HR: 1330h
AN: SM42B-0608    [PDF]
TI: Mesoscale Structures Within the Auroral Bulge
AU: * Partamies, N
EM: noora.partamies@fmi.fi
AF: Finnish Meteorological Institute, Geophysical Research, P.O.Box 503, Helsinki, FIN-00101 Finland
AU: Kauristie, K
EM: kirsti.kauristie@fmi.fi
AF: Finnish Meteorological Institute, Geophysical Research, P.O.Box 503, Helsinki, FIN-00101 Finland
AU: Donovan, E
EM: eric@phys.ucalgary.ca
AF: University of Calgary, Department of Physics and Astronomy, 2500 University Drive, Calgary, T2N 1N4 Canada
AU: Spanswick, E
EM: emma@phys.ucalgary.ca
AF: University of Calgary, Department of Physics and Astronomy, 2500 University Drive, Calgary, T2N 1N4 Canada
AU: Liou, K
EM: kan.liou@jhuapl.edu
AF: The Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, 20723-6099 United States
AB: We present ground-based optical, riometer, and magnetometer, Polar UVI and GOES magnetic field observations from a substorm that occurred on November 24, 1997. This event involved a clear optical onset followed by poleward motion of the auroras which demark the expanding auroral bulge. During the first minutes of the expansive phase, there were three distinct mesoscale (10-1000km) structures embedded in the bulge: at first a series of equatorward moving auroral arcs, followed by a well-defined spiral structure, and finally north-south directed auroras. The spirals occurred several minutes after the onset, and indicate either a field-aligned current or a more global ballooning-type instability. The north-south directed auroral forms occurred roughly 10 minutes after the onset and ostensibly indicate rapid bursty bulk flow type flows in the central plasma sheet. As well, the riometer data suggest high energy electron precipitation in the vicinity of the the poleward moving edge of the auroral bulge, starting at the onset and continuing through until the north-south structure. In this paper, we examine this evolving auroral morphology within the context of substorm theories.
DE: 2407 Auroral ionosphere (2704)
DE: 2716 Energetic particles, precipitating
DE: 2736 Magnetosphere/ionosphere interactions
DE: 2788 Storms and substorms
SC: SPA - Magnetospheric Physics [SM]
MN: 2003 Fall Meeting