Update on SO2, detection of OCS, CS, CS2, and SO3, and upper limits of H2S and HOCl in the Venus mesosphere using SOIR on board Venus Express

• Published in: Icarus (New York, N.Y. 1962) Vol. 399; p. 115556
• Main Authors: Mahieux, A., Robert, S., Mills, F.P., Jessup, K.L., Trompet, L., Aoki, S., Piccialli, A., Peralta, J., Vandaele, A.C.
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 15.07.2023
• Subjects: Infrared spectroscopy; Mesosphere; Sulfur species; Venus; Infrared spectroscopy; Sulfur species; Mesosphere; Venus
• ISSN: 0019-1035; 1090-2643
• DOI: 10.1016/j.icarus.2023.115556

We report on the update of SO2 and first detections of SO3, CS, and CS2, and detection of OCS above the cloud deck using the SOIR instrument on-board Venus Express, and upper limit profiles of H2S and HOCl. Based on the solar occultation spectra measured by SOIR covering all latitudes over the 2006–2014 period, we find an average SO2 volume mixing ratio of ∼0.02 ppm below 90 km which increases to 5 ppm at 100 km; average OCS abundance of 1 ppb to 1 ppm between 65 and 100 km increasing with altitude; mean SO3 values of 0.1 ppm at 75 km, 1 ppm at 85 km, and 10 ppm at 95 km; CS volume mixing ratios varying from 0.1 ppm at 65 km to 40 ppm at 100 km; finally we report 0.03 ppm of CS2 at 70 km and 5 ppm at 90 km. It is important to note the detections for all of these species may be biased to higher volume mixing ratios at higher altitudes based on the detection limits for SOIR. Upper-limits for H2S and HOCl are determined. All abundances show large variabilities with time and/or latitude equal to at least one order of magnitude at all altitudes. We also study the detection statistics of all detected species as a function of time, latitude, and side of the terminator. •First detection in the Venus mesosphere of OCS, SO3, CS, and CS2.•Update of the SO2 concentrations.•Impact on Venus mesospheric chemistry.