Sulfur aerosol in the clouds of Venus

• Published in: Icarus (New York, N.Y. 1962) N.Y. 1962), 2016-08, Vol.274, p.33-36
• Main Author: Krasnopolsky, Vladimir A.
• Format: Article
• Language: English
• Subjects: Abundance; Aerosols; Atmospheres, composition; Boundaries; Clouds; Mathematical models; Mixing ratios; Photochemical; Sulfur; Venus; Venus, atmosphere
• ISSN: 0019-1035; 1090-2643
• DOI: 10.1016/j.icarus.2016.03.010

•Chemistry of the middle atmosphere forms very low abundances of sulfur aerosol.•Significant abundances of sulfur vapor are formed in the lower atmosphere.•Predicted sulfur aerosol constitutes 10% of the lower cloud layer.•Sulfur aerosol is not the NUV absorber. The photochemical model for the middle atmosphere of Venus (Krasnopolsky, V.A. [2012] Icarus, 218, 230–246) predicts sulfur aerosol as a product of the OCS photolysis at 55–60km. The calculated mass loading is much smaller than that of the mode 1 particles in the upper cloud layer. The chemical kinetic model for the lower atmosphere ( Krasnopolsky, V.A. [2013], Icarus, 225, 570–580) results in a constant mixing ratio of 20ppm for OCS+XSX. This means the S8 mixing ratio of 2.5ppm near the model upper boundary at 47km. Using this abundance, the calculated profile of the sulfur aerosol has a bottom that coincides with the lower boundary of modes 2 and 3 and constitutes ∼10% of the total mass loading in the lower cloud layer. Sulfur aerosol cannot be the near UV absorber because its abundance is too low at the cloud tops and disagrees with the profile of the absorber observed by Venera 14.