Heliophysics Science Division
TYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> William J. Burke - Abstract

Stormtime Electric Field Penetration of the Inner Magnetosphere


William J. Burke
Space Vehicles Directorate
Air Force Research Laboratory
Hanscom AFB, MA 01731
(e-mail: william.burke2@hanscom.af.mil)

Intense electric fields were detected by CRRES in the evening sector of the inner magne-tosphere during the initial and main phases of the geomagnetic storms of June 4 - 6, and July 8 - 9, 1991. Simultaneous energetic particle and wave measurements allow us to characterize responses of ring-current and plasmaspheric ions. Simultaneous ionospheric dynamics were monitored with plasma sensors on three DMSP satellites. Our data demonstrate that: (1) Electric fields can energize/transport ring-current ions, independent of substorm activity. (2) Although the auroral electron boundary moved equatorward during the main phase, magnetic inflation by the ring current pushed the conjugate plasma sheet electron boundary away from the Earth. (3) Energetic ring current ions heat plasmaspheric electrons so that significant fluxes are detectable in the 0.1 to 2 keV range both near the equator and above the ionosphere. (4) Mapped to the ionosphere, penetration electric fields cause bands of deep plasma depletions at mid latitudes and fast moving plasma bubbles at equatorial latitudes. These ionospheric phenomena may be understood as effects of expanded DP 2 current systems and partial shielding of magnetospheric electric fields by ring current ions.