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| Titel |
Aspects of magnetosphere–ionosphere coupling in sawtooth substorms: a case study |
| VerfasserIn |
P. E. Sandholt, C. J. Farrugia |
| 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 ; 32, no. 10 ; Nr. 32, no. 10 (2014-10-20), S.1277-1291 |
| Datensatznummer |
250121121
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| Publikation (Nr.) |
 copernicus.org/angeo-32-1277-2014.pdf |
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| Zusammenfassung |
| In a case study we report on
repetitive substorm activity during storm time which was excited during Earth
passage of an interplanetary coronal mass ejection (ICME) on 18 August 2003.
Applying a combination of magnetosphere and ground observations during a
favourable multi-spacecraft configuration in the plasma sheet (GOES-10 at
geostationary altitude) and in the tail lobes (Geotail and Cluster-1), we
monitor the temporal–spatial evolution of basic elements of the substorm
current system. Emphasis is placed on activations of the large-scale substorm
current wedge (SCW), spanning the 21:00–03:00 MLT sector of the near-Earth
plasma sheet (GOES-10 data during the interval 06:00–12:00 UT), and
magnetic perturbations in the tail lobes in relation to ground observations
of auroral electrojets and convection in the polar cap ionosphere. The joint
ground–satellite observations are interpreted in terms of sequential
intensifications and expansions of the outer and inner current loops of the
SCW and their respective associations with the westward electrojet centred
near midnight (24:00 MLT) and the eastward electrojet observed at
14:00–15:00 MLT. Combined magnetic field observations across the tail lobe
from Cluster and Geotail allow us to make estimates of enhancements of the
cross-polar-cap potential (CPCP) amounting to ≈ 30–60 kV (lower
limits), corresponding to monotonic increases of the PCN index by 1.5 to
3 mV m−1 from inductive
electric field coupling in the magnetosphere–ionosphere (M–I) system during the
initial transient phase of the substorm expansion. |
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