Tracking transient events through geosynchronous orbit

Abstract

Impulsive events in high‐latitude dayside ground magnetograms provide evidence for one or more modes of unsteady solar wind‐magnetosphere interaction. We use geosynchronous magnetic field and energetic electron observations to demonstrate that the events correspond to abrupt global variations in both the magnetospheric magnetic field strength and the energetic electron flux and that these variations are particularly marked in the dayside magnetosphere. The multiple spacecraft observations suggest that the events move both dawnward and duskward from a point of origin on the prenoon magnetopause during periods of orthospiral, duskward, and northward interplanetary magnetic field orientation. Event properties are consistent with an interpretation in terms of widespread solar wind pressure fronts striking the bow shock and magnetopause.