ELECTRON TEMPERATURES DURING RAPID SUBAURORAL ION DRIFT EVENTS

Examples of data from DE-2 satellite instruments are presented. These illustrate the behaviour of plasma parameters in the F-region and adja cent topside ionosphere during rapid sub-auroral ion drift (SAID) even ts. In particular, a variety of behaviours of the electron temperature (T-e) is demonstrated, both within and equatorward of the SAID region . The Sheffield University plasmasphere-ionosphere model (SUPIM) is us ed to perform calculations in which a model SAID is applied to a plasm a flux tube. The model results indicate that strongly elevated ion tem perature (a recognised signature of SAID events) is on occasion suffic ient to raise T-e to observed values by ion-electron heat transfer. On other occasions, an additional heat source is required. It is suggest ed that such a source for the electron gas may be clue to interaction between the ring current and the plasmasphere at high altitudes. The m agnitude of the downward heat flux is consistent with that necessary t o produce sub-auroral red arcs. The resulting strongly heated electron gas causes vibrational excitation of molecular nitrogen in the thermo sphere.