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Titel |
A joint Cluster and ground-based instruments study of two magnetospheric substorm events on 1 September 2002 |
VerfasserIn |
N. C. Draper, Mark Lester, J. A. Wild, S. E. Milan, G. Provan, A. Grocott, S. W. H. Cowley, Y. Bogdanova, J. P. Dewhurst, A. N. Fazakerley, J. A. Davies, J.-M. Bosqued |
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 ; 22, no. 12 ; Nr. 22, no. 12 (2004-12-22), S.4217-4228 |
Datensatznummer |
250015086
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Publikation (Nr.) |
copernicus.org/angeo-22-4217-2004.pdf |
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Zusammenfassung |
We present a coordinated ground- and space-based
multi-instrument study of two magnetospheric substorm events that occurred
on 1 September 2002, during the interval from 18:00 UT to 24:00 UT. Data
from the Cluster and Polar spacecraft are considered in combination with
ground-based magnetometer and HF radar data. During the first substorm event
the Cluster spacecraft, which were in the Northern Hemisphere lobe, are to
the west of the main region affected by the expansion phase. Nevertheless,
substorm signatures are seen by Cluster at 18:25 UT (just after the expansion
phase onset as seen on the ground at 18:23 UT), despite the ~5 RE}
distance of the spacecraft from the plasma sheet. The Cluster spacecraft
then encounter an earthward-moving diamagnetic cavity at 19:10 UT, having
just entered the plasma sheet boundary layer. The second substorm expansion
phase is preceded by pseudobreakups at 22:40 and 22:56 UT, at which time
thinning of the near-Earth, L=6.6, plasma sheet occurs. The expansion phase
onset at 23:05 UT is seen simultaneously in the ground magnetic field, in the
magnetotail and at Polar's near-Earth position. The response in the
ionospheric flows occurs one minute later. The second substorm better fits
the near-Earth neutral line model for substorm onset than the cross-field
current instability model.
Key words. Magnetospheric physics (Magnetosphereionosphere
interactions; Magnetic reconnection; Auroral
phenomenon) |
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