Ionospheric currents correlated with geomagnetic induced currents; Freja magnetic field measurements and the Sunburst Monitor System

Abstract

Temporal and spatial fluctuations of large‐scale electric currents totaling millions of amperes in the ionosphere have long been known to induce current and voltage in the Earth's surface and on large manmade conductive structures. A strong, persistent solar wind can interact with the geomagnetic environment and produce auroral zone currents at mid latitudes. Presented here is a specific correlation of ionospheric auroral currents inferred from magnetic field measurements from the Swedish Freja satellite and induced current in the electric power distribution system on the east coast of the United States, in particular the Chalk Point, Maryland, transformer station. The event discussed here registered a Kp level of 6 to 8 and occurred on April 4–5, 1993. An important aspect is that information from both of these space‐ and ground‐based monitoring systems is available automatically and in real time. In addition, satellite data from earlier local times, e.g., data monitored from European ground stations, can give precursor information of later North American geomagnetic activity.