Magnetosphere-ionosphere interactions via electric currents and fields

This paper reviews ionospheric and aeronomic effects associated with electric fields and currents in the magnetosphere-ionosphere system. The effects include (1) the presence of electric current orthogonal to the geomagnetic field in the magnetosphere to support symmetrical systems of field aligned currents; (2) movement and Joule heating of the thermosphere and consequent changes in wind speed, ion and neutral pressure gradients, temperature and composition; also asymmetries of these effects; (3) alteration of ion-velocity distributions and consequent changes in excitation processes chemical reaction rates and knocking neutral particles out of the gravitational field; (4) field-tube interchange leading to redistribution and energization of magnetospheric plasma; (5) heat conduction to the ionosphere; (6) relationship of electric fields to SAR arc deformation; (7) charge-exchange and loss of Earth gases during magnetic storms; (8) generation of wave-particle interactions through changes in magnetosphere densities and anisotropies of energetic particles populations; (9) DEL(EXB) effects on charged particle motion; and (10) coupling between weather systems in the lower atmosphere and the solar wind. (Auth.)