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| Titel |
Meso-scale aurora within the expansion phase bulge |
| VerfasserIn |
N. Partamies, K. Kauristie, E. Donovan, E. Spanswick, K. Liou |
| 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 ; 24, no. 8 ; Nr. 24, no. 8 (2006-09-13), S.2209-2218 |
| Datensatznummer |
250015622
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| Publikation (Nr.) |
 copernicus.org/angeo-24-2209-2006.pdf |
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| Zusammenfassung |
| We present ground-based optical, riometer and magnetometer
recordings together with Polar UVI and GOES magnetic field
observations of a substorm that occurred over Canada on 24 November
1997. This event involved a clear optical onset followed by poleward
motion of the aurora as a signature of an expanding auroral
bulge. During the expansion phase, there were three distinct types
of meso-scale (10–1000 km) auroral structures embedded in the
bulge: at first a series of equatorward moving auroral arcs,
followed by a well-defined spiral pair, and finally north-south
directed aurora (a streamer). The spirals occurred several minutes
after the onset, and indicate a shear in the field-aligned
current. The north-south aligned aurora that formed about 10 min
after the onset suggest bursty bulk flow type flows taking place in
the central plasma sheet. Polar UVI observations of the polar cap
location indicate that the southward drifting arcs were associated
with magnetospheric activity within closed field lines, while the
auroral streamer was launched by the bulge reaching the polar cap
boundary, i.e. the mid-tail reconnection starting on the open field
lines. The riometer data imply high energy electron precipitation
in the vicinity of the the poleward moving edge of the auroral
bulge, starting at the onset and continuing until the formation of
the north-south structure. In this paper, we examine this evolving
auroral morphology within the context of substorm theories. |
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