Radiative energy balance of the Venus mesosphere

Solar heating and thermal cooling rates are calculated for standard temperature profiles and for temperatures retrieved from the Fourier spectrometer experiment aboard Venera 15. An accurate radiative transfer model is used for gaseous absorption (line-by-line) as well as cloud absorption and multiple scattering. Multiple scattering is of great importance in the solar spectral region below 5 mu m, whereas it can be neglected in the thermal region. Heating and cooling rates are found to be strongly dependent on variations in cloud structure. On the hemispheric average, the mesosphere of Venus is characterized by heating of the main cloud cover and cooling of the overlying haze. In the upper cloud and haze layers, there is a poleward energy gradient, but the middle and high latitude temperature inversion causes a gradient reversal below 65 km. The results should be helpful in formulating dynamical models of the Venus atmosphere.