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Magnetic Field Observations of Partial Ring Current during Storm Recovery PhaseWe present results of an extensive survey of the magnetic field observations in the inner magnetosphere using 30 years of magnetospheric magnetic field data from Polar, Cluster, ISEE, and AMPTE/CCE missions. The purpose of this study is to understand the magnetic field evolution during the recovery phase of geomagnetic storms, and its implication to the ring current recovery and loss mechanisms of ring current particles. It is now commonly believed that a strong partial ring current is formed during the storm main phase due to the enhanced earthward convection of energetic ions from nightside plasma sheet. But the presence of a strong partial ring current throughout the recovery phase remains controversial. The magnetic field generated by the ring current inflates the inner magnetosphere and causes magnetic field depressions in the equatorial magnetosphere. During the storm recovery phase, we find that the distribution of the equatorial magnetic field depression exhibits similar local time dependence as the ring current distribution obtained from the combined dataset in the earlier study. It shows that a strong partial ring current is a permanent feature throughout the recovery phase. In the early recovery phase, the partial ring current peaks near the dusk terminator as indicated by the peak of the magnetic field depression. As the recovery phase progresses, the partial ring current decays most quickly near the dusk and results in a dusk-to-midnight moving of the peak of the partial ring current. Thus the loss mechanisms work most effectively near the dusk. The magnetic field depression increases the gyroradius of ring current protons to a scale greater or comparable to the thickness of the magnetopause, which increases the chance of ion drift loss near the dusk magnetopause at larger L-shell (L greater than 5). But the drift loss mechanism alone cannot explain the loss of ring current ions especially in the smaller L-shell (L less than 5). The precipitation loss due to wave-particle interaction is most likely the dominant loss mechanism in the small L-shell as it works most effectively at the same local time.
Document ID
20080031164
Acquisition Source
Goddard Space Flight Center
Document Type
Conference Paper
Authors
Le, G.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Russell, C. T.
(California Univ. Los Angeles, CA, United States)
Slavin, J. A.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Lucek, E. A.
(Imperial Coll. of London London, United Kingdom)
Date Acquired
August 24, 2013
Publication Date
March 9, 2008
Subject Category
Geophysics
Meeting Information
Meeting: 15th Cluster Workshop
Location: Tenerife, Canary Islands
Country: Spain
Start Date: March 11, 2008
End Date: March 14, 2008
Sponsors: European Space Agency
Distribution Limits
Public
Copyright
Other

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