| School of Electrical and Computer Engineering | |
Gaseous sulfur dioxide (SO2) has long been recognized as one of the primary absorbers in the Venus atmosphere at microwave frequencies (3 < f < 30 GHz). However, the effects of gaseous SO2 on the millimeter-wave emission of Venus are not fully understood. This is mainly due to the lack of measurements of opacity under Venus-like conditions at millimeter wavelengths (lambda < 1 cm), 21.7 GHz (1.32 cm), and 94.1 GHz (0.32 cm). The results of our measurements show a close agreement with th absorptivity predicted from a Van Vleck-Weisskopf formalism at the two shortest wavelengths but not at the longest wavelength. In addition, our results show a frequency dependence that is slower than the f2 dependence of absorptivity proposed by Janssen and Poynter (Icarus 46, 51-57, 1981) and Steffes Eshleman (Icarus 48, 180-187, 1981). Our results are incorporated into a radiative transfer model to infer a new abundance profile for gaseous SO2 in the middle atmosphere of Venus. Finally, the developed model is used to determine the effects of a SO2/CO2 gaseous mixture on the millimeter-wavelength spectrum of Venus.