Geophysical Research Letters RESEARCH LETTER Identification of OSSO as a near-UV absorber 10.1002/2016GL070916 in the Venusian atmosphere Key Points: 1 2 1 • Identification of new sulfur oxides in Benjamin N. Frandsen , Paul O. Wennberg , and Henrik G. Kjaergaard the Venusian atmosphere • Near-UV absorption of OSSO matches 1Department of Chemistry, University of Copenhagen, Copenhagen, Denmark, 2Division of Engineering and Applied missing absorber on Venus Science and Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California, USA • Important sulfur oxide reservoir found below 70 km altitude Abstract The planet Venus exhibits atmospheric absorption in the 320–400 nm wavelength range Supporting Information: produced by unknown chemistry. We investigate electronic transitions in molecules that may exist in the • Supporting Information S1 atmosphere of Venus. We identify two different S O isomers, cis-OSSO and trans-OSSO, which are formed • Table S1 2 2 • Table S2 in significant amounts and are removed predominantly by near-UV photolysis. We estimate the rate of photolysis of cis- and trans-OSSO in the Venusian atmosphere and find that they are good candidates to explain the enigmatic 320–400 nm near-UV absorption. Between 58 and 70 km, the calculated OSSO Correspondence to: H. G. Kjaergaard, concentrations are similar to those of sulfur monoxide (SO), generally thought to be the second most
[email protected] abundant sulfur oxide on Venus. Citation: Frandsen, B. N., P. O. Wennberg, and 1. Introduction H. G. Kjaergaard (2016), Identifica- tion of OSSO as a near-UV absorber In 1974, the first spacecraft passed by Venus and took high-resolution spectra of the planet [Dunne, 1974; in the Venusian atmosphere, Geo- Murray et al., 1974].