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| Titel |
Cluster magnetotail observations of a tailward-travelling plasmoid at substorm expansion phase onset and field aligned currents in the plasma sheet boundary layer |
| VerfasserIn |
N. C. Draper, Mark Lester, S. W. H. Cowley, J. A. Wild, S. E. Milan, G. Provan, A. Grocott, A. N. Fazakerley, A. Lahiff, J. A. Davies, J.-M. Bosqued, J. P. Dewhurst, R. Nakamura, C. J. Owen, J. Waterman, M. G. Henderson, H. J. Singer, E. Donovan |
| 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 ; 23, no. 12 ; Nr. 23, no. 12 (2005-12-23), S.3667-3683 |
| Datensatznummer |
250015432
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| Publikation (Nr.) |
 copernicus.org/angeo-23-3667-2005.pdf |
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| Zusammenfassung |
| We present data from both ground- and space-based instruments for a substorm
event which occurred on 5 October 2002, with an expansion phase onset time
of 02:50 UT determined from the ground magnetometer data. During this
substorm, the Cluster spacecraft were located around 15 RE downtail,
8 RE from midnight in the pre-midnight sector and just 2 RE
above the equatorial plane (in GSM coordinates). At expansion phase onset
the Cluster spacecraft were located in the plasma sheet, tailward of a
near-Earth neutral line and detected a significant time delay of 6 min
between the tail field Bz component becoming negative and the
subsequent detection of Earthward flows. This is explained by the formation
of a tailward-directed travelling compression region initially Earthward of
the spacecraft; 7 min later the Cluster spacecraft entered the plasma sheet
boundary layer; they remained in and close to the plasma sheet boundary
layer for around 15 min before exiting to the lobe. The spacecraft then
re-entered the plasma sheet 30 min after onset. Earthward then tailward
directed currents detected in the plasma sheet boundary layer after onset
indicate that the Cluster spacecraft encountered the dawnward and duskward
portions of the reconnection flow associated current system with Region 1
sense, respectively. The reconnection site and current system were initially
skewed towards the pre-midnight sector, consistent with previous
observations that found the majority of substorm onsets located in this
sector. At later times the reconnection site and current system had moved
towards dawn, to be located more centrally in the midnight sector. |
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