Multipoint observations of a small substorm

Abstract

Results are presented of multipoint observations of a small substorm which occurred at about 0110 UT on April 25, 1985, carried out by AMPTE CCE, AMPTE IRM, DMSP F6, and DMSP F7, as well as by ground auroral stations and midlatitude stations. These data yield information on the latitudinal extent of the polar cap and provide visual identification of substorm aurorae, magnetic perturbations produced directly beneath aurorae, and the situ magnetic field. In addition, they provide magnetic-particle observations of the disruption of the cross-tail current sheet and observations concerning the spatial expansion of the current disruption region. Evidence is presented that the current sheet disruption observed by CCE in the neutral sheet was located on field lines which mapped to the westward traveling surge observed directly overhead of the ground station at Syowa.