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| Titel |
Multi-spacecraft observations of the current system around the dipolarization front and its relation to substorm current wedge |
| VerfasserIn |
Zhonghua Yao, Zuyin Pu, Jiang Liu |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250087414
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| Publikation (Nr.) |
 EGU/EGU2014-1460.pdf |
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| Zusammenfassung |
| Recently, the current system around the dipolarization fronts (DFs) of earthward-moving flow
bursts has attracted much research attention. Both simulations and observations revealed
that region-1-sense field-aligned currents (FACs) show up within the DF layer,
while region-2-sense FACs show up ahead of the DF. The DFs are found to be
closely related to multiple substorm intensifications and are able to make major
contributions to substorm onset signatures on ground and in space. This paper briefly
reviews studies of multi-spacecraft observations of the current system around DFs
and its relation to substorm current wedge (SCW) made in a couple of years. It is
shown that (1) behind the DF in the head of the diverted flow near equator, enhanced
dawnward/duskward pressure gradient on the morning/evening side near-Earth tail
causes downward/ upward FACs, which may contribute to the major part of FACs in
the substorm expansion phase and is responsible for the formation of SCWs at
dipolarization onset. (2) On the DF layer, the average current near the neutral sheet is
perpendicular to the average field direction over the DF thickness; away from the
neutral sheet, the average current becomes progressively parallel to the average field
direction with region-1-sense FAC directions. The total current carried by a DF can
account for a sizable portion of a SCW’s current for a typical substorm. (3) In the
magnetic dip region immediately ahead of the DF, there exist region-2-sense FACs.
These region-2-sense currents are suggested to be associated with the compressional
effect ahead of the DF, and the compressional effect can also lead to a local current
disruption, in association with a local disappearance of plasma pressure gradient. |
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