On the distribution of global auroras during intervals of magnetospheric quiet
Defense Meteorological Satellite Program (DMSP) satellite data have been used to derive the instantaneous distribution of auroras during intervals of very quiet magnetic activity. The data were ordered with respect to the magnitude of the auroral electrojet index AE. Results indicate that the size of the instantaneous auroral oval is highly sensitive to relatively small changes in the magnitude of AE. Analysis of the DMSP auroral imagery data suggests that contracted oval substorms are distinct from the more violent substorms observed along the expanded oval in terms of both intensity and morphology. Certain morphological features associated with expanded oval substorms in the morning sector were not observed in this data set. These features include omega bands, torchlike structure, and, to a certain extent, patchy auroras. Sun-aligned arcs in the polar cap were observed on numerous orbits, and were most frequent when the magnetic field disturbance was minimal. Finally, several near-simultaneous orbits of the DMSP and Isis 2 satellites were compared to establish a threshold sensitivity for the DMSP detector system. For the noon-midnight DMSP satellite during late 1972 the equivalent threshold sensitivity at 3914 A was a few kilorayleighs. (AIP)
- Research Organization:
- Auroral Observatory, University of Tromso, Tromso, Norway
- OSTI ID:
- 7261732
- Journal Information:
- J. Geophys. Res.; (United States), Vol. 81:25
- Country of Publication:
- United States
- Language:
- English
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