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Simulation and Twins Observations of the 22 July 2009 StormTWINS is the first mission to perform stereo imaging of the Earth's ring current. The magnetic storm on 22 July 2009 was at the time the largest storm observed since TWINS began routine stereo imaging in June 2008. On 22 July 2009, the Dst dropped to nearly .80 nT at 0700 and 1000 UT. During the main phase, and at the peak of the storm, TWINS 1 and 2 were near apogee and moving between predawn and postdawn local time. The energetic neutral atom (ENA) imagers on the two spacecraft captured the storm intensification and the formation of the partial ring current. The peak of the high-altitude ENA emissions was seen in the midnight-to-dawn local time sector. The development of this storm has been simulated using the comprehensive ring current model (CRCM) to understand and interpret the observed signatures. We perform CRCM runs with constant and time-varying magnetic field. The model calculations are validated by comparing the simulated ENA and ion flux intensities with TWINS ENA images and in situ ion data from a THEMIS satellite. Simulation with a static magnetic field produces a strong shielding electric field that skews the ion drift trajectories toward dawn. The model's corresponding peak ENA emissions are always more eastward than those in the observed TWINS images. On the other hand, the simulation with a dynamic magnetic field gives better spatial agreement with both ENA and in situ particle data, suggesting that temporal variations of the geomagnetic field exert a significant influence upon global ring current ion dynamics.
Document ID
20110010214
Acquisition Source
Goddard Space Flight Center
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Fok, M.-C.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Buzulukova, N.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Chen, S.-H.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Valek, P. W.
(Southwest Research Inst. San Antonio, TX, United States)
Goldstein, J.
(Southwest Research Inst. San Antonio, TX, United States)
McComas, D. J.
(Southwest Research Inst. San Antonio, TX, United States)
Date Acquired
August 25, 2013
Publication Date
January 1, 2011
Publication Information
Publication: Journal of Geophysical Research
Publisher: American Geophysical Union
Volume: 115
ISSN: 0148-0227
Subject Category
Geophysics
Funding Number(s)
WBS: WBS 955518.02.01.02.57
Distribution Limits
Public
Copyright
Other

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