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Ann. Geophys., 20, 1737-1741, 2002
www.ann-geophys.net/20/1737/2002/
© European Geosciences Union 2002
The storm time central plasma sheet
R. Schödel1, K. Dierschke1, W. Baumjohann2, R. Nakamura2, and T. Mukai3
1Max-Planck-Institut für extraterrestrische Physik, Garching, Germany
2Institut für Weltraumforschung der Österreichischen Akademie der Wissenschaften, Graz, Austria
3Institute of Space and Astronautical Science, Sagamihara, Japan
Correspondence to: R. Schödel (rainer@mpe.mpg.de)
Abstract. The plasma sheet plays a
key role during magnetic storms because it is the bottleneck through which
large amounts of magnetic flux that have been eroded from the dayside
magnetopause have to be returned to the dayside magnetosphere. Using about five
years of Geotail data we studied the average properties of the near- and
midtail central plasma sheet (CPS) in the 10–30 RE range
during magnetic storms. The earthward flux transport rate is greatly enhanced
during the storm main phase, but shows a significant earthward decrease. Hence,
since the magnetic flux cannot be circulated at a sufficient rate, this leads
to an average dipolarization of the central plasma sheet. An increase of the
specific entropy of the CPS ion population by a factor of about two during the
storm main phase provides evidence for nonadiabatic heating processes. The
direction of flux transport during the main phase is consistent with the
possible formation of a near-Earth neutral line beyond ~20 RE.
Key words. Magnetospheric physics (plasma convection;
plasma sheet; storms and substorms)
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