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| Titel |
An empirical model of the auroral oval derived from CHAMP field-aligned current signatures – Part 2 |
| VerfasserIn |
C. Xiong, H. Lühr |
| 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 ; 32, no. 6 ; Nr. 32, no. 6 (2014-06-04), S.623-631 |
| Datensatznummer |
250121068
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| Publikation (Nr.) |
 copernicus.org/angeo-32-623-2014.pdf |
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| Zusammenfassung |
| In this paper we introduce a new model for the location of the auroral oval.
The auroral boundaries are derived from small- and medium-scale field-aligned
current (FAC) based on the high-resolution CHAMP (CHAllenging Minisatellite Payload) magnetic field observations
during the years 2000–2010. The basic shape of the auroral oval is
controlled by the dayside merging electric field, Em, and can be
fitted well by ellipses at all levels of activity. All five ellipse
parameters show a dependence on Em which can be described by
quadratic functions. Optimal delay times for the merging electric field at the
bow shock are 30 and 15 min for the equatorward and poleward boundaries,
respectively. A comparison between our model and the British Antarctic Survey
(BAS) auroral model derived from IMAGE (Imager for Magnetopause-to-Aurora Global Exploration) optical observations has been
performed. There is good agreement between the two models regarding both boundaries, and
the differences show a Gaussian distribution with a width of ±2°
in latitude. The difference of the equatorward boundary shows a local-time
dependence, which is 1° in latitude poleward in the morning sector
and 1° equatorward in the afternoon sector of the BAS model. We
think the difference between the two models is caused by the appearance of
auroral forms in connection with upward FACs. All information required for
applying our auroral oval model (CH-Aurora-2014) is provided. |
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