Sulfur dioxide in the Venus atmosphere: Distribution and implications

The Pioneer Venus Orbiter Ultraviolet Spectrometer sees variable disk brightness features similar to the well-known "UV markings" seen at longer wavelengths. The bright features are consistent with a homogeneous cloud of H2SO4 aerosols. The darker features show the presence of a broad-band absorber, which is at some depth in the cloud layer. Additional contrast arises from SO2 absorption. The observed strength of the SO2 absorption as a function of wavelength rules out a uniform mixing ratio for the SO2. The data are well fitted by an inhomogeneous light scattering model in which the SO2 scale height is one-fifth of the CO2 scale height and the mixing ratio of SO2 at 40 mb is 1 × 10−7. A model of the oxidation of sulfur dioxide in the upper cloud reproduces the observed vertical distribution of SO2 and indicates that SO2 alone is sufficient to produce the observed amount of H2SO4 in this region.

[1]  J. Pollack,et al.  Venus Lower Atmospheric Composition: Analysis by Gas Chromatography , 1979, Science.

[2]  R. Prinn.  Venus: Chemistry of the lower atmosphere prior to the Pioneer Venus mission , 1978 .

[3]  U. Zahn,et al.  Venus: eddy coefficients in the thermosphere and the inferred helium content of the lower atmosphere , 1979 .

[4]  D. Hunten,et al.  11. Pioneer venus experiment descriptions , 1977 .

[5]  D. Shemansky,et al.  CO2 Extinction Coefficient 1700–3000 Å , 1972 .

[6]  J. W. Hovenier,et al.  Interpretation of the polarization of Venus , 1974 .

[7]  L. Travis,et al.  On the origin of ultraviolet contrasts on Venus. , 1975 .

[8]  E. Barker.  Detection of SO2 in the UV spectrum of Venus , 1978 .

[9]  P. H. Smith,et al.  Preliminary Results of the Solar Flux Radiometer Experiment Aboard the Pioneer Venus Multiprobe Mission , 1979, Science.

[10]  P. Warneck,et al.  Ultraviolet Absorption of SO2: Dissociation Energies of SO2 and SO , 1964 .

[11]  D. Hunten,et al.  Clouds of Venus: A Preliminary Assessment of Microstructure , 1979, Science.

[12]  A. T. Young.  Chemistry and thermodynamics of sulfur on Venus , 1979 .

[13]  L. Esposito.  An 'adding' algorithm for the Markov chain formalism for radiation transfer , 1979 .

[14]  L. Esposito,et al.  Radiative transfer calculated from a Markov chain formalism , 1977 .

[15]  D. Hunten,et al.  Clouds of Venus: Particle Size Distribution Measurements , 1979, Science.

[16]  L. Esposito,et al.  Ultraviolet Spectroscopy of Venus: Initial Results from the Pioneer Venus Orbiter , 1979, Science.