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| Titel |
Cluster survey of the high-altitude cusp properties: a three-year statistical study |
| VerfasserIn |
B. Lavraud, A. Fedorov, E. Budnik, A. Grigoriev, P. J. Cargill, M. W. Dunlop, H. Rème, I. Dandouras, A. Balogh |
| 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. 8 ; Nr. 22, no. 8 (2004-09-07), S.3009-3019 |
| Datensatznummer |
250014982
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| Publikation (Nr.) |
 copernicus.org/angeo-22-3009-2004.pdf |
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| Zusammenfassung |
| The global characteristics of the high-altitude cusp and its surrounding
regions are investigated using a three-year statistical survey based on data
obtained by the Cluster spacecraft. The analysis involves an elaborate
orbit-sampling methodology that uses a model field and takes into account
the actual solar wind conditions and level of geomagnetic activity. The
spatial distribution of the magnetic field and various plasma parameters in
the vicinity of the low magnetic field exterior cusp are determined and it
is found that: 1) The magnetic field distribution shows the presence of an
intermediate region between the magnetosheath and the magnetosphere: the
exterior cusp, 2) This region is characterized by the presence of dense
plasma of magnetosheath origin; a comparison with the Tsyganenko (1996)
magnetic field model shows that it is diamagnetic in nature, 3) The spatial
distributions show that three distinct boundaries with the lobes, the
dayside plasma sheet and the magnetosheath surround the exterior cusp, 4)
The external boundary with the magnetosheath has a sharp bulk velocity
gradient, as well as a density decrease and temperature increase as one goes
from the magnetosheath to the exterior cusp, 5) While the two inner
boundaries form a funnel, the external boundary shows no clear indentation,
6) The plasma and magnetic pressure distributions suggest that the exterior
cusp is in equilibrium with its surroundings in a statistical sense, and 7)
A preliminary analysis of the bulk flow distributions suggests that the
exterior cusp is stagnant under northward IMF conditions but convective
under southward IMF conditions. |
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