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Ann. Geophys., 23, 2171-2182, 2005
www.ann-geophys.net/23/2171/2005/
© European Geosciences Union 2005
Creation of the substorm current wedge through the perturbation of the directly driven current system: a new model for substorm expansion
G. Rostoker1 and E. Friedrich1,*
1Department of Physics, University of Alberta, Edmonton, Alberta, T6G 2J1, Canada
*now at: NSERC Postdoctoral Fellow at University of Calgary, Calgary, Alberta, Canada
Abstract. The past four decades have seen a considerable amount of research on the
study of magnetospheric substorms, and over most of these years the
expansive phase of the substorm has been associated with the development of
a three dimensional current system that has been termed the substorm current
wedge. This current system has been thought to be a consequence of the
short-circuiting of crosstail current through the ionosphere, and is viewed
as a distinctive current system operating independently from the directly
driven current with which it co-exists. The purpose of this paper is to show
that the substorm current wedge should be viewed as an equivalent current
system rather than a real current system. It will be shown that the magnetic
perturbation pattern associated with the current wedge can be modeled as
purely a perturbation of the directly driven current system in the midnight
sector.
Keywords. Magnetospheric physics (Auroral phenomena;
Current systems; Magnetotail; Storms and substorms
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