Auroral activity and corresponding magnetic signatures at synchronous orbit

Magnetic field variations obtained by the GOES 2 and 3 satellites have been compared with auroral activity observations made using all-sky TV cameras at the ground conjugate areas for three auroral expansions on February 16, 1980. Magnetic field variations at synchronous orbit at the time when an auroral expansion front passes the conjugate region are shown to be characterized by abrupt enhancements of fast field fluctuations, depressions in total magnetic intensity, and transverse fluctations. The most probable conjugate points on the ground of the synchronous satellites on this day are found to be quite far south from those predicted using the Tsyganenko-Usmanov (1982) model.