Geomagnetic signatures of current wedge produced by fast flows in a plasma sheet

This paper uses the plasma data from Cluster and TC‐1 and geomagnetic data to study the geomagnetic signatures of the current wedge produced by fast‐flow braking in the plasma sheet. The three fast flows studied here occurred in a very quiet background and were accompanied by no (or weak) particle i...

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Bibliographic Details
Published in:Journal of Geophysical Research: Space Physics 2010-08, Vol.115 (A8), p.n/a
Main Authors: Cao, Jin-Bin, Yan, Chunxiao, Dunlop, Malcolm, Reme, Henri, Dandouras, Iannis, Zhang, Tielong, Yang, Dongmei, Moiseyev, Alexey, Solovyev, Stepan I., Wang, Z. Q., Leonoviche, A., Zolotukhina, N., Mishin, V.
Format: Article
Language:English
Subjects:
Atmospheric sciences
fast-flow braking
geomagnetic signatures
Latitude
Magnetic fields
Magnetism
substorm current wedge
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Summary:This paper uses the plasma data from Cluster and TC‐1 and geomagnetic data to study the geomagnetic signatures of the current wedge produced by fast‐flow braking in the plasma sheet. The three fast flows studied here occurred in a very quiet background and were accompanied by no (or weak) particle injections, thus avoiding the influences from other disturbances. All the geomagnetic signatures of a substorm current wedge can be found in the geomagnetic signatures of a current system produced by the braking of fast flows, indicating that the fast flows can produce a complete current wedge which contains postmidnight downward and premidnight upward field‐aligned currents, as well as a westward electrojet. The Pi2 precursors exist not only at high latitudes but also at midlatitudes. The starting times of midlatitude Pi2 precursors can be identified more precisely than those of high‐latitude Pi2 precursors, providing a possible method to determine the starting time of fast flows in their source regions. The AL drop that a bursty bulk flow produces is proportional to its velocity and duration. In three cases, the AL drops are 200 nT, whether a substorm can be triggered depends mainly on the conditions of the braking regions before fast flows. The observations of solar wind before the three fast flows suggest that it is difficult for the fast flows to trigger a substorm when the interplanetary magnetic field Bz of solar wind is weakly southward.
ISSN:0148-0227
2169-9380
2156-2202
2169-9402
DOI:10.1029/2009JA014891