Equatorward boundary of auroral ion precipitation

Technical Report · Wed Apr 01 04:00:00 EST 1987

OSTI ID:6148209

Gussenhoven, M S; Hardy, D A; Heinemann, N

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
• Country of Publication: United States
• Language: English

Related Subjects

640201* -- Atmospheric Physics-- Auroral
Ionospheric
& Magetospheric Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
AURORAE
CHARGED PARTICLES
CHARGED-PARTICLE PRECIPITATION
DIFFUSION
ELECTRIC FIELDS
ELECTRON PRECIPITATION
ELECTRONS
ELEMENTARY PARTICLES
FERMIONS
GEOMETRY
ION MOBILITY
IONS
LEPTONS
MAGNETIC FIELDS
MATHEMATICS
MOBILITY
PARTICLE MOBILITY