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| Titel |
A superposed epoch analysis of auroral evolution during substorm growth, onset and recovery: open magnetic flux control of substorm intensity |
| VerfasserIn |
S. E. Milan, A. Grocott, C. Forsyth, S. M. Imber, P. D. Boakes, B. Hubert |
| 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. 2 ; Nr. 27, no. 2 (2009-02-11), S.659-668 |
| Datensatznummer |
250016405
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| Publikation (Nr.) |
 copernicus.org/angeo-27-659-2009.pdf |
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| Zusammenfassung |
| We perform two superposed epoch analyses of the auroral
evolution during substorms using the FUV instrument on the Imager for
Magnetopause-to-Aurora Global Explorer (IMAGE) spacecraft. The larger of the
two studies includes nearly 2000 substorms. We subdivide the substorms by
onset latitude, a measure of the open magnetic flux in the magnetosphere,
and determine average auroral images before and after substorm onset, for
both electron and proton aurora. Our results indicate that substorms are
more intense in terms of auroral brightness when the open flux content of
the magnetosphere is larger, and that magnetic flux closure is more
significant. The increase in auroral brightness at onset is larger for
electrons than protons. We also show that there is a dawn-dusk offset in the
location of the electron and proton aurora that mirrors the relative
locations of the region 1 and region 2 current systems. Superposed epoch
analyses of the solar wind, interplanetary magnetic field, and geomagnetic
indices for the substorms under study indicate that dayside reconnection is
expected to occur at a faster rate prior to low latitude onsets, but also
that the ring current is enhanced for these events. |
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