THE ELECTRODYNAMICS OF THE LOW-LATITUDE IONOSPHERE - RECENT RESULTS AND FUTURE CHALLENGES

Over the last few years, experimental and numerical modeling studies h ave provided extensive new information on the electrodynamics of the l ow-latitude ionosphere. Ground-based studies have determined the avera ge seasonal, solar cycle and magnetic effects on the equatorial and lo w-latitude plasma drifts and thermospheric neutral winds, and their co ntrol over the F-region plasma density distribution. Satellite observa tions have been used, for the first time, to determine the latitudinal and longitudinal dependence of the F-region plasma drifts, and coordi nated ground-based measurements have examined the global response of t he low-latitude ionosphere to different high latitude forcing conditio ns. Recent studies have examined the coupling between storm-time therm ospheric neutral winds and plasma drifts, and have determined the low- latitude signatures of magnetospheric and ionospheric dynamo electric fields. In this review, we initially examine the present understanding of low-latitude F-region electrodynamics focusing on the large-scale distribution of the ionospheric electric fields and their response to magnetospheric disturbances. We also discuss future initiatives necess ary for a more complete understanding of these low-latitude transport processes. (C) 1997 Elsevier Science Ltd.