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| Titel |
Geomagnetic activity effects on plasma sheet energy conversion |
| VerfasserIn |
M. Hamrin, P. Norqvist, O. Marghitu, S. Buchert, B. Klecker, L. M. Kistler, I. Dandouras |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
0992-7689
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| Digitales Dokument |
URL |
| Erschienen |
In: Annales Geophysicae ; 28, no. 10 ; Nr. 28, no. 10 (2010-10-01), S.1813-1825 |
| Datensatznummer |
250016892
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| Publikation (Nr.) |
 copernicus.org/angeo-28-1813-2010.pdf |
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| Zusammenfassung |
| In this article we use three years (2001, 2002, and 2004) of Cluster
plasma sheet data to investigate what happens to localized energy
conversion regions (ECRs) in the plasma sheet during times of high
magnetospheric activity. By examining variations in the power
density, E·J, where E is the
electric field and J is the current density obtained by
Cluster, we have studied the influence on Concentrated Load Regions
(CLRs) and Concentrated Generator Regions (CGRs) from variations in
the geomagnetic disturbance level as expressed by the Kp, the AE,
and the Dst indices. We find that the ECR occurrence frequency
increases during higher magnetospheric activities, and that the ECRs
become stronger. This is true both for CLRs and for CGRs, and the
localized energy conversion therefore concerns energy conversion in
both directions between the particles and the fields in the plasma
sheet. A higher geomagnetic activity hence increases the general
level of energy conversion in the plasma sheet. Moreover, we have
shown that CLRs live longer during magnetically disturbed times,
hence converting more electromagnetic energy. The CGR lifetime, on
the other hand, seems to be unaffected by the geomagnetic activity
level. The evidence for increased energy conversion during
geomagnetically disturbed times is most clear for Kp and for AE, but
there are also some indications that energy conversion increases
during large negative Dst. This is consistent with the plasma sheet
magnetically mapping to the auroral zone, and therefore being more
tightly coupled to auroral activities and variations in the AE and
Kp indices, than to variations in the ring current region as
described by the Dst index. |
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