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JOURNAL OF GEOPHYSICAL RESEARCH,
VOL. 108, NO. A4,
1151,
doi:10.1029/2002JA009544,
2003
Delivery of cold, dense plasma sheet material into the near-Earth region
M. F. Thomsen
Space and Atmospheric Sciences,
Los Alamos National Laboratory,
Los Alamos,
New Mexico,
USA
J. E. Borovsky
Space and Atmospheric Sciences,
Los Alamos National Laboratory,
Los Alamos,
New Mexico,
USA
R. M. Skoug
Space and Atmospheric Sciences,
Los Alamos National Laboratory,
Los Alamos,
New Mexico,
USA
C. W. Smith
University of Delaware,
Bartol Research Institute,
Newark,
Delaware,
USA
Abstract
Observations from several satellites in geosynchronous orbit, combined with solar wind observations from the ACE spacecraft,
demonstrate that cold, dense plasma sheet material can be delivered into the inner magnetosphere under two scenarios: (1)
a sudden southward IMF preceded by an extended interval of northward field and (2) a very strong magnetospheric compression
caused by a large increase in the solar wind dynamic pressure, also under conditions of northward IMF. Examination of 30 “superdense”
plasma sheet events observed during 15 months in 2001 and 2002 shows that these two mechanisms are probably responsible for
the occurrence of most superdense events, if “northward IMF” is generalized to “northward or very weak IMF Bz.” Previous work has shown that a superdense plasma sheet contributes to a strong ring current and geomagnetic disturbance
if it is accompanied by strong magnetospheric convection (which requires southward IMF). Hence this study suggests that the
formation of a strong geomagnetic storm should be favored by an extended interval of strong southward IMF that is preceded
by an earlier interval of northward field or very weak Bz, during which the plasma sheet fills with cool, dense plasma.
Published 11
April
2003.
Index Terms: 2764 Magnetospheric Physics: Plasma sheet; 2784 Magnetospheric Physics: Solar wind/magnetosphere interactions; 2740 Magnetospheric Physics: Magnetospheric configuration and dynamics; 2760 Magnetospheric Physics: Plasma convection.
Read Full Article (file size: 1632953 bytes) Cited by
Citation: Thomsen, M. F., J. E. Borovsky, R. M. Skoug, and C. W. Smith
(2003),
Delivery of cold, dense plasma sheet material into the near-Earth region,
J. Geophys. Res.,
108(A4),
1151,
doi:10.1029/2002JA009544.
Copyright 2003 by the American Geophysical Union.
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