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| Titel |
Sheared magnetospheric plasma flows and discrete auroral arcs: a quasi-static coupling model |
| VerfasserIn |
M. M. Echim, M. Roth, J. Keyser |
| 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 ; 25, no. 1 ; Nr. 25, no. 1 (2007-02-01), S.317-330 |
| Datensatznummer |
250015780
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| Publikation (Nr.) |
 copernicus.org/angeo-25-317-2007.pdf |
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| Zusammenfassung |
| We consider sheared flows in magnetospheric boundary layers of
tangential discontinuity type, forming a structure that is
embedded in a large-scale convergent perpendicular electric
field.
We construct a kinetic model that couples
the magnetospheric structure with
the topside ionosphere. The contribution of magnetospheric
electrons and ionospheric electrons and ions is taken into account
into the current-voltage relationship derived for an electric
potential monotonically decreasing with the altitude.
The solution of the current continuity equation
gives the distribution of the ionospheric potential
consistent with the given magnetospheric electric potential.
The model shows that a sheared magnetospheric flow
generates current sheets corresponding to upward field-aligned
currents, field-aligned potential drops
and narrow bands of precipitating
energy, as in discrete auroral arcs.
Higher velocity magnetospheric sheared flows
have the tendency to produce brighter
and slightly broader arcs. An increase in arc luminosity
is also associated with enhancements of
magnetospheric plasma density, in which case the structures are
narrower. Finally, the model predicts that an increase of the
electron temperature of the magnetospheric flowing plasma
corresponds to slightly wider arcs but does not
modify their luminosity. |
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