Formation of the stable auroral arc that intensifies at substorm onset

Journal Article · Sun Nov 01 04:00:00 EST 1992 · Geophysical Research Letters (American Geophysical Union); (United States)

DOI:https://doi.org/10.1029/92GL02494· OSTI ID:6821019

Lyons, L R; Samson, J C ^[1]

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1. Aerospace Corp., Space and Environmental Technology Center, Los Angeles, CA (United States) Canadian Network for Space Research (Canada) Alberta Univ., Edmonton (Canada)

Observational evidence that the auroral arc that intensifies at substorm onset is formed on magnetic field lines that map to within about 1 to 2 Re of synchronous orbit, where plasma pressures are about 1 to 10 nPa during the substorm growth phase, is discussed. It is proposed that the arc is formed by a perpendicular magnetospheric-current divergence that results from a strong dawn-to-dusk directed pressure gradient in the vicinity of magnetic midnight. It is estimated that the current divergence is sufficiently strong that a greater than 1 kV field-aligned potential drop is required to maintain ionospheric-current continuity. It is suggested that the azimuthal pressure gradient results from proton drifts in the vicinity of synchronous orbit that are directed nearly parallel to the cross-tail electric field. 28 refs.

• OSTI ID: 6821019
• Journal Information: Geophysical Research Letters (American Geophysical Union); (United States), Journal Name: Geophysical Research Letters (American Geophysical Union); (United States) Vol. 19:21; ISSN GPRLAJ; ISSN 0094-8276
• Country of Publication: United States
• Language: English

Related Subjects

661320* -- Auroral
Ionospheric
& Magnetospheric Phenomena-- (1992-)
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
AURORAE
CHARGED-PARTICLE PRECIPITATION
EARTH ATMOSPHERE
EARTH MAGNETOSPHERE
ELECTRON PRECIPITATION
MAGNETIC STORMS
PLASMA PRESSURE
PRESSURE GRADIENTS