Electric fields and currents in the ionosphere

In this paper some theories and experimental data on the electric fields and currents in the ionosphere are reviewed. Electric fields originating in the polarization of the ionosphere as well as in local irregularities are considered. Special attention is paid to field-aligned currents as a regulator of the intensity and configuration of the ionospheric polarization field, the anomalous resistivity being one of the most important characteristics of the magnetospheric plasma. Present-day models of the magnetosphere and corresponding electric field generation mechanisms are discussed. Various models of the DP1 current system are considered and the main characteristics that allow us to distinguish between them are listed. Experimental data on the ionospheric electric field are considered; a modified model of Silsbee and Vestine is shown to fit these data reasonably well.