Equatorward boundary of auroral ion precipitation
Data from the SSJ/4 detector on the Defense Meteorological Satellite Program (DMSP) F6 satellite are used to study the difference in the location of the equatorward boundaries of auroral ion and electron precipitation, and the variation in the difference with magnetic local time and activity. Large geometric factors of the ion sensors of the SSJ/4 detector make identification of the ion boundary unambiguous in most cases. In this study, approximately 900 boundaries each for electrons and ions were determined from all DMSP F6 auroral passes in January of 1983. The boundaries occur over local times from 0400 to 0700 on the morningside of the oval and from 1700 to 2100 on the eveningside. The ion and electron boundaries both move systematically to lower latitudes with increasing magnetic activity, as measured by Kp. Over the evening sector sampled, the ion boundary is on average 1.4 deg equatorward of the electron boundary, with the difference commonly ranging up to 3 deg. For the morning sector sampled, the ion boundary is on average 2.6 deg poleward of the electron boundary with a significant number of cases with difference above 5.0 deg. The separation between the electron and ion boundaries is not dependent on K/sub p/ but but does increase with MLT from midnight toward noon on both the morningside and the eveningside of the oval. The separation in boundaries can be explained by motion in a large-scale, quasi-static convection electric field if the time for development of the ion boundary is explicitly taken into account and if ion pitch angle diffusion is highly energy dependent.
- Research Organization:
- Air Force Geophysics Lab., Hanscom AFB, MA (USA)
- OSTI ID:
- 6148209
- Report Number(s):
- AD-A-180295/8/XAB; AFGL-TR-87-0141
- Resource Relation:
- Other Information: Pub. in J. of Geophysical Research, Vol. 92, No. A4, 3273-3283(1 Apr 1987)
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
GENERAL PHYSICS
AURORAE
ELECTRON PRECIPITATION
ION MOBILITY
DIFFUSION
ELECTRIC FIELDS
ELECTRONS
GEOMETRY
IONS
MAGNETIC FIELDS
CHARGED PARTICLES
CHARGED-PARTICLE PRECIPITATION
ELEMENTARY PARTICLES
FERMIONS
LEPTONS
MATHEMATICS
MOBILITY
PARTICLE MOBILITY
640201* - Atmospheric Physics- Auroral
Ionospheric
& Magetospheric Phenomena