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| Titel |
Coupling between magnetospheric interfaces and evening discrete aurora through field-aligned currents |
| VerfasserIn |
M. M. Echim, R. Maggiolo, M. Roth, J. De Keyser |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250029764
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| Zusammenfassung |
| Current continuity in the auroral circuit involves closure of the current generated in the
magnetosphere through field-aligned currents and the perpendicular, Pedersen and Hall,
currents in the ionosphere. The current-voltage relation (CVR) between field-aligned current
density (j||) and the field-aligned potential drop (ÎΦ) is generally obtained from a kinetic
treatment of the adiabatic motion of particles in a mirroring magnetic field and a field-aligned
electric field. We investigate the coupling between a magnetospheric structure, described by a
Vlasov equilibrium solution, and the evening polar ionosphere. The model solves
the current continuity equation neglecting the divergence of the Hall currents. We
obtain narrow channels of precipitating accelerated magnetospheric electrons and
ionospheric ions that are accelerated upward, intense upward field-aligned currents, and
regions of enhanced Pedersen conductance, all the ingredients for discrete auroral
arcs. Model results are compared with data from a conjunction between Cluster
(above the acceleration region) and DMSP (intersecting Region 1 field-aligned
currents and an auroral arc) from April 28, 2001, reported by Vaivads et al.(2003).
Model results and experimental data suggest that the generator of the auroral arc
observed by DMSP may be located at the interface between the PSBL with the lobe or
at higher altitudes, at the inner edge of the LLBL. The model estimation of the
field-aligned current density, flux of precipitating energy and spatial scales of the arc are in
agreement with observations suggesting that Cluster and DMSP provide evidence for
auroral electron acceleration by a quasi-stationary field-aligned potential drop. |
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