Registered Attendees: (Total = 68)
Name Affiliation Research Group
Dr. Naomi Maruyama NOAA/SEC WG3: Ionospheric Storms
Dr. Paul A. Bernhardt Naval Research Laboratory WG3: Ionospheric Storms
Dr. Tim Fuller-Rowell University of Colorado WG3: Ionospheric Storms
Dr. Larry Paxton JHU/APL WG3: Ionospheric Storms
Dr. Janet Luhmann Space Sciences Laboratory, UC Berkeley WG1: Drivers of geomagnetic storms
Dr. Ramona Kessel NASA HQ Unsure
Dr. Aleksandr Ukhorskiy JHU/APL WG2: Geomagnetic storm mechanisms
David F. Webb Boston College WG1: Drivers of geomagnetic storms
Dr. Michael Wiltberger NCAR/HAO WG2: Geomagnetic storm mechanisms
Dr. Ramon E. Lopez Florida Institute of Technology WG4: Prediction of geomagnetic storms
Ms. Janet Catherine Johnston Air Force Research Laboratory WG4: Prediction of geomagnetic storms
Mr. Robert Bruntz Florida Tech. WG4: Prediction of geomagnetic storms
Dr. Emilia Huttunen University of California, Berkeley WG1: Drivers of geomagnetic storms
Dr. Jie Zhang George Mason University WG1: Drivers of geomagnetic storms
Dr. J D. Huba Naval Research Laboratory WG3: Ionospheric storms
Dr. Nat Gopalswamy NASA GSFC WG1: Drivers of geomagnetic storms
Dr. Mary K. Hudson Dartmouth College WG2: Geomagnetic storm mechanisms
Dr. Dennis L. Gallagher NASA Marshall Space Flight Center WG2: Geomagnetic storm mechanisms
Dr. Vasyl Yurchyshyn Big Bear Solar Observatory WG1: Drivers of geomagnetic storms
Dr. Sunanda Basu Boston University WG3: Ionospheric storms
Dr. Santimay Basu AF Research Laboratory WG3: Ionospheric storms
Dr. William Lotko Dartmouth College Unsure
Prof. Mark B. Moldwin UCLA WG2: Geomagnetic storm mechanisms
Dr. Chaosong Huang MIT Haystack Observatory WG3: Ionospheric storms
Dr. Chin-Chun Wu CSPAR/University of Alabama in Huntsville WG1: Drivers of geomagnetic storms
Dr. Gang Lu HAO/NCAR WG3: Ionospheric storms
Dr. James Wanliss ERAU WG4: Prediction of geomagnetic storms
Dr. John C. Foster MIT Haystack Observatory WG3: Ionospheric storms
Dr. Athina Varotsou Los Alamos National Laboratory WG2: Geomagnetic storm mechanisms
Dr. Xuepu Zhao Stanford University WG1: Drivers of geomagnetic storms
Prof. Paul M. Kintner Cornell University WG3: Ionospheric storms
Dr. Seiji Yashiro Catholic University WG1: Drivers of geomagnetic storms
Dr. Anthony J. Mannucci JPL/Caltech WG3: Ionospheric storms
Dr. Jonathan Krall Naval Research Laboratory WG3: Ionospheric storms
Dr. Mario Mark Bisi Center for Astrophysics and Space Sciences, UCSD Unsure
Dr. Geoff Crowley Atmospheric & Space Technology Research Assoc. WG3: Ionospheric storms
Dr. Douglas P. Drob NRL WG3: Ionospheric storms
Dr. Elsayed Talaat JHU/APL WG3: Ionospheric storms
Dr. Brian T. Kress Dartmouth College WG2: Geomagnetic storm mechanisms
Dr. John Retterer Air Force Research Lab. WG3: Ionospheric storms
Prof. Alexander Nindos University of Ioannina WG1: Drivers of geomagnetic storms
Prof. Robert L. McPherron Institute of Geophysics and Planetary Physics, WG4: Prediction of geomagnetic storms
Dr. David Gary Sibeck NASA/GSFC WG2: Geomagnetic storm mechanisms
Dr. Hong Xie Catholic University of America WG1: Drivers of geomagnetic storms
Dr. Alejandro Lara Instituto de Geofisica, UNAM WG1: Drivers of geomagnetic storms
Mr. Watanachak Poomvises GMU WG1: Drivers of geomagnetic storms
Dr. Thomas Jerome Immel University of California Berkeley WG3: Ionospheric storms
Dr. Nariaki V. Nitta Lockheed Martin Solar and Astrophysics Laboratory WG1: Drivers of geomagnetic storms
Dr. Pontus C. Brandt JHU/APL WG2: Geomagnetic storm mechanisms
Dr. Jerry Goldstein Southwest Research Institute WG2: Geomagnetic storm mechanisms
Richard Eastes University of Central Florida Unsure
Dr. Michael W. Liemohn University of Michigan WG2: Geomagnetic storm mechanisms
Dr. Viacheslav A. Pilipenko Augsburg College (on leave from Space Research WG2: Geomagnetic storm mechanisms
Institute, Moscow)
Dr. Raymond A. Greenwald Johns Hopkins University/Applied Physics Laboratory WG3: Ionospheric storms
Dr. Yuri Shprits UCLA WG2: Geomagnetic storm mechanisms
Dr. Robert DeMajistre JHU/APL WG3: Ionospheric storms
Dr. Gary S. Bust ASTRA WG3: Ionospheric storms
Dr. Ludger Scherliess Utah State University WG3: Ionospheric storms
Ms. Dawn Marie Mueller post-grad Northern IL Univ WG4: Prediction of geomagnetic storms
Dr. Dimitrios Vassiliadis ST at NASA/Goddard Space Flight WG4: Prediction of geomagnetic storms
Salvador Hernandez Florida Institute of Technology WG2: Geomagnetic storm mechanisms
Ms. Sandra Brogl Florida Institute of Technology Unsure
Dr. Manolis Konstantinos Georgoulis JHU/APL WG1: Drivers of geomagnetic storms
Mr. Jorge Emrys Landivar Florida Tech Unsure
Ismael Diaz FIT WG2: Geomagnetic storm mechanisms
Prof. Ming Zhang Florida Institute of Technology WG2: Geomagnetic storm mechanisms
Dr. Hamid K Rassoul Florida Tech WG2: Geomagnetic storm mechanisms
Elizabeth J. Mitchell Florida Institute of Technology WG1: Drivers of geomagnetic storms
Submitted Abstracts:
Working Group 1: Drivers of geomagnetic storms (CME and solar surface source region, CME/ICME relation)
Author(s): J.G. Luhmann - Space Sciences Laboratory, UC Berkeley
Working Group: WG1: Drivers of geomagnetic storms (CME and solar surface source region, CME/ICME relation)
Title: Solar Sources of Geomagnetic Storms
Abstract: The fact that Coronal Mass Ejections (CMEs), through their associated interplanetary counterparts, ICMEs, are the causes of major geomagnetic storms has been a part of the space physics knowledge base for almost two decades. However many will agree that the SOHO mission observations had some of the biggest impact on our regular appreciation and application of that knowledge. The association between halo CMEs in coronagraph images and geomagnetic storms is now regularly used in space weather forecasting, but it is also well known that not all halo CMEs produce storms and that storms are sometimes produced by CMEs not classified as haloes. In addition, solar wind stream interaction regions can sometimes produce a major geomagnetic storm. In this tutorial we take a fresh look at the upstream conditions associated with storms, and from a potential forecasting perspective, consider what particular features of solar observations and models might be better used to anticipate major eruptions and solar wind stream structure of consequence in the STEREO and LWS mission era.
Author(s): Vasyl Yurchyshyn
Working Group: WG1: Drivers of geomagnetic storms (CME and solar surface source region, CME/ICME relation)
Title: Photospheric Sources of Very Fast (>1100 km/s) CMEs Observed Between 1999 and 2006
Abstract: CMEs are eruptions of the solar magnetic field and plasma into interplanetary space, which occur following a large-scale magnetic rearrangement in the solar atmosphere. In general, sources of CMEs are solar active regions (AR) and quiescent chromospheric filaments seen on the solar disk in the H_alpha spectral line as extended dark structures.
Since very fast CMEs are the ones that have a potential to cause most intense geomagnetic storms, it is therefore crucial to know where those CMEs come from and when to expect them. We compiled a list of very fast halo CMEs detected from 1997 though 2005. In this study we used the same CME speed threshold of 1100km/s. Total 150 events had been selected. We were able to determine the associated solar surface activity for only 85 events out of 150 (56\%). Our objective was to look at the underlying configuration of the solar magnetic fields that spawned those eruptions. We thus found the following: 52 CMEs out of 85 (61\%) were associated with only 27 various delta-configurations, which are complex magnetic structures consisting of opposite polarity umbrae within the same penumbra. 15 events (18\%) were found to be originated in a very interesting magnetic configuration mainly consisting of a large twisted leading polarity sunspot with an non-existent or a very small following polarity sunspot. Total 14 such configurations were identified. And finally, 14 very fast CMEs (16\%) erupted from 13 large complexes, which could be described as two very close ARs (very often deltas) or an AR within a vast area of relatively strong fields (often with a large chromospheric filament) possibly remnants of old decayed ARs. We were unable to clearly classify 4 events. The table of events can be found here:
http://www.bbso.njit.edu/~vayur/Fast_Halo_CME_Sources_Sorted.html
In this presentation we will discuss details of the evolution of the magnetic structures responsible for very fast CMEs and possible implications of these results for understanding solar eruptions and space weather forecasts.
We acknowledge the usage of data from the SolarMonitor and the CME catalog. This CME catalog is generated and maintained at the CDAW Data Center by NASA and The Catholic University of America in cooperation with the Naval Research Laboratory. SOHO is a project of international cooperation between ESA and NASA.
Author(s): D. F. Webb, david.webb@hanscom.af.mil, ISR, Boston College
T. A. Howard, Physics Department, Montana State University
B. V. Jackson, CASS, Univ. of California-San Diego
J. C. Johnston, Air Force Research Laboratory, Space Vehicles Directorate
Working Group: WG1: Drivers of geomagnetic storms (CME and solar surface source region, CME/ICME relation)
Title: SMEI Observations of ICMEs Driving CDAW Storms
Abstract: Interplanetary coronal mass ejections (ICMEs) are a primary cause of severe space weather at Earth because they drive shocks and trigger geomagnetic storms that can damage spacecraft and ground-based systems. The Solar Mass Ejection Imager (SMEI) is a U. S. Air Force experiment with the ability to track ICMEs in white light from near the Sun to Earth, thus providing a new dimension for forecasting storms. SMEI has accomplished this by detecting geoeffective ICMEs at elongations of 20o-30o, ~1/3 of the distance from the Sun to Earth, corresponding to advance-warning times of 10 hours to 2 days. SMEI's images of ICMEs, obtained with a cadence of 102 minutes, provide a dynamic view of ICME morphology along trajectories aimed towards Earth. Our investigations of ICME intensity, structure evolution and kinematics should improve our ability to forecast storm effects at Earth. We summarize several studies of SMEI's detection and tracking capability, especially of the ICMEs associated with the intense (peak Dst < - 100nT) geomagnetic storms that are the focus of this CDAW. Since initiating operations in February 2003, SMEI has observed the associated ICMEs for about 85% of such storms. We describe the SMEI observations and analyses for the 27 CDAW storms from May 2003 (No. 63) to September 2005 (No. 89).
Author(s): Chin-Chun Wu, wuc@cspar.uah.edu, CSPAR/University of Alabama in Huntsville
N. Gopalswamy, agopals@ssedmail.gsfc.nasa.gov, NASA/GSFC
S. Yashiro, yashiro@ssedmail.gsfc.nasa.gov, Catholic University of America
Dr. Ronald P. Lepping, GSFC/NASA
Working Group: WG1: Drivers of geomagnetic storms (CME and solar surface source region, CME/ICME relation)
Title: Solar Sources and Geoeffectiveness of Interplanetary Coronal Mass Ejections and Magnetic Clouds: A Comparison
Abstract:
We present the results of a statistical investigation of the
geoeffectiveness of non-cloud interplanetary mass ejections (ICMEs) and
compare them with that of magnetic clouds (MCs) observed during solar
cycle 23. The starting point of this investigation is the set of all
intense geomagnetic storm (Dst =< -100 nT) of the current solar cycle.
We compare the solar source locations of the non-cloud ICMEs with
those of MCs. We also investigate the effects of solar source
location on the properties of ICMEs observed near Earth.
Author(s): Xuepu Zhao - xuepu@sun.stanford.edu - Stanford University
Working Group: WG1: Drivers of geomagnetic storms (CME and solar surface source region, CME/ICME relation)
Title: Determination of the central axis field direction for frontside halo CMEs
Abstract: It have been shown that Bs events, i.e., the intervals of southward HMF with intensity <= -10 nT and duration >= 3 hours, have nearly one-to-one correspondence to geostorms, and that the intensity and duration of magnetic cloud-associated Bs events are largely determined by the direction of the central axis field of magnetic clouds (or interplanetary magnetic ropes). In other words, the central axis field direction is one of the primary characteristics that make a unique halo CME geostorm-effective. By determining the central axis field direction for frontside halo CMEs, the geostorm-effectiveness of the unique frontside halo CMEs may be basically determined.
It is general believed that CMEs are generated by magnetic energies, and the free magnetic energy that accelerates and heats CME plasma is stored in field line-aligned electric current. The magnetic configuration of most, if not all, of CMEs (including halo CMEs) must, therefore, be curved magnetic ropes as evidenced in BDE observations of unique ICMEs.
The curved flux ropes may be approximated by the elliptic cone model with its major axis aligned with the central axis field direction of the top part of the curved flux ropes. This work searches for the influence of various elliptic cone parameters on the orientation of the major axis of elliptic halo CMEs, and presents criteria to determine the central axis field direction for three types of elliptic halo CMEs.
Author(s): Mario M. Bisi - mmbisi@ucsd.edu - Center for Astrophysics and Space Sciences (CASS), UCSD
Bernard V. Jackson - bvjackson@ucsd.edu - Center for Astrophysics and Space Sciences (CASS), UCSD
P. Paul Hick - pphick@ucsd.edu - Center for Astrophysics and Space Sciences (CASS), UCSD
Andy Buffington - abuffington@ucsd.edu - Center for Astrophysics and Space Sciences (CASS), UCSD
Working Group: WG1: Drivers of geomagnetic storms (CME and solar surface source region, CME/ICME relation)
Title: CME Reconstructions Using Interplanetary Scintillation Data
Abstract:
Interplanetary scintillation (IPS) observations provide a view of the solar wind at all heliographic latitudes from around 1 A.U. down to coronagraph fields of view. It can be used to study the evolution of the solar wind and solar transients out into interplanetary space and also the inner heliospheric response to corotating solar structures and coronal mass ejections (CMEs), both in scintillation level and in velocity. With colleagues at STELab, Nagoya University Japan, we have developed near-real-time access of STELab IPS data for use in space-weather forecasting. We use a three-dimensional reconstruction technique that obtains perspective views from solar corotating plasma and outward-flowing solar wind as observed from Earth by iteratively fitting a kinematic solar wind model to IPS observations. This 3D modeling technique permits reconstructions of the density and velocity structures of CMEs and other interplanetary transients at a relatively coarse resolution. These reconstructions have a solar-rotation cadence with 10 latitudinal and longitudinal heliographic resolution for the corotational model, and a one-day cadence and 20 latitudinal and longitudinal heliographic resolution for the time-dependent model. This technique is used to determine solar wind pressure (ram pressure) at Mars. Results are compared with ram pressure observations derived from Mars Global Surveyor magnetometer data for the years 1999 through 2004 and include a reconstruction of a back-side event as seen by SOHO|LASCO.
Author(s): S. Yashiro - yashiro@ssedmail.gsfc.nasa.gov - Catholic University
N. Gopalswamy - gopals@ssedmail.gsfc.nasa.gov - NASA/Goddard Space Flight Center
S. Akiyama - akiyama@ssedmail.gsfc.nasa.gov - Catholic University
Working Group: WG1: Drivers of geomagnetic storms (CME and solar surface source region, CME/ICME relation)
Title: Properties of geoeffective and non-geoeffective CMEs
Abstract: We report on the differences in observed properties of geoeffective (GE)
and non geoeffective (non-GE) coronal mass ejections (CMEs) originating
from disk center (within 30 degree from central meridian). We compiled M- and
X-class flares from NOAAfs Solar Geophysical Data and examined their CME
associations using SOHO/LASCO data. There were 180 disk CMEs between 1996
and 2005. Out of them, 30 disk CMEs produced intense geomagnetic storms,
which were identified by working group I, and 67 disk CMEs were not
followed by geomagnetic storms (Dst < -50 nT) during an interval 1-5
days after the CME onset. We compared the properties of these two
populations of CMEs and found that GE CME were faster (Average speed =
1356 km/s) and wider (halo rate = 87%) than non-GE CMEs (652 km/s, 31%).
On the other hand, there were 21 disk halos not followed by geomagnetic
storms. Five of the non-GE halos were also fast (V>1000 km/s); we discuss
why these were not geoeffective.
Author(s): A. Nindos - anindos@cc.uoi.gr - University of Ioannina Greece
V. Yurchyshyn - vayur@bbso.njit.edu - BBSO/NJIT
J. Zhang - jiez@scs.gmu.edu - GMU
N. Gopalswamy - gopals@ssedmail.gsfc.nasa.gov - NASA's GSFC
D. Webb - David.Webb@hanscom.af.mil - Boston College
I. Richardson - richardson@lheavx.gsfc.nasa.gov - NASA's GSFC
Working Group: WG1: Drivers of geomagnetic storms (CME and solar surface source region, CME/ICME relation)
Title: The magnetic field in geomagnetic storms: properties in the source regions and at 1 AU
Abstract: The properties of the magnetic field in the solar source regions of those
geoeffective events that produce magnetic clouds (MCs) at 1 AU and whose
solar sources have been unanimously identified by different researchers
are compared with the properties of the magnetic field of the
corresponding MCs at 1 AU. Our basic goal is to check whether the
properties of geoeffevtive MCs can be predicted from the properties of the
associated solar sources. The solar source regions have been identified
using observations from several space-borne and ground-based instruments
while for the MCs data from the Wind spacecraft have been used. For the
source regions the chirality (i.e. handedness) of the magnetic field is
estimated using observations in EUV, soft X-rays, and Halpha, while the
polarity (North or South) of the leading field in the low corona is
predicted by the Coronal Flux Rope model. From the "Wind" data we estimate
the associated MC's chiralities and determine their magnetic structure
from the leading, center, and trailing polarity of their field. The
orientations of the magnetic field in the low corona and at 1 AU are
compared with the orientation of the Sun's large-scale bipolar magnetic
field.
Author(s): Jie Zhang - jzhang7@gmu.edu - George Mason University
Watanachak Poomvises - wpoomvis@gmu.edu - George Mason University
Working Group: WG1: Drivers of geomagnetic storms (CME and solar surface source region, CME/ICME relation)
Title: Solar Sources of Major Geomagnetic Storms during 1996 -- 2005
Abstract: Built upon the effort of CDAW working group one on identifying the solar and interplanetary sources of the 88 major geomagnetic storms (Dst <= -100 nT) during 1996 2004, this study focuses on the analysis of the properties of the solar sources. We study the size and velocity distributions of those CMEs causing major storms, in a comparison of all the CMEs observed during the same period. We study the properties of solar flares associated with these geo-effective CMEs. The source region types, including active regions, quiet Sun regions (associated with quiescent filaments or filament channels) and coronal holes, are investigated in terms of their relative numbers in causing major storms. The longitudinal and latitudinal distributions of surface source regions will be investigated along with the solar cycle variation. Based on the known CME transit time, we will try to create a prediction model for CME arrival at 1 AU by incorporating the source heliographic coordinates. The implications on space weather forecasting will be discussed.
Author(s): H. Xie - hong.xie@ssedmail.gsfc.nasa.gov - Catholic University
N. Gopalswamy - gopals@ssedmail.gsfc.nasa.gov - NASA/Goddard Space Flight Center
S. Yashiro - yashiro@ssedmail.gsfc.nasa.gov - Catholic University
Working Group: WG1: Drivers of geomagnetic storms (CME and solar surface source region, CME/ICME relation)
Title: Large Long-lived Geomagnetic Storms
Abstract: Large long-lived geomagnetic storms (LLGMS) are predominantly associated
with multiple successive CMEs. Interactions among CMEs and CMEs with high
speed streams have been found to enhance the intensity of LLGMS (Xie et
al. 2006). In this work, we extend our previous study to a larger data set
of geomagnetic storms of solar cycle 23. In addition, we study the role of
preconditioning of prior storms in LLGMS events. We apply the modified empirical
Burton model for complex storms, where one storm is often preceded by
other storms.
Author(s): Watanachak Poomvises, Jie Zhang
wpoomvis@gmu.edu, jiez@scs.gmu.edu
George Mason University
Working Group: WG1: Drivers of geomagnetic storms (CME and solar surface source region, CME/ICME relation)
Title: Geo-effective Shock Sheaths and ICMEs: Properties and Relations with Solar Sources
Abstract: This study focuses on the 47 major geomagnetic storms (Dst <= -100 nT) during 1996 2004 driven by transient solar wind flows of single interplanetary coronal mass ejections (ICMEs) including their upstream shock sheath regions (SHs). Compared with the other 22 major storms driven by complex ejecta involving multiple ICMEs, the interplanetary (IP) and solar sources of these storms are mostly reliably identified and well characterized. We will present the statistical properties of the SHs and ICMEs, including the distributions of their duration, linear size, mean strength of magnetic field (and southward magnetic field), mean proton temperature and density. In particular, we calculate the estimated solar wind energy input into the magnetosphere using the formula for SHs and ICMEs separately, and study the relative importance of SHs and ICMEs in terms of their geo-effectiveness. We find that 10(21.2%) are shock-sheath-dominant events (defined as SH contributes more than 80% power of the storm), 25 (53%) are ICME-dominant events, and the rest 10 (21.2%) are more balanced events. We further study the possible correlations between various solar wind properties mentioned above with those of solar source regions, including CME speed, source region longitude and latitude. There is an apparent correlation between CME speed and interplanetary shock sheath temperature.
Author(s): Yurchyshyn, Vasyl - vayur@bbso.njit.edu - Big Bear Solar Observatory
Hu, Q. - qiang.hu@ucr.edu - IGPP, University of California, Riverside
Lepping, R. P. - Ronald.P.Lepping@nasa.gov - NASA, Goddard Space Flight Center
Lynch, B. J. - blynch@ssl.berkeley.edu - SSL, University of California, Berkeley
Krall, J. - krall@ppdmail.nrl.navy.mil - PPL, Naval Research Laboratory
Working Group: WG1: Drivers of geomagnetic storms (CME and solar surface source region, CME/ICME relation)
Title: Orientations of Lasco Halo Cmes and their Connection to The Flux Rope Structure of ICMEs
Abstract: Coronal mass ejections (CMEs) are the most important solar drivers of geomagnetic storms. They are observed by remote sensing, such as LASCO coronographic imaging on board SOHO spacecraft. Their interplanetary counterparts, ICMEs, can be detected in-situ, for example, by ACE and Wind spacecraft. An ICME usually exhibits a complex structure that very often includes a magnetic cloud (MC). MCs are distinctive magnetic features that can be commonly modeled as magnetic flux ropes which are capable of providing prolonged periods of southward interplanetary magnetic field at 1 AU, due to the poloidal and/or toroidal component of their internal magnetic field. It is thought that the orientation of a halo CME elongation corresponds to the orientation of the flux rope.
Therefore, in this study we compare orientation angles of elongated halo CMEs observed by the LASCO instrument and the corresponding MCs, measured by Wind and ACE spacecraft. We characterize the ICME structures by using the Grad-Shafranov reconstruction technique and several ICME/MC fitting methods to obtain their axis orientations. The CME and MC angles are compared without taking into account handedness of the underlying flux rope field and the polarity of its axial field.
We report that for about 64% of CME-ICME events, we found a good correspondence between the orientation angles implying that for two thirds of interplanetary ejecta their orientations do not change more significantly (less than 45 deg rotation) while traveling from the sun to the near earth environment.
In the second part of the presentation we will discuss the applications of our results to space weather forecast and possible future studies.
Author(s): Manolis K. Georgoulis - manolis.georgoulis@jhuapl.edu - The Johns Hopkins University Applied Physics Laboratory
David M. Rust - dave.rust@jhuapl.edu - The Johns Hopkins University Applied Physics Laboratory
Working Group: WG1: Drivers of geomagnetic storms (CME and solar surface source region, CME/ICME relation)
Title: Identifying and understanding sources of solar eruptions while in their pre-eruption phases
Abstract: Solar magnetized regions involving massive amounts of magnetic flux
and conspicuous polarity inversion lines has always been viewed as a
strong candidate for hosting major flares and, as revealed later,
for triggering CMEs. Recently, we showed that calculating the minimum
possible magnetic energy in an active region (by means of the current-free
approximation) provides a slightly better measure of the region's
eruptive potential. We hereby describe a much better index that can be
safely used to infer the likelihood of major eruptions in a region in
the coming 12 to 24 hours. By computing a maximum-likelihood magnetic
connectivity matrix in the lower solar boundary (be it the photosphere
or the chromosphere), we find that the magnetic flux committed to a
given connection normalized by the footpoint separation length of the
connection provides the safest, so far, index of eruptive
activity. Our analysis does not even require vector magnetic field
measurements at the moment, so its effectiveness is proven by
application to the largest existing data set of solar magnetic field
measurements, namely the magnetogram archive of SoHO/MDI. The advent
of full-disk vector magnetograms will allow a generalization of the
technique to calculate the total magnetic energy, free magnetic
energy, and relative magnetic helicity of solar active regions in the
nonlinear force-free approximation. This will further lead to the
first detailed, quantitative, connection between CMEs and ICMEs
coupled by a solid physical understanding of these eruptive
manifestations.
Author(s): Nariaki V. Nitta - nitta@lmsal.com - Lockheed Martin Solar and Astrophysics Laboratory
Andrei N. Zhukov - Andrei.Zhukov@oma.be - Royal Observatory of Belgium
Working Group: WG1: Drivers of geomagnetic storms (CME and solar surface source region, CME/ICME relation)
Title: Problem Events
Abstract: A large fraction of the members who belonged to the Working Group (WG) 1 at the LWS CDAW 2005 have participated in the daunting task of identifying the origins of major geomagnetic storms during 1996-2005. Although we have made great progress with extensive and careful analysis, the solar source of at least 10 (14%) of the 78 events through 2004 have been left unknown. In certain events that clearly involve an ICME, we cannot identify the parent halo CME within a reasonable search window. In other events the CME-ICME connection appears to be established, but we fail to find low coronal signatures of the CME. We discuss observational constraints in these events that prevent us from finding clear solar sources, and give possible candidates that have been proposed by different individuals in the WG. We also comment on why we do not put the highest confidence level for some of the remaining events.
Author(s): Alejandro Lara - alara@geofisica.unam.mx - Instituto de Geofisica, UNAM
Veronica Ontiveros
Andrea Borgazzi
Working Group: WG1: Drivers of geomagnetic storms (CME and solar surface source region, CME/ICME relation)
Title: ICME Transport
Abstract: We present preliminary results of the
transport study of 52 Geo-effective
Interplanetary Coronal Mass Ejections (ICMEs).
We analyze different CME, ICME and ambient solar wind parameters
of 52 CDAW events.
We found a CME - Shock speeds linear relationship which may be used
to identify the related pair events.
The major finding of this study is a second order polynomial
relationship between the
ambient density and the ICME driven shock speed, which apply only to low
ambient densities and can be used to quantify the moment exchange between
the ICME and the ambient solar wind.
We discuss the implications of this finding in terms of the ICME
transport in general and the Sun-Earth ICME travel time, in particular.
Author(s): N. Gopalswamy
S. Yashiro
H. Xie
S. Akiyama
Working Group: WG1: Drivers of geomagnetic storms (CME and solar surface source region, CME/ICME relation)
Title: Solar-cycle variation of CMEs, ICMEs, and Geomagnetic Storms
Abstract: The solar and interplanetary events were best observed during solar cycle
23, thanks to the extended and uniform coverage provided by SOHO, Wind,
and ACE spacecraft. We have used data from these spacecraft to study the
solar cycle variation of halo coronal mass ejections (CMEs),
interplanetary CMEs (ICMEs), interplanetary shocks, and the associated
geomagnetic storms. We identified the source regions of CMEs using
near-Sun observations and track their evolution as a function of the solar
cycle. We also study the evolution of magnetic cloud types and
geoeffectiveness rate of halo CMEs as a function of the solar cycle.
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Working Group: WG1: Drivers of geomagnetic storms (CME and solar surface source region, CME/ICME relation)
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Working Group 2: Geomagnetic storm mechanisms (Plasmasphere, ring current, radiation belts)
Author(s): Mary K. Hudson
mary.hudson@dartmouth.edu
Dartmouth College
Working Group: WG2: Geomagnetic storm mechanisms (Plasmasphere, ring current, radiation belts)
Title: Relationship of the Van Allen Radiation Belts to Solar Wind Drivers
Abstract: The dynamic variability of outer zone electrons is tied to distinct types of heliospheric structure which vary with the solar cycle. The largest fluxes occur during the declining phase from solar maximum, when high speed streams and co-rotating interaction regions dominate the inner heliosphere, leading to recurrent storms tied to solar rotation. The most intense events are typically driven by high speed CMEs which prevail around solar maximum. Only about half of moderate storms, defined by intensity of the ring current, lead to an overall flux increase1, emphasizing the need to quantify loss as well as source processes; both increase when the magnetosphere is strongly driven. Three types of acceleration will be described: prompt and diffusive radial transport, which increases energy while conserving the first invariant, and local acceleration by waves which change the first invariant. The latter also produce pitch angle diffusion and loss, as does outward radial transport, especially when the magnetosphere is compressed. The effect of a dynamic magnetosphere boundary on both radiation belt electrons and solar energetic particle access and trapping will be described briefly in the context of MHD-test particle simulations driven by measured solar wind input.
1Reeves G. D., K. L. McAdams, R. H. W. Friedel, T. P. O'Brien, Acceleration and loss of relativistic electrons during geomagnetic storms, Geophys. Res. Lett., 30 (10), 1529, doi:10.1029/2002GL016513, 2003.
Author(s): K.E.J Huttunen - huttunen@ssl.berkeley.edu - Space Sciences Laboratory, University of California, Berkeley, USA
H.E.J Koskinen - Department of Physical Sciences, University of Helsinki, Finland
A. Karinen - Department of Physical Sciences, University of Oulu, Finland
K. Mursula - Department of Physical Sciences, University of Oulu, Finland
Working Group: WG2: Geomagnetic storm mechanisms (Plasmasphere, ring current, radiation belts)
Title: Asymmetry of magnetospheric storms during magnetic clouds and sheath regions
Abstract: We will use Dst, SYM-H and ASY-H indices to examine how the asymmetry in the low-latitude geomagnetic field evolves during sheath and magnetic cloud domains of interplanetary coronal mass ejections. Solar wind properties in sheath and magnetic cloud are highly different We found that sheath region storms are associated with larger morning/afternoon asymmetry than magnetic cloud storms. For sheath storms the station in the dusk sector contributed almost four times as much to Dst as the station in the dawn sector. Furthermore, the disturbance field is strongly variable during sheath storms. The results of this study suggest that for magnetic cloud storms the asymmetry arises mainly from ions drifting on open trajectories whereas in a case of a sheath driven storm the sudden intensifications of the substorm associated current systems add significantly to the asymmetry.
Author(s): Aleksandr Ukhorskiy
JHU/APL
ukhorskiy@jhuapl.edu
Working Group: WG2: Geomagnetic storm mechanisms (Plasmasphere, ring current, radiation belts)
Title: Mechanisms and Properties of Radial Transport in the Outer Electron Belt during Quite Time and Storms.
Abstract: This paper addresses mechanisms and properties of radial transport of relativistic electrons of the outer radiation belt. Electron motion is simulated numerically with the use of a test-particle approach in the guiding center approximation. This provides realistic description of electron transport free of any a priori assumption on its mathematical properties. The description of electromagnetic field in the model is based on the TS05 [Tsyganenko and Sitnov, 2005] storm-time magnetic field model with self-consistent inductive electric field and ULF waves driven by variability in solar wind parameters. It is shown that impulsive changes in solar wind dynamic pressure can result in rapid electron scattering across the drift shells due to induced ULF waves and large-scale inductive electric fields. This identifies dynamic pressure as one of the primary mechanisms of radial transport in the belt. Our calculations show that electron motion is inconsistent with radial diffusion, and hence a more detailed description is required for accurate predictions of electron fluxes in the belt. It is also shown that ring current enhancement during storm main phase can produce a substantial impact on electron motion. In particular, during large storms diamagnetic effect due to partial ring current sufficiently changes magnetic field structure in the inner magnetosphere leading to rapid magnetopause losses of radiation belt electrons.
Author(s): D. G. Sibeck david.g.sibeck@nasa.gov NASA/GSFC
B. H. Mauk barry.mauk@jhuapl.edu JHU/APL
J. M. Grebowsky Joseph.M.Grebowsky@nasa.gov NASA/GOV
N. Fox Nicola.Fox@jhuapl.edu JHU/APL
Working Group: WG2: Geomagnetic storm mechanisms (Plasmasphere, ring current, radiation belts)
Title: The Living With a Star Radiation Belt Storm Probes
Abstract: The goal of NASAs Living With a Star Radiation Belt Storm Probe mission is to understand, ideally to the point of predictability, how populations of relativistic electrons and ions in space form or change in response to the variable inputs of energy from the Sun. The investigations selected for this 2-spacecraft mission scheduled for launch in early 2012 address this task by making extensive observations of the plasma waves, thermal, ring current, and relativistic particle populations, and DC electric and magnetic fields within the Earths inner and outer radiation belts. We first describe the current mission concept within the scope of NASAs strategic plan and the Vision for Exploration, and then consider how its observations will be used to define and quantify the processes that accelerate, transport, and remove particles in the Earth's radiation belts.
Author(s): B. T. Kress - bkress@dartmouth.edu - Dartmouth College
M. K. Hudson - maryk@gaia.dartmouth.edu - Dartmouth College
M. D. Looper - Mark.D.Looper@aero.org - The Aerospace Corporation
J. Albert - jay.albert@hanscom.af.mil - Air Force Research Lab/VSBX
J. G. Lyon - lyon@tinman.dartmouth.edu - Dartmouth College
C. C. Goodrich - ccg@bu.edu - Boston University
Working Group: WG2: Geomagnetic storm mechanisms (Plasmasphere, ring current, radiation belts)
Title: MHD Test-Particle Simulations of >10 MeV Radiation Belt Formation During the 29 Oct 2003 "Halloween" Storm Sudden Commencement
Abstract: In comparison with the Earth's outer zone radiation belts, sudden large variations in inner zone energetic particle fluxes are rare, occurring only during very large geomagnetic storms, usually initiated by coronal mass ejection (CME) driven interplanetary shocks. The violent geomagnetic storms of Oct-Nov 2003 mark the beginning of strong activity characterizing the declining phase of solar cycle No. 23. During the 29 Oct 2003 storm, ultra-relativistic (>10 MeV) electrons were injected below L = 3 producing a stably trapped radiation belt population that persisted for months following this event [Looper et al., 2005]. We present results from a numerical study of shock-induced transport and heating of outer zone electrons in the 1-7 MeV range resulting in a newly formed 10-20 MeV belt; where test-particle trajectories are followed in time-dependent fields from an MHD magnetospheric model simulation of the 29 Oct 2003 Storm Sudden Commencement (SSC), driven by solar wind parameters measured at ACE. An SSC electric field pulse strongly peaked in the equatorial plane produces a new belt that is predominantly equatorially mirroring. The time scale for subsequent pitch angle diffusion of the belt, calculated using quasi-linear bounce-averaged diffusion coefficients, is in agreement with the observed delay in the appearance of peak fluxes at SAMPEX (in low Earth orbit). Solar energetic electrons (SEEs) present during the 29 Oct 2003 event provide a second possible source population for the new belt. MHD Test-Particle results using an SEE source population will also be presented.
Looper, M. D., J. B. Blake, and R. A. Mewaldt (2005), Response of the inner radiation belt to the violent Sun-Earth connection events of October-November 2003, Geophy. Res. Lett., 32, 3, L03S06, doi:10.1029/2004GL021502.
Author(s): Pontus C. Brandt - pontus.brandt@jhuapl.edu - The Johns Hopkins University Applied Physics Laboratory
S. Ohtani - shin.ohtani@jhuapl.edu - JHU/APL
A. Y. Ukhorskiy - JHU/APL
I. Dandouras - CESR, France
D. G. Mitchell - JHU/APL
Working Group: WG2: Geomagnetic storm mechanisms (Plasmasphere, ring current, radiation belts)
Title: Mechanisms and dynamics of the storm-time ring current
Abstract: We present our latest findings about the mechanisms for ring current
intensification and its dynamics during geomagnetic storms. We use
data from the IMAGE/HENA instrument and the RAPID and CODIF ion
spectrometers on board the Cluster satellites. Various supporting
data-model comparisons allow us to draw conclusions about the source
and energization mechanisms of the storm-time ring current. We
summarize by reviewing the role of the ring current in radiation belt
dynamics, and in magnetosphere-ionosphere-thermosphere coupling.
A geomagnetic storm is historically referred to as the intensification
of the ring current. The cause of the intensification is enhanced
magnetospheric convection and substorms. Convection is enhanced
through dayside reconnection during southward IMF, which transport
plasma from the lobes, to the plasmasheet and into the ring current
region where it is energized by betatron acceleration. Substorms
energize plasma further through the rapid dipolarization
reconfiguration of the magnetic field due to a disruption of the tail
current. Substorms energize in particular O+ ions that flow out from
the polar ionospheres during enhanced solar wind dynamics pressure
and/or southward IMF. During the course of the storm ionospheric O+
ions are transported to the plasma sheet mainly through centrifugal
acceleration where they achieve an energy of a keV or so. At the
substorm dipolarization the O+ ions are energized non-adiabatically
and can reach several 100's keV, whereas the protons behave more
adiabatically and experience a much more gradual energization.
The HENA instrument on board IMAGE images the hydrogen and oxygen ring
current in the ~10-200 keV (H) and ~50-300 keV (O) range. HENA has
provided global images of the ring current since May 2000 until Dec
2005. A constrained linear inversion technique is used to extract the
ion distribution in the ring current, which is validated by in-situ
satellite observations.
Cluster carries the RAPID instrument which provides mass resolved
energy spectra in the 20-400 keV for electrons, 40-1500 keV (4000 keV)
for hydrogen, and 10 keV/nuc - 1500 keV (4000 keV) for heavier
ions. The CIS/CODIF instrument on board Cluster resolves H+, He+ and
O+ ions in the 15 eV - 39 keV range.
Author(s): Mark B. Moldwin - mmoldwin@ucla.edu - UCLA
Endawoke Yizengaw - ekassie@igpp.ucla.edu - UCLA
Working Group: WG2: Geomagnetic storm mechanisms (Plasmasphere, ring current, radiation belts)
Title: Development of a 3D topside ionosphere-plasmasphere density model using LEO-Satellite GPS TEC tomography
Abstract: We are currently developing the capability to routinely process low-Earth orbit (LEO) Global Position System (GPS) Total Electron Content (TEC) data into a tomographic reconstruction model. This allows the estimation of electron number density as a function of latitude, longitude and altitude. LEO satellites equipped with dual-band GPS receivers (SAC-C, GPS/MET, CHAMP, GRACE, JASON1, FedSat and COSMIC) offer a breakthrough opportunity for remote sensing and monitoring of the topside ionosphere and plasmasphere. Tomographic imaging of LEO GPS TEC goes beyond two-dimensional TEC maps and allows the determination of topside ionosphere and plasmaspheric density altitude profiles, truly global coverage, and in combination with ground-based TEC tomography the ability to differentiate changes in F region density with topside ionospheric/plasmaspheric density variations. One product of this research will be an improved topside ionosphere/plasmasphere density model to help overcome the well-known deficiencies of the widely used IRI model at high altitudes. This talk will describe our plans and progress.
Author(s): Jerry Goldstein- jgoldstein@swri.edu- Southwest Research Institute
Bill R. Sandel- sandel@arizona.edu- University of Arizona
Working Group: WG2: Geomagnetic storm mechanisms (Plasmasphere, ring current, radiation belts)
Title: Response of the Plasmasphere During Storms and Substorms
Abstract: Global plasmasphere images, in conjunction with in situ satellite observations, have been essential in dramatically improving our ability to model the dynamic state of the plasmasphere, and the inner magnetospheric convection electric field. Quantitatively correct modeling of crucial electrodynamic coupling effects such as sub-auroral polarization stream (SAPS), overshielding, and neutral wind effects is either accomplished or underway. Plasmasphere data from both RPI and EUV have played a crucial role in improving our models of plasmaspheric mass density and ULF wave propagation. We show results of modeling the global plasmasphere for several case studies, achieving 0.2-0.7 RE accuracy in reproducing the stormtime plasmapause location when measurements are available, but indicating a need for better understanding of the recovery-phase plasmasphere.
Author(s): M. Wiltberger
Working Group: WG2: Geomagnetic storm mechanisms (Plasmasphere, ring current, radiation belts)
Title: Simulations of Geomagnetic Storms
Abstract: Numerous magnetic storm intervals have been simulated with the
Lyon-Fedder-Mobbary global magnetospheric simulation. As part of the
presentation I will provide a complete catalog of simulation results which are
available for analysis with the CISM-DX visualization and analysis package. I
will also provide a brief summary of several of the more geoeffective storms and
compare the response in the simulated magnetosphere-ionosphere system,
including the results from coupled radiation belt intervals where available.
Author(s): Athina Varotsou - athina@lanl.gov - Los Alamos National Laboratory
Reiner H. Friedel - friedel@lanl.gov - Los Alamos National Laboratory
Geoffrey D. Reeves - reeves@lanl.gov - Los Alamos National Laboratory
Tom Cayton - tcayton@lanl.gov - Los Alamos National Laboratory
Sebastien Bourdarie - sebastien.bourdarie@onera.fr - ONERA/DESP
Working Group: WG2: Geomagnetic storm mechanisms (Plasmasphere, ring current, radiation belts)
Title: The effect of CME driven storms on the MeV electron outer radiation belt
Abstract: We have analyzed energetic electron data from the ns41 GPS satellite during the period 2001-2006 to investigate relativistic electron rise times in the Earths outer radiation belt. The GPS orbit crosses the heart of the radiation belts, covering the L>4 region and measuring equatorial fluxes at L~4.2 for electron energies E > 100 keV.
We have studied 50 storms during this period and found that MeV electron rise times vary from less than a day to more than 6 days. We have investigated the solar wind conditions for these events and found that CME driven storms can have very different effects on these particles. Very fast rise times (< 1 day) are all related to a CME driver. However,CMEs can also drive storms producing very slow rise of energetic electron fluxes in the recovery phase of a storm.
Here we present the CME driven events for which we compare equatorial electron flux rise times at GPS orbit with those at geosynchronous orbit using LANL data. We also study storms that produce fast increase of MeV fluxes at L~4 and storms that produce slow increase of those fluxes. For these storms we investigate the solar wind and magnetospheric conditions
in an effort to identify the mechanisms responsible for these observations.
Author(s): V.A. Pilipenko, pilipenk@augsburg.edu, Augsburg College MN
M.J. Engebretson, engebret@augsburg.edu, Augsburg College MN
N.V. Romanova, mosc@mail.ru, Moscow Institute of the Physics of the Earth
Working Group: WG2: Geomagnetic storm mechanisms (Plasmasphere, ring current, radiation belts)
Title: ULF Wave Power Indices for the Space Weather Applications
Abstract: The solar wind-magnetosphere interaction has a turbulent character, which is not accounted for by commonly used geomagnetic indices and OMNI parameters. To quantify the level of low-frequency turbulence/variability of the geomagnetic field, IMF, and solar wind plasma, we have introduced ULF wave power indices. These simple hourly indices are based on the band-integrated spectral power in the range 2-7 mHz or wavelet power with time scales ~10-100 min. The ground geomagnetic wave index has been produced from the data of global magnetometer arrays in the northern hemisphere. The interplanetary and geostationary wave indices have been calculated using magnetometer and plasma data from interplanetary and geosynchronous satellites. These indices have turned out to be useful for statistical analysis of various space weather problems. For example, the enhancements of relativistic electrons at the geosynchronous orbit were not directly related to the intensity of magnetic storms, but they correlated well with intervals of elevated time-integrated ULF wave index. This comparison confirmed the importance of magnetospheric ULF turbulence in energizing electrons up to relativistic energies. The interplanetary ULF index has revealed statistically the role of the interplanetary turbulence in driving the magnetosphere by the IMF/solar wind. The application of this index to the analysis of conditions in the solar wind before magnetic storm onsets has shown that a weak irregular increase of the solar wind density is observed on average 2 days prior to storm commencement. In addition to the presented problems, a wide range of space physics and geophysics studies will benefit from the introduction of the ULF wave indices. The ULF index database is freely available via anonymous FTP for all interested researchers for further validation and statistical studies.
Author(s): George V. Khazanov, george.v.khazanov@nasa.gov, NASA Marshall Space Flight Center
Dennis L. Gallagher, dennis.l.gallagher@nasa.gov, NASA Marshall Space Flight Center, (presentor)
Konstantin Gamayunov, konstantin.gamayunov-1@nasa.gov, NASA Marshall Space Flight Center
Working Group: WG2: Geomagnetic storm mechanisms (Plasmasphere, ring current, radiation belts)
Title: Effect of EMIC Wave Normal Angle Distribution on Relativistic Electron Scattering Based on the Newly Developed Self-Consistent RC/EMIC Waves Model by Khazanov et al. [2006]
Abstract: It is well known that the effects of EMIC waves on RC ion and RB electron dynamics strongly depend on such particle/wave characteristics as the phase-space distribution function, frequency, wave-normal angle, wave energy, and the form of wave spectral energy density. Therefore, realistic characteristics of EMIC waves should be properly determined by modeling the RC-EMIC wave evolution self-consistently. Such a self-consistent model progressively has been developing by Khazanov et al. [2002-2006]. It solves a system of two coupled kinetic equations: one equation describes the RC ion dynamics and another equation describes the energy density evolution of EMIC waves. Using this model, we present the effectiveness of relativistic electron scattering and compare our results with previous work in this area of research
Author(s): Ramona Kessel - mona.kessel@nasa.gov - NASA HQ
Working Group: WG2: Geomagnetic storm mechanisms (Plasmasphere, ring current, radiation belts)
Title: Solar wind excitation of Pc5 fluctuations in the magnetosphere
Abstract: The primary purpose of this paper is to show the strong link between solar wind compressional fluctuations in the 0.5-8 mHz frequency range and Pc5 fluctuations in the magnetosphere near the magnetopause, at geostationary orbit, over the poles, and on the ground. We focus on a time interval in March and April 2002 when there was a favorable alignment of satellites combined with ICMEs and high speed streams (HSS). Using four examples and a statistical survey we show that the amplitude and power of magnetospheric and ground fluctuations depends primarily on the amplitude and power of solar wind dynamic pressure fluctuations; magnetospheric Pc5 fluctuations exist regardless of IMF orientation and for a wide range of speeds and dynamic pressures. The driving and response frequency of the fluctuations primarily is in the range 0.5 - 4 mHz. The most striking magnetospheric response occurs after an interval of calm solar wind, and when the speed, dynamic pressure, and dynamic pressure fluctuations all increase at approximately the same time. This combination frequently occurs near the leading edge of HSSs and ICMEs. We show evidence of oscillating Poynting Flux at the magnetopause determined using Geotail data that both excites a FLR observed on the ground and propagates evanescently inward at least to geostationary orbit. The Pc5 excitation is stronger on the dayside than on the flanks or on the nightside suggesting a limited global response for this time interval at spring equinox.
Author(s): R. E. Lopez, relopez@fit.edu
S. Hernandez, hernands@fit.edu
H. Rassoul, rassoul@fit.edu
M. Wiltberger, wiltbemj@hao.ucar.edu
Working Group: WG2: Geomagnetic storm mechanisms (Plasmasphere, ring current, radiation belts)
Title: Solar Wind-Geospace Coupling: Voltage Driven versus Current Driven
Abstract: During weak to moderate driving of the magnetosphere by the solar wind electric field, the transpolar potential responds essentially in a linear fashion to increases in the solar wind electric field. On the other hand, during strong driving the transpolar potential saturates and becomes insensitive to further increases in the solar wind electric field. Using a global 3-D MHD code, we have simulated the response of the transpolar potential to a range of driving, from weak through strong, to investigate this behavior. We find that during normal driving the driving takes the form of a voltage generator driven by the solar wind electric field. For strong driving the dominant force exterted on the solar wind is the JxB force at the bow shock, and the driving is dominated by the current closure of the bow shock current. Hence the driving is in the form of a current generator. This picture explains the dependence of the polar cap potential on solar wind number density and ionospheric conductivity during both weak and strong driving.
Author(s): Yuri Shprits- yshprits@atmos.ucla.edu- UCLA
Dmitri Kondrashov- dkondras@atmos.ucla.edu- UCLA
Yue Chen- cheny@lanl.gov- LANL
Michael Ghil- ghil@atmos.ucla.edu - UCLA
Richard Thorne- rmt@atmos.ucla.edu-UCLA
Reiner Friedel- rfriedel@lanl.gov- LANL
Geoff Reeves -reeves@lanl.gov -LANL
Working Group: WG2: Geomagnetic storm mechanisms (Plasmasphere, ring current, radiation belts)
Title: Data assimilation and parameter estimation in the radiation belts
Abstract: Data assimilation models combine measurements and first
principles models to provide the most realistic possible picture of the
present condition or updates and corrections to the propagation of
conditions forward in time. The Kalman filter incorporates measurements
and physics based model according to underlined error structure of the
model and data. It provides a powerful framework to estimate the state of
the system in a way that minimizes mean of the squared errors. In
particular for applications in the radiation belts, data at different
L-shells can be combined with the model and will affect the forecasted
fluxes at all radial locations. We present analysis of the phase space
density measured on CRRES using Kalman filter and the radial diffusion
model. The results indicate the presence of the local acceleration source
at L~5.5. We also present results of the parameter estimation using
extended Kalman filtering. We also present the results of the 3D simulations
and discuss future applications of data assimilation.
Working Group 3: Ionospheric Storms
Author(s): Paul A. Bernhardt - Plasma Physics Division, Naval Research Laboratory
Working Group: WG3: Ionospheric Storms
Title: Thirteen Years of Ionospheric TEC Data from Low Earth Orbit Satellites - RADCAL, DORIS and COSMIC
Abstract: Ground based total electron content (TEC) receivers at 20 locations ranging from McMurdo Antarctica, to the near the equator at Ascension Island and Kwajalein to the north high latitudes at Tule, Greenland and Poker Flat, Alaska have been recorded ionospheric data from the RADCAL, GFO, and DMSP/F15 satellites using the RADCAL network of receivers. Similarly, over 56 ground beacons have provided TEC data to the DORIS receivers on SPOT (1-5), TOPEX, ENVISAT, and JASON from 1990 to the present. Finally, the six FORMOSAT3/COSMIC satellites launched in April 2006 are using the tri-band-beacon (TBB/CERTO) instrument to give TEC data to receivers located in Taiwan, Alaska, Continental USA, Puerto Rico, Peru, and others. Samples of ionospheric storm effects on these data from a wide range of latitudes and local times will be presented. Other users may access this largely untapped database for future studies.
Author(s): Bruce Tsurutani, Jet Propulsion Laboratory, Calif. Inst. Tech.
Anthony Mannucci, Jet Propulsion Laboratory, Calif. Inst. Tech
Fernando Guarnieri, Universidade do Vale do Paraiso, Brazil
Working Group: WG3: Ionospheric Storms
Title: Comments on The Extreme October 28, 29 and Nov 2, 2003 Solar Flares (and Bastille Day, 2000 Flare) and Resultant Ionospheric Effects
Abstract: We show the Halloween 2003 solar flare intensity-time profiles in x-rays and EUV wavelengths and the resultant ionospheric effects measured by ground GPS receivers. Several important points will be discussed: 1. the baseline of solar irradiation is often overlooked and should be compensated for, 2. the spectra of solar flares may be highly variable and it is presently not possible to determine this throughout the duration of the flare, and 3. one of the best ways to determine the spectra might be through tomographic analyses of ionospheric data.
Author(s): A. J. Mannucci - tony.mannucci@jpl.nasa.gov - Jet Propulsion Laboratory, California Institute of Technology
G. Crowley - gcrowley@astraspace.net - ASTRA
B. T. Tsurutani - Bruce.Tsurutani@jpl.nasa.gov - Jet Propulsion Laboratory, California Institute of Technology
O. Verkhoglyadova - olgav@ucr.edu - University of California, Riverside
Working Group: WG3: Ionospheric storms
Title: Analyzing The Dayside Ionospheric Response To Intense Geomagnetic Storms To Reveal The Geoeffective Physical Processes At Work
Abstract: Dramatic large scale increases in ionospheric plasma content are observed for daytime local times during intense geomagnetic storms. Ionospheric increases during the main phase of geomagnetic storms were identified many years ago and categorized as the "positive phase" ionospheric response. Recent work using satellite data and distributed ground-based measurements has provided important new information on the positive phase storm, revealing considerably more detail on plasma spatial structure and temporal evolution. The importance of electric fields penetrating to low latitudes on the dayside has received a great deal of attention recently, and has led to revised theoretical and modeling constructs to account for the observations. The importance of electric fields that originate in the solar wind and magnetosphere suggests that measurements from these upstream regions are important for understanding the "downstream" ionospheric response. We will present ground and space-based Global Positioning System (GPS) electron content data for focus storms and analyze the data in light of the upstream conditions. Modeling studies of the storm-time ionospheric behavior will be shown, using the ASPEN-TIMEGCM fully-coupled thermosphere-ionosphere (T-I) model with low-latitude electrodynamics. The ASPEN-TIMEGCM model contains storm-time effects such as winds and the resulting dynamo electric fields, but penetration E-fields are not currently included. The model runs are driven by carefully reconstructed high latitude drivers based in part on the AMIE high latitude electrodynamics model. By comparing between different storms and analyzing the time history of ionospheric behavior within a storm, we will reveal those aspects of the ionospheric response that are plausibly explained by the physics of the coupled T-I model. We will highlight those aspects of the response where the models are inaccurate and identify outstanding science questions in need of further research.
Author(s): Sunanda Basu - sbasu@bu.edu - Boston University
Santimay Basu - santimay@aol.com - Air Force Research Laboratory
J. Makela - University of Illinois
P. Doherty - Boston College
F.J. Rich - Air Force Research Laboratory
Working Group: WG3: Ionospheric storms
Title: The Impact of Large Nighttime ionospheric Flows on Mid-Latitude Plasma Structuring During Intense Magnetic Storms
Abstract: During intense magnetic storms, two broad classes of ionospheric plasma structures are encountered, one associated with the well-documented Storm Enhanced Density (SED) and total electron content (TEC) plumes and the other, observed in the late evening hours associated with intense auroral and sub-auroral flows within a very wide ionospheric signature of the plasmapause. The convecting SEDs, observed primarily in the afternoon sector, introduce steep plasma density gradients in the ionosphere and are associated with intense plasma density irregularities. Surprisingly, the large velocities observed in the plasmapause region, in an environment of much reduced plasma densities covering much of the mid-latitude region in the North American sector, seem to create equally large impacts on phase sensitive systems such as the ubiquitous GPS network. Thus, in addition to tracking SEDs, a far better understanding of the magnetosphere-ionosphere coupling responsible for the generation and maintenance of intense sub-auroral and auroral nighttime flows is necessary to provide reliability to space weather networks.
Author(s): Chaosong Huang - cshuang@haystack.mit.edu - Massachusetts Institute of Technology, Haystack Observatory
John Foster - jcf@haystack.mit.edu - Massachusetts Institute of Technology, Haystack Observatory
Working Group: WG3: Ionospheric storms
Title: Correlation between the subauroral polarization stream (SAPS) and Dst index during magnetic superstorms
Abstract: The subauroral polarization stream (SAPS) is the poleward electric field in the region equatorward of the auroral electron precipitation boundary in the dusk-mignight sector. The westward plasma flow driven by the SAPS electric field is significantly enhanced during magnetic storms. However, the relationship of SAPS characteristics to the strength of magnetic storms is not well known. Using DMSP satellite measurements, we have examined the the location (magnetic latitude) of the SAPS channel during four magnetic superstorms with minimum Dst velues between -270 and -410 nT. We find that the latitude of center of the SAPS channel at 21 MLT varies directly with the magnitude of the Dst index. For example, in one storm case, SAPS moved from ~60 degree magnetic latitude at the storm sudden commencement with Dst of near zero to ~39 degrees at the end of the storm main phase with Dst of -410 nT. We have identified more than 300 locations of SAPS and corresponding Dst values during the four recent storms. The most important finding is that the SAPS latitude is linearly correlated with Dst, and an empirical formula is derived for the first time. We compared the empirical formula with observations and found a very good agreement. The SAPS corresponds to the inner boundary of the plasma sheet, and the Dst index represents the strength of the ring current. The linear correlation between SAPS and Dst found in our study will provide new insight into the development of the storm-time ring current and magnetospheric-ionospheric coupling.
Author(s): John C. Foster - jfoster@haystack.mit.edu - MIT Haystack Observatory
Working Group: WG3: Ionospheric storms
Title: Magnetic Conjugacy of Stormtime Ionospheric Disturbances
Abstract: Ground-based and low-altitude observations provide a wide-ranging point of view on the role played by ionosphere-magnetosphere-heliosphere coupling in shaping mid-latitude ionospheric dynamics and disturbances. Modern distributed-instrument arrays contribute a multi-dimensional, time-dependent point of view to the detailed observations made from single-site Class-I facilities. Such a combination provides the spatial breadth and resolution needed to identify and to begin to understand the structures and processes which characterize the disturbed mid, low, and auroral-latitude ionosphere. Low-altitude satellite observations help to image and characterize the ionospheric responses and the magnetospheric and heliospheric drivers which produce them. The evolving picture reveals a closely-coupled system in which localized, medium, and small-scale features must be addressed and understood in light of the workings of the system as a whole.
In the early phases of a magnetosphere-heliosphere disturbance, the low and mid-latitude ionosphere are greatly perturbed. Prompt penetration electric fields uplift, perturb, and redistribute the low-latitude ionosphere plasma - sometimes in ways which are difficult to interpret and understand. Plasma depletions and enhancements form inside the plasmasphere boundary layer (PBL) in a complex interplay of dynamo, penetration, and polarization electric fields coupled with varying solar production, hemispheric, and magnetic field asymmetries. In the PBL, the sub-auroral polarization stream electric field (SAPS) forms as pressure gradients at the inner edge of the magnetospheric ring current drive Region-2 field-aligned currents into the evening-sector ionosphere. Large poleward-directed electric fields at ionospheric heights are set up to drive closure currents across the low-conductivity region equatorward of the auroral electron precipitation. The inward extent of the SAPS overlaps and erodes the outer plasmasphere and mid-latitude ionosphere, drawing out the extended plumes of storm enhanced density (SED) which span the dusk sector, transporting plasmaspheric material to the noontime cusp. Recent observations indicate that many of these mid-latitude ionospheric disturbance effects exhibit degrees of magnetic conjugacy and simultaneity which implicate the workings of electric fields in creating the observed perturbations.
This presentation will emphasize the combined use of satellite and ground-based observations to investigate the degree of magnetic conjugacy associated with specific features of the stormtime ionospheric perturbation. It is found that features related to the workings of the SAPS electric field - associated with magnetospheric drivers in the stormtime ring current - exhibit clear, striking conjugacy characteristics. TEC enhancements on inner-magnetospheric field lines exhibit localized and longitude-dependent features which are not strictly magnetically conjugate.
Author(s): J. W. Meriwether meriwej@clemson.edu Clemson University
M. Faivre, faivre@clemson.edu, Clemson University
Working Group: WG3: Ionospheric storms
Title: Observations of thermospheric winds during active geomagnetic conditions
Abstract: Fabry-Perot observations of geomagnetic storms near the magnetic equator have been obtained at Arequipa, Peru, for five different cases over a period of 3 to 5 nights. These case study results were obtained between 1997 and 2001. These results are compared with quiet-time averaged windsand temperatures and with the NCAR model predictions of thermospheric winds. Increases of the thermospheric temperatures during the peak period of magnetic activity relative to the temperature observed prior to the storm onset were found to be 100 to 200 K. The zonal component of the thermospheric wind showed no consistent behavior between one storm to the next: in two cases, there was a decrease of the eastward flow and in the remaining cases there was found to be an increase in the eastward flow. It appears that no generalized statement about the expected results of the magnetic storm activity upon the equatorial thermosphere can be projected on the basis of these specific cases.
Author(s): John Retterer - john.retterer@hanscom.af.mil - AFRL/VSBXP
Odile de la Beaujardiere - odile.delabeaujardiere@hanscom.af.mil - AFRL/VSBXP
Working Group: WG3: Ionospheric storms
Title: The Impact of the October 2003 Storms on Equatorial Radio Scintillation
Abstract: Radio scintillation caused by plasma turbulence in the low-latitude ionosphere is controlled by a number of processes that are greatly affected when the effects of solar storms such as those of October 2003 reach the earth. We use data from ionosondes, GPS receivers, scintillation monitors, and data from the DMSP, ACE and other satellites to investigate the effect on radio scintillation caused by the October storms.
These data are interpreted with the aid of a scintillation forecast system being developed in preparation for the launch of the Communication and Navigation Outage Forecast System (C/NOFS) satellite. This system uses data for plasma drifts and other parameters to forecast the state of the ambient ionosphere, examine it for regions of plasma instability, and then perform local plasma turbulence calculations to estimate the strength of radio scintillation. Results will be presented for the history of the ionospheric plasma inferred from equatorial ionosondes and the strength of scintillation measured by adjacent satellite receivers, and these results will analyzed in light of the electrodynamics and aeronomical physics of the low-latitude plasma response.
Author(s): Thomas Immel - immel@ssl.berkeley.edu - U. Cal. Berkeley
Geoff Crowley - gcrowley@astraspace.net - Astraspace
Working Group: WG3: Ionospheric storms
Title: Large hemispheric differences in composition effects during the October-November 2003 geomagnetic storms.
Abstract: During the powerful geomagnetic storms that occurred after major CME events on the sun in October and November of 2003, the thermosphere exhibited global scale composition changes. These changes were observed by the IMAGE-FUV and TIMED-GUVI satellites, which were able to identify regions of both greatly reduced and enhanced column densities of atomic oxygen relative to molecular nitrogen. The great hemispheric assymetry in the observations is compared to TIMEGCM model runs for the same periods. Though providing overall agreement, some discrepancies imply possibly that, 1) the TIMEGCM does not sufficiently account for seasonal changes in the baseline north-south distribution of O and N2, or that 2) larger differences in the north and south high-latitude forcing exist in nature than are currently being used in the model. We investigate the remaining differences between the model runs and FUV observations for better understanding of the N-S asymmetry in composition effects.
Author(s): Robert W. Spiro - spiro@rice.edu - Rice University
S. Sazykin - sazykin@rice.edu - Rice University
R. A. Wolf - rawolf@rice.edu - Rice University
Working Group: WG3: Ionospheric storms
Title: RCM Modeling of Stormtime Sub-Auroral Electric Fields
Abstract: We use the Rice Convection Model (RCM) to examine prompt-penetration storm-time sub-auroral electric fields. Region 2 field-aligned currents associated with plasma pressure gradients in the inner magnetosphere flow between the magnetosphere and ionosphere, creating a dusk-dawn directed electric field that acts to shield the inner magnetosphere and sub-auroral ionosphere from some of the effects of the large-scale dawn-dusk convection electric field. We simulate selected storms using the RCM to investigate the efficiency of this shielding process during storm periods.
Author(s): N. Maruyama (naomi.maruyama@noaa.gov), T. Fuller-Rowell, M. Codrescu, D. Anderson - CIRES, Univ. of Colorado, and SEC, NOAA
A.Richmond, A. Maute - HAO, NCAR
S. Sazykin, F. Toffoletto, R. Spiro, R. Wolf - Physics and Astronomy Department, Rice University
G. Millward - Atmospheric Physics Laboratory
Working Group: WG3: Ionospheric storms
Title: Modeling of the Storm-Time Ionospheric Electric Fields
Abstract: Modeling of the storm-time ionospheric electric fields requires a
description of the two disturbance mechanisms: prompt penetration and
disturbance dynamo. In order to investigate the storm-time interaction
between the two sources and the role of the electrodynamics in
restructuring the ionosphere, plasmasphere and thermosphere, we have
combined the Rice Convection Model (RCM), used to calculate inner
magnetospheric electric fields, and the Coupled Thermosphere Ionosphere
Plasmasphere electrodynamics (CTIPe) model, driven, in part, by
RCM-computed electric fields. As compared to the historical picture of
prompt penetration, our model results suggest the possibility that
penetration effects can have a longer lifetime when the IMF Bz is large
and negative as a consequence of the ineffective shielding resulting
from the magnetospheric reconfiguration. Furthermore, our simulations
indicate that the arrival of the disturbance dynamo effect in the low
latitude ionosphere can possibly be faster than previously believed, as
the disturbance dynamo is modified by the changes in the conductivity
and neutral wind initiated by the penetration effect. Comparison of the
results from the combined models with observations under a variety of
conditions demonstrates that our models are capable of reproducing many
of the measurements in the ionosphere. In order to address the feedback
of the storm-time conductivity and neutral wind on the inner
magnetospheric electric field, the CTIPe conductivity and neutral wind
are imposed on the RCM. With an ultimate purpose of developing a
self-consistent first-principles model, we have initiated coupling
between CTIPe and the RCM, some preliminary results from this coupled
model will be presented.
Working Group 4: Prediction of geomagnetic storms
Author(s): Robert L. McPherron
rmcpherron@igpp.ucla.edu
Institute of Geophysics and Planetary Physics,
Working Group: WG4: Prediction of geomagnetic storms
Title: A Comparison of Recurrent Magnetic Storms in Solar Cycles 22 and 23
Abstract: Corotating interaction regions (CIRs) produce recurrent magnetic storms during the declining phase of the solar cycle. These storms are organized in time by the arrival of the stream interface at the center of the CIR. The Wang-Sheeley-Arge model enables forecasters to predict relatively well the arrival of the stream interface at the Earth. With this information air mass climatology can be used to make probabilistic forecasts of the expected level of activity as measured by a variety of indices. For example, the day before arrival of the interface will be extremely quiet while the passage of the interface causes a maximum in activity. We have developed climatology of a variety of indices for all stream interfaces in the declining phase of solar cycle 22 (1994-1996) and compare this to the climatology of cycle 23 (2004-2006). We find in cycle 23 that virtually all indicators are only half as disturbed as they were in cycle 22. We considered the possibility that this is a result of the Hale cycle with an even-odd cycle difference in activity. However, when we separate the data for each cycle into geoeffective and ineffective interplanetary magnetic field (IMF) sectors we find that for each type of sector there is little difference in activity between cycles. The apparent discrepancy between our initial and final results is explained by a different ratio of the number of effective and ineffective sectors in the two cycles. In this work we define a geoeffective sector as an equinoctial CIR in which the IMF obeys the Russell-McPherron rule Spring To Fall Away during the high speed stream. The Russell-McPherron effect projects the spiral IMF in the ecliptic plane onto the GSM axis biasing it southward. Alfven waves in the stream rotate the IMF further southward producing long intervals of southward IMF and short intervals of northward field. The high speed of the solar wind multiplies the southward component producing a moderate electric field that drives magnetic reconnection and produces activity. The Wang-Sheeley-Arge model is also able to predict the IMF polarity so the combination of predicted speed, predicted polarity, and climatology enables more accurate forecasts.
Author(s): R. E. Lopez - relopez@fit.edu - Department of Physics and Space Sciences, Florida Institute of Technology
S. Hernandez - Department of Physics and Space Sciences, Florida Institute of Technology
M. Wiltberger - NCAR/HAO
C.-L. Huang - Department of Astronomy, Boston University
E. L. Kepko - Department of Astronomy, Boston University
H. Spence - Department of Astronomy, Boston University
C.C. Goodrich - Department of Astronomy, Boston University
J. G. Lyon - Department of Physics and Astronomy, Dartmouth College
Working Group: WG4: Prediction of geomagnetic storms
Title: Predicting Magnetopause Crossings at Geosynchronous Orbit During the Halloween Storms
Abstract: In late October and early November of 2003 the Sun unleashed a powerful series of events known as the Halloween storms. The coronal mass ejections launched by the Sun produced several severe compressions of the magnetosphere that moved the magnetopause inside of geosynchronous orbit. Such events are of interest to satellite operators, and the ability to predict magnetopause crossings along a given orbit is an important space weather capability. In this paper we compare geosynchronous observations of magnetopause crossings during the Halloween storms to crossings determined from the Lyon-Fedder-Mobarry global magnetohydrodynamic simulation of the magnetosphere, as well to predictions of several empirical models of the magnetopause position. We calculate basic statistical information about the predictions as well as several standard skill scores. We find that the current Lyon-Fedder-Mobarry simulation of the storm provides a slightly better prediction of the magnetopause position than the empirical models we examined for the extreme conditions present in this study. While this is not surprising, given that conditions during the Halloween storms were well outside the parameter space of the empirical models, it does point out the need for physics-based models that can predict the effects of the most extreme events that are of significant interest to users of space weather forecasts.
Author(s): M. Wiltberger
Working Group: WG4: Prediction of geomagnetic storms
Title: Metrics and Space Weather
Abstract: Forecast Verification is a well developed field of study in meteorological
weather forecasting that attempts to improve models by quantitatively studying
how well models are improving overtime, where there deficiencies exists, and
compare models against each other. The 'goodness' of a forecast depends upon
its consistency, quality, and value. The quality of forecast is assessed by a
series of statistical tests including bias, accuracy, skill, resolution. In
this presentation I will discuss how these factors are determined and show
applications to phenomena in space weather including magnetometer measurements
and polar potential.
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