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Cusp and LLBL as Sources of the Isolated Dayside Auroral Feature During Northward IMFAn intense dayside proton aurora was observed by Imager for Magnetopause-to- Aurora Global Exploration Far Ultra-Violet imager (IMAGE FUV) for an extensive period of northward interplanetary magnetic field (IMF) on 17 and 18 September 2000. This aurora partially coincided with the auroral oval and intruded farther poleward into the polar cap, and it showed longitudinal motions in response to IMF By variation. Intense magnetosheath-like electron and ion precipitations have been simultaneously detected by Defense Meteorological Satellite Program (DMSP) above the poleward portion of the high-latitude dayside aurora. They resemble the typical plasmas observed in the low-altitude cusp. However, less intense electrons and more energetic ions were detected over the equatonvard part of the aurora. These plasmas are closer to the low-latitude boundary layer (LLBL) plasmas. Under strongly northward IMF, global ionospheric convection derived from Super Dual Auroral Radar Network (SuperDARN) radar measurements showed a four-cell pattern with sunward convection in the middle of the dayside polar cap and the dayside aurora corresponded to two different convection cells. This result further supports two source regions for the aurora. The cusp proton aurora is on open magnetic field lines convecting sunward whereas the LLBL proton aurora is on closed field lines convecting antisunward. These IMAGE, DMSP, and SuperDARN observations reveal the structure and dynamics of the aurora and provide strong evidence for magnetic merging occurring at the high-latitude magnetopause poleward from the cusp. This merging process was very likely quasi-stationary.
Document ID
20050163121
Acquisition Source
Marshall Space Flight Center
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Chang, S.-W.
(NASA Marshall Space Flight Center Huntsville, AL, United States)
Gallagher, D. L.
(NASA Marshall Space Flight Center Huntsville, AL, United States)
Spann, J. F.
(NASA Marshall Space Flight Center Huntsville, AL, United States)
Mende, S. B.
(California Univ. Berkeley, CA, United States)
Greenwald, R. A.
(Johns Hopkins Univ. Laurel, MD, United States)
Newell, P. T.
(Johns Hopkins Univ. Laurel, MD, United States)
Date Acquired
August 23, 2013
Publication Date
December 27, 2004
Publication Information
Publication: Journal of Geophysical Research
Volume: 109
ISSN: 0148-0227
Subject Category
Geophysics
Funding Number(s)
CONTRACT_GRANT: NSF ATM-02-42427
CONTRACT_GRANT: NCC8-200
CONTRACT_GRANT: NAG5-12008
Distribution Limits
Public
Copyright
Public Use Permitted.
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