the
Wide-field Imager for Solar PRobe (WISPR). WISPR will take advantage
of the proximity of the spacecraft to the Sun to perform local imaging
of the near-Sun environment. WISPR will observe coronal structures at
high spatial and time resolutions, although the observed plane-of-sky
will rapidly change because of the fast transit at the perihelia. We
present a concise description of the PSP mission, with particular
regard to the WISPR instrument, discussing its main scientific goals,
targets of observations, and outlining the possible synergies with
current and upcoming space missions.
Title: Oscillations of cometary tails: a vortex shedding phenomenon?
Authors: Nisticò, G.; Vladimirov, V.; Nakariakov, V. M.; Battams,
K.; Bothmer, V.
Bibcode: 2018A&A...615A.143N
Altcode: 2018arXiv180400997N
Context. During their journey to perihelion, comets may appear in the
field of view of space-borne optical instruments, showing in some
cases a nicely developed plasma tail extending from their coma and
exhibiting an oscillatory behaviour.
Aims: The oscillations of
cometary tails may be explained in terms of vortex shedding because of
the interaction of the comet with the solar wind streams. Therefore,
it is possible to exploit these oscillations in order to infer the
value of the Strouhal number S t, which quantifies the vortex shedding
phenomenon, and the physical properties of the local medium.
Methods: We used the Heliospheric Imager (HI) data of the Solar
TErrestrial Relations Observatory (STEREO) mission to study the
oscillations of the tails of comets 2P/Encke and C/2012 S1 (ISON) during
their perihelion in Nov 2013. We determined the corresponding Strouhal
numbers from the estimates of the halo size, the relative speed of the
solar wind flow, and the period of the oscillations.
Results:
We found that the estimated Strouhal numbers are very small, and the
typical value of S t 0.2 would be extrapolated for size of the halo
larger than 106 km.
Conclusions: Although the vortex
shedding phenomenon has not been unambiguously revealed, the findings
suggest that some kind of magnetohydrodynamic (MHD) instability process
is responsible for the observed behaviour of cometary tails, which
can be exploited for probing the physical conditions of the near-Sun
region. The movies associated to Figs. 1 and 4 are available at http://www.aanda.org
Title: Probing the inner heliosphere with comets
Authors: Nisticò, Giuseppe; Vladimirov, Vangelis; Nakariakov, Valery
M.; Battams, Karl; Bothmer, Volker
Bibcode: 2018shin.confE..41N
Altcode:
Optical instruments aboard space missions have recently provided
us with exciting observations of comets in the vicinity of their
perihelion. At this stage, a tail of dust and ions from the comet
nucleus is formed, which interacts with the local solar wind flow and
exhibits an oscillatory dynamics. The observed phenomenon is attributed
to the formation of a Kármán vortex street in the wake of the cometary
coma, whose properties depend upon the characteristics of the comet
itself and the local medium. We present observations of the comets
Encke and ISON detected in 2013 with the Heliospheric Imager aboard
the STEREO spacecraft, and discuss the possibility to exploit comets
as natural probes of the inner heliosphere, by relating the physical
behaviour of cometary tails with the local conditions of the solar wind.
Title: Preparing for Parker Solar Probe: Tracking Moving Solar Wind
Features in Images from the Wide-field Imager for Parker Solar Probe
(WISPR)
Authors: Liewer, Paulett C.; Qiu, Jiong; Nisticò, Giuseppe;
Vourlidas, Angelos; Penteado, Paulo; Thernisien, Arnaud; Howard,
Russell; Bothmer, Volker
Bibcode: 2018shin.confE..43L
Altcode:
The Parker Solar Probe (PSP) trajectory, approaching within 10 solar
radii, will allow the white light imager, WISPR, to view the inner
corona with unprecedented spatial resolution. WISPR, with a field of
view extending from 13.5° to 108° elongation angle from the Sun,
will image the fine-scale coronal structure with arcminute resolution
at high cadence ( 5 - 60 min). The dependency of Thomson scattering on
the distance between the observer and the Sun dictates that WISPR will
be a “local" heliospheric imager, and thus can provide a crucial link
between the visible corona and PSP's in-situ measurements. To prepare
for this unprecedented viewing of the structures in the inner corona,
we are creating synthetic white light images and animations, viewed from
the PSP trajectory, using the white-light ray-tracing package developed
at NRL (available through SolarSoft). We will present results for small
flux ropes moving outward through the corona as well as fly-throughs
of finely structured coronal streamers. We also investigated whether
the 3-D trajectory (direction and velocity) of a density enhancement
(flux rope or
Title: Simulations of PSP/WISPR observations of the corona/inner
heliosphere with raytracing software
Authors: Nisticò, Giuseppe; Liewer, Paulett; Qiu, Jiong; Vourlidas,
Angelos; Bothmer, Volker; Thernisien, Arnaud
Bibcode: 2018shin.confE..40N
Altcode:
The Wide-Field Imager for Parker Solar Probe (WISPR) will observe the
Thomson scattered emission of the corona/inner heliosphere, covering
a range of elongation angles from 13.5 to 108 deg, at high temporal
(0.05-60 min) and spatial resolution (plate scale of 1.2-1.7 arcmin
per pixel). Such images will be taken from unprecedented points of
observation thanks to the highly-eccentric orbits of Parker Solar Probe
(PSP), which will reach the minimum perihelion distance below 10 solar
radii from the Sun's centre.
Title: Preparing for Parker Solar Probe: Synthetic White-light
Imagery and Analysis for the Wide-field Imager (WISPR)
Authors: Liewer, Paulett; Nisticó, Giuseppe; Howard, Russell; Bothmer,
Volker; Thernisien, Arnaud; Vourlidas, Angelos; Penteado, Paulo
Bibcode: 2018cosp...42E2010L
Altcode:
The Parker Solar Probe (PSP) trajectory, approaching within 10 solar
radii, will allow the white light imager, WISPR, to view the inner
corona with unprecedented spatial resolution. WISPR, with a field of
view extending from 13.5° to 108° elongation angle from the Sun, will
image the fine-scale coronal structure with arcminute resolution. The
dependency of the Thomson scattering on the imaging geometry (distance
and angle from the Sun) dictates that WISPR will be very sensitive to
the emission from plasma close to the spacecraft, in contrast to the
situation for imaging from 1 AU. Thus, WISPR will be the first 'local'
imager providing a crucial link between the large-scale corona and
PSP's in-situ measurements. To prepare for this unprecedented viewing
of the structures in the inner corona, we are creating synthetic
white light images and animations, viewed from the PSP trajectory,
using the white-light ray-tracing package developed at NRL (available
through SolarSoft). We will present results for small flux ropes moving
outward through the corona as well as fly-throughs of finely structured
coronal streamers. Using the synthetic images, analysis techniques
similar to traditional white light "jmaps" are used to find the "track"
of a flux rope's elongation versus time. The "track" is compared with
predictions using simple geometric expressions to gain information on
the 3D trajectory of the flux rope. Additional analysis techniques,
such as re-projections of the images, will also be discussed.
Title: CMEs in the Heliosphere: I. A Statistical Analysis of the
Observational Properties of CMEs Detected in the Heliosphere from
2007 to 2017 by STEREO/HI-1
Authors: Harrison, R. A.; Davies, J. A.; Barnes, D.; Byrne, J. P.;
Perry, C. H.; Bothmer, V.; Eastwood, J. P.; Gallagher, P. T.; Kilpua,
E. K. J.; Möstl, C.; Rodriguez, L.; Rouillard, A. P.; Odstrčil, D.
Bibcode: 2018SoPh..293...77H
Altcode: 2018arXiv180402320H
We present a statistical analysis of coronal mass ejections (CMEs)
imaged by the Heliospheric Imager (HI) instruments on board NASA's
twin-spacecraft STEREO mission between April 2007 and August 2017 for
STEREO-A and between April 2007 and September 2014 for STEREO-B. The
analysis exploits a catalogue that was generated within the FP7
HELCATS project. Here, we focus on the observational characteristics
of CMEs imaged in the heliosphere by the inner (HI-1) cameras, while
following papers will present analyses of CME propagation through
the entire HI fields of view. More specifically, in this paper we
present distributions of the basic observational parameters - namely
occurrence frequency, central position angle (PA) and PA span - derived
from nearly 2000 detections of CMEs in the heliosphere by HI-1 on
STEREO-A or STEREO-B from the minimum between Solar Cycles 23 and 24
to the maximum of Cycle 24; STEREO-A analysis includes a further 158
CME detections from the descending phase of Cycle 24, by which time
communication with STEREO-B had been lost. We compare heliospheric CME
characteristics with properties of CMEs observed at coronal altitudes,
and with sunspot number. As expected, heliospheric CME rates correlate
with sunspot number, and are not inconsistent with coronal rates
once instrumental factors/differences in cataloguing philosophy are
considered. As well as being more abundant, heliospheric CMEs, like
their coronal counterparts, tend to be wider during solar maximum. Our
results confirm previous coronagraph analyses suggesting that CME launch
sites do not simply migrate to higher latitudes with increasing solar
activity. At solar minimum, CMEs tend to be launched from equatorial
latitudes, while at maximum, CMEs appear to be launched over a much
wider latitude range; this has implications for understanding the
CME/solar source association. Our analysis provides some supporting
evidence for the systematic dragging of CMEs to lower latitude as they
propagate outwards.
Title: Coronal Magnetic Structure of Earthbound CMEs and In Situ
Comparison
Authors: Palmerio, E.; Kilpua, E. K. J.; Möstl, C.; Bothmer, V.;
James, A. W.; Green, L. M.; Isavnin, A.; Davies, J. A.; Harrison, R. A.
Bibcode: 2018SpWea..16..442P
Altcode: 2018arXiv180304769P
Predicting the magnetic field within an Earth-directed coronal
mass ejection (CME) well before its arrival at Earth is one of the
most important issues in space weather research. In this article,
we compare the intrinsic flux rope type, that is, the CME orientation
and handedness during eruption, with the in situ flux rope type for 20
CME events that have been uniquely linked from Sun to Earth through
heliospheric imaging. Our study shows that the intrinsic flux rope
type can be estimated for CMEs originating from different source
regions using a combination of indirect proxies. We find that only
20% of the events studied match strictly between the intrinsic and in
situ flux rope types. The percentage rises to 55% when intermediate
cases (where the orientation at the Sun and/or in situ is close to
45°) are considered as a match. We also determine the change in the
flux rope tilt angle between the Sun and Earth. For the majority of
the cases, the rotation is several tens of degrees, while 35% of the
events change by more than 90°. While occasionally the intrinsic flux
rope type is a good proxy for the magnetic structure impacting Earth,
our study highlights the importance of capturing the CME evolution
for space weather forecasting purposes. Moreover, we emphasize that
determination of the intrinsic flux rope type is a crucial input for
CME forecasting models.
Title: Simulating observations of the corona/inner heliosphere with
the Wide-Field Imager for Parker Solar Probe by raytracing software
Authors: Nisticò, Giuseppe; Liewer, Paulett; Bothmer, Volker;
Vourlidas, Angelos
Bibcode: 2018EGUGA..2018677N
Altcode:
The Wide-Field Imager for Parker Solar PRobe (WISPR) will provide us
with white-light images of the corona/inner heliosphere offset from the
Sun, covering a range of elongation angles from 13.5 to 108 deg, with
a high temporal (0.05-60 min) and spatial resolution (plate scale of
1.2-1.7 arcmin per pixel). Such images will be taken from unprecedented
points of observation thanks to the highly-eccentric orbits of
Parker Solar Probe (PSP), which will reach the minimum perihelion
distance below 10 solar radii from the Sun's centre. Therefore,
it is important to understand how WISPR images will look during the
perihelion phases and when PSP will eventually fly throughout various
coronal structures, e.g. streamers, expanding flux ropes, and jets. In
this talk we will provide a collection of synthetic WISPR images for
different coronal structures by using the raytracing tools available
with the SolarSoftWare package. We will discuss the effects due to the
varying radial distance and the high orbital speed ( 200 km/s) of PSP
on the WISPR images, including the possibility of 3D reconstruction
and the determination of the correct kinematics for expanding flux
ropes and jets.
Title: Connecting Coronal Mass Ejections to Their Solar Active Region
Sources: Combining Results from the HELCATS and FLARECAST Projects
Authors: Murray, Sophie A.; Guerra, Jordan A.; Zucca, Pietro; Park,
Sung-Hong; Carley, Eoin P.; Gallagher, Peter T.; Vilmer, Nicole;
Bothmer, Volker
Bibcode: 2018SoPh..293...60M
Altcode: 2018arXiv180306529M
Coronal mass ejections (CMEs) and other solar eruptive phenomena can be
physically linked by combining data from a multitude of ground-based
and space-based instruments alongside models; however, this can be
challenging for automated operational systems. The EU Framework Package
7 HELCATS project provides catalogues of CME observations and properties
from the Heliospheric Imagers on board the two NASA/STEREO spacecraft
in order to track the evolution of CMEs in the inner heliosphere. From
the main HICAT catalogue of over 2,000 CME detections, an automated
algorithm has been developed to connect the CMEs observed by STEREO
to any corresponding solar flares and active-region (AR) sources
on the solar surface. CME kinematic properties, such as speed and
angular width, are compared with AR magnetic field properties, such as
magnetic flux, area, and neutral line characteristics. The resulting
LOWCAT catalogue is also compared to the extensive AR property
database created by the EU Horizon 2020 FLARECAST project, which
provides more complex magnetic field parameters derived from vector
magnetograms. Initial statistical analysis has been undertaken on the
new data to provide insight into the link between flare and CME events,
and characteristics of eruptive ARs. Warning thresholds determined
from analysis of the evolution of these parameters is shown to be a
useful output for operational space weather purposes. Parameters of
particular interest for further analysis include total unsigned flux,
vertical current, and current helicity. The automated method developed
to create the LOWCAT catalogue may also be useful for future efforts
to develop operational CME forecasting.
Title: Key results and services of HELCATS
Authors: Bothmer, Volker; Harrison, Richard; Davies, Jackie; Rouillard,
Alexis
Bibcode: 2018EGUGA..20.7441B
Altcode:
The EU FP7 project HELCATS (HELIOSPHERIC CATALOGUING, ANALYSIS &
TECHNIQUES SERVICE) has provided new insights into solar wind structure
through combining the comprehensive analysis of heliospheric imaging
observations from the NASA STEREO spacecraft, in concert with associated
remote-sensing and in-situ measurements, with a thorough assessment
of appropriate techniques and models. The project recognised that the
advent of wide-angle imaging of the inner heliosphere has revolutionised
the study of transient and quasi-stationary structures in the solar
wind, in particular Coronal Mass Ejections (CMEs) and Co-rotating
Interaction Regions (CIRs). Prior to the development of wide-angle
imaging of the inner heliosphere, signatures of such solar wind
features could only be observed within a few solar radii of the Sun,
and in the vicinity of a few near-Earth and interplanetary probes making
in-situ measurements of the solar wind. Heliospheric imaging has, for
the first time, filled that vast and crucial observational gap. This
presentation summarises the key results and services established by
the HELCATS project.
Title: Solar-wind predictions for the Parker Solar Probe orbit
Authors: Bothmer, Volker; Venzmer, Malte
Bibcode: 2018EGUGA..20.5245B
Altcode:
The Parker Solar Probe (PSP) (formerly Solar Probe Plus) mission
will be humanity's first in situ exploration of the solar corona
with closest perihelia at 9.86 solar radii distance to the Sun. It
will help answer hitherto unresolved questions on the heating of the
solar corona and the source and acceleration of the solar wind and
solar energetic particles. The scope of the study presented here is
to model the solar-wind environment for PSP's unprecedented distances
in its prime mission phase during the years 2018-2025. The study is
performed within the Coronagraphic German And US SolarProbePlus Survey
(CGAUSS) which is the German contribution to the PSP mission as part
of the Wide-field Imager for Solar PRobe (WISPR). Here we present an
empirical solar-wind model for the inner heliosphere which has been
derived from OMNI and Helios data.
Title: Solar-wind predictions for the Parker Solar Probe
orbit. Near-Sun extrapolations derived from an empirical solar-wind
model based on Helios and OMNI observations
Authors: Venzmer, M. S.; Bothmer, V.
Bibcode: 2018A&A...611A..36V
Altcode: 2017arXiv171107534V
Context. The Parker Solar Probe (PSP; formerly Solar Probe Plus) mission
will be humanitys first in situ exploration of the solar corona with
closest perihelia at 9.86 solar radii (R⊙) distance to
the Sun. It will help answer hitherto unresolved questions on the
heating of the solar corona and the source and acceleration of the
solar wind and solar energetic particles. The scope of this study is
to model the solar-wind environment for PSPs unprecedented distances
in its prime mission phase during the years 2018 to 2025. The study
is performed within the Coronagraphic German And US SolarProbePlus
Survey (CGAUSS) which is the German contribution to the PSP mission
as part of the Wide-field Imager for Solar PRobe. Aim. We present an
empirical solar-wind model for the inner heliosphere which is derived
from OMNI and Helios data. The German-US space probes Helios 1 and
Helios 2 flew in the 1970s and observed solar wind in the ecliptic
within heliocentric distances of 0.29 au to 0.98 au. The OMNI database
consists of multi-spacecraft intercalibrated in situ data obtained near
1 au over more than five solar cycles. The international sunspot number
(SSN) and its predictions are used to derive dependencies of the major
solar-wind parameters on solar activity and to forecast their properties
for the PSP mission.
Methods: The frequency distributions for the
solar-wind key parameters, magnetic field strength, proton velocity,
density, and temperature, are represented by lognormal functions. In
addition, we consider the velocity distributions bi-componental shape,
consisting of a slower and a faster part. Functional relations to
solar activity are compiled with use of the OMNI data by correlating
and fitting the frequency distributions with the SSN. Further, based
on the combined data set from both Helios probes, the parameters
frequency distributions are fitted with respect to solar distance
to obtain power law dependencies. Thus an empirical solar-wind model
for the inner heliosphere confined to the ecliptic region is derived,
accounting for solar activity and for solar distance through adequate
shifts of the lognormal distributions. Finally, the inclusion of SSN
predictions and the extrapolation down to PSPs perihelion region enables
us to estimate the solar-wind environment for PSPs planned trajectory
during its mission duration.
Results: The CGAUSS empirical
solar-wind model for PSP yields dependencies on solar activity and solar
distance for the solar-wind parameters' frequency distributions. The
estimated solar-wind median values for PSPs first perihelion in 2018
at a solar distance of 0.16 au are 87 nT, 340 km s-1, 214
cm-3, and 503 000 K. The estimates for PSPs first closest
perihelion, occurring in 2024 at 0.046 au (9.86 R⊙),
are 943 nT, 290 km s-1, 2951 cm-3, and 1 930 000
K. Since the modeled velocity and temperature values below approximately
20 R⊙appear overestimated in comparison with existing
observations, this suggests that PSP will directly measure solar-wind
acceleration and heating processes below 20 R⊙ as planned.
Title: The Solar Orbiter Heliospheric Imager (SoloHI) for the Solar
Orbiter Mission
Authors: Howard, R.; Colaninno, R. C.; Plunkett, S. P.; Thernisien,
A. F.; Wang, D.; Rich, N.; Korendyke, C.; Socker, D. G.; Linton, M.;
McMullin, D. R.; Vourlidas, A.; Liewer, P. C.; De Jong, E.; Velli,
M.; Mikic, Z.; Bothmer, V.; Philippe, L.; Carter, M. T.
Bibcode: 2017AGUFMSH23D2681H
Altcode:
The SoloHI instrument has completed its development effort and has been
integrated onto the Solar Orbiter (SolO) spacecraft. The SolO mission,
scheduled for launch in February 2019, will undergo gravity assist
maneuvers around Venus to change both the perihelion distance as well
as the plane of the orbit to ultimately achieve a minimum perihelion
of 0.28 AU and an orbital inclination of about 35° relative to the
ecliptic plane. The remote sensing instruments will operate for three
10-day periods out of the nominal 6-month orbit. SoloHI will observe
sunlight scattered by free electrons in the corona/solar wind from 5°
to 45° elongation in visible wavelengths and will provide a coupling
between remote sensing and in situ observations. It is very similar
to the HI-1 instrument on STEREO/SECCHI except that the FOV is twice
the size at 40o. We present our efforts to prepare for the mission
including our observing plans, quick-look plans and some results of
the calibration activities. We gratefully acknowledge the support of
the NASA Solar Orbiter Collaboration project.
Title: The Wide-Field Imager for the Parker Solar Probe Mission
(WISPR)
Authors: Plunkett, S. P.; Howard, R.; Chua, D. H.; Crump, N. A.;
Dennison, H.; Korendyke, C.; Linton, M.; Rich, N.; Socker, D. G.;
Thernisien, A. F.; Wang, D.; Vourlidas, A.; Baugh, R.; Van Duyne,
J. P.; Liewer, P. C.; De Jong, E.; Boies, M. T.; Mikic, Z.; Bothmer,
V.; Rochus, P.; Halain, J. P.
Bibcode: 2017AGUFMSH23D2693P
Altcode:
The Parker Solar Probe (PSP) mission will be humanity's first visit
to the atmosphere of our nearest star, the Sun, when it is launched
in July 2018. PSP will complete 24 orbits between the Sun and Venus
with diminishing perihelia reaching as close as 7 million km (9.86
solar radii) from Sun center. In addition to a suite of in-situ probes
for the magnetic field, plasma, and energetic particles, the payload
includes the Wide Field Imager for Solar Probe (WISPR) that will
record unprecedented visible light images of the solar corona and the
inner heliosphere. WISPR is the smallest heliospheric imager to date,
and comprises two nested wide-field telescopes with large-format (2K
x 2K) APS CMOS detectors to optimize the performance over a combined
95º radial by 58º transverse field of view and to minimize the risk
of dust damage, which may be considerable close to the Sun. WISPR will
discover - in this never-before explored region of the heliosphere - the
fundamental nature of coronal structures and the source regions of the
solar wind as the PSP flies through them, and will determine whether a
dust-free zone exists near the Sun. WISPR has completed its development
effort and has been integrated onto the PSP spacecraft. In this paper,
we will present our efforts to prepare for the mission including our
observing plans and some results of the calibration activities.
Title: The Heliospheric Cataloguing, Analysis and Techniques Service
(HELCATS) project
Authors: Barnes, D.; Harrison, R. A.; Davies, J. A.; Perry, C. H.;
Moestl, C.; Rouillard, A.; Bothmer, V.; Rodriguez, L.; Eastwood,
J. P.; Kilpua, E.; Gallagher, P.; Odstrcil, D.
Bibcode: 2017AGUFMSH31A2713B
Altcode:
Understanding solar wind evolution is fundamental to advancing our
knowledge of energy and mass transport in the solar system, whilst
also being crucial to space weather and its prediction. The advent of
truly wide-angle heliospheric imaging has revolutionised the study of
solar wind evolution, by enabling direct and continuous observation
of both transient and background components of the solar wind as they
propagate from the Sun to 1 AU and beyond. The recently completed,
EU-funded FP7 Heliospheric Cataloguing, Analysis and Techniques
Service (HELCATS) project (1st May 2014 - 30th April 2017) combined
European expertise in heliospheric imaging, built up over the last
decade in particular through leadership of the Heliospheric Imager
(HI) instruments aboard NASA's STEREO mission, with expertise in
solar and coronal imaging as well as the interpretation of in-situ
and radio diagnostic measurements of solar wind phenomena. HELCATS
involved: (1) the cataloguing of transient (coronal mass ejections)
and background (stream/corotating interaction regions) solar wind
structures observed by the STEREO/HI instruments, including estimates of
their kinematic properties based on a variety of modelling techniques;
(2) the verification of these kinematic properties through comparison
with solar source observations and in-situ measurements at multiple
points throughout the heliosphere; (3) the assessment of the potential
for initialising numerical models based on the derived kinematic
properties of transient and background solar wind components; and (4)
the assessment of the complementarity of radio observations (Type II
radio bursts and interplanetary scintillation) in the detection and
analysis of heliospheric structure in combination with heliospheric
imaging observations. In this presentation, we provide an overview
of the HELCATS project emphasising, in particular, the principal
achievements and legacy of this unprecedented project.
Title: Comparison of CME and ICME Structures Derived from
Remote-Sensing and In Situ Observations
Authors: Bothmer, V.; Mrotzek, N.
Bibcode: 2017SoPh..292..157B
Altcode:
We present results from the comparison of the near-Sun and in situ
analysis of two Earth-directed coronal mass ejections (CMEs) with
different 3D orientations and solar source region characteristics. The
CME on 14 July 2000, the so-called Bastille Day storm, a well-studied
event, was observed from a single-point perspective by the Large Angle
and Spectrometric Coronagraph (LASCO) onboard the Solar and Heliospheric
Observatory (SOHO). It caused a major geomagnetic storm with a peak Kp
of 9. The CME originated from a magnetic bipolar photospheric source
region with the polarity inversion line being oriented rather parallel
to the heliographic equator. In contrast, the CME on 29 September
2013, which caused a geomagnetic storm with a peak Kp intensity of 8-,
originated from a magnetic quadrupolar photospheric source region with
the polarity inversion line between the two bipoles almost vertically
oriented with respect to the heliographic equator. The results of a
graduated cylindrical shell (GCS) analysis of the CMEs near the Sun
are compared with the minimum variance analysis (MVA) of the magnetic
field structure of the interplanetary CME (ICME) measured in situ near
Earth's orbit. The results are in good agreement for the September
2013 CME and ICME, whereas the July 2000 ICME appears substantially
inclined near Earth's orbit. The discrepancy can likely be explained
taking into account kinks in the CME's near-Sun structure of the CME
that expands into the interplanetary medium.
Title: CME Dynamics Using STEREO and LASCO Observations: The Relative
Importance of Lorentz Forces and Solar Wind Drag
Authors: Sachdeva, Nishtha; Subramanian, Prasad; Vourlidas, Angelos;
Bothmer, Volker
Bibcode: 2017SoPh..292..118S
Altcode: 2017arXiv170504871S
We seek to quantify the relative contributions of Lorentz forces and
aerodynamic drag on the propagation of solar coronal mass ejections
(CMEs). We use Graduated Cylindrical Shell (GCS) model fits to a
representative set of 38 CMEs observed with the Solar and Heliospheric
Observatory (SOHO) and the Solar and Terrestrial Relations Observatory
(STEREO) spacecraft. We find that the Lorentz forces generally peak
between 1.65 and 2.45 R⊙ for all CMEs. For fast CMEs,
Lorentz forces become negligible in comparison to aerodynamic drag as
early as 3.5 - 4 R⊙. For slow CMEs, however, they become
negligible only by 12 - 50 R⊙. For these slow events,
our results suggest that some of the magnetic flux might be expended in
CME expansion or heating. In other words, not all of it contributes to
the propagation. Our results are expected to be important in building
a physical model for understanding the Sun-Earth dynamics of CMEs.
Title: Modeling observations of solar coronal mass ejections with
heliospheric imagers verified with the Heliophysics System Observatory
Authors: Möstl, C.; Isavnin, A.; Boakes, P. D.; Kilpua, E. K. J.;
Davies, J. A.; Harrison, R. A.; Barnes, D.; Krupar, V.; Eastwood,
J. P.; Good, S. W.; Forsyth, R. J.; Bothmer, V.; Reiss, M. A.;
Amerstorfer, T.; Winslow, R. M.; Anderson, B. J.; Philpott, L. C.;
Rodriguez, L.; Rouillard, A. P.; Gallagher, P.; Nieves-Chinchilla,
T.; Zhang, T. L.
Bibcode: 2017SpWea..15..955M
Altcode: 2017arXiv170300705M
We present an advance toward accurately predicting the arrivals of
coronal mass ejections (CMEs) at the terrestrial planets, including
Earth. For the first time, we are able to assess a CME prediction model
using data over two thirds of a solar cycle of observations with the
Heliophysics System Observatory. We validate modeling results of 1337
CMEs observed with the Solar Terrestrial Relations Observatory (STEREO)
heliospheric imagers (HI) (science data) from 8 years of observations
by five in situ observing spacecraft. We use the self-similar expansion
model for CME fronts assuming 60° longitudinal width, constant speed,
and constant propagation direction. With these assumptions we find that
23%-35% of all CMEs that were predicted to hit a certain spacecraft
lead to clear in situ signatures, so that for one correct prediction,
two to three false alarms would have been issued. In addition, we find
that the prediction accuracy does not degrade with the HI longitudinal
separation from Earth. Predicted arrival times are on average within 2.6
± 16.6 h difference of the in situ arrival time, similar to analytical
and numerical modeling, and a true skill statistic of 0.21. We also
discuss various factors that may improve the accuracy of space weather
forecasting using wide-angle heliospheric imager observations. These
results form a first-order approximated baseline of the prediction
accuracy that is possible with HI and other methods used for data by
an operational space weather mission at the Sun-Earth L5 point.
Title: Radio triangulation of solar radio emissions associated with
the 2012 July 23 CME
Authors: Krupar, Vratislav; Kruparova, Oksana; Santolik, Ondrej;
Bothmer, Volker; Mrotzek, Niclas; Eastwood, Jonathan P.
Bibcode: 2017EGUGA..19.8836K
Altcode:
Coronal mass ejections (CMEs) are large-scale eruptions of magnetized
plasma that may cause severe geomagnetic storms if Earth directed. The
backside CME from 2012 July 23 belongs among historical extreme solar
events due to associated solar energetic particle fluxes and the
CME-driven shock speed above 2000 kms-1. Here, we focus on analysis of
associated interplanetary (IP) radio emissions. The frequency drift
of the IP type II burst provides us with a reasonable speed of the
CME-driven shock. We have successfully applied a radio direction-finding
technique to IP type II and type III bursts observed by the two
identical radio receivers aboard the two STEREO spacecraft. The radio
triangulation technique allows us to localize radio sources in the
IP medium. The obtained locations of the type II and type III bursts
are in a very good agreement with the CME direction. We demonstrate
the complementarity between radio triangulation and 3D reconstruction
techniques for space weather applications.
Title: CME properties and solar source region characteristics -
HELCATS results
Authors: Bothmer, Volker; Mrotzek, Niclas; Murray, Sophie; Gallagher,
Peter; Barnes, David; Davies, Jackie; Harrison, Richard
Bibcode: 2017EGUGA..19.5107B
Altcode:
One objective of the EU FP7 project HELCATS is to derive and
catalogue the characteristics of CMEs observed with the STEREO/COR2
& HI imagers based on geometrical and forward modelling. Here
we present the results of the analysis of a subset of the 122 CME
events that have been dynamically modelled with the GCS-method in
the COR2 field of view and which are compiled in the KINCAT database
at http://www.affects-fp7.eu/helcats-database/database.php. The
CME properties, such as speeds, masses, angular widths, as derived
from modelling, are compared with magnetic field properties of the
corresponding solar source active region, such as magnetic flux,
area, and polarity line characteristics. The results show which solar
parameters define the structure of CMEs at distances around 12 solar
radii and how they can be used for space weather forecast services.
Title: Using helispheric imager observations in predicting the impact
of coronal mass ejections (CMEs) at planets
Authors: Kilpua, Emilia; Möstl, Christian; Bothmer, Volker; Isavnin,
Alexey; Harrison, Richard; Davies, Jackie; Palmerio, Erika; Boakes,
Peter; Mrotzek, Niclas
Bibcode: 2017EGUGA..19.9051K
Altcode:
Connecting coronal mass ejections (CMEs) in remote-sensing and in-situ
observations can be surprisingly difficult. Coronagraphs can detect
CMEs only about 10% of their journey from Sun to 1 AU. One viable
way to track CMEs through the inner heliosphere is using heliospheric
imaging. HELCATS (Heliospheric Cataloguing, Analysis And Techniques
Service) LINKCAT catalogue is the first concerted effort to establish
such linkage automatically by the systematic use of STEREO Heliospheric
Imager (HI) observations and related modelling. This presentation gives
and overview of how the LINKCAT catalogue is generated and evaluates
the potential of HI-based imagining in connecting CMEs near the Sun
and in-situ. We will also discuss the possible problems in our approach
and the key future improvements.
Title: Impacts of Space Weather Effects on the Ionospheric Vertical
Total Electron Content
Authors: Hinrichs, Johannes; Bothmer, Volker; Mrotzek, Niclas;
Venzmer, Malte; Erdogan, Eren; Dettmering, Denise; Goss, Andreas;
Schmidt, Michael; Seitz, Florian; Börger, Klaus; Brandert, Sylvia;
Görres, Barbara; Kersten, Wilhelm F.
Bibcode: 2017EGUGA..19.5229H
Altcode:
In the space weather project OPTIMAP (OPerational Tool for Ionosphere
Mapping And Prediction) we investigate and analyse the solar influences
on the Earth's ionosphere, to help establish an improved forecast
for global VTEC maps, taking into account space weather effects. The
resulting service will be implemented at the German Space Situational
Awareness Centre. Here we present results from the analysis of a time
series of global ionospheric VTEC-maps provided through computations at
DGFI-TUM and the IGS analysis center CODE, in conjunction with EUV and
X-ray radiation and solar wind parameters measured by space missions
in operation (GOES, SDO, ACE, SOHO and STEREO). The individual impacts
of radiation and different solar wind structures, such as coronal mass
ejections, high speed streams and CIRs, are described. This includes
an analysis of the strongest geomagnetic storms measured since the
launch of ACE.
Title: A Catalogue of Coronal Mass Ejections Observed by the STEREO
Heliospheric Imagers: Results from HELCATS
Authors: Barnes, David; Davies, Jackie; Harrison, Richard; Perry,
Chris; Möstl, Christian; Rouillard, Alexis; Bothmer, Volker;
Rodriguez, Luciano; Eastwood, Jonathan; Kilpua, Emilia; Gallagher,
Peter
Bibcode: 2017EGUGA..19.8160B
Altcode:
The wide fields of view provided by the STEREO Heliospheric Imagers
(HIs) allow far greater coverage of Coronal Mass Ejections (CMEs) than
are typically available from coronagraph observations. As part of the EU
FP7 HELCATS (Heliospheric Cataloguing, Analysis and Techniques Service)
project we present a comprehensive catalogue of CMEs that are observed
in HI data, throughout the lifetime of the instruments. This spans
the period from April 2007 to September 2014 for both STEREO-A and -B,
with additional STEREO-A observations continuing from October 2015 to
present, covering the majority of solar cycle 24. A subset of these
CMEs are tracked through the HI fields of view, to which we apply both
single-spacecraft and stereoscopic models to determine CME kinematic
properties such as propagation directions, speeds and accelerations. The
statistical properties of these results are discussed and they are
compared with coronagraph observations during the same period.
Title: A Multi-Model Approach to the Analysis of the Kinematics of
CMEs Based on Multi-point Space Observations
Authors: Mrotzek, Niclas; Bothmer, Volker; Davies, Jackie; Harrison,
Richard
Bibcode: 2017EGUGA..19.3532M
Altcode:
The interaction between Coronal Mass Ejections (CMEs) and the
ambient solar wind is a crucial factor affecting their interplanetary
evolution. It is believed that acceleration due to the Lorenz force
dominates CME evolution near the Sun and that the aerodynamic drag force
becomes dominant further away. In this study, we present results of a
distance-dependent aerodynamic drag force model taking into account
solar wind measurements from the Helios spacecraft over the spatial
range 0.3 to 0.9 AU. We undertake GCS modelling of the investigated CMEs
based on observations from the coronagraphs on SOHO and STEREO as well
as observations from the STEREO heliospheric imagers (HIs). Application
of the CGS modelling to the HI data enables the height-time profiles of
the CMEs to be extended further from the Sun. To derive transit times
to 1 AU, the height-time profiles are then fitted using a kinematic
drag model and compared with in-situ solar wind measurements. The
study is carried out in the framework of the EU FP7 project HELCATS
(Heliospheric Cataloguing, Analysis and Techniques Service).
Title: Modeling of coronal mass ejections with the STEREO heliospheric
imagers verified with in situ observations by the Heliophysics
System Observatory
Authors: Möstl, Christian; Isavnin, Alexey; Kilpua, Emilia; Bothmer,
Volker; Mrotzek, Nicolas; Boakes, Peter; Rodriguez, Luciano; Krupar,
Vratislav; Eastwood, Jonathan; Davies, Jackie; Harrison, Richard;
Barnes, David; Winslow, Reka; Helcats Team
Bibcode: 2017EGUGA..19.4536M
Altcode:
We present the first study to verify modeling of CMEs as observed by
the heliospheric imagers on the two STEREO spacecraft with a large
scale dataset of in situ plasma and magnetic field observations from
the Heliophysics System Observatory, including MESSENGER, VEX, Wind,
and the in situ measurements on the two STEREO spacecraft. To this end,
we have established a new interplanetary CME catalog (ICMECAT) for these
spacecraft by gathering and updating individual ICME lists. In addition,
we have re-calculated the in situ parameters in a consistent way,
resulting in 668 events observed between 2007-2015. We then calculated
the efficacy of the STEREO/HI instruments for predicting (in hindsight)
with the SSEF30 model the arrival time and speed of CMEs as well as
hit/miss ratios. We also show how ICMECAT gives decent statistics
concerning CME impacts on all of the terrestrial planets, including
Mars. The results show some major implications for future heliospheric
imagers which may be used for space weather forecasting. Our effort
should also serve as a baseline for the upcoming new era in heliospheric
science with Solar Orbiter, Solar Probe Plus, BepiColombo returning
partly comparable observations in the next decade. The presented work
has received funding from the European Union Seventh Framework Programme
(FP7/ 2007-2013) under grant agreement No. 606692 [HELCATS].
Title: Regional Densification of a Global VTEC Model Based on
B-Spline Representations
Authors: Erdogan, Eren; Schmidt, Michael; Dettmering, Denise; Goss,
Andreas; Seitz, Florian; Börger, Klaus; Brandert, Sylvia; Görres,
Barbara; Kersten, Wilhelm F.; Bothmer, Volker; Hinrichs, Johannes;
Mrotzek, Niclas
Bibcode: 2017EGUGA..19.8860E
Altcode:
The project OPTIMAP is a joint initiative of the Bundeswehr
GeoInformation Centre (BGIC), the German Space Situational Awareness
Centre (GSSAC), the German Geodetic Research Institute of the Technical
University Munich (DGFI-TUM) and the Institute for Astrophysics at
the University of Göttingen (IAG). The main goal of the project
is the development of an operational tool for ionospheric mapping
and prediction (OPTIMAP). Two key features of the project are the
combination of different satellite observation techniques (GNSS,
satellite altimetry, radio occultations and DORIS) and the regional
densification as a remedy against problems encountered with the
inhomogeneous data distribution. Since the data from space-geoscientific
mission which can be used for modeling ionospheric parameters, such
as the Vertical Total Electron Content (VTEC) or the electron density,
are distributed rather unevenly over the globe at different altitudes,
appropriate modeling approaches have to be developed to handle this
inhomogeneity. Our approach is based on a two-level strategy. To be
more specific, in the first level we compute a global VTEC model with
a moderate regional and spectral resolution which will be complemented
in the second level by a regional model in a densification area. The
latter is a region characterized by a dense data distribution to obtain
a high spatial and spectral resolution VTEC product. Additionally,
the global representation means a background model for the regional
one to avoid edge effects at the boundaries of the densification
area. The presented approach based on a global and a regional model
part, i.e. the consideration of a regional densification is called
the Two-Level VTEC Model (TLVM). The global VTEC model part is based
on a series expansion in terms of polynomial B-Splines in latitude
direction and trigonometric B-Splines in longitude direction. The
additional regional model part is set up by a series expansion in terms
of polynomial B-splines for both directions. The spectral resolution of
both model parts is defined by the number of B-spline basis functions
introduced for longitude and latitude directions related to appropriate
coordinate systems. Furthermore, the TLVM has to be developed under the
postulation that the global model part will be computed continuously
in near real-time (NRT) and routinely predicted into the future by an
algorithm based on deterministic and statistical forecast models. Thus,
the additional regional densification model part, which will be computed
also in NRT, but possibly only for a specified time duration, must be
estimated independently from the global one. For that purpose a data
separation procedure has to be developed in order to estimate the
unknown series coefficients of both model parts independently. This
procedure must also consider additional technique-dependent unknowns
such as the Differential Code Biases (DCBs) within GNSS and intersystem
biases. In this contribution we will present the concept to set up the
TLVM including the data combination and the Kalman filtering procedure;
first numerical results will be presented.
Title: Overview of the HELCATS project
Authors: Harrison, Richard; Davies, Jackie; Perry, Chris; Moestl,
Christian; Rouillard, Alexis; Bothmer, Volker; Rodriguez, Luciano;
Eastwood, Jonathan; Kilpua, Emilia; Gallagher, Peter; Odstrcil, Dusan
Bibcode: 2017EGUGA..19.5296H
Altcode:
Understanding solar wind evolution is fundamental to advancing our
knowledge of energy and mass transport in the solar system, whilst
also being crucial to space weather and its prediction. The advent of
truly wide-angle heliospheric imaging has revolutionised the study of
solar wind evolution, by enabling direct and continuous observation
of both transient and background components of the solar wind as
they propagate from the Sun to 1 AU and beyond. The EU-funded FP7
Heliospheric Cataloguing, Analysis and Techniques Service (HELCATS)
project combines European expertise in heliospheric imaging, built up
over the last decade in particular through lead involvement in NASA's
STEREO mission, with expertise in solar and coronal imaging as well
as the interpretation of in-situ and radio diagnostic measurements of
solar wind phenomena. HELCATS involves: (1) cataloguing of transient
(coronal mass ejections) and background (stream/corotating interaction
regions) solar wind structures observed by the STEREO/Heliospheric
Imagers, including estimates of their kinematic properties based on
a variety of modelling techniques; (2) verifying these kinematic
properties through comparison with solar source observations and
in-situ measurements at multiple points throughout the heliosphere;
(3) assessing the potential for initialising numerical models based
on the derived kinematic properties of transient and background
solar wind components; (4) assessing the complementarity of radio
observations (Type II radio bursts and interplanetary scintillation)
in the detection and analysis of heliospheric structure in combination
with heliospheric imaging observations. We provide an overview of the
achievements of the HELCATS project, as it reaches its conclusion, and
present selected results that seek to illustrate the value and legacy of
this unprecedented, coordinated study of structures in the heliosphere.
Title: Magnetic structure of Earth-directed events in the HELCATS
LINKCAT catalog during 2011-2013
Authors: Palmerio, Erika; Kilpua, Emilia; Bothmer, Volker; Isavnin,
Alexey; Möstl, Christian; Green, Lucie; James, Alexander; Davies,
Jackie; Harrison, Richard
Bibcode: 2017EGUGA..19.3874P
Altcode:
Coronal mass ejections (CMEs) are the main drivers of intense magnetic
storms and various subsequent space weather phenomena at Earth. The
parameter that defines the ability of a CME to drive geomagnetic
storms is the north-south magnetic field component. One of the most
significant problems in current long-term space weather forecasts is
that there is no practical method to measure the magnetic structure
of CMEs routinely in the outer corona. The magnetic structure of CME
flux ropes can however be inferred based on the properties of the
CME's source region characteristics, such as filament details, coronal
EUV arcades, X-ray sigmoids, taking into account nearby coronal and
photospheric features. The linked catalogue (LINKCAT) of solar CMEs
during the STEREO era is part of the HELCATS project. It aims at
connecting CME observations at the Sun and in interplanetary space,
using heliospheric imager observations from the HI1 cameras onboard the
two STEREO spacecraft to connect the different datasets. The HELCATS
LINKCAT catalogue contains 45 Earth-directed events in the period
2011-2013 (https://www.helcats-fp7.eu/catalogues/wp4_cat.html). Here we
present a statistical study based on the LINKCAT Earth-directed events
during 2011-2013 in which we determine the magnetic properties of
the erupting CMEs, i.e. their magnetic helicity sign, flux rope tilt,
and flux rope axial field direction, by using a synthesis of indirect
proxies based on multi-wavelength remote sensing observations from the
STEREO, SOHO, Hinode, and SDO satellites. These parameters define the
``intrinsic'' flux rope configuration at the time of the eruption which
is compared with the magnetic structures detected in situ near Earth.
Title: The Wide-Field Imager for Solar Probe Plus (WISPR)
Authors: Vourlidas, Angelos; Howard, Russell A.; Plunkett, Simon P.;
Korendyke, Clarence M.; Thernisien, Arnaud F. R.; Wang, Dennis; Rich,
Nathan; Carter, Michael T.; Chua, Damien H.; Socker, Dennis G.; Linton,
Mark G.; Morrill, Jeff S.; Lynch, Sean; Thurn, Adam; Van Duyne, Peter;
Hagood, Robert; Clifford, Greg; Grey, Phares J.; Velli, Marco; Liewer,
Paulett C.; Hall, Jeffrey R.; DeJong, Eric M.; Mikic, Zoran; Rochus,
Pierre; Mazy, Emanuel; Bothmer, Volker; Rodmann, Jens
Bibcode: 2016SSRv..204...83V
Altcode: 2015SSRv..tmp....8V; 2015SSRv..tmp...66B
The Wide-field Imager for Solar PRobe Plus (WISPR) is the sole imager
aboard the Solar Probe Plus (SPP) mission scheduled for launch in
2018. SPP will be a unique mission designed to orbit as close as
7 million km (9.86 solar radii) from Sun center. WISPR employs a
95∘ radial by 58∘ transverse field of view
to image the fine-scale structure of the solar corona, derive the 3D
structure of the large-scale corona, and determine whether a dust-free
zone exists near the Sun. WISPR is the smallest heliospheric imager to
date yet it comprises two nested wide-field telescopes with large-format
(2 K × 2 K) APS CMOS detectors to optimize the performance for their
respective fields of view and to minimize the risk of dust damage,
which may be considerable close to the Sun. The WISPR electronics are
very flexible allowing the collection of individual images at cadences
up to 1 second at perihelion or the summing of multiple images to
increase the signal-to-noise when the spacecraft is further from the
Sun. The dependency of the Thomson scattering emission of the corona
on the imaging geometry dictates that WISPR will be very sensitive
to the emission from plasma close to the spacecraft in contrast to
the situation for imaging from Earth orbit. WISPR will be the first
`local' imager providing a crucial link between the large-scale corona
and the in-situ measurements.
Title: A Catalogue of Geometrically-Modelled Coronal Mass Ejections
Observed by the STEREO Heliospheric Imagers
Authors: Barnes, D.; Davies, J. A.; Harrison, R. A.; Perry, C. H.;
Moestl, C.; Rouillard, A.; Bothmer, V.; Rodriguez, L.; Eastwood,
J. P.; Kilpua, E.; Gallagher, P.
Bibcode: 2016AGUFMSH31B2588B
Altcode:
We present a catalogue of Coronal Mass Ejections (CMEs) observed by the
Heliospheric Imagers (HIs) onboard the two NASA STEREO spacecraft. This
catalogue contains all CMEs observed during the operational phase of the
STEREO mission, April 2007 to September 2014, for both spacecraft and
resumes from November 2015 for STEREO-A. These CMEs are tracked using
time-elongation plots through the HI-1 and HI-2 fields of view and to
them we apply geometric models to determine their kinematic properties,
such as speed, propagation direction and launch time. A subset of
these CMEs, which are observed simultaneously by both spacecraft,
are identified and to which stereoscopic modelling techniques are
applied. The statistical properties of these catalogues are discussed
as are their results compared to existing CME catalogues covering the
same periods. This work is carried out as part of the EU FP7 HELCATS
(Heliospheric Cataloguing, Analysis and Techniques Service) project.
Title: A small mission concept to the Sun-Earth Lagrangian L5 point
for innovative solar, heliospheric and space weather science
Authors: Lavraud, B.; Liu, Y.; Segura, K.; He, J.; Qin, G.; Temmer,
M.; Vial, J. -C.; Xiong, M.; Davies, J. A.; Rouillard, A. P.; Pinto,
R.; Auchère, F.; Harrison, R. A.; Eyles, C.; Gan, W.; Lamy, P.;
Xia, L.; Eastwood, J. P.; Kong, L.; Wang, J.; Wimmer-Schweingruber,
R. F.; Zhang, S.; Zong, Q.; Soucek, J.; An, J.; Prech, L.; Zhang,
A.; Rochus, P.; Bothmer, V.; Janvier, M.; Maksimovic, M.; Escoubet,
C. P.; Kilpua, E. K. J.; Tappin, J.; Vainio, R.; Poedts, S.; Dunlop,
M. W.; Savani, N.; Gopalswamy, N.; Bale, S. D.; Li, G.; Howard, T.;
DeForest, C.; Webb, D.; Lugaz, N.; Fuselier, S. A.; Dalmasse, K.;
Tallineau, J.; Vranken, D.; Fernández, J. G.
Bibcode: 2016JASTP.146..171L
Altcode:
We present a concept for a small mission to the Sun-Earth Lagrangian L5
point for innovative solar, heliospheric and space weather science. The
proposed INvestigation of Solar-Terrestrial Activity aNd Transients
(INSTANT) mission is designed to identify how solar coronal magnetic
fields drive eruptions, mass transport and particle acceleration that
impact the Earth and the heliosphere. INSTANT is the first mission
designed to (1) obtain measurements of coronal magnetic fields from
space and (2) determine coronal mass ejection (CME) kinematics with
unparalleled accuracy. Thanks to innovative instrumentation at a vantage
point that provides the most suitable perspective view of the Sun-Earth
system, INSTANT would uniquely track the whole chain of fundamental
processes driving space weather at Earth. We present the science
requirements, payload and mission profile that fulfill ambitious science
objectives within small mission programmatic boundary conditions.
Title: Long-Term Tracking of Corotating Density Structures Using
Heliospheric Imaging
Authors: Plotnikov, I.; Rouillard, A. P.; Davies, J. A.; Bothmer,
V.; Eastwood, J. P.; Gallagher, P.; Harrison, R. A.; Kilpua, E.;
Möstl, C.; Perry, C. H.; Rodriguez, L.; Lavraud, B.; Génot, V.;
Pinto, R. F.; Sanchez-Diaz, E.
Bibcode: 2016SoPh..291.1853P
Altcode: 2016SoPh..tmp..118P; 2016arXiv160601127P
The systematic monitoring of the solar wind in high-cadence and
high-resolution heliospheric images taken by the Solar-Terrestrial
Relation Observatory (STEREO) spacecraft permits the study of the
spatial and temporal evolution of variable solar wind flows from
the Sun out to 1 AU, and beyond. As part of the EU Framework 7 (FP7)
Heliospheric Cataloguing, Analysis and Techniques Service (HELCATS)
project, we have generated a catalog listing the properties of 190
corotating structures well-observed in images taken by the Heliospheric
Imager (HI) instruments onboard STEREO-A (ST-A). Based on this catalog,
we present here one of very few long-term analyses of solar wind
structures advected by the background solar wind. We concentrate on the
subset of plasma density structures clearly identified inside corotating
structures. This analysis confirms that most of the corotating density
structures detected by the heliospheric imagers comprises a series
of density inhomogeneities advected by the slow solar wind that
eventually become entrained by stream interaction regions. We have
derived the spatial-temporal evolution of each of these corotating
density structures by using a well-established fitting technique. The
mean radial propagation speed of the corotating structures is found
to be 311 ±31 kms−1. Such a low mean value corresponds
to the terminal speed of the slow solar wind rather than the speed of
stream interfaces, which is typically intermediate between the slow and
fast solar wind speeds (∼400 kms−1). Using our fitting
technique, we predicted the arrival time of each corotating density
structure at different probes in the inner heliosphere. We find that our
derived speeds are systematically lower by ∼100 kms−1
than those measured in situ at the predicted impact times. Moreover,
for cases when a stream interaction region is clearly detected in situ
at the estimated impact time, we find that our derived speeds are lower
than the speed of the stream interface measured in situ by an average
of 55 kms−1 at ST-A and 84 kms−1 at STEREO-B
(ST-B). We show that the speeds of the corotating density structures
derived using our fitting technique track well the long-term variation
of the radial speed of the slow solar wind during solar minimum years
(2007 - 2008). Furthermore, we demonstrate that these features originate
near the coronal neutral line that eventually becomes the heliospheric
current sheet.
Title: An Analysis of Interplanetary Solar Radio Emissions Associated
with a Coronal Mass Ejection
Authors: Krupar, V.; Eastwood, J. P.; Kruparova, O.; Santolik, O.;
Soucek, J.; Magdalenić, J.; Vourlidas, A.; Maksimovic, M.; Bonnin,
X.; Bothmer, V.; Mrotzek, N.; Pluta, A.; Barnes, D.; Davies, J. A.;
Martínez Oliveros, J. C.; Bale, S. D.
Bibcode: 2016ApJ...823L...5K
Altcode: 2016arXiv160604301K
Coronal mass ejections (CMEs) are large-scale eruptions of magnetized
plasma that may cause severe geomagnetic storms if Earth directed. Here,
we report a rare instance with comprehensive in situ and remote
sensing observations of a CME combining white-light, radio, and plasma
measurements from four different vantage points. For the first time,
we have successfully applied a radio direction-finding technique
to an interplanetary type II burst detected by two identical widely
separated radio receivers. The derived locations of the type II and
type III bursts are in general agreement with the white-light CME
reconstruction. We find that the radio emission arises from the flanks
of the CME and are most likely associated with the CME-driven shock. Our
work demonstrates the complementarity between radio triangulation and
3D reconstruction techniques for space weather applications.
Title: The combination of satellite observation techniques for
sequential ionosphere VTEC modeling
Authors: Erdogan, Eren; Limberger, Marco; Schmidt, Michael; Seitz,
Florian; Dettmering, Denise; Börger, Klaus; Brandert, Sylvia; Görres,
Barbara; Kersten, Wilhelm F.; Bothmer, Volker; Hinrichs, Johannes;
Venzmer, Malte; Mrotzek, Niclas
Bibcode: 2016EGUGA..1812685E
Altcode:
The project OPTIMAP is a joint initiative by the Bundeswehr
GeoInformation Centre (BGIC), the German Space Situational Awareness
Centre (GSSAC), the German Geodetic Research Institute of the
Technical University of Munich (DGFI-TUM) and the Institute for
Astrophysics at the University of Göttingen (IAG). The main goal is
to develop an operational tool for ionospheric mapping and prediction
(OPTIMAP). A key feature of the project is the combination of different
satellite observation techniques to improve the spatio-temporal data
coverage and the sensitivity for selected target parameters. In the
current status, information about the vertical total electron content
(VTEC) is derived from the dual frequency signal processing of four
techniques: (1) Terrestrial observations of GPS and GLONASS ensure the
high-resolution coverage of continental regions, (2) the satellite
altimetry mission Jason-2 is taken into account to provide VTEC in
nadir direction along the satellite tracks over the oceans, (3) GPS
radio occultations to Formosat-3/COSMIC are exploited for the retrieval
of electron density profiles that are integrated to obtain VTEC and
(4) Jason-2 carrier-phase observations tracked by the on-board DORIS
receiver are processed to determine the relative VTEC. All measurements
are sequentially pre-processed in hourly batches serving as input data
of a Kalman filter (KF) for modeling the global VTEC distribution. The
KF runs in a predictor-corrector mode allowing for the sequential
processing of the measurements where update steps are performed with
one-minute sampling in the current configuration. The spatial VTEC
distribution is represented by B-spline series expansions, i.e., the
corresponding B-spline series coefficients together with additional
technique-dependent unknowns such as Differential Code Biases and
Intersystem Biases are estimated by the KF. As a preliminary solution,
the prediction model to propagate the filter state through time is
defined by a random walk.
Title: Deriving CME kinematics from multipoint space observations
Authors: Mrotzek, Niclas; Pluta, Adam; Bothmer, Volker; Davies,
Jackie; Harrison, Richard
Bibcode: 2016EGUGA..18.8058M
Altcode:
It is commonly believed that the kinematics of CMEs consist of an early
Lorentz acceleration phase near the Sun followed by a decelerating
drag-force phase at distances further out. To better understand
the physical processes of CME evolution, and also to predict more
accurately their arrival times at other heliospheric locations,
we have analysed CMEs using multipoint coronagraph observations
from STEREO and SOHO. The CME speed evolution is analysed by applying
time-series GCS-modelling. The analysis is extended to distances further
away from the Sun through analysis of observations from the STEREO
heliospheric imagers. The results are compared to those obtained from
the geometrical modelling of time-elongation profiles of CMEs extracted
from J-maps. We discuss the implications of our results in the context
of state-of-the-art space weather predictions. The studies are carried
out in the EU FP7 project HELCATS (Heliospheric Cataloguing, Analysis
and Techniques Service).
Title: HELCATS - Heliospheric Cataloguing, Analysis and Techniques
Service
Authors: Harrison, Richard; Davies, Jackie; Perry, Chris; Moestl,
Christian; Rouillard, Alexis; Bothmer, Volker; Rodriguez, Luciano;
Eastwood, Jonathan; Kilpua, Emilia; Gallagher, Peter
Bibcode: 2016EGUGA..1810220H
Altcode:
Understanding the evolution of the solar wind is fundamental to
advancing our knowledge of energy and mass transport in the solar
system, rendering it crucial to space weather and its prediction. The
advent of truly wide-angle heliospheric imaging has revolutionised the
study of both transient (CMEs) and background (SIRs/CIRs) solar wind
plasma structures, by enabling their direct and continuous observation
out to 1 AU and beyond. The EU-funded FP7 HELCATS project combines
European expertise in heliospheric imaging, built up in particular
through lead involvement in NASA's STEREO mission, with expertise in
solar and coronal imaging as well as in-situ and radio measurements
of solar wind phenomena, in a programme of work that will enable a
much wider exploitation and understanding of heliospheric imaging
observations. With HELCATS, we are (1.) cataloguing transient and
background solar wind structures imaged in the heliosphere by STEREO/HI,
since launch in late October 2006 to date, including estimates of their
kinematic properties based on a variety of established techniques
and more speculative, approaches; (2.) evaluating these kinematic
properties, and thereby the validity of these techniques, through
comparison with solar source observations and in-situ measurements
made at multiple points throughout the heliosphere; (3.) appraising
the potential for initialising advanced numerical models based on
these kinematic properties; (4.) assessing the complementarity of radio
observations (in particular of Type II radio bursts and interplanetary
scintillation) in combination with heliospheric imagery. We will,
in this presentation, provide an overview of progress from the first
18 months of the HELCATS project.
Title: Impacts of Space Weather Effects on the Ionospheric Vertical
Total Electron Content
Authors: Hinrichs, Johannes; Bothmer, Volker; Mrotzek, Niclas; Venzmer,
Malte; Erdogan, Eren; Dettmering, Denise; Limberger, Marco; Schmidt,
Michael; Seitz, Florian; Börger, Klaus; Brandert, Sylvia; Görres,
Barbara; Kersten, Wilhelm F.
Bibcode: 2016EGUGA..18.7375H
Altcode:
Space weather effects on the terrestrial ionospheric vertical total
electron content (VTEC) are caused by solar EUV- and X-Ray emissions,
solar wind streams and coronal mass ejections (CMEs), amongst other
processes. They can lead to major disturbances of telecommunication and
navigation systems. Accurately predicting the global VTEC distribution
is thus of utmost importance for our societal infrastructure. Here
we present results obtained within the German space situational
awareness project OPTIMAP (OPerational Tool for Ionosphere Mapping
And Prediction) through analyzing the solar effects on the global and
regional distribution as well as on the temporal variation of the
ionospheric VTEC. For the state-of-the-art analysis in the OPTIMAP
project, key data from the GOES, SDO, ACE, SOHO, Proba2 and STEREO
missions are analysed together with ground based parameters such as
the F10.7 index. The ionospheric data are taken from global VTEC-maps
provided by the International GNSS Service (IGS). The results will
be used as input for the development of an improved operational VTEC
forecast service providing forecasts up to five days in advance.
Title: Global VTEC-modelling in near real-time based on space geodetic
techniques, adapted B-spline expansions and Kalman-filtering including
observations of the Sun's radiation
Authors: Börger, Klaus; Schmidt, Michael; Dettmering, Denise;
Limberger, Marco; Erdogan, Eren; Seitz, Florian; Brandert, Sylvia;
Görres, Barbara; Kersten, Wilhelm; Bothmer, Volker; Hinrichs,
Johannes; Venzmer, Malte; Mrotzek, Niclas
Bibcode: 2016EGUGA..1812905B
Altcode:
Today, the observations of space geodetic techniques are usually
available with a rather low latency which applies to space missions
observing the solar terrestrial environment, too. Therefore, we
can use all these measurements in near real-time to compute and to
provide ionosphere information, e.g. the vertical total electron
content (VTEC). GSSAC and BGIC support a project aiming at a service
for providing ionosphere information. This project is called OPTIMAP,
meaning "Operational Tool for Ionosphere Mapping and Prediction"; the
scientific work is mainly done by the German Geodetic Research Institute
of the Technical University Munich (DGFI-TUM) and the Institute for
Astrophysics of the University of Goettingen (IAG). The OPTIMAP strategy
for providing ionosphere target quantities of high quality, such as VTEC
or the electron density, includes mathematical approaches and tools
allowing for the model adaptation to the real observational scenario
as a significant improvement w.r.t. the traditional well-established
methods. For example, OPTIMAP combines different observation types
such as GNSS (GPS, GLONASS), Satellite Altimetry (Jason-2), DORIS as
well as radio-occultation measurements (FORMOSAT#3/COSMIC). All these
observations run into a Kalman-filter to compute global ionosphere
maps, i.e. VTEC, for the current instant of time and as a forecast for
a couple of subsequent days. Mathematically, the global VTEC is set
up as a series expansion in terms of two-dimensional basis functions
defined as tensor products of trigonometric B-splines for longitude and
polynomial B-splines for latitude. Compared to the classical spherical
harmonics, B-splines have a localizing character and, therefore, can
handle an inhomogeneous data distribution properly. Finally, B-splines
enable a so-called multi-resolution-representation (MRR) enabling the
combination of global and regional modelling approaches. In addition
to the geodetic measurements, Sun observations are pre-processed and
integrated in the data analysis. Sun observations provide very important
and useful information that is passed into the Kalman-filter to improve
the ionosphere predictions.
Title: First Results on Visualization and Verification of the
STEREO Heliospheric Imager CME Catalogue with In Situ Data from the
Heliophysics System Observatory
Authors: Rollett, T.; Moestl, C.; Boakes, P. D.; Isavnin, A.; Davies,
J. A.; Byrne, J.; Barnes, D.; Good, S. W.; Perry, C. H.; Kubicka,
M.; Harrison, R. A.; Kilpua, E.; Forsyth, R. J.; Bothmer, V.
Bibcode: 2015AGUFMSH53A2466R
Altcode:
The space weather community has recently seen major advances in the
prediction of the speed and arrival time of solar coronal mass ejections
at Earth and other planets. Since the start of the STEREO mission
in 2006, each of the heliospheric imagers (HIs) onboard the Ahead
and Behind spacecraft has successfully tracked hundreds of CMEs. The
advantage of HI is that CMEs can be followed for a significant part of
the inner heliosphere, and the CME evolution in direction and speed
is better constrained than by coronagraphs alone. By tracking and
cataloguing each of those CMEs in the EU HELCATS project, we can apply
geometrical modeling (FPF, HMF, SSEF) techniques on single-spacecraft
HI observations to extract the expected planetary impacts of each
CME. These arrivals are then verified or refuted by in situ solar wind
plasma and magnetic field observations provided by the spacecraft
forming the Heliophysics System Observatory (HSO), such as Wind,
ACE, Venus Express, MESSENGER, and STEREO-A/B, for which various ICME
catalogues are gathered and updated in the course of HELCATS.A first
assessment on the relationship between CME HI and in situ observations
is discussed, such as occurrence rates, speeds and arrival times and
magnetic field strength. We also present visualizations of the HI CME
catalogue and the corresponding in situ observations. The presented
work has received funding from the European Union Seventh Framework
Programme (FP7/ 2007-2013) under grant agreement No. 606692 [HELCATS].
Title: Radio Triangulation of Type II Bursts Associated with a CME -
CME Interaction
Authors: Krupar, V.; Bothmer, V.; Davies, J. A.; Eastwood, J. P.;
Forsyth, R. J.; Kruparova, O.; Magdalenic, J.; Maksimovic, M.;
Santolik, O.; Soucek, J.; Vourlidas, A.
Bibcode: 2015AGUFMSH53B2498K
Altcode:
Coronal Mass Ejections (CMEs) are large-scale magnetized plasma
disturbances propagating through the corona and the interplanetary
(IP) medium. Along their path, some CMEs can drive shock waves, which
accelerate ions and electrons. These fast electrons can generate
type II radio bursts at the local plasma frequency and/or its first
harmonic. In this study we use data from the two STEREO spacecraft
which carry both imaging and radio instruments with direction-finding
capabilities allowing us to track energetic electrons responsible
for radio bursts. We present an analysis of type II bursts observed
on the November 29 - 30, 2013. The shock wave signatures were
possibly generated by an interaction of two consecutive CMEs. We have
investigated three time-frequency intervals when received radio waves
were sufficiently intense for direction-finding analysis. The obtained
positions of triangulated radio sources suggest that the CMEs propagate
towards the STEREO-A. The IP shock associated with this event has been
also observed in situ by the MESSENGER and STEREO-A spacecraft.
Title: HELCATS - Heliospheric Cataloguing, Analysis and Techniques
Service
Authors: Barnes, D.; Harrison, R. A.; Davies, J. A.; Byrne, J.;
Perry, C. H.; Moestl, C.; Rouillard, A. P.; Bothmer, V.; Rodriguez,
L.; Eastwood, J. P.; Kilpua, E.; Odstrcil, D.; Gallagher, P.
Bibcode: 2015AGUFMSH21B2410B
Altcode:
Understanding the evolution of the solar wind is fundamental to
advancing our knowledge of energy and mass transport in the Solar
System, making it crucial to space weather and its prediction. The
advent of truly wide-angle heliospheric imaging has revolutionised
the study of both transient (CMEs) and background (IRs) solar wind
plasma structures, by enabling their direct and continuous observation
out to 1 AU and beyond. The EU-funded FP7 HELCATS project combines
European expertise in heliospheric imaging, built up in particular
through lead involvement in NASA's STEREO mission, with expertise in
solar and coronal imaging as well as in-situ and radio measurements
of solar wind phenomena, in a programme of work that will enable
a much wider exploitation and understanding of heliospheric imaging
observations. The HELCATS project endeavors to catalogue transient and
background solar wind structures imaged by STEREO/HI throughout the
duration of the mission. This catalogue will include estimates of their
kinematic properties using a variety of established and more speculative
approaches, which are to be evaluated through comparisons with solar
source and in-situ measurements. The potential for driving numerical
models from these kinematic properties is to be assessed, as is their
complementarity to radio observations, specifically Type II bursts and
interplanetary scintillation. This presentation provides an overview of
the HELCATS project and its progress in first 18 months of operations.
Title: North-south asymmetry in the magnetic deflection of polar
coronal hole jets
Authors: Nisticò, G.; Zimbardo, G.; Patsourakos, S.; Bothmer, V.;
Nakariakov, V. M.
Bibcode: 2015A&A...583A.127N
Altcode: 2015arXiv150801072N
Context. Measurements of the sunspots area, of the magnetic field in
the interplanetary medium, and of the heliospheric current sheet (HCS)
position, reveal a possible north-south (N-S) asymmetry in the magnetic
field of the Sun. This asymmetry could cause the bending of the HCS of
the order of 5-10 deg in the southward direction, and it appears to
be a recurrent characteristic of the Sun during the minima of solar
activity.
Aims: We study the N-S asymmetry as inferred from
measurements of the deflection of polar coronal hole jets when they
propagate throughout the corona.
Methods: Since the corona is
an environment where the magnetic pressure is greater than the kinetic
pressure (β ≪ 1), we can assume that the magnetic field controls the
dynamics of plasma. On average, jets follow magnetic field lines during
their propagation, highlighting their local direction. We measured
the position angles at 1 R⊙ and at 2 R⊙ of
79 jets, based on the Solar TErrestrial RElations Observatory (STEREO)
ultraviolet and white-light coronagraph observations during the solar
minimum period March 2007-April 2008. The average jet deflection is
studied both in the plane perpendicular to the line of sight and, for
a reduced number of jets, in 3D space. The observed jet deflection is
studied in terms of an axisymmetric magnetic field model comprising
dipole (g1), quadrupole (g2), and esapole
(g3) moments.
Results: We found that the propagation
of the jets is not radial, which is in agreement with the deflection
due to magnetic field lines. Moreover, the amount of the deflection is
different between jets over the north and those from the south pole. A
comparison of jet deflections and field line tracing shows that a ratio
g2/g1 ≃ -0.5 for the quadrupole and a ratio
g3/g1 ≃ 1.6-2.0 for the esapole can describe
the field. The presence of a non-negligible quadrupole moment confirms
the N-S asymmetry of the solar magnetic field for the considered
period.
Conclusions: We find that the magnetic deflection of
jets is larger in the north than in the south of the order of 25-40%,
with an asymmetry that is consistent with a southward deflection of
the heliospheric current sheet of the order of 10 deg, consistent with
that inferred from other independent datasets and instruments.
Title: Where does the Thermospheric Ionospheric GEospheric Research
(TIGER) Program go?
Authors: Schmidtke, G.; Avakyan, S. V.; Berdermann, J.; Bothmer,
V.; Cessateur, G.; Ciraolo, L.; Didkovsky, L.; Dudok de Wit, T.;
Eparvier, F. G.; Gottwald, A.; Haberreiter, M.; Hammer, R.; Jacobi,
Ch.; Jakowski, N.; Kretzschmar, M.; Lilensten, J.; Pfeifer, M.;
Radicella, S. M.; Schäfer, R.; Schmidt, W.; Solomon, S. C.; Thuillier,
G.; Tobiska, W. K.; Wieman, S.; Woods, T. N.
Bibcode: 2015AdSpR..56.1547S
Altcode:
At the 10th Thermospheric Ionospheric GEospheric Research (TIGER/COSPAR)
symposium held in Moscow in 2014 the achievements from the start of
TIGER in 1998 were summarized. During that period, great progress was
made in measuring, understanding, and modeling the highly variable
UV-Soft X-ray (XUV) solar spectral irradiance (SSI), and its effects
on the upper atmosphere. However, after more than 50 years of work the
radiometric accuracy of SSI observation is still an issue and requires
further improvement. Based on the extreme ultraviolet (EUV) data from
the SOLAR/SolACES, and SDO/EVE instruments, we present a combined data
set for the spectral range from 16.5 to 105.5 nm covering a period
of 3.5 years from 2011 through mid of 2014. This data set is used
in ionospheric modeling of the global Total Electron Content (TEC),
and in validating EUV SSI modeling. For further investigations the
period of 3.5 years is being extended to about 12 years by including
data from SOHO/SEM and TIMED/SEE instruments. Similarly, UV data are
used in modeling activities. After summarizing the results, concepts
are proposed for future real-time SSI measurements with in-flight
calibration as experienced with the ISS SOLAR payload, for the
development of a space weather camera for observing and investigating
space weather phenomena in real-time, and for providing data sets for
SSI and climate modeling. Other planned topics are the investigation
of the relationship between solar EUV/UV and visible/near-infrared
emissions, the impact of X-rays on the upper atmosphere, the development
of solar EUV/UV indices for different applications, and establishing a
shared TIGER data system for EUV/UV SSI data distribution and real-time
streaming, also taking into account the achievements of the FP7 SOLID
(First European SOLar Irradiance Data Exploitation) project. For further
progress it is imperative that coordinating activities in this special
field of solar-terrestrial relations and solar physics is emphasized.
Title: An Application of the Stereoscopic Self-similar-Expansion
Model to the Determination of CME-Driven Shock Parameters
Authors: Volpes, L.; Bothmer, V.
Bibcode: 2015SoPh..290.3005V
Altcode: 2015SoPh..tmp..121V; 2015arXiv150903181V
We present an application of the stereoscopic self-similar-expansion
model (SSSEM) to Solar Terrestrial Relations Observatory
(STEREO)/Sun-Earth Connection Coronal and Heliospheric Investigation
(SECCHI) observations of the CME on 3 April 2010 and its associated
shock. The aim is to verify whether CME-driven shock parameters can
be inferred from the analysis of j-maps. For this purpose, we used
the SSSEM to derive the CME and the shock kinematics. Arrival times
and speeds, inferred assuming either propagation at constant speed
or with uniform deceleration, agree well with Advanced Composition
Explorer (ACE) measurements. The shock standoff distance [Δ ], the
density compression [ρ/dρu], and the Mach
number [M ] were calculated by combining the results obtained for the
CME and shock kinematics with models for the shock location. Their
values were extrapolated to L1 and compared to in-situ
data. The in-situ standoff distance was obtained from ACE solar-wind
measurements, and the Mach number and compression ratio were provided by
the interplanetary shock database of the Harvard-Smithsonian Center
for Astrophysics. They are ρ/dρu=2.84 and
M =2.2 . The best fit to observations was obtained when the SSSEM
half-width λ =40∘, and the CME and shock propagate with
uniform deceleration. In this case we found Δ =23 R⊙,
ρ/dρu=2.61 , and M =2.93 . The study shows
that CME-driven shock parameters can be estimated from the analysis of
time-elongation plots and can be used to predict their in-situ values.
Title: On the interplanetary evolution of CME-driven shocks: a
comparison between remote sensing observations and in-situ data
Authors: Volpes, Laura; Bothmer, Volker
Bibcode: 2015IAUGA..2256648V
Altcode:
Fast coronal mass ejections (CMEs) are a prime driver of major space
weather effects and strong geomagnetic storms. When the CME propagation
speed is higher than the Alfvén speed a shock forms in front of the CME
leading edge. CME-driven shocks are observed in in-situ data and, with
the advent of increasingly sensitive imaging instruments, also in remote
sensing observations in the form of bright fronts ahead of the CMEs.In
this work we present the study of 4 Earth-directed CMEs which drove
shocks detected in STEREO COR 2 and HI observations. For each event we
identify the source region and the signatures of CME eruption such as
waves, EUV dimmings, flare and prominence eruptions. The shock and CME
interplanetary evolution is determined from COR2 and HI observations via
an application of triangulation techniques. Furthermore, propagation
speed and arrival times are inferred. The CME geometry is modelled in
COR2 via the graduated cylindrical shell (GCS) model and the assumption
on self-similar expansion is tested by expanding the flux rope to the
HI1 field of view. A combination of these results with models for the
shock location allows to infer the time evolution of the compression
ratio ρd/ρu across the shock and of the upstream
Mach number M at locations where no direct plasma measurements are
available. These values, as well as the arrival time and speed, are
compared to ACE in-situ measurements to validate the results. For
the 03 April 2010 event, e.g., the values of the Mach number and the
compression ratio extrapolated to the position of ACE are respectively
2.1 < ρd/ρu < 2.4 and 2.3 < M <
2.5, in good agreement with the in-situ values found in literature,
ρd/ρu = 2.84 and M = 2.2. This study is carried
out in conjunction to simulations of CME initiation. Combined results
from observations and simulations allow to connect the interplanetary
and near-Earth properties of CMEs to those of their source regions,
and to the mechanisms of CME onset.
Title: On the interplanetary evolution of CME-driven shocks: a
comparison between remote sensing observations and in-situ data
Authors: Volpes, Laura; Bothmer, Volker
Bibcode: 2015IAUGA..2254866V
Altcode:
Fast coronal mass ejections (CMEs) are a prime driver of major space
weather effects and strong geomagnetic storms. When the CME propagation
speed is higher than the Alfvén speed a shock forms in front of the CME
leading edge. CME-driven shocks are observed in in-situ data and, with
the advent of increasingly sensitive imaging instruments, also in remote
sensing observations in the form of bright fronts ahead of the CMEs.In
this work we present the study of 4 Earth-directed CMEs which drove
shocks detected in STEREO COR 2 and HI observations. For each event we
identify the source region and the signatures of CME eruption such as
waves, EUV dimmings, flare and prominence eruptions. The shock and CME
interplanetary evolution is determined from COR2 and HI observations via
an application of triangulation techniques. Furthermore, propagation
speed and arrival times are inferred. The CME geometry is modelled in
COR2 via the graduated cylindrical shell (GCS) model and the assumption
on self-similar expansion is tested by expanding the flux rope to the
HI1 field of view. A combination of these results with models for the
shock location allows to infer the time evolution of the compression
ratio ρd/ρu across the shock and of the upstream
Mach number M at locations where no direct plasma measurements are
available. These values, as well as the arrival time and speed, are
compared to ACE in-situ measurements to validate the results. For
the 03 April 2010 event, e.g., the values of the Mach number and the
compression ratio extrapolated to the position of ACE are respectively
2.1 < ρd/ρu < 2.4 and 2.3 < M <
2.5, in good agreement with the in-situ values found in literature,
ρd/ρu = 2.84 and M = 2.2. This study is carried
out in conjunction to simulations of CME initiation. Combined results
from observations and simulations allow to connect the interplanetary
and near-Earth properties of CMEs to those of their source regions,
and to the mechanisms of CME onset.
Title: Where no dust instrument has gone before: Dust science with
Solar Probe Plus
Authors: Rodmann, Jens; Bothmer, Volker; Thernisien, Arnaud
Bibcode: 2015EGUGA..1712390R
Altcode:
Solar Probe Plus will be a ground-breaking mission to explore the
innermost regions of the solar system. By flying down to less than 10
solar radii (~0.05 AU), the mission will greatly enhance our knowledge
of the Near-Sun dust environment. This region is governed by a poorly
understood interplay of dust delivery by sungrazing comets and radiation
forces, the destruction of dust by sublimation, and interactions of dust
particles with the ambient coronal plasma. We will focus on two Solar
Probe Plus instruments relevant for dust: (1) the Wide-field Imager
for SolarPRobe (WISPR), a white-light heliospheric imager dedicated
to study the solar wind, coronal mass ejections, and dust-plasma
interactions; (2) the FIELDS Experiment aimed at electric and magnetic
field measurements in the solar wind, that can also detect telltale
voltage signatures of dust-particle impacts on the spacecraft. We
will highlight recent simulations of the scattered-light emission
from dust particles (F-corona) in order to assess the capabilities of
the WISPR instrument to image the dust-free zone around the Sun. We
will test whether dust density enhancements as predicted by dynamical
simulations can be identified and resolved. Furthermore, we will discuss
whether WISPR imagery will allow us to separate composition-dependent
sublimation fronts, e.g. for silicates or carbonaceous dust. For FIELDS,
we will present predictions for count rates and impact velocities of
micron-sized dust particle hits expected over the 7-year mission.
Title: The HELCATS Project: Characterising the Evolution of Coronal
Mass Ejections Observed During Solar Cycle 24
Authors: Bisi, M. M.; Harrison, R. A.; Davies, J. A.; Perry, C. H.;
Moestl, C.; Rouillard, A. P.; Bothmer, V.; Rodriguez, L.; Eastwood,
J. P.; Kilpua, E.; Gallagher, P.; Odstrcil, D.
Bibcode: 2014AGUFMSH43B4214B
Altcode:
Understanding the evolution of coronal mass ejections (CMEs) is
fundamental to advancing our knowledge of energy and mass transport in
the solar system, thus also rendering it crucial to space weather and
its prediction. The advent of truly wide-angle heliospheric imaging
has revolutionised the study of CMEs, by enabling their direct and
continuous observation as they propagate from the Sun out to 1 AU and
beyond. The recently initiated EU-funded FP7 Heliospheric Cataloguing,
Analysis and Technique Service (HELCATS) project combines European
expertise in the field of heliospheric imaging, built up over the last
decade in particular through lead involvement in NASA's STEREO mission,
with expertise in such areas as solar and coronal imaging as well as
the interpretation of in-situ and radio diagnostic measurements of
solar wind phenomena. The goals of HELCATS include the cataloguing
of CMEs observed in the heliosphere by the Heliospheric Imager
(HI) instruments on the STEREO spacecraft, since their launch in
late October 2006 to date, an interval that covers much of the
historically weak solar cycle 24. Included in the catalogue will be
estimates of the kinematic properties of the imaged CMEs, based on a
variety of established, and some more speculative, modelling approaches
(geometrical, forward, inverse, magneto-hydrodynamic); these kinematic
properties will be verified through comparison with solar disc and
coronal imaging observations, as well as through comparison with radio
diagnostic and in-situ measurements made at multiple points throughout
the heliosphere. We will provide an overview of the HELCATS project,
and present initial results that will seek to illuminate the unusual
nature of solar cycle 24.
Title: North-South Asymmetry in the Magnetic Deflection of Polar
Coronal Jets
Authors: Nisticò, Giuseppe; Zimbardo, Gaetano; Bothmer, Volker;
Patsourakos, Spiros
Bibcode: 2014cosp...40E2295N
Altcode:
Solar jets observed with the Extreme Ultra-Violet Imager (EUVI) and
CORonagraphs (COR) instruments aboard the STEREO mission provide a tool
to probe and understand the magnetic structure of the corona. Since
the corona is an environment where the magnetic pressure is greater
than the kinetic pressure, the magnetic field controls the dynamics
of plasma and, on average, jets during their propagation trace
the magnetic field lines. We discuss the North-South asymmetry of
the magnetic field of the Sun as inferred from measurements of the
deflection of polar coronal hole jets when they propagate throughout
the corona. We measured the position angle at 1 and at 2 solar radii
for the 79 jets of the catalogue of Nisticò et al. (2009), based on
the STEREO ultraviolet and visible observations, and we found that the
propagation is not radial. The average jet deflection is studied both in
the plane perpendicular to the line of sight, and, for a reduced number
of jets in the three dimensional (3D) space. We find that the magnetic
deflection of jets is larger in the North than in the South, with an
asymmetry which is consistent with the N-S asymmetry of the heliospheric
magnetic field inferred from the Ulysses in situ measurements, and
gives clues to the study of the large scale solar magnetic field.
Title: 3D forecast of major geomagnetic storms
Authors: Bosman, Eckhard; Odstrcil, Dusan; Hesemann, Jonas; Milward,
George; Venzmer, Malte; Volpes, Laura; Bothmer, Volker; Viereck, Rodney
Bibcode: 2013EGUGA..1511840B
Altcode:
A 3D analysis of coronal mass ejection events leading to major
geomagnetic storms in solar cycle 24 has been carried out with help
of STEREO and SOHO multipoint observations. The results from the CME
modeling through application of the GCS and CAT methods were used as
inner boundary conditions for the ENLIL simulations. Comparison of
multipoint in situ CME measurements with the ENLIL results provides
information on the 3D accuracy of the space weather forecasts and
implications for future mission plannings near L5 or sub L1 orbits.
Title: AFFECTS - Advanced Forecast For Ensuring Communications
Through Space
Authors: Bothmer, Volker
Bibcode: 2013EGUGA..1511752B
Altcode:
Through the AFFECTS project funded by the European Union's 7th
Framework Programme, European and US scientists develop an advanced
proto-type space weather warning system to safeguard the operation of
telecommunication and navigation systems on Earth to the threat of solar
storms. The project is led by the University of Göttingen's Institute
for Astrophysics and comprises worldwide leading research and academic
institutions and industrial enterprises from Germany, Belgium, Ukraine,
Norway and the United States. The key objectives of the AFFECTS project
are: State-of-the-art analysis and modelling of the Sun-Earth chain
of effects on the Earth's ionosphere and their subsequent impacts
on communication systems based on multipoint space observations and
complementary ground-based data. Development of a prototype space
weather early warning system and reliable space weather forecasts,
with specific emphasis on ionospheric applications. Dissemination of
new space weather products and services to end users, the scientific
community and general public. The presentation summarizes the project
highlights, with special emphasis on the developed space weather
forecast tools.
Title: Three-Dimensional Properties of Coronal Mass Ejections from
STEREO/SECCHI Observations
Authors: Bosman, E.; Bothmer, V.; Nisticò, G.; Vourlidas, A.; Howard,
R. A.; Davies, J. A.
Bibcode: 2012SoPh..281..167B
Altcode: 2012SoPh..tmp..234B
We identify 565 coronal mass ejections (CMEs) between January 2007
and December 2010 in observations from the twin STEREO/SECCHI/COR2
coronagraphs aboard the STEREO mission. Our list is in full
agreement with the corresponding SOHO/LASCO CME Catalog
(http://cdaw.gsfc.nasa.gov/CME_list/) for events with angular
widths of 45∘ and up. The monthly event rates behave
similarly to sunspot rates showing a three- to fourfold rise between
September 2009 and March 2010. We select 51 events with well-defined
white-light structure and model them as three-dimensional (3D) flux
ropes using a forward-modeling technique developed by Thernisien,
Howard and Vourlidas (Astrophys. J. 652, 763 - 773, 2006). We derive
their 3D properties and identify their source regions. We find that
the majority of the CME flux ropes (82 %) lie within 30∘
of the solar equator. Also, 82 % of the events are displaced from their
source region, to a lower latitude, by 25∘ or less. These
findings provide strong support for the deflection of CMEs towards
the solar equator reported in earlier observations, e.g. by Cremades
and Bothmer (Astron. Astrophys.422, 307 - 322, 2004).
Title: Observational Tracking of the 2D Structure of Coronal Mass
Ejections Between the Sun and 1 AU
Authors: Savani, N. P.; Davies, J. A.; Davis, C. J.; Shiota, D.;
Rouillard, A. P.; Owens, M. J.; Kusano, K.; Bothmer, V.; Bamford,
S. P.; Lintott, C. J.; Smith, A.
Bibcode: 2012SoPh..279..517S
Altcode: 2015arXiv150308774S
The Solar TErrestrial RElations Observatory (STEREO) provides high
cadence and high resolution images of the structure and morphology of
coronal mass ejections (CMEs) in the inner heliosphere. CME directions
and propagation speeds have often been estimated through the use of
time-elongation maps obtained from the STEREO Heliospheric Imager (HI)
data. Many of these CMEs have been identified by citizen scientists
working within the SolarStormWatch project (www.solarstormwatch.com)
as they work towards providing robust real-time identification of
Earth-directed CMEs. The wide field of view of HI allows scientists
to directly observe the two-dimensional (2D) structures, while the
relative simplicity of time-elongation analysis means that it can be
easily applied to many such events, thereby enabling a much deeper
understanding of how CMEs evolve between the Sun and the Earth. For
events with certain orientations, both the rear and front edges of the
CME can be monitored at varying heliocentric distances (R) between
the Sun and 1 AU. Here we take four example events with measurable
position angle widths and identified by the citizen scientists. These
events were chosen for the clarity of their structure within the HI
cameras and their long track lengths in the time-elongation maps. We
show a linear dependency with R for the growth of the radial width
(W) and the 2D aspect ratio (χ) of these CMEs, which are measured
out to ≈ 0.7 AU. We estimated the radial width from a linear best
fit for the average of the four CMEs. We obtained the relationships
W=0.14R+0.04 for the width and χ=2.5R+0.86 for the aspect ratio
(W and R in units of AU).
Title: Solar and Interplanetary Data availability for space weather
Authors: Bothmer, Volker
Bibcode: 2012cosp...39..227B
Altcode: 2012cosp.meet..227B
Multi-point space missions, such as STEREO, SDO, SOHO, ACE and
Proba2, with dedicated instrumentations operating in the Sun-Earth
system currently provide a huge amount of unprecedented solar and
interplanetary observations. The data from these missions as well as
unique other long-term datasets already established provide to date
unique input resources for quantification of space weather processes and
the development of reliable space weather models. In this presentation
I will give an overview on the availability of these datasets to the
scientific community, the tools required for access of these datasets,
namely the VOs and website resources, and brief comments on their
individual importance for the various fields of space weather research.
Title: Observing Space Weather towards building Predictive
Capabilities
Authors: Bothmer, Volker
Bibcode: 2012cosp...39..226B
Altcode: 2012cosp.meet..226B
Simultaneous data from multi-point space missions operating in
the Sun-Earth system in conjunction with dedicated ground- based
networks have facilitated major steps towards the quantification of
space weather processes, better understandings of their impacts on
the various high level systems of modern societal infrastructure and
fundamental developments in space weather forecasting. Through the
EU FP7 program and the ESA Space Situational Awareness (SSA) program
several dedicated space weather projects and studies have currently
been initiated, such as the AFFECTS (Advanced Forecast For Ensuring
Communications Through Space), aiming in establishing prototype
space weather services, instruments and missions as precursors of a
future space weather operational system. This presentation provides
an overview of the ongoing European activities, upcoming challenges
and opportunities for international collaborations.
Title: 3D Modeling of CMEs observed with STEREO
Authors: Bosman, E.; Bothmer, V.
Bibcode: 2012EGUGA..1411632B
Altcode:
From January 2007 until end of 2010, 565 typical large-scale coronal
mass ejections (CMEs) have been identified in the SECCHI/COR2 synoptic
movies of the STEREO Mission. A subset comprising 114 CME events,
selected based on the CME's brightness appearance in the SECCHI/COR2
images, has been modeled through the Graduated Cylindrical Shell (GCS)
Model developed by Thernisien et al. (2006). This study presents an
overview of the GCS forward-modeling results and an interpretation of
the CME characteristics in relationship to their solar source region
properties and solar cycle appearances.
Title: CME-CME interaction during the 2010 August 1 events
Authors: Temmer, M.; Vrsnak, B.; Rollett, T.; Bein, B.; deKoning,
C. A.; Liu, Y.; Bosman, E.; Davies, J. A.; Möstl, C.; Zic, T.;
Veronig, A. M.; Bothmer, V.; Harrison, R.; Nitta, N.; Bisi, M.; Flor,
O.; Eastwood, J.; Odstrcil, D.; Forsyth, R.
Bibcode: 2012EGUGA..14.1677T
Altcode:
We study a CME-CME interaction that occurred during the 2010 August 1
events using STEREO/SECCHI data (COR and HI). The CMEs were Earth
directed where clear signatures of magnetic flux ropes could be
measured from in situ Wind data. To give evidence of the actual
interaction we derive the direction of motion for both CMEs applying
several independent methods. From this we obtain that both CMEs head
into similar directions enabling us to actually observe the merging
in the HI1 field-of-view (and rule out the possibility that this is
just a line of sight effect). The full de-projected kinematics of the
faster CME from Sun to Earth is derived when combining data points from
remote observations with in situ parameters of the ICME measured at
1 AU. We study the evolution of the kinematical profile of the faster
CME by applying a drag based model.
Title: Characteristics of Kinematics of a Coronal Mass Ejection
during the 2010 August 1 CME-CME Interaction Event
Authors: Temmer, Manuela; Vršnak, Bojan; Rollett, Tanja; Bein, Bianca;
de Koning, Curt A.; Liu, Ying; Bosman, Eckhard; Davies, Jackie A.;
Möstl, Christian; Žic, Tomislav; Veronig, Astrid M.; Bothmer, Volker;
Harrison, Richard; Nitta, Nariaki; Bisi, Mario; Flor, Olga; Eastwood,
Jonathan; Odstrcil, Dusan; Forsyth, Robert
Bibcode: 2012ApJ...749...57T
Altcode: 2012arXiv1202.0629T
We study the interaction of two successive coronal mass ejections (CMEs)
during the 2010 August 1 events using STEREO/SECCHI COR and heliospheric
imager (HI) data. We obtain the direction of motion for both CMEs by
applying several independent reconstruction methods and find that the
CMEs head in similar directions. This provides evidence that a full
interaction takes place between the two CMEs that can be observed in the
HI1 field of view. The full de-projected kinematics of the faster CME
from Sun to Earth is derived by combining remote observations with in
situ measurements of the CME at 1 AU. The speed profile of the faster
CME (CME2; ~1200 km s-1) shows a strong deceleration over
the distance range at which it reaches the slower, preceding CME (CME1;
~700 km s-1). By applying a drag-based model we are able
to reproduce the kinematical profile of CME2, suggesting that CME1
represents a magnetohydrodynamic obstacle for CME2 and that, after
the interaction, the merged entity propagates as a single structure
in an ambient flow of speed and density typical for quiet solar wind
conditions. Observational facts show that magnetic forces may contribute
to the enhanced deceleration of CME2. We speculate that the increase
in magnetic tension and pressure, when CME2 bends and compresses the
magnetic field lines of CME1, increases the efficiency of drag.
Title: Observations of the White Light Corona from Solar Orbiter
and Solar Probe Plus
Authors: Howard, R. A.; Thernisien, A. F.; Vourlidas, A.; Plunkett,
S. P.; Korendyke, C. M.; Sheeley, N. R.; Morrill, J. S.; Socker,
D. G.; Linton, M. G.; Liewer, P. C.; De Jong, E. M.; Velli, M. M.;
Mikic, Z.; Bothmer, V.; Lamy, P. L.
Bibcode: 2011AGUFMSH43F..06H
Altcode:
The SoloHI instrument on Solar Orbiter and the WISPR instrument on Solar
Probe+ will make white light coronagraphic images of the corona as the
two spacecraft orbit the Sun. The minimum perihelia for Solar Orbiter
is about 60 Rsun and for SP+ is 9.5 Rsun. The wide field of view of the
WISPR instrument (about 105 degrees radially) corresponds to viewing
the corona from 2.2 Rsun to 20 Rsun. Thus the entire Thomson hemisphere
is contained within the telescope's field and we need to think of
the instrument as being a traditional remote sensing instrument and
then transitioning to a local in-situ instrument. The local behavior
derives from the fact that the maximum Thomson scattering will favor
the electron plasma close to the spacecraft - exactly what the in-situ
instruments will be sampling. SoloHI and WISPR will also observe
scattered light from dust in the inner heliosphere, which will be an
entirely new spatial regime for dust observations from a coronagraph,
which we assume to arise from dust in the general neighborhood of about
half way between the observer and the Sun. As the dust grains approach
the Sun, they evaporate and do not contribute to the scattering. A
dust free zone has been postulated to exist somewhere inside of 5 Rsun
where all dust is evaporated, but this has never been observed. The
radial position where the evaporation occurs will depend on the
precise molecular composition of the individual grains. The orbital
plane of Solar Orbiter will gradually increase up to about 35 degrees,
enabling a very different view through the zodiacal dust cloud to test
the models generated from in-ecliptic observations. In this paper we
will explore some of the issues associated with the observation of
the dust and will present a simple model to explore the sensitivity
of the instrument to observe such evaporations.
Title: Determination of temperature maps of EUV coronal hole jets
Authors: Nisticò, Giuseppe; Patsourakos, Spiros; Bothmer, Volker;
Zimbardo, Gaetano
Bibcode: 2011AdSpR..48.1490N
Altcode:
Coronal hole jets are fast ejections of plasma occurring within
coronal holes, observed at Extreme-UltraViolet (EUV) and X-ray
wavelengths. Recent observations of jets by the STEREO and Hinode
missions show that they are transient phenomena which occur at much
higher rates than large-scale impulsive phenomena like flares and
Coronal Mass Ejections (CMEs). In this paper we describe some typical
characteristics of coronal jets observed by the SECCHI instruments
of STEREO spacecraft. We show an example of 3D reconstruction of
the helical structure for a south pole jet, and present how the
angular distribution of the jet position angles changes from the
Extreme-UltraViolet-Imager (EUVI) field of view to the CORonagraph1
(COR1) (height ∼2.0 R⊙ heliocentric distance) field
of view. Then we discuss a preliminary temperature determination for
the jet plasma by using the filter ratio method at 171 and 195 Å and
applying a technique for subtracting the EUV background radiation. The
results show that jets are characterized by electron temperatures
ranging between 0.8 and 1.3 MK. We present the thermal structure of
the jet as temperature maps and we describe its thermal evolution.
Title: Evolution of Coronal Mass Ejection Morphology with Increasing
Heliocentric Distance. II. In Situ Observations
Authors: Savani, N. P.; Owens, M. J.; Rouillard, A. P.; Forsyth,
R. J.; Kusano, K.; Shiota, D.; Kataoka, R.; Jian, L.; Bothmer, V.
Bibcode: 2011ApJ...732..117S
Altcode:
Interplanetary coronal mass ejections (ICMEs) are often observed to
travel much faster than the ambient solar wind. If the relative speed
between the two exceeds the fast magnetosonic velocity, then a shock
wave will form. The Mach number and the shock standoff distance ahead
of the ICME leading edge is measured to infer the vertical size of an
ICME in a direction that is perpendicular to the solar wind flow. We
analyze the shock standoff distance for 45 events varying between
0.5 AU and 5.5 AU in order to infer their physical dimensions. We
find that the average ratio of the inferred vertical size to measured
radial width, referred to as the aspect ratio, of an ICME is 2.8 ±
0.5. We also compare these results to the geometrical predictions from
Paper I that forecast an aspect ratio between 3 and 6. The geometrical
solution varies with heliocentric distance and appears to provide a
theoretical maximum for the aspect ratio of ICMEs. The minimum aspect
ratio appears to remain constant at 1 (i.e., a circular cross section)
for all distances. These results suggest that possible distortions to
the leading edge of ICMEs are frequent. But, these results may also
indicate that the constants calculated in the empirical relationship
correlating the different shock front need to be modified; or perhaps
both distortions and a change in the empirical formulae are required.
Title: Observational features of equatorial coronal hole jets
Authors: Nisticò, G.; Bothmer, V.; Patsourakos, S.; Zimbardo, G.
Bibcode: 2010AnGeo..28..687N
Altcode: 2010arXiv1002.2181N
Collimated ejections of plasma called "coronal hole jets" are commonly
observed in polar coronal holes. However, such coronal jets are not only
a specific features of polar coronal holes but they can also be found
in coronal holes appearing at lower heliographic latitudes. In this
paper we present some observations of "equatorial coronal hole jets"
made up with data provided by the STEREO/SECCHI instruments during
a period comprising March 2007 and December 2007. The jet events
are selected by requiring at least some visibility in both COR1 and
EUVI instruments. We report 15 jet events, and we discuss their main
features. For one event, the uplift velocity has been determined as
about 200 km s-1, while the deceleration rate appears to
be about 0.11 km s-2, less than solar gravity. The average
jet visibility time is about 30 min, consistent with jet observed in
polar regions. On the basis of the present dataset, we provisionally
conclude that there are not substantial physical differences between
polar and equatorial coronal hole jets.
Title: The nature of micro CMEs within coronal holes
Authors: Bothmer, Volker; Nistico, Giuseppe; Zimbardo, Gaetano;
Patsourakos, Spiros; Bosman, Eckhard
Bibcode: 2010cosp...38.2840B
Altcode: 2010cosp.meet.2840B
Whilst investigating the origin and characteristics of coronal jets
and large-scale CMEs identi-fied in data from the SECCHI (Sun Earth
Connection Coronal and Heliospheric Investigation) instrument suites
on board the two STEREO satellites, we discovered transient events
that originated in the low corona with a morphology resembling that of
typical three-part struc-tured coronal mass ejections (CMEs). However,
the CMEs occurred on considerably smaller spatial scales. In this
presentation we show evidence for the existence of small-scale CMEs
from inside coronal holes and present quantitative estimates of their
speeds and masses. We interprete the origin and evolution of micro
CMEs as a natural consequence of the emergence of small-scale magnetic
bipoles related to the Sun's ever changing photospheric magnetic flux
on various scales and their interactions with the ambient plasma and
magnetic field. The analysis of CMEs is performed within the framework
of the EU Erasmus and FP7 SOTERIA projects.
Title: Solar Observations -What is needed for Space Weather
Monitoring ?
Authors: Bothmer, Volker
Bibcode: 2010cosp...38.4182B
Altcode: 2010cosp.meet.4182B
The Sun is our star and the prime source of space weather. Over the
past decades, space missions with sophisticated payloads have led us
to discover and explore the dynamics of our Sun and its impact on the
heliosphere in unprecedented detail. A new level of understanding of the
physics behind solar activity has been achieved and state-of-the-art
missions like STEREO, Hinode, SDO, Proba2 and ACE, as well as future
missions like Proba3, Solar Orbiter, Solar Probe Plus or Solar-C will
close existing gaps in our knowledge. Accordingly, what was formerly
known as the field of "solar-terrestrial research" has basically evolved
into the field of "space weather", a highly interdisciplinary field of
science that includes the impacts of space weather on those technical
systems that are crucial to modern society. In order to proceed to the
next stage, it is necessary to quantify the key physical processes
in the Sun-Earth system and to define those space-and ground-based
solar observations and measurements that are needed to provide
operational space weather forecasts, given the technical and budgetary
thresholds. This presentation summarises the state-of-the-art assets,
near-term and future projects and identifies existing observational
gaps. Based on these conclusions, dedicated concepts for Sun and
interplanetary monitoring systems for space weather purposes are
presented.
Title: 3D structure of CMEs observed with STEREO/SECCHI
Authors: Bothmer, Volker; Bosman, Eckhard; Thernisien, Arnaud
Bibcode: 2010cosp...38.1870B
Altcode: 2010cosp.meet.1870B
Since launch in October 2006, the SECCHI remote sensing suites on
board the two STEREO spacecraft have observed so far more than 300
coronal mass ejections (CMEs) at increasing angular separation. Using
SECCHI and additionally SOHO/MDI/EIT observations, we have studied
the CME 3D structure and source regions for these events. Here we
present a summary of first results of this analysis performed within
the framework of the EU FP7 project SOTERIA.
Title: Classification and Physical parameters EUV coronal jets with
STEREO/SECCHI.
Authors: Nistico, Giuseppe; Bothmer, Volker; Patsourakos, Spiro;
Zimbardo, Gaetano
Bibcode: 2010cosp...38.1820N
Altcode: 2010cosp.meet.1820N
In this work we present observations of EUV coronal jets, detected with
the SECCHI (Sun Earth Connection Coronal and Heliospheric Investigation)
imaging suites of the two STEREO spacecraft. Starting from catalogues of
polar and equatorial coronal hole jets (Nistico' et al., Solar Phys.,
259, 87, 2009; Ann. Geophys. in press), identified from simultaneous
EUV and white-light coronagraph observations, taken during the time
period March 2007 to April 2008 when solar activity was at minimum,
we perfom a detailed study of some events. A basic char-acterisation of
the magnetic morphology and identification of the presence of helical
structure were established with respect to recently proposed models
for their origin and temporal evo-lution. A classification of the
events with respect to previous jet studies shows that amongst the 79
events, identified into polar coronal holes, there were 37 Eiffel tower
-type jet events commonly interpreted as a small-scale ( 35 arcsec)
magnetic bipole reconnecting with the ambi-ent unipolar open coronal
magnetic fields at its looptops, 12 lambda-type jet events commonly
interpreted as reconnection with the ambient field happening at the
bipoles footpoints. Five events were termed micro-CME type jet events
because they resembled classical three-part structured coronal mass
ejections (CMEs) but on much smaller scales. The remainig 25 cases
could not be uniquely classified. Thirty-one of the total number of
events exhibited a helical magnetic field structure, indicative for a
torsional motion of the jet around its axis of propaga-tion. The jet
events are found to be also present in equatorial coronal holes. We
also present the 3-D reconstruction, temperature, velocity, and density
measurements of a number of jets during their evolution.
Title: Solar Weather Event Modelling and Prediction
Authors: Messerotti, Mauro; Zuccarello, Francesca; Guglielmino,
Salvatore L.; Bothmer, Volker; Lilensten, Jean; Noci, Giancarlo;
Storini, Marisa; Lundstedt, Henrik
Bibcode: 2009SSRv..147..121M
Altcode:
Key drivers of solar weather and mid-term solar weather are reviewed
by considering a selection of relevant physics- and statistics-based
scientific models as well as a selection of related prediction models,
in order to provide an updated operational scenario for space weather
applications. The characteristics and outcomes of the considered
scientific and prediction models indicate that they only partially cope
with the complex nature of solar activity for the lack of a detailed
knowledge of the underlying physics. This is indicated by the fact that,
on one hand, scientific models based on chaos theory and non-linear
dynamics reproduce better the observed features, and, on the other
hand, that prediction models based on statistics and artificial neural
networks perform better. To date, the solar weather prediction success
at most time and spatial scales is far from being satisfactory, but
the forthcoming ground- and space-based high-resolution observations
can add fundamental tiles to the modelling and predicting frameworks
as well as the application of advanced mathematical approaches in the
analysis of diachronic solar observations, that are a must to provide
comprehensive and homogeneous data sets.
Title: Characteristics of EUV Coronal Jets Observed with STEREO/SECCHI
Authors: Nisticò, G.; Bothmer, V.; Patsourakos, S.; Zimbardo, G.
Bibcode: 2009SoPh..259...87N
Altcode: 2009arXiv0906.4407N
In this paper we present the first comprehensive statistical study
of EUV coronal jets observed with the SECCHI (Sun Earth Connection
Coronal and Heliospheric Investigation) imaging suites of the two
STEREO spacecraft. A catalogue of 79 polar jets is presented, identified
from simultaneous EUV and white-light coronagraph observations, taken
during the time period March 2007 to April 2008, when solar activity
was at a minimum. The twin spacecraft angular separation increased
during this time interval from 2 to 48 degrees. The appearances of
the coronal jets were always correlated with underlying small-scale
chromospheric bright points. A basic characterization of the morphology
and identification of the presence of helical structure were established
with respect to recently proposed models for their origin and temporal
evolution. Though each jet appeared morphologically similar in the
coronagraph field of view, in the sense of a narrow collimated outward
flow of matter, at the source region in the low corona the jet showed
different characteristics, which may correspond to different magnetic
structures. A classification of the events with respect to previous
jet studies shows that amongst the 79 events there were 37 Eiffel
tower-type jet events, commonly interpreted as a small-scale (∼35
arc sec) magnetic bipole reconnecting with the ambient unipolar open
coronal magnetic fields at its loop tops, and 12 lambda-type jet events
commonly interpreted as reconnection with the ambient field happening at
the bipole footpoints. Five events were termed micro-CME-type jet events
because they resembled the classical coronal mass ejections (CMEs) but
on much smaller scales. The remaining 25 cases could not be uniquely
classified. Thirty-one of the total number of events exhibited a helical
magnetic field structure, indicative for a torsional motion of the jet
around its axis of propagation. A few jets are also found in equatorial
coronal holes. In this study we present sample events for each of
the jet types using both, STEREO A and STEREO B, perspectives. The
typical lifetimes in the SECCHI/EUVI (Extreme UltraViolet Imager)
field of view between 1.0 to 1.7 R⊙ and in SECCHI/COR1
field of view between 1.4 to 4 R⊙ are obtained, and the
derived speeds are roughly estimated. In summary, the observations
support the assumption of continuous small-scale reconnection as an
intrinsic feature of the solar corona, with its role for the heating of
the corona, particle acceleration, structuring and acceleration of the
solar wind remaining to be explored in more detail in further studies.
Title: Theoretical modeling for the stereo mission
Authors: Aschwanden, Markus J.; Burlaga, L. F.; Kaiser, M. L.; Ng,
C. K.; Reames, D. V.; Reiner, M. J.; Gombosi, T. I.; Lugaz, N.;
Manchester, W.; Roussev, I. I.; Zurbuchen, T. H.; Farrugia, C. J.;
Galvin, A. B.; Lee, M. A.; Linker, J. A.; Mikić, Z.; Riley, P.;
Alexander, D.; Sandman, A. W.; Cook, J. W.; Howard, R. A.; Odstrčil,
D.; Pizzo, V. J.; Kóta, J.; Liewer, P. C.; Luhmann, J. G.; Inhester,
B.; Schwenn, R. W.; Solanki, S. K.; Vasyliunas, V. M.; Wiegelmann, T.;
Blush, L.; Bochsler, P.; Cairns, I. H.; Robinson, P. A.; Bothmer,
V.; Kecskemety, K.; Llebaria, A.; Maksimovic, M.; Scholer, M.;
Wimmer-Schweingruber, R. F.
Bibcode: 2008SSRv..136..565A
Altcode: 2006SSRv..tmp...75A
We summarize the theory and modeling efforts for the STEREO mission,
which will be used to interpret the data of both the remote-sensing
(SECCHI, SWAVES) and in-situ instruments (IMPACT, PLASTIC). The
modeling includes the coronal plasma, in both open and closed magnetic
structures, and the solar wind and its expansion outwards from the Sun,
which defines the heliosphere. Particular emphasis is given to modeling
of dynamic phenomena associated with the initiation and propagation
of coronal mass ejections (CMEs). The modeling of the CME initiation
includes magnetic shearing, kink instability, filament eruption, and
magnetic reconnection in the flaring lower corona. The modeling of CME
propagation entails interplanetary shocks, interplanetary particle
beams, solar energetic particles (SEPs), geoeffective connections,
and space weather. This review describes mostly existing models of
groups that have committed their work to the STEREO mission, but is by
no means exhaustive or comprehensive regarding alternative theoretical
approaches.
Title: Sun Earth Connection Coronal and Heliospheric Investigation
(SECCHI)
Authors: Howard, R. A.; Moses, J. D.; Vourlidas, A.; Newmark, J. S.;
Socker, D. G.; Plunkett, S. P.; Korendyke, C. M.; Cook, J. W.; Hurley,
A.; Davila, J. M.; Thompson, W. T.; St Cyr, O. C.; Mentzell, E.;
Mehalick, K.; Lemen, J. R.; Wuelser, J. P.; Duncan, D. W.; Tarbell,
T. D.; Wolfson, C. J.; Moore, A.; Harrison, R. A.; Waltham, N. R.;
Lang, J.; Davis, C. J.; Eyles, C. J.; Mapson-Menard, H.; Simnett,
G. M.; Halain, J. P.; Defise, J. M.; Mazy, E.; Rochus, P.; Mercier,
R.; Ravet, M. F.; Delmotte, F.; Auchere, F.; Delaboudiniere, J. P.;
Bothmer, V.; Deutsch, W.; Wang, D.; Rich, N.; Cooper, S.; Stephens,
V.; Maahs, G.; Baugh, R.; McMullin, D.; Carter, T.
Bibcode: 2008SSRv..136...67H
Altcode: 2008SSRv..tmp...64H
The Sun Earth Connection Coronal and Heliospheric Investigation
(SECCHI) is a five telescope package, which has been developed for
the Solar Terrestrial Relation Observatory (STEREO) mission by the
Naval Research Laboratory (USA), the Lockheed Solar and Astrophysics
Laboratory (USA), the Goddard Space Flight Center (USA), the University
of Birmingham (UK), the Rutherford Appleton Laboratory (UK), the
Max Planck Institute for Solar System Research (Germany), the Centre
Spatiale de Leige (Belgium), the Institut d’Optique (France) and the
Institut d’Astrophysique Spatiale (France). SECCHI comprises five
telescopes, which together image the solar corona from the solar disk to
beyond 1 AU. These telescopes are: an extreme ultraviolet imager (EUVI:
1 1.7 R⊙), two traditional Lyot coronagraphs (COR1: 1.5 4
R⊙ and COR2: 2.5 15 R⊙) and two new designs
of heliospheric imagers (HI-1: 15 84 R⊙ and HI-2: 66 318
R⊙). All the instruments use 2048×2048 pixel CCD arrays
in a backside-in mode. The EUVI backside surface has been specially
processed for EUV sensitivity, while the others have an anti-reflection
coating applied. A multi-tasking operating system, running on a PowerPC
CPU, receives commands from the spacecraft, controls the instrument
operations, acquires the images and compresses them for downlink
through the main science channel (at compression factors typically
up to 20×) and also through a low bandwidth channel to be used for
space weather forecasting (at compression factors up to 200×). An
image compression factor of about 10× enable the collection of images
at the rate of about one every 2 3 minutes. Identical instruments,
except for different sizes of occulters, are included on the STEREO-A
and STEREO-B spacecraft.
Title: Interplanetary Space Weather and Its Planetary Connection
Authors: Crosby, Norma; Bothmer, Volker; Facius, Rainer; Grießmeier,
Jean-Mathias; Moussas, Xenophon; Panasyuk, Mikhail; Romanova, Natalia;
Withers, Paul
Bibcode: 2008SpWea...6.1003C
Altcode:
Interplanetary travel is not just a science fiction scenario anymore,
but a goal as realistic as when our ancestors started to cross the
oceans. With curiosity driving humans to visit other planets in our
solar system, the understanding of interplanetary space weather is
a vital subject today, particularly because the physical conditions
faced during a space vehicle's transit to its targeted solar system
object are crucial to a mission's success and vital to the health
and safety of spacecraft crew, especially when scheduling planned
extravehicular activities.
Title: The SECCHI Experiment on the STEREO Mission
Authors: Howard, R. A.; Moses, J. D.; Vourlidas, A.; Newmark, J. S.;
Socker, D. G.; Wang, D.; Plunkett, S. P.; Baugh, R.; McMullin, D. R.;
Davila, J. M.; Thompson, W. T.; Lemen, J. R.; Wuelser, J.; Harrison,
R. A.; Waltham, N. R.; Davis, C. J.; Eyles, C. J.; Defise, J.; Halain,
J.; Bothmer, V.; Delaboudiniere, J.; Auchere, F.; Mercier, R.; Ravet,
M. F.
Bibcode: 2007AGUSMSH33A..01H
Altcode:
The Sun Earth Connection Coronal and Heliospheric Investigation
(SECCHI) on the NASA Solar Terrestrial Relations Observatory (STEREO)
mission is a suite of remote sensing instruments consisting of an
extreme ultraviolet (EUV) imager, two white light coronagraphs, and
two telescopes that comprise the heliospheric imager. SECCHI will
observe coronal mass ejections (CMEs) from their birth at the sun,
through the corona and into the heliosphere. A complete instrument
suite is being carried on each of the two STEREO spacecraft, which
will provide the first sampling of a CME from two vantage points. The
spacecraft, launched 25 October 2006, are orbiting the Sun, one Ahead
of the Earth and the other Behind, each separating from Earth at about
22 degrees per year. The varying separation means that we will have
different observational capabilities as the spacecraft separate and
therefore differing science goals. The primary science objectives
all are focused on understanding the physics of the CME process
their initiation, 3D morphology, propagation, interaction with the
interplanetary medium and space weather effects. By observing the CME
from multiple viewpoints with UV and coronagraphic telescopes and by
combining these observations with radio and in-situ observations from
the other instruments on STEREO as well as from other satellites and
ground based observatories operating at the same time, answers to some
of the outstanding questions will be obtained. We will show some of
the initial results.
Title: Stereo Observations Of The Solar Corona Using The Secchi
Experiment
Authors: Plunkett, Simon P.; Howard, R. A.; Moses, J. D.; Vourlidas,
A.; Socker, D.; Newmark, J.; Wang, D.; Baugh, R.; Davila, J.;
Thompson, W.; St. Cyr, O. C.; Lemen, J.; Wuelser, J. P.; Harrison,
R. A.; Waltham, N.; Davis, C. J.; Eyles, C. J.; Defise, J. M.; Halain,
J. P.; Bothmer, V.; Delaboudiniere, J. P.; Auchere, F.; Mercier, R.;
Ravet, M. F.
Bibcode: 2007AAS...21011901P
Altcode: 2007BAAS...39..243P
The Sun Earth Connection Coronal and Heliospheric Investigation
(SECCHI) on the NASA Solar Terrestrial Relations Observatory (STEREO)
mission is a suite of remote sensing instruments consisting of an
extreme ultraviolet (EUV) imager, two white light coronagraphs,
and two telescopes that comprise the heliospheric imager. The main
objective of SECCHI is to observe coronal mass ejections (CMEs) from
their birth at the sun, through the corona and into the heliosphere. A
complete instrument suite is being carried on each of the two STEREO
spacecraft, which will provide the first sampling of a CME from two
vantage points as the spacecraft separate from each other at the rate
of about 45 degrees per year. We will show examples of some of the
data and some of the initial stereo results.
Title: Understanding coronal heating and solar wind acceleration:
Case for in situ near-Sun measurements
Authors: McComas, D. J.; Velli, M.; Lewis, W. S.; Acton, L. W.;
Balat-Pichelin, M.; Bothmer, V.; Dirling, R. B.; Feldman, W. C.;
Gloeckler, G.; Habbal, S. R.; Hassler, D. M.; Mann, I.; Matthaeus,
W. H.; McNutt, R. L.; Mewaldt, R. A.; Murphy, N.; Ofman, L.; Sittler,
E. C.; Smith, C. W.; Zurbuchen, T. H.
Bibcode: 2007RvGeo..45.1004M
Altcode:
The solar wind has been measured directly from 0.3 AU outward,
and the Sun's atmosphere has been imaged from the photosphere out
through the corona. These observations have significantly advanced our
understanding of the influence of the Sun's varying magnetic field on
the structure and dynamics of the corona and the solar wind. However,
how the corona is heated and accelerated to produce the solar wind
remains a mystery. Answering these fundamental questions requires
in situ observations near the Sun, from a few solar radii (R S
) out to ~20 R S , where the internal, magnetic, and
turbulent energy in the coronal plasma is channeled into the bulk energy
of the supersonic solar wind. A mission to make such observations has
long been a top priority of the solar and space physics community. The
recent Solar Probe study has proven that such a mission is technically
feasible and can be accomplished within reasonable resources.
Title: Evolution of the photospheric magnetic field in the source
regions of coronal mass ejections
Authors: Bothmer, V.; Tripathi, D.
Bibcode: 2007msfa.conf..257B
Altcode:
Six coronal mass ejections associated with erupting quiescent filaments
on the visible solar disk were identified in data from SoHO (Solar
and Heliospheric Observatory) LASCO (Large Angle and Spectrometric
Coronagraph), EIT (Extreme ultraviolet Imaging Telescope) and MDI
(Michelson Doppler Imager) data and ground-based Hα observations
from Big Bear and Meudon observatories. These events were analysed to
investigate whether their initiations could be related to changes of
the underlying photospheric field. The results show that in five out
of the six events, substantial changes in the photospheric magnetic
field occurred in the source regions prior and around the CME's lift-off
times as identified from emerging/diminishing flux detected by MDI. In
one event large magnetic flux changes could be identified not in the
source region itself, but in a neighbouring active region. The results
demonstrate that new missions, such as STEREO and Hinode (Solar-B)
in conjunction with SoHO and ground-based measurements, will provide
joint data sets that have the potential to provide new insight into
the physical causes of CMEs.
Title: The SECCHI Experiment on the STEREO Mission
Authors: Howard, R. A.; Moses, D.; Vourlidas, A.; Newmark, J.; Socker,
D. G.; Plunkett, S.; Wang, D.; Baugh, R.; McMullin, D.; Davila, J.;
St. Cyr, C.; Thompson, W. T.; Lemen, J.; Wuelser, J.; Harrison, R. A.;
Waltham, N. R.; Davis, C.; Eyles, C. J.; Defise, J.; Halain, J.;
Bothmer, V.; Delaboudiniere, J.; Auchere, F.; Mercier, R.; Ravet, M.
Bibcode: 2006AGUFMSM12A..02H
Altcode:
The Sun Earth Connection Coronal and Heliospheric Investigation
(SECCHI) on the NASA Solar Terrestrial Relations Observatory (STEREO)
mission is a suite of remote sensing instruments consisting of an
extreme ultraviolet (EUV) imager, two white light coronagraphs, and
two telescopes that comprise the heliospheric imager. SECCHI will
observe coronal mass ejections (CMEs) from their birth at the sun,
through the corona and into the heliosphere. A complete instrument
suite is being carried on each of the two STEREO spacecraft, which
will provide the first sampling of a CME from two vantage points. The
spacecraft will orbit the Sun, one Ahead of the Earth and the other
Behind, each separating from Earth at about 22 degrees per year. The
varying separation means that we will have different observational
capabilities as the spacecraft separate and therefore differing science
goals. The primary science objectives all are focused on understanding
the physics of the CME process their initiation, 3D morphology,
propagation, interaction with the interplanetary medium and space
weather effects. By observing the CME from multiple viewpoints with UV
and coronagraphic telescopes and by combining these observations with
radio and in-situ observations from the other instruments on STEREO as
well as from other satellites and ground based observatories operating
at the same time, answers to some of the outstanding questions will
be obtained. STEREO follows the very successful SOHO mission. SOHO's
success was primarily due to the highly complementary nature of the
instruments, but it was partly due to the very stable platform. The
L1 orbit enables an extremely stable thermal environment and thus
very stable pointing, as well as uninterrupted solar viewing. The
STEREO will have both of these characteristics, but in addition will
have multi-viewpoint viewing of CMEs, which will greatly enhance the
many discoveries that SOHO data have produced. We have been developing
techniques to interpret the observations from multiple viewpoints and
to perform 3-dimensional deconvolution of the CME observations using
forward modeling and inversion techniques. A continuous downlink of
STEREO data will provide a low-resolution, real- time view from all
of the instruments. The full data are downlinked once a day and will
be available about 24 hours later. We will present some preliminary
results from the instrument, which is expected to be launched in
October/November, 2006
Title: Photospheric Field Evolution in the Source Regions of Coronal
Mass Ejections
Authors: Bothmer, V.; Tripathi, D.
Bibcode: 2006ESASP.617E..20B
Altcode: 2006soho...17E..20B
No abstract at ADS
Title: Observation of a bright coronal downflow by SOHO/EIT
Authors: Tripathi, D.; Solanki, S. K.; Schwenn, R.; Bothmer, V.;
Mierla, M.; Stenborg, G.
Bibcode: 2006A&A...449..369T
Altcode:
A distinct coronal downflow has been discovered in the course of a
prominence eruption associated coronal mass ejection (CME) imaged by
EIT (Extreme ultraviolet Imaging Telescope) and LASCO (Large Angle
Spectrometric Coronagraph) on board SOHO (Solar and Heliospheric
Observatory) on 5-Mar.-2000. Evolution of the prominences seen by EIT
was tracked into the LASCO/C2 and C3 field-of-view where they developed
as the core of a typical three-part CME. In contrast to the inflow
structures reported earlier in the literatures, which were dark and
were interpreted as plasma voids moving down, the downflow reported
here was bright. The downflow, which was only seen in EIT FOV had an
onset time that coincided with the deceleration phase of the core
of the CME. The downflow showed a rapid acceleration followed by a
strong deceleration. The downflow followed a curved path which may be
explained by material following the apex of a contracting magnetic loop
sliding down along other field lines, although other explanations are
also possible. Irrespective of the detailed geometry, this observation
provides support for the pinching off of the field lines drawn-out by
the erupting prominences and the contraction of the arcade formed by
the reconnection.
Title: Understanding Interplanetary Coronal Mass Ejection Signatures.
Report of Working Group B
Authors: Wimmer-Schweingruber, R. F.; Crooker, N. U.; Balogh, A.;
Bothmer, V.; Forsyth, R. J.; Gazis, P.; Gosling, J. T.; Horbury, T.;
Kilchenmann, A.; Richardson, I. G.; Richardson, J. D.; Riley, P.;
Rodriguez, L.; von Steiger, R.; Wurz, P.; Zurbuchen, T. H.
Bibcode: 2006SSRv..123..177W
Altcode: 2006SSRv..tmp...66W
While interplanetary coronal mass ejections (ICMEs) are understood to
be the heliospheric counterparts of CMEs, with signatures undeniably
linked to the CME process, the variability of these signatures and
questions about mapping to observed CME features raise issues that
remain on the cutting edge of ICME research. These issues are discussed
in the context of traditional understanding, and recent results using
innovative analysis techniques are reviewed.
Title: ICMEs in the Inner Heliosphere: Origin, Evolution and
Propagation Effects. Report of Working Group G
Authors: Forsyth, R. J.; Bothmer, V.; Cid, C.; Crooker, N. U.; Horbury,
T. S.; Kecskemety, K.; Klecker, B.; Linker, J. A.; Odstrcil, D.;
Reiner, M. J.; Richardson, I. G.; Rodriguez-Pacheco, J.; Schmidt,
J. M.; Wimmer-Schweingruber, R. F.
Bibcode: 2006SSRv..123..383F
Altcode: 2006SSRv..tmp...69F
This report assesses the current status of research relating the origin
at the Sun, the evolution through the inner heliosphere and the effects
on the inner heliosphere of the interplanetary counterparts of coronal
mass ejections (ICMEs). The signatures of ICMEs measured by in-situ
spacecraft are determined both by the physical processes associated
with their origin in the low corona, as observed by space-borne
coronagraphs, and by the physical processes occurring as the ICMEs
propagate out through the inner heliosphere, interacting with the
ambient solar wind. The solar and in-situ observations are discussed
as are efforts to model the evolution of ICMEs from the Sun out to 1 AU.
Title: The SECCHI Experiment on the STEREO Mission
Authors: Howard, R.; Moses, D.; Vourlidas, A.; Davila, J.; Lemen, J.;
Harrison, R.; Eyles, C.; Defise, J. -M.; Bothmer, V.; Ravet, M. -F.;
Secchi Team
Bibcode: 2006cosp...36..870H
Altcode: 2006cosp.meet..870H
The Sun Earth Connection Coronal and Heliospheric Investigation SECCHI
on the NASA Solar Terrestrial Relations Observatory STEREO mission
is a suite of remote sensing instruments consisting of an extreme
ultraviolet EUV imager two white light coronagraphs and two telescopes
that comprise the heliospheric imager SECCHI will observe coronal mass
ejections CMEs from their birth at the sun through the corona and into
the heliosphere A complete instrument suite is being carried on each
of the two STEREO spacecraft which will provide the first sampling of
a CME from two vantage points The spacecraft will orbit the Sun one
Ahead of the Earth and the other Behind each separating from Earth at
about 22 degrees per year The varying separation means that we will
have different observational capabilities as the spacecraft separate
and therefore differing science goals The primary science objectives
all are focused on understanding the physics of the CME process -
their initiation 3D morphology propagation interaction with the
interplanetary medium and space weather effects By observing the CME
from multiple viewpoints with UV and coronagraphic telescopes and by
combining these observations with radio and in-situ observations from
the other instruments on STEREO as well as from other satellites and
ground based observatories operating at the same time answers to some
of the outstanding questions will be obtained STEREO follows the very
successful SOHO mission SOHO s success was primarily due to the highly
complementary nature of the instruments but it was
Title: Properties of structured coronal mass ejections in solar
cycle 23
Authors: Cremades, H.; Bothmer, V.; Tripathi, D.
Bibcode: 2006AdSpR..38..461C
Altcode:
The Solar and Heliospheric Observatory has provided to date doubtlessly
the best dataset of coronal observations ever taken over the course
of a solar cycle. Structured coronal mass ejections, i.e. events
with clear white-light fine structures, have been selected from the
dataset of the large angle spectroscopic coronagraph during the period
1996 2002. Their source regions in the low corona and photosphere
have been deduced by analyzing data from the Extreme-ultraviolet
Imaging Telescope and Michelson Doppler Imager onboard the Solar and
Heliospheric Observatory and from ground-based Hα measurements. Based
on this subset of coronal mass ejections, originally compiled to study
their three-dimensional configuration, we have analyzed the variation
of their properties during the present solar cycle. These properties
include latitude and tilt angle of source regions of coronal mass
ejections, position angle of coronal mass ejections, and deviation
of coronal mass ejections with respect to their corresponding source
regions. The results show a pronounced and systematic confinement of
position angles at equatorial latitudes and equatorward deviations
during low solar activity. In contrast, fluctuating position angles
and deviations in all directions were found at times of high solar
activity. A method to explain the observed deflections is presented.
Title: Solar Activity and its Magnetic Origin
Authors: Bothmer, Volker; Hady, Ahmed Abdel
Bibcode: 2006IAUS..233.....B
Altcode:
No abstract at ADS
Title: Solar Activity and its Magnetic Origin
Authors: Bothmer, Volker; Hady, Ahmed Abdel
Bibcode: 2006IAUS..233....7B
Altcode:
The variability of the Sun's magnetic field is the main driver of
solar activity. IAU S233 was held to further our understanding about
solar magnetic processes and also its interplanetary consequences. The
Symposium was organized into seven sessions covering: the generation
and transport of solar magnetic fields; magnetic fields and coupling
processes in the solar atmosphere; coronal heating and small-scale
dynamics; large-scale coronal structure; the origin and evolution of
the solar wind; flares, CMEs and SEPs; and new instrumentation and
missions. Each session included contributions by leading scientists
in the form of tutorials, research reviews and presentations of the
latest results. A special eighth session was dedicated to educating
young national and international astronomers. With reviews and
research contributions covering a broad range of disciplines in solar
and heliospheric research, this volume is a valuable interdisciplinary
resource for professional astronomers and graduate students.
Title: Understanding Interplanetary Coronal Mass Ejection Signatures
Authors: Wimmer-Schweingruber, R. F.; Crooker, N. U.; Balogh, A.;
Bothmer, V.; Forsyth, R. J.; Gazis, P.; Gosling, J. T.; Horbury, T.;
Kilchenmann, A.; Richardson, I. G.; Richardson, J. D.; Riley, P.;
Rodriguez, L.; von Steiger, R.; Wurz, P.; Zurbuchen, T. H.
Bibcode: 2006cme..book..177W
Altcode:
While interplanetary coronal mass ejections (ICMEs) are understood to
be the heliospheric counterparts of CMEs, with signatures undeniably
linked to the CME process, the variability of these signatures and
questions about mapping to observed CME features raise issues that
remain on the cutting edge of ICME research. These issues are discussed
in the context of traditional understanding, and recent results using
innovative analysis techniques are reviewed.
Title: ICMEs in the Inner Heliosphere: Origin, Evolution and
Propagation Effects
Authors: Forsyth, R. J.; Bothmer, V.; Cid, C.; Crooker, N. U.; Horbury,
T. S.; Kecskemety, K.; Klecker, B.; Linker, J. A.; Odstrcil, D.;
Reiner, M. J.; Richardson, I. G.; Rodriguez-Pacheco, J.; Schmidt,
J. M.; Wimmer-Schweingruber, R. F.
Bibcode: 2006cme..book..383F
Altcode:
This report assesses the current status of research relating the origin
at the Sun, the evolution through the inner heliosphere and the effects
on the inner heliosphere of the interplanetary counterparts of coronal
mass ejections (ICMEs). The signatures of ICMEs measured by in-situ
spacecraft are determined both by the physical processes associated
with their origin in the low corona, as observed by space-borne
coronagraphs, and by the physical processes occurring as the ICMEs
propagate out through the inner heliosphere, interacting with the
ambient solar wind. The solar and in-situ observations are discussed
as are efforts to model the evolution of ICMEs from the Sun out to 1 AU.
Title: The Solar Atmosphere and Space Weather
Authors: Bothmer, Volker
Bibcode: 2006ssu..book....1B
Altcode:
First ideas about possible physical influences of the Sun on Earth other
than by electromagnetic (EM) radiation were scientifically discussed
more seriously after Richard Carrington's famous observation of a
spectacular white-light flare in 1859 and the subsequent conclusion
that this flash of EM radiation was connected with the origin of
strong perturbations of the Earth's outer magnetic field, commonly
referred to as geomagnetic storms, which were recorded about 24 hours
after the solar flare. Tentatively significant correlations of the
number of geomagnetic storms and aurorae with the varying number of
sunspots seen on the visible solar disk were found in the long-term
with respect to the roughly 11-year periodicity of the solar activity
cycle. Although theories of sporadic solar eruptions were postulated
soon after the Carrington observations, the physical mechanism of the
transfer of energy from the Sun to the Earth remained unknown. Early
in the 20th century Chapman and Ferraro proposed the
concept of huge clouds of charged particles emitted by the Sun as
the triggers of geomagnetic storms. Based on the inference of the
existence of a solar magnetic field, magnetized plasma clouds were
subsequently introduced. Eugene Parker derived theoretical evidence for
a continuous stream of ionized particles, the solar wind, leading to
continuous convection of the Sun's magnetic field into interplanetary
space. The existence of the solar wind was confirmed soon after the
launch of the first satellites. Since then the Sun is known to be a
permanent source of particles filling interplanetary space. However,
it was still thought that the Sun's outer atmosphere, the solar corona,
is a static rather than a dynamic object, undergoing only long-term
structural changes in phase with the Sun's activity cycle. This view
completely changed after space borne telescopes provided extended series
of solar images in the EUV and soft X-ray range of the EM spectrum,
invisible to ground-based observers. The remote-sensing observations
undertaken by Yohkoh, followed by multi-wavelength movies from SoHO
(Solar Heliospheric Observatory) and high resolution EUV imaging by
TRACE (Transition Region and Coronal Explorer) have revealed to date
that the Sun's atmosphere is highly dynamic and never at rest. Solar
eruptions have been tracked into space in unprecedented detail. In
combination with near-Earth satellites, their interplanetary and
geo-space effects could be investigated in depth, having provided
the roots for space weather forecasts. This chapter summarizes the
discoveries about the origin and evolution of solar storms and their
space weather effects, providing a comprehensive picture of the most
important links in the Sun-Earth system. It finally provides an outlook
to future research in the field of space weather.
Title: Solar Probe: Humanity's First Visit to a Star (Invited)
Authors: McComas, D. J.; Velli, M.; Lewis, W. S.; Acton, L. W.;
Balat-Pichelin, M.; Bothmer, V.; Dirling, R. B.; Eng, D. A.; Feldman,
W. C.; Gloeckler, G.; Guhathakurtha, M.; Habbal, S. R.; Hassler, D. M.;
Mann, I.; Maldonado, H. M.; Matthaeus, W. H.; McNutt, R. L.; Mewaldt,
R. A.; Murphy, N.; Ofman, L.; Potocki, K. A.; Sittler, E. C.; Smith,
C. W.; Zurbuchen, T. H.
Bibcode: 2005ESASP.592..279M
Altcode: 2005ESASP.592E..42M; 2005soho...16E..42M
No abstract at ADS
Title: Properties and geoeffectiveness of magnetic clouds in the
rising, maximum and early declining phases of solar cycle 23
Authors: Huttunen, K. E. J.; Schwenn, R.; Bothmer, V.; Koskinen,
H. E. J.
Bibcode: 2005AnGeo..23..625H
Altcode:
The magnetic structure and geomagnetic response of 73 magnetic clouds
(MC) observed by the WIND and ACE satellites in solar cycle 23 are
examined. The results have been compared with the surveys from the
previous solar cycles. The preselected candidate MC events were
investigated using the minimum variance analysis to determine if
they have a flux-rope structure and to obtain the estimation for the
axial orientation (θC, φC). Depending on the calculated inclination
relative to the ecliptic we divided MCs into "bipolar" (θC<45°)
and "unipolar" (θC>45°). The number of observed MCs was largest in
the early rising phase, although the halo CME rate was still low. It
is likely that near solar maximum we did not identify all MCs at 1AU,
as they were crossed far from the axis or they had interacted strongly
with the ambient solar wind or with other CMEs. The occurrence rate of
MCs at 1AU is also modified by the migration of the filament sites on
the Sun towards the poles near solar maximum and by the deflection of
CMEs towards the equator due to the fast solar wind flow from large
polar coronal holes near solar minimum. In the rising phase nearly
all bipolar MCs were associated with the rotation of the magnetic
field from the south at the leading edge to the north at the trailing
edge. The results for solar cycles 21-22 showed that the direction
of the magnetic field in the leading portion of the MC starts to
reverse at solar maximum. At solar maximum and in the declining
phase (2000-2003) we observed several MCs with the rotation from
the north to the south. We observed unipolar (i.e. highly inclined)
MCs frequently during the whole investigated period. For solar cycles
21-22 the majority of MCs identified in the rising phase were bipolar
while in the declining phase most MCs were unipolar. The geomagnetic
response of a given MC depends greatly on its magnetic structure and the
orientation of the sheath fields. For each event we distinguished the
effect of the sheath fields and the MC fields. All unipolar MCs with
magnetic field southward at the axis were geoeffective (Dst<-50nT)
while those with the field pointing northward did not cause magnetic
storms at all. About half of the all identified MCs were not geoffective
or the sheath fields preceding the MC caused the storm. MCs caused
more intense magnetic storms (Dst<-100nT) than moderate magnetic
storms (-50nT ≥Dst≥-100nT). <p style="line-height: 20px;">
</td> </tr>
Title: SoHO/EIT Observation of a Coronal Inflow
Authors: Tripathi, D.; Bothmer, V.; Solanki, S. K.; Schwenn, R.;
Mierla, M.; Stenborg, G.
Bibcode: 2005IAUS..226..133T
Altcode:
A distinct coronal inflow has been discovered after ∼90 min
of prominence eruption associated coronal mass ejection (CME) on
05-Mar-2000 by EIT (Extreme ultraviolet Imaging Telescope) aboard SoHO
(Solar and Heliospheric Observatory). Evolution of the prominence seen
by EIT was tracked into the LASCO/C2 and C3 field-of-view (FOV; 4-10
R⊙) where it developed as the core of a typical three-part
CME. The speed of the inflow, which was only seen in EIT FOV, was 70-80
km/s at a height between 1.5-1.2 R⊙ coinciding with the
deceleration phase of the core of the CME in LASCO/C2. In contrast to
dark inflow structures observed earlier and interpreted as plasma void
moving down, the inflow reported here was bright. The inflow showed a
constant deceleration and followed a curved path suggesting the apex
of a contracting magnetic loop sliding down along other field lines.
Title: Solar Cycle Variation of the Internal Magnetic Field Structure
of CMEs
Authors: Bothmer, Volker
Bibcode: 2005IAUS..226..208B
Altcode:
The internal magnetic field structure of CMEs and the field structure
of the solar source regions were systematically investigated during
different phases of the solar cycle in cycles 19-23 based on plasma
and magnetic field measurements sampled by various satellites and
through multi-wavelength remote sensing observations. It is found that:
1. To first order, the internal magnetic structure of CMEs varies
systematically from one solar cycle to the next with respect to the
prevailing hemispheric magnetic patterns of bipolar regions following
the law of hemispheric helicity dependence. 2. To second order, the
field structure in CMEs varies with respect to the complex spatial
evolution of the magnetic flux in the photosphere in both hemispheres
over the course of the cycle itself. The two effects can naturally
explain the cyclic behavior of the SN, NS variations of the internal
magnetic fields in CMEs in the solar wind as well as intermittent
periods of mixed distributions.
Title: Solar origins of intense geomagnetic storms in 2002 as seen
by the CORONAS-F satellite
Authors: Panasenco, O.; Veselovsky, I. S.; Dmitriev, A. V.; Zhukov,
A. N.; Yakovchouk, O. S.; Zhitnik, I. A.; Ignat'ev, A. P.; Kuzin,
S. V.; Pertsov, A. A.; Slemzin, V. A.; Boldyrev, S. I.; Romashets,
E. P.; Stepanov, A.; Bugaenco, O. I.; Bothmer, V.; Koutchmy, S.;
Adjabshirizadeh, A.; Fazel, Z.; Sobhanian, S.
Bibcode: 2005AdSpR..36.1595P
Altcode:
We analyze solar origins of intense geomagnetic perturbations recorded
during 2002. All of them were related to coronal mass ejections
(CMEs). The initiation of CMEs was documented using the SPIRIT
instrument (SPectrohelIographic Soft X-Ray Imaging Telescope) onboard
the CORONAS-F satellite. Monochromatic full Sun images taken in the Mg
XII doublet at 8.418 and 8.423 Å showed the appearance of free energy
release sites at altitudes up to 0.4 solar radii. CMEs were initiated
at these sites and propagated in interplanetary space under appropriate
local conditions including the geometry of the magnetic fields.
Title: Magnetic storm cessation during sustained northward IMF
Authors: Veselovsky, I. S.; Bothmer, V.; Cargill, P.; Dmitriev, A. V.;
Ivanov, K. G.; Romashets, E.; Zhukov, A. N.; Yakovchouk, O. S.
Bibcode: 2005AdSpR..36.2460V
Altcode:
Times of sustained strong northward IMF can interrupt the magnetic
storm development and lead to lower levels of geomagnetic activity
for many hours. During 1997-2000 we have found two events of this
kind observed on November 8, 1998 and October 13, 2000. In both
cases, the storms started as usual after arrival of ejecta with a
southward IMF component from the Sun to the Earth, but ceased after
several hours due to the onset of sustained northward IMF leading
to the faster recovery process. After the passage of this so-called
positive domain, the storm development started again. The heliospheric
magnetic field intensity remained enhanced and nearly constant. The
solar origins of the geomagnetic storm interruptions have been
investigated. Tentatively they may be related to strong nonlinear
Alfvйn type solitary waves excited by non-stationary coronal current
variations with a characteristic time-scale of about a day.
Title: Geometrical Properties of Coronal Mass Ejections
Authors: Cremades, Hebe; Bothmer, Volker
Bibcode: 2005IAUS..226...48C
Altcode:
Based on the SOHO/LASCO dataset, a collection of "structured" coronal
mass ejections (CMEs) has been compiled within the period 1996-2002,
in order to analyze their three-dimensional configuration. These CME
events exhibit white-light fine structures, likely indicative of their
possible 3D topology. From a detailed investigation of the associated
low coronal and photospheric source regions, a generic scheme has been
deduced, which considers the white-light topology of a CME projected
in the plane of the sky as being primarily dependent on the orientation
and position of the source region's neutral line on the solar disk. The
obtained results imply that structured CMEs are essentially organized
along a symmetry axis, in a cylindrical manner. The measured dimensions
of the cylinder's base and length yield a ratio of 1.6. These CMEs
seem to be better approximated by elliptic cones, rather than by the
classical ice cream cone, characterized by a circular cross section.
Title: IMPACT: Science goals and firsts with STEREO
Authors: Luhmann, J. G.; Curtis, D. W.; Lin, R. P.; Larson, D.;
Schroeder, P.; Cummings, A.; Mewaldt, R. A.; Stone, E. C.; Davis, A.;
von Rosenvinge, T.; Acuna, M. H.; Reames, D.; Ng, C.; Ogilvie, K.;
Mueller-Mellin, R.; Kunow, H.; Mason, G. M.; Wiedenbeck, M.; Sauvaud,
A.; Aoustin, C.; Louarn, P.; Dandouras, J.; Korth, A.; Bothmer, V.;
Vasyliunas, V.; Sanderson, T.; Marsden, R. G.; Russell, C. T.; Gosling,
J. T.; Bougeret, J. L.; McComas, D. J.; Linker, J. A.; Riley, P.;
Odstrcil, D.; Pizzo, V. J.; Gombosi, T.; DeZeeuw, D.; Kecskemety, K.
Bibcode: 2005AdSpR..36.1534L
Altcode:
The in situ measurements of particles and CME transients (IMPACT)
investigation on the twin STEREO spacecraft focuses on the solar
energetic particle, solar wind and suprathermal electron, and magnetic
field measurements needed to address STEREO's goals. IMPACT will provide
regular, identical, in situ multipoint measurements bracketing Earth
as each spacecraft separates from it at a rate of ∼22°/yr along
Earth's orbit. Combined with the PLASTIC and SWAVES investigations,
IMPACT fills a critical role in the STEREO quest to connect SECCHI's
3D coronal images to their interplanetary consequences.
Title: Morphology Indicators of the Three-Dimensional Size of Flux
Rope CMEs: A Prediction for STEREO
Authors: St. Cyr, O. C.; Cremades, H.; Bothmer, V.; Krall, J.;
Burkepile, J. T.
Bibcode: 2004AGUFMSH22A..04S
Altcode:
We provide a new estimate of the three-dimensional sizes of flux
rope coronal mass ejections (CMEs). We base our estimate on the
interpretation of two CME morphologies that have previously been
considered distinct. We believe these morphologies represent two
perspectives of the same large scale cylindrical structure (a magnetic
flux rope) seen axially versus broadside. This distinction has not been
previously recognized because both morphologies have been classified
as "three-part structures". Our preliminary study based on 21 events
(13 axial and 8 broadside) indicated an average diameter of 46° and
an average length of 76° for these flux rope CMEs. We compare our
statistical results to those obtained using an elliptical flux rope
model, and we present the current status of this work-in-progress. This
result will be tested in the future by observations of individual CMEs
from different locations by NASA's STEREO mission.
Title: Solar and Heliospheric Phenomena in October-November 2003:
Causes and Effects
Authors: Veselovsky, I. S.; Panasyuk, M. I.; Avdyushin, S. I.;
Bazilevskaya, G. A.; Belov, A. V.; Bogachev, S. A.; Bogod, V. M.;
Bogomolov, A. V.; Bothmer, V.; Boyarchuk, K. A.; Vashenyuk, E. V.;
Vlasov, V. I.; Gnezdilov, A. A.; Gorgutsa, R. V.; Grechnev,
V. V.; Denisov, Yu. I.; Dmitriev, A. V.; Dryer, M.; Yermolaev,
Yu. I.; Eroshenko, E. A.; Zherebtsov, G. A.; Zhitnik, I. A.;
Zhukov, A. N.; Zastenker, G. N.; Zelenyi, L. M.; Zeldovich,
M. A.; Ivanov-Kholodnyi, G. S.; Ignat'ev, A. P.; Ishkov, V. N.;
Kolomiytsev, O. P.; Krasheninnikov, I. A.; Kudela, K.; Kuzhevsky,
B. M.; Kuzin, S. V.; Kuznetsov, V. D.; Kuznetsov, S. N.; Kurt, V. G.;
Lazutin, L. L.; Leshchenko, L. N.; Litvak, M. L.; Logachev, Yu. I.;
Lawrence, G.; Markeev, A. K.; Makhmutov, V. S.; Mitrofanov, A. V.;
Mitrofanov, I. G.; Morozov, O. V.; Myagkova, I. N.; Nusinov, A. A.;
Oparin, S. N.; Panasenco, O. A.; Pertsov, A. A.; Petrukovich, A. A.;
Podorol'sky, A. N.; Romashets, E. P.; Svertilov, S. I.; Svidsky, P. M.;
Svirzhevskaya, A. K.; Svirzhevsky, N. S.; Slemzin, V. A.; Smith, Z.;
Sobel'man, I. I.; Sobolev, D. E.; Stozhkov, Yu. I.; Suvorova, A. V.;
Sukhodrev, N. K.; Tindo, I. P.; Tokhchukova, S. Kh.; Fomichev, V. V.;
Chashey, I. V.; Chertok, I. M.; Shishov, V. I.; Yushkov, B. Yu.;
Yakovchouk, O. S.; Yanke, V. G.
Bibcode: 2004CosRe..42..435V
Altcode:
We present new observational data on the phenomena of extremely
high activity on the Sun and in the heliosphere that took place
in October-November 2003. A large variety of solar and heliospheric
parameters give evidence that the interval under consideration is unique
over the entire observation time. Based on these data, comparing them
with similar situations in the past and using available theoretical
concepts, we discuss possible cause-and-effect connections between
the processes observed. The paper includes the first results and
conclusions derived by the collaboration ``Solar Extreme Events-2003''
organized in Russia for detailed investigations of these events. As a
result of our consideration, it is beyond question that the physical
causes of solar and heliospheric phenomena in October-November 2003
are not exclusively local and do not belong only to the active regions
and solar atmosphere above them. The energy reservoirs and driving
forces of these processes have a more global nature. In general, they
are hidden from an observer, since ultimately their sources lie in
the subphotospheric layers of the Sun, where changes that are fast
and difficult to predict can sometimes take place (and indeed they
do). Solar flares can serve as sufficiently good tracers of these sudden
changes and reconstructions on the Sun, although one can still find
other diagnostic indicators among the parameters of magnetic fields,
motions of matter, and emission characteristics.
Title: The Solar and Interplanetary Causes of Space Storms in Solar
Cycle 23
Authors: Bothmer, V.
Bibcode: 2004ITPS...32.1411B
Altcode:
No abstract at ADS
Title: On the three-dimensional configuration of coronal mass
ejections
Authors: Cremades, H.; Bothmer, V.
Bibcode: 2004A&A...422..307C
Altcode:
Coronal mass ejections (CMEs) are a direct consequence of the dynamic
nature of the solar atmosphere. They represent fundamental processes
in which energy is transferred from the Sun into interplanetary
space, including geospace. Their origin, 3D structure and internal
magnetic field configuration are to date not well understood. The SOHO
spacecraft, launched by the end of 1995, has provided unprecedented
data on CMEs since instruments switched on in 1996. From a detailed
investigation of the full set of LASCO (Large Angle Spectroscopic
Coronagraph) observations from 1996 to the end of 2002, a set of
structured CME events has been identified, which exhibits white-light
fine structures likely indicative of their internal magnetic field
configuration and possible 3D structure. Their source regions in the
low corona and photosphere have been inferred by means of complementary
analyses of data from the Extreme-Ultraviolet Imaging Telescope (EIT)
and Michelson Doppler Imager (MDI) on board SOHO, and ground-based
Hα measurements. According to the results of this study, structured
CMEs arise in a self-similar manner from pre-existing small scale
loop systems, overlying regions of opposite magnetic polarities. From
the characteristic pattern of the CMEs' source regions in both solar
hemispheres, a generic scheme is presented in which the projected
white-light topology of a CME depends primarily on the orientation and
position of the source region's neutral line on the solar disk. The
paper also provides information about the white-light characteristics
of the analysed CMEs, such as angular width and position angle,
with respect to their source region properties, such as heliographic
location, inclination and length, including the frequency and variation
of these parameters over the investigated time period.
Title: The basic characteristics of EUV post-eruptive arcades and
their role as tracers of coronal mass ejection source regions
Authors: Tripathi, D.; Bothmer, V.; Cremades, H.
Bibcode: 2004A&A...422..337T
Altcode:
The Extreme ultraviolet Imaging Telescope (EIT) on board the Solar and
Heliospheric Observatory (SOHO) spacecraft provides unique observations
of dynamic processes in the low corona. The EIT 195 Å data taken from
1997 to the end of 2002 were investigated to study the basic physical
properties of post-eruptive arcades (PEAs) and their relationship with
coronal mass ejections (CMEs) as detected by SOHO/LASCO (Large Angle
Spectrometric Coronagraph). Over the investigated time period, 236 PEA
events have been identified in total. For each PEA, its EUV lifetime
as derived from the emission time at 195 Å, its heliographic position
and length, and its corresponding photospheric source region inferred
from SOHO/MDI (Michelson Doppler Imager) data has been studied, as well
as the variation of these parameters over the investigated phase of
solar cycle 23. An almost one to one correspondence is found between
EUV PEAs and white-light CMEs. Based on this finding, PEAs can be
considered as reliable tracers of CME events even without simultaneous
coronagraph observations. A detailed comparison of the white-light,
soft X-ray and EUV observation for some of the events shows, that PEAs
form in the aftermath of CMEs likely in the course of the magnetic
restructurings taking place at the coronal source sites. The average
EUV emission life-time for the selected events ranged from 2 to 20
h, with an average of 7 h. The heliographic length of the PEAs was
in the range of 2 to 40 degrees, with an average of 15 degrees. The
length increased by a factor of 3 to 4 in the latitude range of 20
to 40 degrees in the northern and southern hemispheres, with longer
PEAs being observed preferentially at higher latitudes. The PEAs were
located mainly in the activity belts in both hemispheres, with the
southern hemispheric ones being shifted by about 15 degree in latitude
further away from the solar equator during 1997-2002. The decrease
in latitude of the PEA positions was 10 to 15 degrees in the northern
and southern hemispheres over this period. The axes of the PEAs were
overlying magnetic polarity inversion lines when traced back to the
MDI synoptic charts of the photospheric field. The magnetic polarities
on both sides of the inversion lines agreed with the dominant magnetic
pattern expected in cycle 23, i.e. being preferentially positive to the
West of the PEA axes in the North and negative in the South. One third
(31%) of the PEA events showed reversed polarities. The origin of PEAs
is found not just in single bipolar regions (BPRs), but also in between
pairs of neighboring BPRs. Table 1 is available in electronic
form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5)
or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/422/337
Title: VizieR Online Data Catalog: Solar EUV Post-Eruptive Arcades
(Tripathi+, 2004)
Authors: Tripathi, D.; Bothmer, V.; Cremades, H.
Bibcode: 2004yCat..34220337T
Altcode:
The Extreme ultraviolet Imaging Telescope (EIT) on board the Solar and
Heliospheric Observatory (SOHO) spacecraft provides unique observations
of dynamic processes in the low corona. The EIT 195{AA} data taken from
1997 to the end of 2002 were investigated to study the basic physical
properties of post-eruptive arcades (PEAs) and their relationship with
coronal mass ejections (CMEs) as detected by SOHO/LASCO (Large Angle
Spectrometric Coronagraph). Over the investigated time period, 236 PEA
events have been identified in total. For each PEA, its EUV lifetime as
derived from the emission time at 195{AA}, its heliographic position
and length, and its corresponding photospheric source region inferred
from SOHO/MDI (Michelson Doppler Imager) data has been studied, as
well as the variation of these parameters over the investigated phase
of solar cycle 23. (1 data file).
Title: MAGRITTE: an instrument suite for the solar atmospheric
imaging assembly (AIA) aboard the Solar Dynamics Observatory
Authors: Rochus, Pierre L.; Defise, Jean-Marc; Halain, Jean-Philippe;
Jamar, Claude A. J.; Mazy, Emmanuel; Rossi, Laurence; Thibert,
Tanguy; Clette, Frederic; Cugnon, Pierre; Berghmans, David; Hochedez,
Jean-Francois E.; Delaboudiniere, Jean-Pierre; Auchere, Frederic;
Mercier, Raymond; Ravet, Marie-Francoise; Delmotte, Franck; Idir,
Mourad; Schuehle, Udo H.; Bothmer, Volker; Fineschi, Silvano; Howard,
Russell A.; Moses, John D.; Newmark, Jeffrey S.
Bibcode: 2004SPIE.5171...53R
Altcode:
The Solar Atmospheric Imaging Assembly (AIA) aboard the Solar Dynamics
Observatory will characterize the dynamical evolution of the solar
plasma from the chromosphere to the corona, and will follow the
connection of plasma dynamics with magnetic activity throughout the
solar atmosphere. The AIA consists of 7 high-resolution imaging
telescopes in the following spectral bandpasses: 1215Å. Ly-a,
304 Å He II, 629 Å OV, 465 Å Ne VII, 195 Å Fe XII (includes Fe
XXIV), 284 Å Fe XV, and 335 Å Fe XVI. The telescopes are grouped
by instrumental approach: the MAGRITTE Filtergraphs (R. MAGRITTE,
famous 20th Century Belgian Surrealistic Artist), five multilayer EUV
channels with bandpasses ranging from 195 to 1216 Å, and the SPECTRE
Spectroheliograph with one soft-EUV channel at OV 629 Å. They will be
simultaneously operated with a 10-second imaging cadence. These two
instruments, the electronic boxes and two redundant Guide Telescopes
(GT) constitute the AIA suite. They will be mounted and coaligned on a
dedicated common optical bench. The GTs will provide pointing jitter
information to the whole SHARPP assembly. This paper presents the
selected technologies, the different challenges, the trade-offs to be
made in phase A, and the model philosophy. From a scientific viewpoint,
the unique combination high temporal and spatial resolutions with the
simultaneous multi-channel capability will allow MAGRITTE / SPECTRE
to explore new domains in the dynamics of the solar atmosphere, in
particular the fast small-scale phenomena. We show how the spectral
channels of the different instruments were derived to fulfill the
AIA scientific objectives, and we outline how this imager array will
address key science issues, like the transition region and coronal waves
or flare precursors, in coordination with other SDO experiments. We
finally describe the real-time solar monitoring products that will be
made available for space-weather forecasting applications.
Title: EUVI: the STEREO-SECCHI extreme ultraviolet imager
Authors: Wuelser, Jean-Pierre; Lemen, James R.; Tarbell, Theodore
D.; Wolfson, C. J.; Cannon, Joseph C.; Carpenter, Brock A.; Duncan,
Dexter W.; Gradwohl, Glenn S.; Meyer, Syndie B.; Moore, Augustus S.;
Navarro, Rosemarie L.; Pearson, J. D.; Rossi, George R.; Springer,
Larry A.; Howard, Russell A.; Moses, John D.; Newmark, Jeffrey S.;
Delaboudiniere, Jean-Pierre; Artzner, Guy E.; Auchere, Frederic;
Bougnet, Marie; Bouyries, Philippe; Bridou, Francoise; Clotaire,
Jean-Yves; Colas, Gerard; Delmotte, Franck; Jerome, Arnaud; Lamare,
Michel; Mercier, Raymond; Mullot, Michel; Ravet, Marie-Francoise;
Song, Xueyan; Bothmer, Volker; Deutsch, Werner
Bibcode: 2004SPIE.5171..111W
Altcode:
The Extreme Ultraviolet Imager (EUVI) is part of the SECCHI instrument
suite currently being developed for the NASA STEREO mission. Identical
EUVI telescopes on the two STEREO spacecraft will study the structure
and evolution of the solar corona in three dimensions, and specifically
focus on the initiation and early evolution of coronal mass ejections
(CMEs). The EUVI telescope is being developed at the Lockheed Martin
Solar and Astrophysics Lab. The SECCHI investigation is led by the
Naval Research Lab. The EUVI"s 2048 x 2048 pixel detectors have a
field of view out to 1.7 solar radii, and observe in four spectral
channels that span the 0.1 to 20 MK temperature range. In addition to
its view from two vantage points, the EUVI will provide a substantial
improvement in image resolution and image cadence over its predecessor
SOHO-EIT, while complying with the more restricted mass, power, and
volume allocations on the STEREO mission.
Title: Plasma dynamics of a prominence associated coronal mass
ejection
Authors: Tripathi, D.; Bothmer, V.; Solanki, S. K.; Schwenn, R.;
Mierla, M.; Stenborg, G.
Bibcode: 2004IAUS..223..401T
Altcode: 2005IAUS..223..401T
An erupting prominence seen by SOHO/EIT was tracked into the field of
view of the LASCO C2 and C3 coronagraphs where it developed into the
core of a structured CME. The erupting prominence was deflected by an
angle of sim 20^{circ} towards the north pole whereas the consequent
core of the CME and it's leading edge propagated in the outer corona at
constant position angle. The prominence material underwent a constant
acceleration phase until a height of sim1.5 solar radii before it
started to decelerate up to a distance of 5.0 solar radii. An inflow
of plasma with a speed of about 70-80 km/s was discovered in the EIT
observations at a height of 1.5-1.2 solar radii in the course of the
prominence eruption, matching in time the prominence deceleration
phase. The downflowing material followed a curved path, suggestive
of the apex of a contracting magnetic loop sliding down along other
field lines.
Title: Properties of slow magnetic clouds
Authors: Tsurutani, B. T.; Gonzalez, W. D.; Zhou, X. -Y.; Lepping,
R. P.; Bothmer, V.
Bibcode: 2004JASTP..66..147T
Altcode: 2004JATP...66..147T
Slow (VSW<400kms-1) magnetic clouds
have been analyzed to determine their characteristics and
geoeffectiveness. It is found that slow clouds have mean magnetic
field strengths of ~13nT, peak BS~9nT, and dawn-dusk
electric fields of ESW~2.5mVm-1. The clouds
are small in spatial size, typically ~0.18AU. The slowest events
may have been accelerated to their speeds by interaction with the
slow solar wind. Slow clouds are surprisingly geoeffective. Five
out of 27 events caused major (DST<=-100nT) magnetic
storms. Likewise, these geoeffective clouds may have been decelerated
to VSW<400kms-1. The issue of interplanetary
acceleration/deceleration will be examined with SOHO coronal mass
ejection data in the near future.
Title: Properties of Structured Coronal Mass Ejections in Solar
Cycle 23
Authors: Cremades, H.; Bothmer, V.; Tripathi, D.
Bibcode: 2004cosp...35.1939C
Altcode: 2004cosp.meet.1939C
The Solar and Heliospheric Observatory (SOHO) has provided to date the
best dataset of coronal observations ever taken over the course of
a solar cycle. Structured CMEs, i. e. events with clear white-light
fine structures, have been selected from the LASCO (Large Angle
Spectroscopic Coronagraph) dataset during the period 1996-2002. Their
source regions (SRs) in the low corona and photosphere have been deduced
by analyzing data from the EIT (Extreme-Ultraviolet Imaging Telescope)
and MDI (Michelson Doppler Imager) instruments on board SOHO, and
from ground-based Hα measurements. Based on this subset of CMEs,
originally compiled to study the three-dimensional configuration of
CMEs, we have analyzed the variation of their properties along the
present solar cycle. These properties include SR latitude, tilt angle
of CME SRs, CME position angle, and deviation of CMEs with respect to
their corresponding SRs.
Title: Evolution of the photospheric magnetic field in the source
regions of coronal mass ejections
Authors: Tripathi, D.; Bothmer, V.; Cremades, H.
Bibcode: 2004cosp...35.1966T
Altcode: 2004cosp.meet.1966T
EIT (Extreme ultraviolet Imaging Telescope) and MDI (Michelson Doppler
Imager) instruments on board SoHO (Solar and Heliospheric Observatory)
provide an unprecedented opportunity to study the source regions of
coronal mass ejections (CMEs) in the low corona and photosphere. Eight
CMEs associated with filament eruptions observed by EIT near disk
center were studied in detail. In five events new emerging magnetic
flux occurred in spatial and temporal relationship with the instability
sites of the filaments. In two cases field changes in nearby active
regions seem to have triggered the filament eruptions. In one case,
evidence for flux cancellation was found. The different possible causes
of the eruptions are discussed in context with the related changes of
the photospheric field.
Title: Determination of the source regions, 3-D structures and
magnetic field configurations of CMEs at the Sun and in the
interplanetary medium
Authors: Bothmer, V.; Cremades, H.; Tripathi, D.
Bibcode: 2004cosp...35.1976B
Altcode: 2004cosp.meet.1976B
There are numerous unanswered questions concerning the origin, nature,
evolution and consequences of coronal mass ejections at the Sun
and in the interplanetary medium. STEREO will provide the first 3-D
view of the Sun-Earth system and Solar-B will provide unprecedented
measurements of the magnetic field structure of their photospheric
source regions. The two NASA missions, scheduled for launch in 2006,
will hence provide us with a new view of CMEs. In order to establish
the scientific goals of these missions, this talk will provide: - A
brief summary of our current understanding of the origin and evolution
of CMEs based on the latest results obtained from SOHO, Yohkoh, TRACE,
ACE and Wind observations. - A basic scheme explaining the 3-D structure
and near-Sun evolution of CMEs that can be directly proven with STEREO
and Solar-B. - An outline for joint science operations required to test
existing models for the onset and evolution of CMEs up to Earth's orbit.
Title: Solar Wind Disturbances and Their Sources in the EUV Solar
Corona
Authors: Zhukov, A. N.; Veselovsky, I. S.; Clette, F.; Hochedez,
J. -F.; Dmitriev, A. V.; Romashets, E. P.; Bothmer, V.; Cargill, P.
Bibcode: 2003AIPC..679..711Z
Altcode:
We investigate possible links between the activity manifestations in the
solar corona and conditions in the solar wind. For the reduction of this
immense task we have selected 206 events in the solar wind in 1997 -
2000 corresponding to geomagnetic events with Ap > 20 (compiled into
a database at <emph TYPE="46">http://alpha.sinp.msu.ru/apev). Up
to now, 24 events during the epoch of low solar activity (January 1997 -
January 1998) are investigated. The solar wind conditions monitored by
ACE and WIND spacecraft were traced back to the solar corona observed
by SOHO/EIT. The search for coronal signatures which are probably
associated with the disturbed solar wind conditions was performed. The
coronal sources of these 24 events are identified, namely: eruptions in
active regions, filament eruptions and coronal holes. It is shown that
halo and partial halo CMEs observed within the SOHO/LASCO sensitivity
limits are not necessary indicators of Earth-directed eruptions, and
coronal EUV dimmings can be used as a complementary indicator. We also
found that a structure now conventionally called a ``sigmoid'' cannot
be represented as a single S-shaped loop (flux tube), but exhibits an
assembly of many smaller structures. It could be formed and destroyed
via eruptions.
Title: Sources of magnetic helicity over the solar cycle
Authors: Bothmer, Volker
Bibcode: 2003ESASP.535..419B
Altcode: 2003iscs.symp..419B
The magnetic field characteristics of a sample set of helical
magnetic flux rope ICMEs (magnetic clouds) observed by the Wind and
ACE satellites in solar cycle 23 and their related space weather
effects are investigated. The solar source regions of the magnetic
clouds were identified using remote sensing observations of the SOHO,
Yohkoh and TRACE spacecraft together with ground-based Hα images. Each
cloud observed at 1 AU could be uniquely associated with a well defined
frontside halo CME some days before the cloud's arrival at 1 AU. The
hemispheric origin is consistent with the expected hemispheric helicity
pattern. The space weather effects of the clouds were quite variable,
depending on their internal magnetic field configuration and speed
of progagation.
Title: How to forecast geomagnetic storms reliably - The
characteristics of storms in the rising phase of solar cycle 23
Authors: Bothmer, V.; Cargill, P.; Dmitriev, A.; Romashets, E.;
Veselovsky, I.; Zhukov, A.
Bibcode: 2003EAEJA.....2018B
Altcode:
The solar wind input parameters were studied for geomagnetic disturbed
days in which Ap exceeded its average value by using plasma and magnetic
field data from various near-Earth satellites. More than 270 events
occurred during the time-period 1997 to 2002. The interplanetary
and solar characteristics of these events have been summarised
at http://alpha.sinp.msu.ru/apev. A unique identification of the
corresponding solar sources was not possible for all of the events,
but in general they could be classified based on SOHO white-light and
EUV observations taken by the LASCO/EIT telescopes into disturbances
caused by coronal hole flows and coronal mass ejections or interactions
between them. Compression regions caused by stream interactions
effects including compressed Alfven-waves are also an important
cause of enhanced geomagnetic activity. Our results imply that the
forecast of an individual storms does not only require sufficient
real-time observations of the solar corona, but as well modelling of
the heliospheric situation, finally taking into account a seasonal
dependence of the coupling efficiency of the IMF with the Earth’s
magnetosphere. The work is supported by grants INTAS-ESA 99-00727 and
INTAS 00-752 .
Title: 3D Magnetic Field Configuration and Evolution of Coronal
Mass Ejections
Authors: Cremades, H.; Bothmer, V.; Tripathi, D.
Bibcode: 2003EAEJA......852C
Altcode:
Coronal Mass Ejections (CMEs) are the most energetic transient
phenomena in the solar atmosphere. The origins of CMEs, their 3D
structure and internal magnetic field configuration, as well as their
evolution into interplanetary space are not well understood. Thanks
to the high resolution telescopes of the SOHO Mission, for the first
time magnetic fine structures can be resolved within CMEs observed
close to the Sun. A set of CME events has been identified from a
detailed investigation of LASCO (Large Angle Spectroscopic Coronagraph)
observations taken since launch in 1995. This data set comprises those
cases exhibiting white-light fine structures, from which their magnetic
field configuration could be deduced. Since the observed white-light
features are the result of an inherent line-of-sight integration
projected on the plane of the sky, inferring the three-dimensional
topology of CMEs is a challenging and complicated task. In order
to reveal the actual 3D profile of a CME, an approach based on the
characterization of their respective source region magnetic field
configuration is addressed. The study indicates that many CMEs are
comprised either of arcades of magnetic field lines or magnetic
flux tubes which are trailed by prominence material. The analysis of
additional coronal and magnetic field observations (EIT, MDI) shows
that these magnetic structures seem to arise from already existing loop
systems of much smaller scale that originate in bipolar field regions.
Title: Solar wind disturbances and their sources in the EUV solar
corona
Authors: Zhukov, A.; Veselovsky, I.; Bothmer, V.; Dmitriev, A.;
Clette, F.; Romashets, E.; Cargill, P.
Bibcode: 2003EAEJA.....2682Z
Altcode:
We investigate possible links between the activity manifestations in
the solar corona and conditions in the solar wind. For the reduction
of this immense task we have selected 206 events in the solar wind
in 1997 -- 2000 corresponding to geomagnetic events with Ap > 20
(compiled into a database at http://alpha.sinp.msu.ru/apev). The solar
wind conditions monitored by ACE and WIND spacecraft were traced back to
the solar corona observed by SOHO/EIT. The search for coronal signatures
that are probably associated with the disturbed solar wind conditions
was performed. The coronal sources of the events are identified, namely:
eruptions in active regions, filament eruptions and coronal holes. It is
shown that halo and partial halo CMEs observed within the SOHO/LASCO
sensitivity limits are not necessary indicators of Earth-directed
eruptions, and coronal EUV dimmings can be used as a complementary
indicator. We also found that a structure now conventionally called a
''sigmoid'' cannot be represented as a single S-shaped loop (flux tube),
but exhibits an assembly of many smaller structures. It could be formed
and destroyed via eruptions.
Title: Identification of Solar Sources of Major Geomagnetic Storms
between 1996 and 2000
Authors: Zhang, J.; Dere, K. P.; Howard, R. A.; Bothmer, V.
Bibcode: 2003ApJ...582..520Z
Altcode:
This paper presents identification of solar coronal mass ejection (CME)
sources for 27 major geomagnetic storms (defined by disturbance storm
timeindex<=-100 nT) occurring between 1996 and 2000. Observations of
CMEs and their solar surface origins are obtained from the Large Angle
and Spectrometric Coronagraph (LASCO) and the EUV Imaging Telescope
(EIT) instruments on the SOHO spacecraft. Our identification has
two steps. The first step is to select candidate front-side halo
(FSH) CMEs using a fixed 120 hr time window. The second step is
to use solar wind data to provide further constraints, e.g., an
adaptive time window defined based on the solar wind speed of the
corresponding interplanetary CMEs. We finally find that 16 of the
27 (59%) major geomagnetic storms are identified with unique FSH
CMEs. Six of the 27 events (22%) are associated with multiple FSH
CMEs. These six events show complex solar wind flows and complex
geomagnetic activity, which are probably the result of multiple halo
CMEs interacting in interplanetary space. A complex event occurs when
multiple FSH CMEs are produced within a short period. Four of the 27
(15%) events are associated with partial-halo gradual CMEs emerging
from the east limb. The surface origin of these events is not known
because of a lack of any EIT signature. We believe that they are
longitudinally extended CMEs having a component moving along the
Sun-Earth connection line. One of the 27 major geomagnetic storms is
caused by a corotating interaction region. We find an asymmetry in
the longitudinal distribution of solar source region for the CMEs
responsible for major geomagnetic storms. They are more likely
to originate from the western hemisphere than from the eastern
hemisphere. In terms of latitude, most geoeffective CMEs originate
within a latitude strip of +/-30°. The average transit time for a
solar CME to arrive at the near-Earth space is found to be 64 hr,
while it takes 78 hr on average to reach the peak of the geomagnetic
storm. There is a correlation between CME transit time from the Sun
to the near-Earth space (T, in hours) and the CME initial velocity
(V, in unit of kilometers per second) at the Sun, which can be simply
described as T=96-(V/21). We also find that while these geoeffective
CMEs are either full-halo CMEs (67%) or partial-halo CMEs (30%),
there is no preference for them to be fast CMEs or to be associated
with major flares and erupting filaments.
Title: Dynamics of open solar magnetic fields, active longitudes,
and near earth disturbances
Authors: Ivanov, K.; Bothmer, V.; Kharshiladze, A.; Romashets, E.;
Veselovsky, I.
Bibcode: 2002ESASP.506..141I
Altcode: 2002ESPM...10..141I; 2002svco.conf..141I
Open magnetic field lines in the solar corona are calculated in order to
study their relationship to solar activity and near Earth disturbances
in 2000. Slow, rotation by rotation, dynamics of photospheric regions
with open fields show a correlation with generating and decay of
active complexes located at longitudes 280-360 degrees, and with the
series of the near Earth recurrent extra storms on May 24, July 15,
August 12, and October 5.
Title: Solar and Heliospheric Causes of Geomagnetic Perturbations
during the Growth Phase of Solar Cycle 23
Authors: Bothmer, V.; Veselovsky, I. S.; Dmitriev, A. V.; Zhukov,
A. N.; Cargill, P.; Romashets, E. P.; Yakovchouk, O. S.
Bibcode: 2002SoSyR..36..499B
Altcode:
A database is compiled for the study of solar and heliospheric causes
of geomagnetic perturbations with the daily average index Ar
> 20 that were observed in the period 1997-2000. The number of such
events (more than 200) progressively increased and fluctuated as the
current solar cycle developed. It is established that geomagnetic
storms are generated by dynamical processes and structures near
the center of the solar disk in a zone of several tens of degrees,
and these processes are responsible for the appearance in the Earth's
region, within several tens of hours, of quasistationary and transient
solar wind streams with a sufficiently strong southward component of
the heliospheric magnetic field. These streams lasted more than a few
hours. The following structures can serve as morphological indicators
for the prediction of the appearance of such streams: (1) active and
disappearing filaments derived from synoptic Nα-maps of the
Sun, (2) solar flares, (3) coronal holes and evolving active regions,
and (4) the heliospheric current sheet. The geometry of coronal mass
ejections needs further observational study.
Title: Solar energetic electron events and coronal shocks
Authors: Klassen, A.; Bothmer, V.; Mann, G.; Reiner, M. J.; Krucker,
S.; Vourlidas, A.; Kunow, H.
Bibcode: 2002A&A...385.1078K
Altcode:
Mildly relativistic electrons appear during the solar energetic particle
events. A detailed investigation on the origin of such electrons is
presented for four particlular solar events. The mildly relativistic
electrons have been detected at energies of 0.25-0.7 MeV by COSTEP/SOHO
and below 0.392 MeV by Wind 3-DP experiments. Coronal shocks associated
with these electron events are identified from the metric-to-decametric
solar type II radio bursts. All selected events were associated with
solar activity at western longitudes, so that the magnetic footpoints
connecting the spacecraft with the Sun were close to the flare/shock/CME
site. The associated type II bursts were accompanied by so-called shock
accelerated (SA) type III bursts appearing to be emerging from the type
II emission site. We found: (1) that all of the 0.25-0.7 MeV electron
events were released during or after, but never simultaneously with the
onset of type II bursts and CMEs. The time delay between the type II
burst onset and the release of the mildly relativistic electrons is in
the range of 11.5-45 min; (2) that the mildly relativistic electrons
were released rather at the end of SA type III bursts or somewhat
later; (3) that the mildly relativistic electrons were released when
the associated type II burst and the CME reached a certain height
(h ~ 1-4 R_s) above the photosphere. For the four events studied,
it is concluded that mildly relativistic electrons at 0.25-0.7 MeV
energies measured in the interplanetary medium from solar energetic
particle events are accelerated by coronal shock waves, commonly in
association with white-light CMEs.
Title: Solar and heliospheric origins of geomagnetic perturbations
in the rising phase of Solar Cycle 23
Authors: Bothmer, V.; Cargill, P.; Romashets, E. P.; Veselovsky, I. S.
Bibcode: 2002ESASP.477..331B
Altcode: 2002scsw.conf..331B
Solar sources of strong geomagnetic perturbations are connected
to coronal mass ejections and corotating inhomogeneities in the
heliosphere. Geomagnetic perturbations with Ap > 20 in 1997-2000 were
produced by heliospheric magnetic fields and solar wind plasma streams
related to the following morphological features observed at the Sun:
1) active and disappearing filaments and prominences (sdf) seen in Hα
synoptic maps; 2) solar flares; 3) evolving active regions and coronal
holes (CH); 4) heliospheric current sheet (HCS) positions deduced from
photospheric magnetic field measurements. Strong geomagnetic storms
during this period of time were observed when compound plasma streams
from several sources on the Sun reached the Earth's magnetosphere. The
combination of the transient processes and corotating inhomogeneities
in the solar corona and deeper layers of the solar atmosphere not far
from the center of the solar disk (first tens of degrees) represent
a sufficient condition for the formation of such compound streams
exemplified by sdf-CH-HCS passage.
Title: Subsector structure of the interplanetary space - SOLSPA 2001
Authors: Ivanov, K. G.; Bothmer, V.; Cargill, P.; Kharshiladze, A. F.;
Romashets, E. P.; Veselovsky, I. S.
Bibcode: 2002ESASP.477..317I
Altcode: 2002scsw.conf..317I
A new conception about sub-sector structure of the interplanetary
space is introduced. It is shown that in a potential model of the
solar magnetic field there exist direct relations between photospheric
regions of open magnetic field lines and corresponding magnetic domains
at the source surface and in the interplanetary magnetic field. These
domains generate a large-scale sub-sector structure of the solar and
interplanetary magnetic field, with boundaries between domains of the
same polarities. Solar, interplanetary, and ground-based observations
of 1999-2000 were used to test this conclusion.
Title: The solar sources of magnetic helicity in interplanetary space
Authors: Bothmer, V.
Bibcode: 2002cosp...34E1390B
Altcode: 2002cosp.meetE1390B
About one third of all coronal mass ejections (CMEs) in the solar wind
possess the internal structure of helical magnetic flux ropes. Recent
studies have shown that the magnetic chiralities of the flux ropes can
be traced back to individual bipolar regions in the Sun's northern
and southern hemispheres. This presentations presents an overview
about the solar source regions that lead to helical flux rope CMEs
in the interplanetary medium including their solar cycle variability
and addresses the possibility of conservation of magnetic helicity in
space plasmas.
Title: Magnetic storm cessation during sustained Northward IMF
Authors: Veselovsky, I.; Bothmer, V.; Cargill, P.; Ivanov, K.;
Romashets, E.; Yakovchouk, O.
Bibcode: 2002cosp...34E.420V
Altcode: 2002cosp.meetE.420V
Times of sustained strong Northward IMF can interrupt the magnetic
storm development and lead to lower levels of geomagnetic activity
for many hours. During 1997-2000 we have found two events of this kind
observed on November 8, 1998 and October 13, 2000. In both cases, the
storms started as usual after arrival of ejecta with a southward IMF
component from the Sun to the Earth, but ceased after several hours
due to the onset of sustained Northward IMF. After the passage of
this so called positive domain storm development started again. The
heliospheric magnetic field intensity remained enhanced and nearly
constant. The solar origins of the geomagnetic storm interruptions have
been investigated. Tentatively they may be related to strong nonlinear
Alfven type solitary waves excited by nonstationary coronal current
variations with a characteristic time-scale of about a day.
Title: Formation and Development of Shock Waves in the Solar Corona
and Near-Sun Interplanetary Space and Solar Energetic Particle Events
Authors: Mann, G. J.; Klassen, A.; Aurass, H.; Classen, H.; Bothmer,
V.; Reiner, M. J.
Bibcode: 2001AGUFMSH21B..03M
Altcode:
At the Sun shock waves are produced either by flares or by coronal mass
ejections and are regarded as the source of solar energetic particle
events. In the corona shock waves appear as solar type II radio bursts
often associated with coronal transient (or EIT) waves. The propagation
of a disturbance through the corona away from an active region into the
interplanetary space is considered by evaluating the radial behaviour
of the Alfven speed. The magnetic field of an active region is modelled
by a magnetic dipole and is superimposed on that of the quiet Sun as
deduced from the EIT wave analysis. Such a behaviour of the magnetic
field leads to a local minimum of the Alfven speed in the range 1.2-1.8
solar radii in the corona as well as a maximum of 740 km/2 at a distance
of 3.8 solar radii. The occurrence of such a minimum and maximum of the
Alfven speed has important consequences to the formation and development
of shock waves in the corona and near-Sun interplanetary space and to
their ability to accelerate particles leading to a special temporal
behaviour of solar energetic particle events.
Title: 3He-enrichments in solar energetic particle events:
SOHO/COSTEP observations
Authors: Bothmer, V.; Sierks, H.; Böhm, E.; Kunow, H.
Bibcode: 2001AIPC..598..349B
Altcode: 2001sgc..conf..349B
We present first results based on a systematic survey of 4-41
MeV/N 3He/4He isotope abundances with ratios
>0.01 detected by the COmprehensive SupraThermal and Energetic
Particle analyzer (COSTEP) onboard the SOHO (SOlar and Heliospheric
Observatory) spacecraft. During 53 out of 148 identified days with a
3He/4He ratio >=0.01, the ratio was in the
range 0.1-1.0. For days with sufficiently high detector count rates,
the atomic mass plots could be resolved up to a time resolution of
1 hour. These days were most suitable for comparisons with in situ
solar wind plasma and magnetic field measurements and SOHO's optical
white-light and extreme ultraviolet (EUV) observations of the Sun. Here
we present a brief overview of a 3He/4He-rich
particle event detected on October 30, 2000 that was associated with
the passage of a fast CME. .
Title: Galactic abundances: Report of working group 3
Authors: Klecker, B.; Bothmer, V.; Cummings, A. C.; George, J. S.;
Keller, J. W.; Salerno, E.; Sofia, U. J.; Stone, E. C.; Thielemann,
F. -K.; Wiedenbeck, M. E.; Buclin, F.; Christian, E. R.; Flückiger,
E. O.; Hofer, M. Y.; Jones, F. C.; Kirilova, D.; Kunow, H.; Laming,
M.; Tranquille, C.; Wenzel, K. -P.
Bibcode: 2001AIPC..598..207K
Altcode: 2001sgc..conf..207K
We summarize the various methods and their limitations and strengths
to derive galactic abundances from in-situ and remote-sensing
measurements, both from ground-based observations and from instruments
in space. Because galactic abundances evolve in time and space it is
important to obtain information with a variety of different methods
covering different regions from the Very Local Insterstellar Medium
(VLISM) to the distant galaxy, and different times throughout the
evolution of the galaxy. We discuss the study of the present-day VLISM
with neutral gas, pickup ions, and Anomalous Cosmic Rays, the study of
the local interstellar medium (ISM) at distances <1.5 kpc utilizing
absorption line me asurements in H I clouds, and the study of galactic
cosmic rays, sampling contemporary (~15 Myr) sources in the local ISM
within a few kiloparsec of the solar system. Solar system abundances,
derived from solar abundances and meteorite studies are discussed
in several other chapters of this volume. They provide samples of
matter from the ISM from the time of solar system format ion, about
4.5 Gyr ago. The evolution of galactic abundances on longer time
scales is discussed in the context of nuclear synthesis in the various
contributing stellar objects. .
Title: MeV He3/He4 isotope abundances in solar energetic particle
events: SOHO/COSTEP observations
Authors: Bothmer, V. :; Sierks, H.; Böhm, E.; Kunow, H.
Bibcode: 2001ICRC....8.3095B
Altcode: 2001ICRC...27.3095B
We present first results based on a systematic survey of 4-41 MeV/N
3He/4He isotope abundances with ratios >0.01 detected by the
COmprehensive SupraThermal and Energetic Particle analyzer (COSTEP)
onboard the SOHO (SOlar and Heliospheric Observatory) spacecraft. More
than about 25% of the identified events showed 3He/4He ratios in
the range 0.1-1. For events with sufficiently high detector count
rates the atomic mass plots can be resolved up to a time resolution
of about 1 hour. These events are most suitable for comparisons with
in situ solar wind plasma and magnetic field measurements and SOHO's
optical white-light and extreme ultraviolet (EUV) observations of
the Sun. The correlations show an association with passages of shock
associated coronal mass ejections (CMEs) in the solar wind that
inhibit high He/H plasma overabundances. It is likely that the CMEs
have been released in strong magnetic reconfiguration processes at
the solar source sites. Here we present a brief overview of such an
event detected on October 30, 2000. 1. Introduction The SOHO/COSTEP
instrument measures solar energetic particles (SEPs) at MeV energies
in the interplanetary medium. The solid state detectors are capable
to detect 3 He/4 He-enrichments at these energies (Müller-Mellin
et al., 1995). Usually, the 3 He/4 He-ratio in the solar wind is at
the order of 10-4 , but occasionally ratios up to about values of ~1
or even above have been observed in SEP events (e.g., Mason et al.,
1999). The origin of these isotope abundances has commonly been
attributed to impulsive solar flares and wave-particle interaction
mechanisms (Temerin and Roth, 1992). However, fully satisfying physical
explanations are still lacking. Here we present first results of a
systematic survey of the He-measurements taken by COSTEP since launch
in 1995 until the end of the year 2000. 2. Data For this study we have
analyzed SOHO/COSTEP measurements of 4.3-40.9 MeV/N helium particles
as well as COSTEP data covering proton and electron measurements at
energies below 10 MeV. These data were compared with magnetic field
and plasma data from the Advanced Coposition Explorer (ACE), SOHO/LASCO
(Large Angle Spectroscopic COronagraph) observations of CMEs and X-ray
flare measurements taken by the GOES satellite. 3. Identification of
3 He/4 He-rich events Figure 1 shows an example of a 3 He/4 He-rich
event as identified from the COSTEP mass separation plot for Oct. 30,
2000. The vertical axis in Figure 1 provides information about the
detector count rates, the horizontal axis is labelled such that 4 He
corresponds to a value of 0. The two largest peaks in the count rates
at -0.6 and 0 correspond to proton (-0.6) and 4 He particles. The
presence of a major contribution of 3 He isotopes at about -0.05
is very distinguished. The ratio of 3 He/4 He was 0.7 (see Table 1,
doy 304 in 2000). All identified ratios >0.01 are listed in Table
1. Figure 1. COSTEP mass plot for 30 October 2000. The peaks at -0.6,
-0.05 and 0 correspond to p, 3 He and 4 He. p 3 He 4 He
Title: EIT Waves, Coronal Shock Waves, and Solar Energetic Particle
Events
Authors: Mann, G.; Klassen, A.; Aurass, H.; Classen, H. T.; Bothmer,
V.; Reiner, M. J.
Bibcode: 2001pre5.conf..445M
Altcode:
EIT waves are often associated with Solar type II radio bursts as
recently revealed by Klassen et al. [2000]. It is well-known that Solar
type II radio bursts are generated by shock waves traveling through the
corona of the Sun. Since both phenomena are causally connected with each
other, they can be used as a diagnostic tool of the magnetic field in
the corona. Thus, a magnetic field of 2.2 G and 0.5 G is deduced to be
at the photosphere and at a distance of 2 Solar radii above quiet Solar
regions, respectively. Such a behaviour of the magnetic field leads to
a local maximum of the Alfven speed of about 740 km/s at a distance
of 3.8 Solar radii. The occurrence of such a maximum has important
consequences for the formation and development of shock waves in the
Solar corona and the near-sun interplanetary space and their ability
to accelerate particles leading to Solar energetic particle events.
Title: Recurrent modulation of galactic cosmic ray electrons and
protons: Ulysses COSPIN/KET observations
Authors: Heber, B.; Blake, J. B.; Paizis, C.; Bothmer, V.; Kunow,
H.; Wibberenz, G.; Burger, R. A.; Potgieter, M. S.
Bibcode: 2000AIPC..528..357H
Altcode: 2000atep.conf..357H
Since measurements of space probes in the interplanetary space became
available it has been known that associated with the occurrence
of recurrent fast and slow solar wind streams, forming Corotating
Interaction Regions, recurrent variations in the cosmic ray nuclei
flux are observed (1). As pointed out recently by Jokipii and Kota (2)
recurrent modulation for positively and negatively charged particles
may be different. In the time interval extending from July 1992 to
July 1994, Ulysses on its journey to high heliographic latitudes
registered ~20 stable and long-lasting Corotating Interaction Regions
(CIRs). In this work we use data from the Cosmic Ray and Solar Particle
Investigation Kiel Electron Telescope (COSPIN/KET) instrument on
board Ulysses to study the recurrent variation of 2.5 GV electrons and
protons. We find that 1) electrons are indeed periodically modulated,
but that 2) the periodicity of ~29 days is longer than the period of
~26 days for protons, and that 3) the amplitude is larger than the
one observed for protons. .
Title: Solar energetic particle event and radio bursts associated
with the 1996 July 9 flare and coronal mass ejection
Authors: Laitinen, T.; Klein, K. -L.; Kocharov, L.; Torsti, J.;
Trottet, G.; Bothmer, V.; Kaiser, M. L.; Rank, G.; Reiner, M. J.
Bibcode: 2000A&A...360..729L
Altcode:
Using spaceborne particle and gamma-ray detection and radio diagnostics
we study solar energetic particle (SEP) production in the 1996 July
9 event. This event is associated with an impulsive soft X-ray flare
(9:10 UT) and a coronal mass ejection (CME). In a global classification
the event is considered as mixed-impulsive. A sequence of acceleration
processes is identified, starting early in the flare impulsive phase
and continuing throughout the period when the CME propagated up to
several Rsolar above the photosphere: (1) Gamma-ray,
hard X-ray and cm-wave emitting particles seen during the flare
impulsive phase in the low corona had no counterpart at the Solar and
Heliospheric Observatory (SoHO) spacecraft. (2) Electrons accelerated
at a coronal shock wave were revealed by decimetric- to-metric type II
radio emission and by simultaneous radio signatures of beams traveling
to 1 AU. (3) Mildly relativistic (>=250 keV) electrons detected by
SoHO did not correspond to these shock-accelerated populations, but
to later mainly impulsive injection which was associated with radio
brightenings over a large range of coronal altitudes. (4) Energetic
protons detected by SoHO were accelerated during about 100 min after
the flare impulsive phase with a gradually evolving production profile
that bore some similarity with the time profile of broadband metric
(type IV) emission. (5) While all other particle signatures decayed,
a second period of interplanetary proton production took place >=2
hours after flare onset. The first, 100 min period of SEP acceleration,
post-impulsive phase coronal acceleration, is definitely dominant in
mildly relativistic electrons. Two acceleration periods nearly equally
contribute to the production of ~ 20 MeV protons. However, the second
period is more productive in low energy, ~ 1 MeV, protons. The timing
of the SEP injections indicates that neither the impulsive flare
acceleration in the low corona nor the interplanetary CME at >=
10 Rsolar are the main sources of the high-energy particles
observed onboard SoHO. We suggest that various acceleration processes
related to the reconfiguration of the corona in the course of the flare
and CME lift-off contribute to the interacting and escaping particle
populations, with different signatures at different energies and in
different species.
Title: Energetic Particle Signatures of a Corotating Interaction
Region from a High Latitude Coronal Hole: SOHO, Wind and Ulysses
Observations
Authors: Posner, A.; Bothmer, V.; Kunow, H.; Gosling, J. T.; Heber,
B.; Lazarus, A. J.; Linker, J. A.; Marsden, R. G.; Mikić, Z.;
Müller-Mellin, R.; Sanderson, T. R.; Szabo, A.; Thompson, B. J.
Bibcode: 2000AdSpR..26..865P
Altcode:
In mid 1996 the Comprehensive Suprathermal and Energetic Particle
Analyser (COSTEP) onboard the Solar and Heliospheric Observatory, at
1 AU in the ecliptic plane, detected recurrent periods of enhanced
MeV ions in association with a corotating interaction region
(CIR). Measurements of energetic ions from the Cosmic Ray and Solar
Particle Instrument/Low Energy Telescope (COSPIN/LET) onboard Ulysses
taken at 5 AU, at mid-northern heliographic latitudes, showed that
Ulysses encountered recurrent particle events during the same time
period. We used the solar wind speeds observed at both locations to
estimate the cor-responding solar source longitudes of the particle
events. These longitudes are related to warps of the Sun's large high
latitude northern coronal hole boundaries observed by SOHO's Extreme
Ultraviolet Imaging Telescope (EIT). The findings are supported
by threedimensional magnetohydrodynamic (MHD) calculations of the
footpoint positions of the magnetic field lines at both spacecraft. The
observations suggest that close to the Sun a superradial expansion of
the fast solar wind from the Sun's high latitude northern coronal hole
down to ecliptic latitudes is present
Title: SOHO und das neue Bild der Sonne.
Authors: Bothmer, V.
Bibcode: 1999A&R....36...28B
Altcode:
No abstract at ADS
Title: Reply
Authors: Kahler, S. W.; Cane, H. V.; Hudson, H. S.; Kurt, V. G.;
Gotselyuk, Y. V.; MacDowall, R. J.; Bothmer, V.
Bibcode: 1999JGR...10422411K
Altcode:
No abstract at ADS
Title: Differences in the temporal variations of galactic cosmic
ray electrons and protons: Implications from Ulysses at solar minimum
Authors: Heber, B.; Ferrando, P.; Raviart, A.; Wibberenz, G.;
Müller-Mellin, R.; Kunow, H.; Sierks, H.; Bothmer, V.; Posner, A.;
Paizis, C.; Potgieter, M. S.
Bibcode: 1999GeoRL..26.2133H
Altcode:
According to standard drift dominated modulation models the intensity
variations of galactic cosmic ray protons and electrons respond
differently to the latitudinal extension of the heliospheric current
sheet α. In an A>0 solar cycle intensities of protons should vary
weakly with the latitudinal extension, whereas electrons should show
a strong response. We investigate this charge dependent variation
in the 1990s (A>0) using Ulysses Kiel Electron Telescope (KET)
measurements. Proton measurements at 2.5 GV corrected for latitudinal
variations show the same time profile as electrons from mid 1994 until
the beginning of 1996, and later from September 1997 to the end of
1997. In 1996 and 1997, when α was below ∼25°, two long lasting time
periods were found when electrons had a ∼5-10% higher level. These
variations are in agreement with our computations indicating that drift
effects play an important role in determining the temporal variation
of electrons close to solar minimum.
Title: CIR Morphology, Turbulence, Discontinuities, and Energetic
Particles
Authors: Crooker, N. U.; Gosling, J. T.; Bothmer, V.; Forsyth, R. J.;
Gazis, P. R.; Hewish, A.; Horbury, T. S.; Intriligator, D. S.; Jokipii,
J. R.; Kóta, J.; Lazarus, A. J.; Lee, M. A.; Lucek, E.; Marsch, E.;
Posner, A.; Richardson, I. G.; Roelof, E. C.; Schmidt, J. M.; Siscoe,
G. L.; Tsurutani, B. T.; Wimmer-Schweingruber, R. F.
Bibcode: 1999SSRv...89..179C
Altcode:
Corotating interaction regions (CIRs) in the middle heliosphere have
distinct morphological features and associated patterns of turbulence
and energetic particles. This report summarizes current understanding
of those features and patterns, discusses how they can vary from
case to case and with distance from the Sun and possible causes of
those variations, presents an analytical model of the morphological
features found in earlier qualitative models and numerical simulations,
and identifies aspects of the features and patterns that have yet to
be resolved.
Title: The Solar Origin of Corotating Interaction Regions and Their
Formation in the Inner Heliosphere
Authors: Balogh, A.; Bothmer, V.; Crooker, N. U.; Forsyth, R. J.;
Gloeckler, G.; Hewish, A.; Hilchenbach, M.; Kallenbach, R.; Klecker,
B.; Linker, J. A.; Lucek, E.; Mann, G.; Marsch, E.; Posner, A.;
Richardson, I. G.; Schmidt, J. M.; Scholer, M.; Wang, Y. -M.;
Wimmer-Schweingruber, R. F.; Aellig, M. R.; Bochsler, P.; Hefti, S.;
Mikić, Z.
Bibcode: 1999SSRv...89..141B
Altcode:
Corotating Interaction Regions (CIRs) form as a consequence of the
compression of the solar wind at the interface between fast speed
streams and slow streams. Dynamic interaction of solar wind streams
is a general feature of the heliospheric medium; when the sources of
the solar wind streams are relatively stable, the interaction regions
form a pattern which corotates with the Sun. The regions of origin
of the high speed solar wind streams have been clearly identified
as the coronal holes with their open magnetic field structures. The
origin of the slow speed solar wind is less clear; slow streams may
well originate from a range of coronal configurations adjacent to,
or above magnetically closed structures. This article addresses
the coronal origin of the stable pattern of solar wind streams
which leads to the formation of CIRs. In particular, coronal models
based on photospheric measurements are reviewed; we also examine
the observations of kinematic and compositional solar wind features
at 1 AU, their appearance in the stream interfaces (SIs) of CIRs,
and their relationship to the structure of the solar surface and the
inner corona; finally we summarise the Helios observations in the
inner heliosphere of CIRs and their precursors to give a link between
the optical observations on their solar origin and the in-situ plasma
observations at 1 AU after their formation. The most important question
that remains to be answered concerning the solar origin of CIRs is
related to the origin and morphology of the slow solar wind.
Title: Magnetic field structure and topology within CMEs in the
solar wind
Authors: Bothmer, Volker
Bibcode: 1999AIPC..471..119B
Altcode: 1999sowi.conf..119B
This paper provides a brief overview on the magnetic field structure and
topology within coronal mass ejections (CMEs) in the solar wind. The
overview starts summarizing the magnetic field characteristics within
CMEs (magnetic clouds) which exhibit large-scale internal magnetic field
rotations indicative of helical magnetic flux ropes and those of non
flux rope CMEs lacking smooth internal field rotations. The overview
continues with a presentation of Ulysses observations showing evidence
for mixed magnetic topologies of open and closed field lines within some
CMEs followed by a discussion of the magnetic field structure of CMEs
near the Sun in relationship with the observed field properties of CMEs
in the solar wind. Finally, the to date main open questions concerning
the magnetic origin, evolution and fate of CMEs are addressed.
Title: In-ecliptic CIR-associated energetic particle events and polar
coronal hole structures: SOHO/COSTEP observations for the Whole Sun
Month Campaign
Authors: Posner, Arik; Bothmer, Volker; Thompson, Barbara J.; Kunow,
Horst; Heber, Bernd; Müller-Mellin, Reinhold; Lazarus, Alan J.;
Szabo, Adam; Mikić, Zoran; Linker, Jon A.
Bibcode: 1999JGR...104.9881P
Altcode:
The Solar and Heliospheric Observatory (SOHO), in halo orbit around
the L1 Lagrangian point of the Sun-Earth system, combines a unique
set of instruments for studies of the Sun and the heliosphere. SOHO's
Comprehensive Suprathermal and Energetic Particle Analyser measures
in situ particles in the energy range 44 keV/particle to above 53
MeV/nucleon. For the time period of the Whole Sun Month Campaign in
mid 1996 we have identified recurrent energetic particle intensity
increases in association with corotating interaction regions (CIRs)
in the energy range <10 MeV. Solar wind measurements of the Wind
spacecraft were used to estimate the corresponding magnetic source
location in Carrington longitude for comparison of energetic particles
with synoptic maps of the lower corona, derived from images of SOHO's
Extreme-ultraviolet Imaging Telescope. The comparison reveals a close
relationship of latitudinal extensions of polar coronal holes, situated
in regions up to 40° away from the ecliptic, with CIR-associated
in-ecliptic particle events.
Title: Determination of 7-30 MeV electron intensities: ULYSSES
COSPIN/KET Results
Authors: Heber, Bernd; Raviart, A.; Ferrando, P.; Sierks, H.; Paizis,
C.; Kunow, H.; Muller-Mellin, R.; Bothmer, V.; Posner, A.
Bibcode: 1999ICRC....7..186H
Altcode: 1999ICRC...26g.186H
The COsmic and Solar Particle INvestigation Kiel Electron Telescope
was designed to measure electrons from a few MeV up to a few
GeV using particle energy loss and particle velocity measurement
techniques. Unfortunately the KET channel measuring electrons in the
energy range from 7-170 MeV is contaminated by a γ-ray background
(Ferrando et al., 1996). Besides a possible slight contribution from the
RTG radiation, we have shown that this background is mainly generated
by high energy protons interacting with the spacecraft matter. Such
γ-rays can enter "unseen" the instrument and are partially converted
into electrons in the calorimeter consisting of a high Z lead fluoride
Cherenkov detector. Such electrons could be counted in the 7-170 MeV
electron channels. In this paper we present a method to quantify this
background and thus determine lower and upper limits for the intensities
of electrons with energies from 7 to 30 MeV. Our analysis shows that
above 30 MeV the background in this specific channel is so dominant,
that no correction is possible.
Title: CIR Morphology, Turbulence, Discontinuities, and Energetic
Particles
Authors: Crooker, N. U.; Gosling, J. T.; Bothmer, V.; Forsyth, R. J.;
Gazis, P. R.; Hewish, A.; Horbury, T. S.; Intriligator, D. S.; Jokipii,
J. R.; Kóta, J.; Lazarus, A. J.; Lee, M. A.; Lucek, E.; Marsch, E.;
Posner, A.; Richardson, I. G.; Roelof, E. C.; Schmidt, J. M.; Siscoe,
G. L.; Tsurutani, B. T.; Wimmer-Schweingruber, R. F.
Bibcode: 1999cir..book..179C
Altcode:
No abstract at ADS
Title: Solar Energetic Particle Events recorded aboard SOHO on
December 24, 1996 and on May 6, 1998
Authors: McKenna-Lawlor, Susan M. P.; Kecskeméty; K.; Bothmer, V.;
Rodriguez-Pacheco, J.; Facskó, G.; St. Cyr, C.
Bibcode: 1999ICRC....6..423M
Altcode: 1999ICRC...26f.423M
The LION experiment on SOHO (which records protons from 44 keV-6 MeV
and electrons from 44 keV-300 keV), and the energetically complementary
EPHIN experiment (which measures protons + helium ions to >53 MeV/n
and electrons to >5 MeV), each detected many energetic particle
events (SEPs) in the early rising phase of Solar Cycle 23 (from ~
July 1996) - a period commonly associated with Coronal Mass Ejections
(CMEs). The present paper contains an account of two representative
rapid intensity increases recorded simultaneously by LION and
EPHIN, each of which was accompanied by a CME and by impulsive type
flaring. The SEPs have characteristics typical of both Gradual and
Impulsive events and may be described as `Mixed'.
Title: Solar Corona, Solar Wind Structure and Solar Particle Events
Authors: Bothmer, V.
Bibcode: 1999spwe.work..117B
Altcode:
No abstract at ADS
Title: Energy spectra of protons, deuterium, and helium nuclei during
quiet solar activity periods in 1996-97
Authors: Kecskemety, Karoly; Kunow, H.; Valtonen, E.; Kiraly, P.;
Muller-Mellin, R.; Torsti, J.; Bothmer, V.
Bibcode: 1999ICRC....6..167K
Altcode: 1999ICRC...26f.167K
A background reduction method based on pulse-height analysis (see
accompanying paper by Valtonen et al.) is applied for the data of
the ERNE and EPHIN energetic particle telescopes aboard SOHO. Energy
spectra of protons, deuterons, 3He and 4He nuclei have been obtained
during very low activity periods in 1996-97 in the energy range of 1.3
to 22 MeV/n. The proton spectra are comparable to the lowest spectra
of the Ulysses (COSPIN/LET, 1996) and near-Earth IMP-8 (1985-87)
measurements. Deuterons and 3He are only significantly seen above about
10 MeV/n, their spectra are consistent with an increase proportional
to kinetic energy, expected for purely galactic origin.
Title: Latitudinal and radial variation of >2 GeV/n protons and
α-particles in the northern heliosphere: ulysses cospin/ket and
neutron monitor network observations
Authors: Belov, A. V.; Eroshenko, E. A.; Heber, B.; Yanke, V. G.;
Ferrando, P.; Raviart, A.; Bothmer, V.; Dröge, W.; Kunow, H.;
Müller-Mellin, R.; Röhrs, K.; Wibberenz, G.; Paizis, C.
Bibcode: 1999AdSpR..23..443B
Altcode:
Ulysses, launched in October 1990, crossed in December 1997
the heliographic equator and completed its first out of ecliptic
orbit. During the time period from February 1995 to November 1997 solar
activity was low and the spacecraft scanned the latitude range from 80°
N to the heliographic equator. The Kiel Electron Telescope on-board
Ulysses measures protons and α-particles in the energy range from 5
MeV/n to > 2 GeV/n. To separate spatial and temporal variations of
> 2 GeV/n protons and α-particles along the spacecraft trajectory
we used the data set from the world wide neutron monitor network. We
found negligible latitudinal gradients below ~29° N and for the radial
gradient an upper limit of ≈ 0.5 %/AU for > 2 GeV/n protons and
α-particles. In the latitudinal range from ≈ 25 to > 70° N the
latitudinal gradient is ~0.17 %/° and ~0.12 %/° for > 2 GeV/n
protons and α-particles, respectively, independent of spacecraft
latitude and radial distance.
Title: Observation of a ~ 7 MeV Electron Super-flux at 5 AU by Ulysses
Authors: Ferrando, Philippe; Raviart, A.; Heber, B.; Bothmer, V.;
Kunow, H.; Muller-Mellin, R.; Paizis, C.
Bibcode: 1999ICRC....7..135F
Altcode: 1999ICRC...26g.135F
From the Ulysses launch up to the end of 1995, the 4-10 MeV energy
electron count rate of the COSPIN/KET instrument has been consistent
with simple expectations from Jovian electrons propagation. From the
beginning of 1996 to the end of 1998, Ulysses was below ~ 30 degrees
of heliographic latitude and between 4.5 and 5.4 AUs from the Sun,
making it the first spacecraft to reach the region around the Jupiter
orbit but with the planet being very far away. During this period,
this electron flux around 7 MeV has surprisingly increased and has
stayed at a high level up to the latest data of early 1999. In this
paper, we present these data and discuss the possible origin of this
electron super-flux, which reaches a level similar to that obtained
in 1991 when Ulysses was perfectly magnetically connected to Jupiter.
Title: Charge sign dependent modulation: Ulysses COSPIN/KET results
Authors: Heber, Bernd; Ferrando, P.; Raviart, A.; Wibberenz, G.;
Paizis, C.; Bothmer, V.; Kunow, H.; Muller-Melin, R.; Posner, A.;
Sierks, H.; Potgieter, M. S.
Bibcode: 1999ICRC....7...99H
Altcode: 1999ICRC...26g..99H
According to drift dominated modulation models galactic cosmic
ray protons and electrons respond differently to the latitudinal
extension of the heliospheric current sheet. In an A 0 solar magnetic
cycle intensities of ¥ positively charged particles should vary only
weakly with the latitudinal extension, whereas electrons should show
a much stronger response. In this paper we investigate the charge sign
dependent modulation in the 1990s using measurements of 2.5 GV protons
and electrons of the Cosmic and Solar Particle Investigation Kiel
Electron Telescope (COSPIN/KET) on board Ulysses from the beginning of
1992 to the end of 1998. Only close to solar minimum, when the maximum
latitudinal extend is below 30 , differences in the temporal variation
of electrons and protons are observed.
Title: The Solar Origin of Corotating Interaction Regions and their
Formation in the Inner Heliosphere
Authors: Balogh, A.; Bothmer, V.; Crooker, N. U.; Forsyth, R. J.;
Gloeckler, G.; Hewish, A.; Hilchenbach, M.; Kallenbach, R.; Klecker,
B.; Linker, J. A.; Lucek, E.; Mann, G.; Marsch, E.; Posner, A.;
Richardson, I. G.; Schmidt, J. M.; Scholer, M.; Wang, Y. -M.;
Wimmer-Schweingruber, R. F.; Aellig, M. R.; Bochsler, P.; Hefti, S.;
Mikić, Z.
Bibcode: 1999cir..book..141B
Altcode:
No abstract at ADS
Title: Amplitude evolution and rigidity dependence of the 26-day
recurrent cosmic ray decreases: COSPIN/KET results
Authors: Paizis, C.; Heber, B.; Ferrando, P.; Raviart, A.; Falconi, B.;
Marzolla, S.; Potgieter, M. S.; Bothmer, V.; Kunow, H.; Müller-Mellin,
R.; Posner, A.
Bibcode: 1999JGR...10428241P
Altcode:
In the time interval extending from July 1992 to July 1994, Ulysses
climbed from 10°S heliographic latitude up to over 70°S. During this
time lapse, solar minimum conditions were gradually approached, which,
in turn, led to stable and long-lasting corotating interaction regions
(CIRs). The corotating particle events observed during this period,
associated with ~30 registered CIRs, offer a unique opportunity to
probe the three-dimensional structures of the heliosphere. In this work
we use data from the Cosmic Ray and Solar Particle Investigation Kiel
Electron Telescope (COSPIN/KET) instrument on board Ulysses to study
the amplitude evolution of the 26-day recurrent cosmic ray decreases,
generated by these CIRs, at different energies and derive its rigidity
dependence. We find that the amplitude has a maximum around 25°-30°
heliolatitude. We also find that the rigidity dependence of both the
latitudinal gradient as well as the 26-day variation amplitude show
a remarkable similarity. We discuss these observations within the
framework of our current understanding of heliospheric phenomena.
Title: The solar energetic particle event of April 14, 1994, as a
probe of shock formation and particle acceleration
Authors: Kahler, S. W.; Cane, H. V.; Hudson, H. S.; Kurt, V. G.;
Gotselyuk, Y. V.; MacDowall, R. J.; Bothmer, V.
Bibcode: 1998JGR...10312069K
Altcode:
Gradual solar energetic particle (SEP) events observed at 1 AU are
associated with coronal mass ejections (CME) that drive shocks which
are presumed to accelerate the ions and electrons to suprathermal
energies. However, high-energy (>30 MeV) proton and (>1 MeV)
electron events are nearly always associated with both CMEs and flares,
suggesting that the acceleration of those particles, particularly
the electrons, could be attributed to the associated flares. Only one
clear example of a high-energy SEP event without an active region flare
association has been reported previously. We discuss a second such SEP
event, on April 14, 1994, associated with a well-observed solar X ray
arcade structure spanning ~150° of solar longitude. The SEP event,
observed by detectors on the IMP 8 and Koronas I spacecraft, began
~10 hrs after the beginning of the X ray event and was temporally
and spatially associated with the last of three weak interplanetary
type III radio bursts observed by the Ulysses low-frequency radio
experiment. The delayed onset and rapid rise of the SEP intensities
preclude a recent interpretation in which SEPs were presumed to be
accelerated by a shock driven by a CME which erupted at the onset of
the X ray event. Yohkoh soft X ray subtracted images show a large-scale
arcade brightening west of ~E10° beginning about 8 hours after the
initial brightening near the east limb. We suggest that the April 14
SEP event at Earth was produced by a shock driven by a CME associated
with the later brightening near central meridian. The initial X ray
brightening may also have been associated with an earlier CME.
Title: Latitudinal distribution of >106MeV protons and its
relation to the ambient solar wind in the inner southern and northern
heliosphere: Ulysses Cosmic and Solar Particle Investigation Kiel
Electron Telescope results
Authors: Heber, B.; Bothmer, V.; Dröge, W.; Kunow, H.; Müller-Mellin,
R.; Sierks, H.; Wibberenz, G.; Ferrando, P.; Raviart, A.; Paizis,
C.; Potgieter, M. S.; Burger, R. A.; Hattingh, M.; Haasbroek, L. J.;
McComas, D.
Bibcode: 1998JGR...103.4809H
Altcode:
We present observations and model calculations of the modulated
intensities of galactic cosmic ray protons above 106 MeV/n along the
Ulysses trajectory. Data are taken by the Cosmic and Solar Particle
Investigation (COSPIN) Kiel Electron Telescope (KET) from spring 1993
to fall 1996. During this time period solar activity decreased and
galactic cosmic rays recovered. To separate spatial from temporal
variations we used the University of Chicago measurements from IMP
8 near Earth and compare the residual spatial variation with time
independent modulation models. According to standard drift dominated
modulation model, one would expect a radial gradient of ~2%/AU and
a latitudinal gradient of ~1.2%/degree in both hemispheres. The
measured mean radial gradient of ~3%/AU is within the uncertainties
in good agreement with the model predictions. However, the measured
mean latitudinal gradient has a value of (0.33+/-0.04)%/degree in
both hemispheres at intermediate latitudes and is by a factor of 4
lower than expected. In the modified models the latitudinal gradient
is in agreement with the measured ones when we increase the diffusion
coefficient κθθ perpendicular to the magnetic field in
polar direction to a value of 15% of the diffusion coefficient parallel
to the magnetic field. The latitudinal gradients >106MeV protons
calculated by modified modulation models are in very good agreement
with the measured ones at intermediate latitudes. At lower latitudes,
when Ulysses is embedded in the streamer belt, the models predict
approximately the same latitudinal gradient than at intermediate
latitudes, whereas the measured ones are significant smaller, or
even vanishing. The observations support the previous conclusion
from Paizis et al. [1995] that a significant latitudinal gradient
is only observed when Ulysses is outside the streamer belt. Another
remarkable observation is the difference of the radial gradient
Gr at ~3.5AU in the southern (Gr~3.5%/AU) and in
the northern hemisphere (Gr~2.3%/AU). Probable reasons for
the significantly lower radial gradient in the northern hemisphere can
be either a spatial asymmetry of the heliosphere or temporal variations.
Title: Acceleration in Energetic Ions (~1 MeV) in Corotating
Interaction Regions
Authors: Desai, M. I.; Bothmer, V.; Marsden, R. G.; Sanderson, T. R.;
Balogh, A.; Forsyth, R. J.; Goldstein, B. E.
Bibcode: 1998paac.conf..555D
Altcode:
No abstract at ADS
Title: European Plans for the Solar/Heliospheric Stereo Mission
Authors: Bothmer, V.; Bougeret, J. -L.; Cargill, P.; Davila, J.;
Delaboudiniere, J. -P.; Harrison, R.; Koutchmy, S.; Liewer, P.;
Maltby, P.; Rust, D.; Schwenn, R.
Bibcode: 1998ESASP.417..145B
Altcode: 1998cesh.conf..145B
No abstract at ADS
Title: Acceleration in energetics ions (~1MeV) in corotating
interaction regions
Authors: Desai, M. I.; Bothmer, V.; Marsden, R. G.; Sanderson, T. R.;
Balogh, A.; Forsyth, R. J.; Goldstein, B. E.
Bibcode: 1998AdSpR..21..555D
Altcode:
We have correlated the ~1 MeV proton intensity (J) measured at
corotating reverse shocks detected by Ulysses near the ecliptic plane
and in the southern hemisphere with the shock strength and shock
normal angle. We find that J is essentially independent of the shock
strength below 29 degS, whereas between 29 deg and 41 degS J showed
a good correlation with the same. The poor correlation below 29 degS
is attributed to temporal variations in the background intensity
and to the presence of particles accelerated at other corotating and
transient shocks. J is also independent of the shock normal angle at all
latitudes, which is probably due to the combined effects of the drift
and diffusive acceleration processes. We compensate for the effects
of variations in the background by assuming that two reverse shocks
observed during the same ~26 day period accelerate particles out of
the same background population. By correlating the ratio of the proton
intensities with the ratios of the shock parameters for such pairs of
reverse shocks, we show that the shock acceleration efficiency is well
correlated with the strength but is independent of the normal angle.
Title: The structure and origin of magnetic clouds in the solar wind
Authors: Bothmer, V.; Schwenn, R.
Bibcode: 1998AnGeo..16....1B
Altcode: 1998AnG....16....1B
Plasma and magnetic field data from the Helios 1/2 spacecraft have
been used to investigate the structure of magnetic clouds (MCs) in the
inner heliosphere. 46 MCs were identified in the Helios data for the
period 1974-1981 between 0.3 and 1 AU. 85% of the MCs were associated
with fast-forward interplanetary shock waves, supporting the close
association between MCs and SMEs (solar mass ejections). Seven MCs
were identified as direct consequences of Helios-directed SMEs, and
the passage of MCs agreed with that of interplanetary plasma clouds
(IPCs) identified as white-light brightness enhancements in the Helios
photometer data. The total (plasma and magnetic field) pressure in MCs
was higher and the plasma-<beta> lower than in the surrounding
solar wind. Minimum variance analysis (MVA) showed that MCs can best be
described as large-scale quasi-cylindrical magnetic flux tubes. The axes
of the flux tubes usually had a small inclination to the ecliptic plane,
with their azimuthal direction close to the east-west direction. The
large-scale flux tube model for MCs was validated by the analysis
of multi-spacecraft observations. MCs were observed over a range
of up to ~60° in solar longitude in the ecliptic having the same
magnetic configuration. The Helios observations further showed that
over-expansion is a common feature of MCs. From a combined study of
Helios, Voyager and IMP data we found that the radial diameter of MCs
increases between 0.3 and 4.2 AU proportional to the distance, R, from
the Sun as R0.8 (R in AU). The density decrease inside MCs was found to
be proportional to R-2.4, thus being stronger compared to the average
solar wind. Four different magnetic configurations, as expected from
the flux-tube concept, for MCs have been observed in situ by the Helios
probes. MCs with left- and right-handed magnetic helicity occurred
with about equal frequencies during 1974-1981, but surprisingly,
the majority (74%) of the MCs had a south to north (SN) rotation of
the magnetic field vector relative to the ecliptic. In contrast, an
investigation of solar wind data obtained near Earth's orbit during
1984-1991 showed a preference for NS-clouds. A direct correlation
was found between MCs and large quiescent filament disappearances
(disparition brusques, DBs). The magnetic configurations of the
filaments, as inferred from the orientation of the prominence axis,
the polarity of the overlying field lines and the hemispheric helicity
pattern observed for filaments, agreed well with the in situ observed
magnetic structure of the associated MCs. The results support the model
of MCs as large-scale expanding quasi-cylindrical magnetic flux tubes in
the solar wind, most likely caused by SMEs associated with eruptions of
large quiescent filaments. We suggest that the hemispheric dependence
of the magnetic helicity structure observed for solar filaments can
explain the preferred orientation of MCs in interplanetary space as
well as their solar cycle behavior. However, the white-light features
of SMEs and the measured volumes of their interplanetary counterparts
suggest that MCs may not simply be just H<alpha>-prominences,
but that SMEs likely convect large-scale coronal loops overlying the
prominence axis out of the solar atmosphere.
Title: Development of Coronal Mass Ejections and Association with
Interplanetary Events
Authors: Pick, M.; Maia, D.; Howard, R.; Thompson, B.; Lanzerotti,
L. J. L.; Bothmer, V.; Lamy, P.
Bibcode: 1997ESASP.415..195P
Altcode: 1997cpsh.conf..195P
No abstract at ADS
Title: Solar Energetic Particle Events and Coronal Mass Ejections:
New Insights from SOHO
Authors: Bothmer, V.; Posner, A.; Kunow, H.; Müller-Mellin, R.;
Herber, B.; Pick, M.; Thompson, B. J.; Delaboudinière, J. -P.;
Brueckner, G. E.; Howard, R. A.; Michels, D. J.; Cyr, C. St.; Szabo,
A.; Hudson, H. S.; Mann, G.; Classen, H. -T.; McKenna-Lawlor, S.
Bibcode: 1997ESASP.415..207B
Altcode: 1997cpsh.conf..207B
No abstract at ADS
Title: Fluxes of MeV Particles at Earth's Orbit and their Relationship
with the Global Structure of the Solar Corona: Observations from SOHO
Authors: Posner, A.; Bothmer, V.; Kunow, H.; Herber, B.;
Müller-Mellin, R.; Delaboudinière, J. -P.; Thompson, B. J.;
Brückner, G. E.; Howard, R. A.; Muchels, D. J.
Bibcode: 1997ESASP.415..377P
Altcode: 1997cpsh.conf..377P
No abstract at ADS
Title: The Solar Energetic Particle Event of 14 April 1994 as a
Probe of Shock Formation and Particle Acceleration
Authors: Kahler, S. W.; Cane, H. V.; Hudson, H. S.; Kurt, V. G.;
MacDowall, R. J.; Bothmer, V.
Bibcode: 1997AAS...191.7412K
Altcode: 1997BAAS...29.1326K
Gradual solar energetic particle (SEP) events observed at 1 AU are
associated with coronal mass ejections (CMEs) that drive shocks which
accelerate the ions and electrons to suprathermal energies. However,
high energy (> 30 MeV) proton and (> 1 MeV) electron events are
nearly always associated with both CMEs and flares, suggesting that
the acceleration of those particles, particularly the electrons, could
be attributed to the associated flares. Only one clear example of a
high energy SEP event without a flare association has been reported
previously. We discuss a second such SEP event, on 14 April 1994,
associated with a well observed solar X-ray arcade structure spanning ~
150deg of solar longitude. The SEP event, observed by detectors on the
IMP-8 and Koronas-I space craft, began about 10 hrs after the beginning
of the X-ray event and was temporally and spatially associated with
the last of three weak interplanetary type III radio bursts observed
by the Ulysses low frequency radio experiment. The delayed onset and
rapid rise of the SEP intensities preclude a recent interpretation in
which SEPs were accelerated by a shock driven by a CME which erupted
at the onset of the X-ray event. Yohkoh soft X-ray subtracted images
show a large-scale arcade brightening west of ~ E10deg beginning about 8
hours after the initial brightening near the east limb. We suggest that
the 14 April event consisted of at least two CMEs with progressively
westward source regions and that the SEP event was produced in a second
shock driven by a later CME.
Title: Spatial Evolution of 26-day Recurrent Galactic Cosmic Ray
Decreases: Correlated Ulysses COSPIN/KET and SOHO COSTEP Observations
Authors: Heber, B.; Bothmer, V.; Dröge, W.; Kunow, H.; Müller-Mellin,
R.; Posner, A.; Ferrando, P.; Raviart, A.; Raviart, A.; Paizis, C.;
McComas, D.; Forsyth, R. J.; Szabo, A.; Lazarus, A. J.
Bibcode: 1997ESASP.415..331H
Altcode: 1997cpsh.conf..331H
No abstract at ADS
Title: Search for the Origin of Quiet-Time Particle Fluxes in the
Inner Heliosphere
Authors: Kiraly, P.; Bothmer, V.; Kecskemety, K.; Keppler, E.;
Kudela, K.; Kunow, H.; Logachev, Yu. I.; sMüller-Mellin, R.;
Rodriguez-Pacheco, J.; von Steiger, R.; Torsti, J.; Valtonen, E.;
Zeldovich, M. A.
Bibcode: 1997ICRC....2..477K
Altcode: 1997ICRC...25b.477K
No abstract at ADS
Title: The Effects of Coronal Mass Ejections on Galactic Cosmic
Rays in the High Latitude Heliosphere: Observations from Ulysses'
First Orbit
Authors: Bothmer, V.; Heber, B.; Kunow, H.; Mueller-Mellin, R.;
Wibberenz, G.
Bibcode: 1997ICRC....1..333B
Altcode: 1997STIN...9928408B
During its first solar orbit, the Ulysses spacecraft detected several
coronal mass ejections (CMEs) at high heliographic latitudes. The
authors present first observations on the effects of these high latitude
CMEs on galactic cosmic rays (GCRs) using measurements from the Kiel
Electron Telescope (KET) which is part of the Cosmic Ray and Solar
Particle Investigation (COSPIN) experiment, the Los Alamos SWOOPS
(Solar Wind Observations Over the Poles of the Sun) experiment and
the magnetic field experiments. They find the passage of these CMEs
over the spacecraft to be associated with short term decreases of GCR
intensities The relatively weak shocks in these events, driven by
the CMEs' over-expansion, had no strong influence on the GCRs. The
intensity minimums of GCRs occurred on closed magnetic field lines
inside the CMEs themselves as indicated by bidirectional fluxes of
suprathermal electrons. Short episodes of intensity increases of GCRs
inside CMEs at times when the bidirectional fluxes of suprathermal
electrons disappeared, can be interpreted as evidence that GCRs can
easily access the interior of those CMEs in which open magnetic field
lines are embedded.
Title: Time and Energy Dependence of 26-Day Recurrent Decreases
of >100 MeV Protons in the Inner Southern Heliosphere and its
Correlation to Latitudinal Gradients: Ulysses COSPIN/KET Results
Authors: Kunow, H.; Heber, B.; Raviart, A.; Paizis, C.; Bothmer, V.;
Droege, W.; Schmidt, J.
Bibcode: 1997ICRC....1..381K
Altcode: 1997ICRC...25a.381K
No abstract at ADS
Title: Evolution of Cosmic Ray Electron Spectra above 350 MeV along
the Ulysses Trajectory
Authors: Raviart, A.; ferrando, P.; Heber, B.; Paizis, C.; Bothmer,
V.; Dröge, W.; Kunow, H.; Müller-Mellin, R.; Wibberenz, G.
Bibcode: 1997ICRC....2...37R
Altcode: 1997ICRC...25b..37R
No abstract at ADS
Title: EPHIN Observations of Energetic Particles during Solar Minimum
Authors: Müller-Mellin, R.; Bothmer, V.; Kunow, H.; Posner, A.;
Sierks, H.; Sequeiros, J.; del Peral, L.; Rodriguez-Frias, M. D.;
Potgieter, M.; Haasbroek, L.
Bibcode: 1997ICRC....1..301M
Altcode: 1997ICRC...25a.301M
No abstract at ADS
Title: Development and Effects of Corotating Interaction Regions:
Workshop Report
Authors: Kunow, H.; Bothmer, V.
Bibcode: 1997ICRC....1..357K
Altcode: 1997ICRC...25a.357K
No abstract at ADS
Title: Joint ULYSSES and WIND observations of a particle event in
April 1995.
Authors: Buttighoffer, A.; Pick, M.; Raviart, A.; Hoang, S.; Lin,
R. P.; Simnett, G. M.; Lanzerotti, L. J.; Bothmer, V.
Bibcode: 1996A&A...316..499B
Altcode:
In this paper we analyze a solar particle event that was measured
at two locations in the heliosphere. Ulysses was at 40°north
heliolatitude and 130°west in heliolongitude from Earth while WIND
was near Earth at 1 AU in the ecliptic plane. To establish the origin
of the particle events, solar coronal activity is investigated. Direct
observational evidence of the association between long-duration electron
acceleration and a solar radio noise storm is shown. We also establish
that the interplanetary type III burst studied here is produced by
successive electron injections from distinct coronal locations. Two
particle increases are observed during the event. For the first one,
the particles are shown to be from coronal origin; for the second one,
which is associated with a Forbush decrease, the particles are primarily
shock accelerated. The differences in particle intensities observed at
WIND and Ulysses are explained by the nature of the particle propagation
to the spacecraft locations.
Title: ULYSSES COSPIN/LET: latitudinal gradients of anomalous cosmic
ray O, N and Ne.
Authors: Trattner, K. J.; Marsden, R. G.; Bothmer, V.; Sanderson,
T. R.; Wenzel, K. -P.; Klecker, B.; Hovestadt, D.
Bibcode: 1996A&A...316..519T
Altcode:
A key goal of the Ulysses mission is the measurement of the latitudinal
gradient of the Anomalous Cosmic Ray (ACR) component. Earlier studies
using data from the COSPIN/LET experiment on board Ulysses together
with in-ecliptic data from the HILT instrument on SAMPEX have shown
a small (~2% per degree) positive latitudinal gradient for anomalous
oxygen in the energy range 8 to 16MeV/n. This result is consistent
with the effects of curvature and gradient drifts in the heliospheric
magnetic field for the current polarity configuration: positively
charged particles are expected to flow down to the heliographic equator
from the polar regions. In this paper we extend our previous work and
include two additional ACR species, nitrogen (4 to 20MeV/n) and neon
(4 to 30MeV/n). We also present our latest results on the ACR oxygen
latitudinal gradient over an extended energy range (4 to 20MeV/n). The
period covered for all three species include the Ulysses south polar
pass, the rapid transit from the south pole to the ecliptic and a
significant portion of the climb to high northern latitudes. For all
species and energy ranges the latitudinal gradients are between 1%
and 2%, consistent with earlier studies, and show a slight tendency
to larger gradients for higher magnetic rigidity.
Title: ULYSSES observations of open and closed magnetic field lines
within a coronal mass ejection.
Authors: Bothmer, V.; Desai, M. I.; Marsden, R. G.; Sanderson, T. R.;
Trattner, K. J.; Wenzel, K. -P.; Gosling, J. T.; Balogh, A.; Forsyth,
R. J.; Goldstein, B. E.
Bibcode: 1996A&A...316..493B
Altcode:
During the rapid passage from the Sun's south to north polar regions,
the Ulysses spacecraft encountered in February 1995, at 24°S, a coronal
mass ejection (CME) exactly at the time when it crossed from high speed
solar wind coronal hole flow into low speed streamer belt flows. We have
investigated this CME, which was superimposed on an energetic particle
event associated with a corotating interaction region (CIR), using
energetic particle, plasma and magnetic field measurements. Ulysses'
entry into the CME was accompanied by a strong decrease in the intensity
of 1-3MeV protons. The leading portion of the CME with a helical
magnetic flux rope topology characteristic of magnetic clouds apparently
consisted of closed magnetic loops as indicated by counterstreaming
suprathermal electron fluxes along the interplanetary magnetic field
(IMF) and bi-directional streaming 0.4-0.7MeV ions. In contrast, the
absence of counterstreaming electrons and ions, the presence of sunward
streaming 0.4-5MeV ions and sunward bursts of suprathermal electrons
at energies from ~40eV up to several 100eV inside another portion of
the CME suggest that here the magnetic field lines were "open" i.e.,
with only one end rooted in the solar corona. These field lines were
most likely connected to the reverse shock of a CIR beyond Ulysses. We
suggest that 3-dimensional reconnection processes are responsible for
the formation of magnetic flux rope CMEs from rising coronal loops
leading to open and closed field topologies.
Title: Ulysses observations of energetic ions over the south pole
of the sun
Authors: Sanderson, T. R.; Bothmer, V.; Marsden, R. G.; Trattner,
K. J.; Wenzel, K. -P.; Balogh, A.; Forsyth, R. J.; Goldstein, B. E.
Bibcode: 1996AIPC..382..411S
Altcode:
We present here observations of energetic ions during the following
phases of the Ulysses prime mission: the first south polar pass,
the low-latitude pass and part of the first north polar pass. Peaks
are observed in the energetic ion intensity which recur either once
per solar rotation during the ascent to high southern latitudes,
or twice per rotation during the low latitude pass. The intensity
of the peaks also rises with each major solar event, decaying slowly
thereafter over a period of several rotations. The peaks are observed
up to ~70° during the ascent to high southern latitudes, but not seen
again until around 45° during the descent, this asymmetry most likely
being caused by a decrease in the number of solar events.
Title: Energetic particles and coronal mass ejections in the high
latitude heliosphere: Ulysses-LET observations
Authors: Bothmer, V.; Marsden, R. G.; Sanderson, T. R.; Trattner,
K. J.; Wenzel, K. -P.; Balogh, A.; Forsyth, R. J.; Goldstein, B. E.;
Uchida, Y.; Hudson, H. S.
Bibcode: 1996AIPC..382..445B
Altcode:
We have investigated energetic ions of non-corotating nature in the high
latitude heliosphere. Major particle events were observed by Ulysses up
to latitudes of 60 °S. All were associated with passage of coronal mass
ejections (CMEs) over the spacecraft. The relationship of these events
with solar activity was investigated using Yohkoh soft X-ray images.
Title: Signatures of fast CMEs in interplanetary space
Authors: Bothmer, V.; Schwenn, R.
Bibcode: 1996AdSpR..17d.319B
Altcode: 1996AdSpR..17..319B
While fast coronal mass ejections (CMEs) have been uniquely identified
as sources of transient shock-disturbances in interplanetary space,
it is less understood why different kinds of plasma and magnetic field
signatures are found in the individual post-shock flows. It is an
open question if CMEs can produce various types of solar wind ejecta,
e.g. magnetic flux ropes or flows without highly ordered internal
fields. To help further clarify the consequences of fast CMEs in
interplanetary space we have examined shock events measured by the
Helios 1 spacecraft during the years 1979-1981 for which the associated
CME has been directly observed with the coronagraph onboard the P78/1
satellite. Seventeen (68%) out of 25 shock-disturbances were followed
by clearly discernible driver gas signatures, but only 7 (41%) of the
driver gases were magnetic clouds.
Title: Stereoscopic viewing of solar coronal and interplanetary
activity
Authors: Schmidt, W. K. H.; Bothmer, V.
Bibcode: 1996AdSpR..17d.369S
Altcode: 1996AdSpR..17..369S
The object of this presentation is to propose a concept for a space
mission that would facilitate stereoscopic observations of the sun and
interplanetary space, and to outline its scientific objectives. It is
envisaged to place a spacecraft with a few lightweight telescopes,
covering the wavelength range from the visible to the extreme UV,
into orbit around the triangular libration point L5 of the sun-earth
system. This point is also known as one of the Lagrangian points,
which is in earth orbit around the sun, and lagging the sun-earth line
by 60 degrees. A satellite (or perhaps more than one) with similar
instrumentation is assumed to operate simultaneously in near earth
orbit. Together, these observations would allow three dimensional
viewing of the sun and interplanetary space. One of the main subjects
of investigation would be to study the morphology and dynamics of
coronal plasma structures and their extension into interplanetary
space. Coronal structures would be imaged in EUV and soft X rays, while
interplanetary events such as Coronal Mass Ejections (CMEs) and shock
waves would be seen as density enhancements in white light. CMEs could
be tracked from their start in the solar corona until their arrival
and impact on the earth's magnetosphere. Thus the observations could
also be used to predict major geomagnetic storms.
Title: The Ulysses south polar pass: Transient fluxes of energetic
ions
Authors: Bothmer, V.; Marsden, R. G.; Sanderson, T. R.; Trattner,
K. J.; Wenzel, K. -P.; Balogh, A.; Forsyth, R. J.; Goldstein, B. E.
Bibcode: 1995GeoRL..22.3369B
Altcode:
Using Ulysses low energy telescope (LET) measurements of protons
and alpha particles with energies of ∼1-5 MeV/n, we present first
observations of transient energetic particle events in the high latitude
heliosphere. Three transient particle events with gradual onsets and
time durations of several days have been identified in the LET data
at heliographic latitudes as high as ∼60°S, at radial distances
from the Sun between 3.3-3.6 AU. No transient increases were observed
polewards of 60°S. All three of the events were associated with
passage of a coronal mass ejection (CME) over Ulysses, and two were
associated with the newly identified type of forward/reverse shock
pairs in the solar wind caused by over-expanding CMEs. The largest of
the three transient events has also been observed at Earth's orbit,
i.e. in the ecliptic. The observations show that energetic particles
can be convected into the high latitude heliosphere through CMEs.
Title: The Ulysses south polar pass: Anomalous component of cosmic
rays
Authors: Trattner, K. J.; Marsden, R. G.; Bothmer, V.; Sanderson,
T. R.; Wenzel, K. -P.; Klecker, B.; Hovestadt, D.
Bibcode: 1995GeoRL..22.3349T
Altcode:
We have expanded our previous study of latitudinal gradients of
anomalous cosmic ray oxygen (8 to 12 MeV/n and 12 to 16 MeV/n) by
using also helium (11 to 20 MeV/n) as an additional component and a
larger ULYSSES/LET data set including the segment up to the maximum
southern latitude and the pole-to-equator segment of the mission down
to 38°S. The ULYSSES observations are compared with observations
in the vicinity of the Earth, provided by SAMPEX and IMP 8. The data
sets cover a time period from August 1992 to end of January 1995. Only
quiet time periods which contain no increases due to solar energetic
particles are taken into account. Both oxygen energy channels show a
decrease of the SAMPEX to ULYSSES flux ratio which is equivalent to a
positive latitudinal gradient of ∼2%/degree. However, no significant
latitudinal gradient for helium was found using the IMP 8 to ULYSSES
flux ratio.
Title: The Ulysses south polar pass: Energetic ion observations
Authors: Sanderson, T. R.; Bothmer, V.; Marsden, R. G.; Trattner,
K. J.; Wenzel, K. -P.; Balogh, A.; Forsyth, R. J.; Goldstein, B. E.
Bibcode: 1995GeoRL..22.3357S
Altcode:
We present here a preliminary analysis of observations of energetic ions
during the first polar pass of the Ulysses spacecraft, concentrating
mainly on the region where the spacecraft was continually immersed
in high speed flow from the polar coronal hole. During the ascent to
high latitudes, a single recurrent peak was observed once per solar
rotation. From 70°S during ascent to 43°S during descent no major
peaks were observed. Thereafter, two peaks per solar rotation were
observed.
Title: Energetic particles and coronal mass ejections in the high
latitude heliosphere: Ulysses-LET observations
Authors: Bothmer, V.; Sanderson, T. R.; Marsden, R. G.; Wenzel,
K. -P.; Goldstein, B. E.; Balogh, A.; Forsyth, R. J.; Uchida, Y.
Bibcode: 1995sowi.conf...47B
Altcode:
The COSPIN Low Energy Telescope (LET) onboard the Ulysses spacecraft
measures protons, alphas and heavier ions at energies of approximately
1 to 50 MeV/n. Ulysses measurements offer favorable opportunities to
study the effects of solar activity in the out-of-ecliptic regions of
the heliosphere. Using LET data, we have investigated the properties of
transient energetic ions at high heliographic latitudes when Ulysses
was permanently immersed in high speed solar wind and magnetically
connected to the Sun on open magnetic field lines. Recurrent increases
in the fluxes of energetic ions at high heliographic latitudes at
frequencies related to the solar rotation period were found to occur
in association with co-rotating interaction regions (CIRs). Here we
investigate fluxes of energetic particles that showed no relationship
to ClRs. From the investigation of plasma and magnetic held data it
is found that all of the transient high latitude particle events
were associated with the passage of a coronal mass ejection (CME)
over Ulysses. Enhancements in particle fluxes several days prior to
the arrival of a CME, but with a significant time delay with respect
to the estimated CME-onset at the Sun, were most probably associated
with interplanetary shocks driven by fast CMEs. These particle events
exhibit unusually high rho/alpha-ratios and are not observed for
CMEs not driving a shock. However, not all CMEs that passed Ulysses
were associated with a particle event. We find evidence that at high
solar latitudes, solar flare particles cannot reach Ulysses on open
magnetic field lines, but can reach the spacecraft if particles are
injected into magnetic flux-ropes (CMEs) at the Sun. These findings are
supported by soft X-ray observations from the Japanese Yohkoh-satellite.
Title: ULYSSES observations of energetic ions over the south pole
of the Sun
Authors: Sanderson, T. R.; Marsden, R. G.; Bothmer, V.; Trattner,
K. J.; Wenzel, K. P.; Balogh, A.; Forsyth, R. J.; Goldstein, B. E.
Bibcode: 1995sowi.conf...44S
Altcode:
The Ulysses spacecraft began its journey out-of-the-ecliptic in February
of 1992, when it encountered the planet Jupiter. In April of 1993,
the spacecraft had reached 29 deg S, and from then on was completely
immersed in the flow from the southern polar coronal hole. Accelerated
ions were observed, recurring with a main peak once per solar rotation,
with the intensity at the peak slowly decreasing with increasing
latitude. This decrease continued to the end of 1993, when the
spacecraft was at approximately 50 deg S. During the first three months
of 1994 the intensity of the accelerated ions rose again, due either
to an increase in magnetic activity on the sun or a reconfiguration
of the heliospheric magnetic field. Recurrent accelerated ions were
still being seen at the beginning of July 1994, when the spacecraft
was at a latitude of 70 deg S, although with reduced intensity. The
accelerated ions were no longer seen at latitudes higher than 70 deg S,
the ion intensity staying constant at around the cosmic ray background
level. This continued on until the highest latitude reached, 80.2 deg
S, on 13 September 1994. The spacecraft then began its journey back
towards lower latitudes, a small increase in the particle intensity
being observed at the end of October whilst at approximately 72 deg
S, and thereafter no more increases until the end of 1994, when the
spacecraft was at approximately 45 deg S. We present interpretations
for this asymmetry in latitude dependence.
Title: Cosmic Ray and Solar Particle Investigations Over the South
Polar Regions of the Sun
Authors: Simpson, J. A.; Anglin, J. D.; Bothmer, V.; Connell, J. J.;
Ferrando, P.; Heber, B.; Kunow, H.; Lopate, C.; Marsden, R. G.;
McKibben, R. B.; Muller-Mellin, R.; Paizis, C.; Rastoin, C.; Raviart,
A.; Sanderson, T. R.; Sierks, H.; Trattner, K. J.; Wenzel, K. -P.;
Wibberenz, G.; Zhang, M.
Bibcode: 1995Sci...268.1019S
Altcode:
Observations of galactic cosmic radiation and anomalous component nuclei
with charged particle sensors on the Ulysses spacecraft showed that
heliospheric magnetic field structure over the south solar pole does
not permit substantially more direct access to the local interstellar
cosmic ray spectrum than is possible in the equatorial zone. Fluxes
of galactic cosmic rays and the anomalous component increased as
a result of latitude gradients by less than 50% from the equator
to -80^circ. Thus, the modulated cosmic ray nucleon, electron, and
anomalous component fluxes are nearly spherically symmetric in the
inner solar system. The cosmic rays and the anomalous nuclear component
underwent a continuous, ~26 day recurrent modulation to -80.2^circ,
whereas all recurring magnetic field compressions and recurring streams
in the solar wind disappeared above ~55^circS latitude.
Title: Eruptive prominences as sources of magnetic clouds in the
solar wind
Authors: Bothmer, V.; Schwenn, R.
Bibcode: 1994SSRv...70..215B
Altcode:
Large amounts of coronal material are propelled outward into
interplanetary space by Coronal Mass Ejections (CMEs). Thus one might
expect to find evidence for expanding flux ropes in the solar wind
as well. To prove this assumption magnetic clouds were analyzed and
correlated with Hα-observations of disappearing filaments. When clouds
were found to be directly associated with a disappearing filament,
the magnetic structure of the cloud was compared with that of the
associated filament. Additionally the expansion of magnetic clouds
was examined over a wide range of the heliosphere and compared with
the expansion observed for erupting prominences.
Title: Comparison of CMEs, magnetic clouds, and bidirectionally
streaming proton events in the heliosphere using helios data
Authors: Webb, D.; Jackson, B.; Hick, P.; Schwenn, R.; Bothmer, V.;
Reames, D.
Bibcode: 1993AdSpR..13i..71W
Altcode: 1993AdSpR..13...71W
Coronal Mass Ejections (CMEs) are large, energetic expulsions of mass
and magnetic fields from the Sun; they can significantly affect large
volumes of the heliosphere and appear to be a key cause of geomagnetic
storms. We have compiled a list of all significant CMEs detected by
the HELIOS white light photometers from 1975-1982. We are studying the
characteristics of these CMEs, and present preliminary results of their
associations with in-situ features, especially magnetic ``clouds'' and
periods of bidirectionally streaming ions, two classes of structures
considered indicative of interplanetary loops. Advantages of this data
set include reliable association in the interplanetary medium of the
white light CME plasma with the in-situ features, and observations of
a large number of events over a long time base.
Title: Magnetic cloud observations by the HELIOS spacecraft
Authors: Bothmer, V.; Schwenn, R.
Bibcode: 1992sws..coll..599B
Altcode:
A possible interpretation for the observed characteristics of an
interplanetary magnetic cloud is the passage of a magnetic flux
rope. For simplification the flux rope might be considered as a
cylindrically symmetric structure with the magnetic field lines being
directed parallel to the axis at its center and circular at its outer
edges. Near the center of this flux rope the magnetic field strength
would be strongest. The minimum variance technique was applied to
several magnetic clouds observed by the Helios spacecraft between 0.3
and 1 AU in order to determine the orientations of the magnetic flux
rope axis. The calculated orientations are examined with respect to the
global solar wind stream structure, the surrounding solar wind flow,
the radial distance to the sun and their solar origin.
Title: Magnetic structures at sector boundaries in the inner
heliosphere
Authors: Bothmer, V.; Schwenn, R.
Bibcode: 1992sws..coll..151B
Altcode:
The strong deflections of the IMF out of the ecliptic plane that
have been noted at sector boundaries, and are therefore related to
the heliospheric current sheet, have north-to-south turnings in the
case of magnetic field deflections at sector boundaries that point
to an origin for this phenomenon in magnetic field lines that remain
parallel to the inclined current sheet. The plasma and magnetic field
properties at sector boundaries closer to the sun may show interesting
coronal streamer belt features.