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| Titel |
Transient plasma injections in the dayside magnetosphere: one-to-one correlated observations by Cluster and SuperDARN |
| VerfasserIn |
A. Marchaudon, J.-C. Cerisier, J.-M. Bosqued, M. W. Dunlop, J. A. Wild, P. M. E. Décréau, M. Forster, D. Fontaine, H. Laakso  |
| 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. 1 ; Nr. 22, no. 1 (2004-01-01), S.141-158 |
| Datensatznummer |
250014756
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| Publikation (Nr.) |
 copernicus.org/angeo-22-141-2004.pdf |
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| Zusammenfassung |
| Conjunctions in the cusp between the four Cluster spacecraft and SuperDARN
ground-based radars offer unique opportunities to compare the signatures of transient plasma
injections simultaneously in the high-altitude dayside magnetosphere and in the ionosphere.
We report here on such observations on 17 March 2001, when the IMF initially northward
and duskward, turns southward and dawnward for a short period. The changes in the
convection direction at Cluster are well correlated with the interplanetary magnetic field
(IMF) By variations. Moreover, the changes in the ionosphere follow those in the
magnetosphere, with a 2–3min delay. When mapped into the ionosphere, the convection
velocity at Cluster is about 1.5 times larger than measured by SuperDARN.
In the high-altitude cusp, field and particle observations by Cluster display the
characteristic signatures of plasma injections into the magnetosphere suggestive of Flux
Transfer Events (FTEs). Simultaneous impulsive and localized convection plasma flows are
observed in the ionospheric cusp by the HF radars. A clear one-to-one correlation is observed
for three successive injections, with a 2–3min delay between the magnetospheric and
ionospheric observations. For each event, the drift velocity of reconnected flux tubes (phase
velocity) has been compared in the magnetosphere and in the ionosphere. The drift velocity
measured at Cluster is of the order of 400–600ms–1 when mapped into the ionosphere, in
qualitative agreement with SuperDARN observations. Finally, the reconnected flux tubes
are elongated in the north-south direction, with an east-west
dimension of 30–60km in the ionosphere from mapped Cluster observations, which is
consistent with SuperDARN observations, although slightly smaller.
Key words. Ionosphere (plasma convection) – Magnetospheric
physics (magnetopause, cusp, and boundary layers;
magnetosphere-ionosphere interactions) |
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