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| Titel |
Small-scale characteristics of extremely high latitude aurora |
| VerfasserIn |
J. A. Cumnock, L. G. Blomberg, A. Kullen, T. Karlsson, K. Å. T. Sundberg |
| 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 ; 27, no. 9 ; Nr. 27, no. 9 (2009-09-01), S.3335-3347 |
| Datensatznummer |
250016634
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| Publikation (Nr.) |
 copernicus.org/angeo-27-3335-2009.pdf |
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| Zusammenfassung |
| We examine 14 cases of an interesting type of extremely high latitude aurora
as identified in the precipitating particles measured by the DMSP F13
satellite. In particular we investigate structures within large-scale arcs
for which the particle signatures are made up of a group of multiple
distinct thin arcs. These cases are chosen without regard to IMF orientation
and are part of a group of 87 events where DMSP F13 SSJ/4 measures emissions
which occur near the noon-midnight meridian and are spatially separated from
both the dawnside and duskside auroral ovals by wide regions with
precipitating particles typical of the polar cap. For 73 of these events the
high-latitude aurora consists of a continuous region of precipitating
particles. We focus on the remaining 14 of these events where the particle
signatures show multiple distinct thin arcs. These events occur during
northward or weakly southward IMF conditions and follow a change in IMF
By. Correlations are seen between the field-aligned currents and plasma
flows associated with the arcs, implying local closure of the FACs. Strong
correlations are seen only in the sunlit hemisphere. The convection
associated with the multiple thin arcs is localized and has little influence
on the large-scale convection. This also implies that the sunward flow along
the arcs is unrelated to the overall ionospheric convection. |
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