Solar wind control of the penetration of electric fields in the inner magnetosphere

Abstract

Particle and field measurements from the DMSP F8 and CRRES satellites were used to study interplanetary influences on the electrodynamics of the duskside inner magnetosphere during the magnetic storm of June 1991. The storm was triggered by an increase in the solar wind dynamic pressure accompanied by a southward turning of the interplanetary magnetic field (IMF). Satellite data show that: (1) Particle and field boundaries initially moved equatorward/earthward, probably in response to the strong southward IMF turning. (2) Electric field boundaries were close to the inner edge of ring current ions throughout the main and early recovery phases, except during rapid increases in the polar cap potential when shielding was ineffective. (3) Potentials at subauroral latitudes were large fractions of the total potentials of the afternoon cell, twice exceeding 60 kV. This source of ring current energization depends on the polar cap potential to magnetopause standoff distance ratio. (4) Auroral electron boundaries mapped to lower L shells than where CRRES detected plasma sheet electrons reflecting magnetic inflation by the ring current.