The 6300-¿ auroral emission intensity at Kilpisj¿rvi, Finland, was monitored during the 1978--1979 winter, and comparisions made with data from the geostationary Geos 2 spacecraft located on the same magnitude field line. Optical 6300-¿ events with a rise time of a few minutes and a decay time of about 1 hour were regularly observed, and four events from the night of December 18, 1978, were analyzed in detail. All-sky camera data showed that the events arose from poleward propagating auroras associated with auroral breakup. The Geos 2 plasma and field signatures for these events were remarkably well defined and consistent. About 1 hour prior to an event the tailward component of the magnetic field at Geos 2 begins to grow; it relaxes suddenly to a dipolar configuration at the even onset. At the same time there is a short-lived electric field enhancement up to 15 mV/m and a burst of ULF waves (a short irregular pulsation event). There is a dropout in E20-keV intensity, and an onset of VLF activity, all of which persists for roughly 1 hour, in parallel with the decaying 6300-¿ emission. The observed electric field values are comparable to the inductive electric field expected from the observed magnetic field changes and appear to play a crucial role in the processes. The energy release associated with the 6300-¿ emission is comparable to the energy stored in the E<500-eV electrons prior to the onset. These events appear to correspond to injection events, occurring at the onset of the locally detected expansion phase.