Effects of heating at high latitudes on global thermospheric dynamics

Abstract

Three dimensional numerical calculations of thermospheric wind, density and temperature fields generated by solar EuV heating were described in a recent paper by Straus et al. (1975). These model calculations indicated that many of the global characteristics of the thermosphere are generated by EUV heating alone. However, several observed features were found to be poorly represented by the model results. These include the amplitude of the diurnal temperature variation and properties of the diurnal variations of the meridional wind and pressure gradient fields. The present paper describes investigation of the extent to which heating of the thermosphere at high latitudes would contribute to the resolution of these difficulties. This heating lowers the day to night temperature ratio, since it provides a heat source at night. It brings calculated meridional winds and pressure gradients into better agreement with observations, since it raises isobaric surfaces at high latitudes. The amount of heating at high latitudes required to make these modifications is consistent with that due to quiet time joule heating.