Composition of the Venus mesosphere measured by Solar Occultation at Infrared on board Venus Express

Abstract

Solar Occultation at Infrared (SOIR), which is a part of the Spectroscopy for Investigation of Characteristics of the Atmosphere of Venus (SPICAV) instrument on board Venus Express, combines an echelle‐grating spectrometer with an acoustooptical tunable filter. It performs solar occultation measurements in the IR region at a high spectral resolution better than all previously flown planetary spectrometers. The wavelength range probed allows for a detailed chemical inventory of the Venus atmosphere above the cloud layer, with an emphasis on the vertical distribution of the gases. A general description of the retrieval technique is given and is illustrated by some results obtained for CO 2 and for a series of minor constituents, such as H 2 O, HDO, CO, HCl, and HF. Detection limits for previously undetected species will also be discussed.