Dynamical behavior of the polar topside ionosphere.

A review is given of magnetospheric interactions with the polar ionosphere using recent experimental and theoretical results. The effect of the polar wind is discussed with reference to the observational data of J. Hoffman. These and the results of other experiments support the concept of polar wind ion flows as a general feature of the topside ionosphere for all regions outside the plasmasphere. It is shown that most of the semi-permanent topside density features result from changes in plasma temperature and F2-region effects rather than being associated with changes in ion composition. Finally, the polar peak density enhancement is discussed in terms of recent observations of the polar cusp.