On the formation of the nightside ionospheric bulge in the Venus wake

Abstract

A study of the distribution of ionopause crossings obtained from the Pioneer Venus electron temperature probe measurements is presented and its results discussed in connection with the configuration of the nightside ionospheric bulge. It is shown that the available experimental evidence indicates that in addition to showing decreasing heights with increasing latitude, the bulge of the nightside ionopause is also less frequently formed at high latitudes. This result is consistent with the predictions of the viscous entry model and the penetration of ionosheath fluxes into the umbra through the polar terminator.