A comprehensive magnetohydrodynamic model of the Venus ionosphere

Abstract

The MHD Venus ionospheric model developed by Shinagawa and Cravens (1988) has been improved by including the energy equations for ions and electrons in a self‐consistent manner. This new model reproduces observed electron density and magnetic field profiles very well, and the basic MHD processes of the Venus ionosphere, as described by Shinagawa and Cravens (1988), remain virtually unchanged. The results indicate that including energetics does not significantly alter the density and magnetic field profiles. Under unmagnetized conditions, it is necessary to impose heat fluxes for both ions and electrons in order to reproduce the observed plasma temperature profiles, which are consistent with the studies by Cravens et al. (1979, 1980) and Kim et al. (1990). In the magnetized ionosphere, it is likely that a heat source for the ions is present at higher altitudes. On the other hand, the observed very high electron temperatures can be reproduced with a reduced conductivity or with a heat source at high altitudes. It is also found that heating processes do not play a significant role in the dynamics at low altitudes. Thus a nearly supersonic downward velocity layer in the lower ionosphere of Venus, proposed by Cloutier et al. (1987), is unlikely, suggesting that their flow/field model is not applicable to the solar wind‐Venus interaction and other unmagnetized bodies in magnetized plasma flows.