SATELLITE STUDIES OF MID-LATITUDE AND LOW-LATITUDE IONOSPHERIC DISTURBANCE ZONAL PLASMA DRIFTS

We use low-and mid-latitude zonal ion drift observations from the DE-2 satellite and auroral electrojet indices to study the temporal and la titudinal variations of F-region perturbation drifts during magnetical ly disturbed conditions. These perturbation drifts are driven by magne tospheric and ionospheric disturbance dynamo electric fields with time constants from less than one to several hours. We determine, initiall y, the drift patterns due to the prompt penetration of magnetospheric electric fields and of longer lasting disturbances. In this study, we concentrate on the properties of the longer lasting perturbations whic h occur with latitude-dependent time delays after enhancements in the high-latitude ionospheric currents. These perturbation drifts are pred ominantly westward at all latitudes with largest amplitudes in the mid night sector and smallest near noon. The daily variation of these dist urbance drifts derived from the satellite data is in good agreement wi th results from incoherent scatter radar observations. Our results ind icate that these longer lasting perturbations are due to the combined effects of ionospheric disturbance dynamo electric fields and leakage of high-latitude steady-state electric fields to lower latitudes.