Analyses of spectroscopic and atmospheric parameter influences on radiative heating and cooling rates in the middle and lower atmosphere of Venus

Abstract

Radiative fluxes and temperature change rates in the middle and lower atmosphere of Venus (0-100 km) are calculated over the broad spectral range 0.125- 1000 μm applying a radiative transfer model. Responses of these quantities to both spectroscopic model parameter changes and atmospheric parameter variations are examined in great detail. A new model for the unknown UV absorber is proposed. The calculated radiative cooling/heating rates are very reliable at altitudes below 95/85 km at fixed atmospheric conditions with maximum uncertainties of about 0.25 K/day. Heating uncertainties may reach 3-5 K/day at 100 km. Cooling rates strongly respond to variations of atmospheric thermal structure, while heating rates are less sensitive. Except for episodic SO2 boosts, the influence of mesospheric minor gas abundance variations is rather small, but variations of cloud mode parameters may significantly alter radiative temperature change rates up to 50% in Venus’ lower mesosphere and upper troposphere.