Simulations of the Atmospheric Microwave and Millimeter Wave Emission from Venus using a Radiative

Introduction: The Georgia Tech Venus Radiative Transfer Model (VRTM) can be used to model the effects of the abundances of microwave and millimeter wave absorbing constituents on the emission from the Venus troposphere and mesosphere. The primary components of the Venus atmosphere are CO2 and N2, but variation in concentration of sulfur compounds, specifically gaseous H2SO4 and SO2, result in continuum brightness temperature variations from the troposphere at microwave and millimeter wavelengths. Sulfur compound opacity formalisms have been empirically verified through laboratory experiments that use cavity and open resonators to differentially measure the complex permittivity of gas mixtures at temperatures and pressures representative of Venus conditions [1]. Such experiments can be used to validate pressure-broadened lineshape models. In cases where such line-based models do not match measured data, continuum best fit models are developed. These opacity formalisms are combined with temperature/pressure profiles from previous Venus missions to form the radiative transfer model. Estimates of microwave and millimeter wave emission derived from this model have many applications in Venus radio astronomy, such as the interpretation of observations from the Combined Array for Research in Millimeter-wave Astronomy (CARMA) [2] and the Atacama Large Millimeter Array (ALMA) [3]. This radiative transfer model will be of specific use to remote study of atmospheric abundances of sulfur dioxide and sulfuric acid in accordance with VEXAG Goals I.C and III.B [4].