Minor gaseous constituents and aerosols of the Venus mesosphere measured by SPICAV/SOIR on board Venus Express
Résumé
The SOIR instrument performs solar occultation measurements in the IR region (2.2 - 4.3 μm) at a resolution of 0.12 cm-1, the highest on board Venus Express. It combines an echelle spectrometer and an AOTF (Acousto-Optical Tunable Filter) for the order selection. A brief description of the instrument and its in- flight measured performances will be presented. The wavelength range probed by SOIR allows a detailed chemical inventory of the Venus atmosphere above the cloud layer (65 to 150 km) with an emphasis on vertical distribution of the gases. In particular, measurements of HDO, H2O, HCl, HF, CO and CO2 vertical profiles have been routinely performed. Temperature retrieval will be described and tentative results presented. Aerosols extinction profiles are also simultaneously retrieved from the SOIR spectra. Some results for selected orbits will be investigated and discussed. It will be shown that size distribution can be addressed but only when considering all three channels of the SPICAV/SOIR instrument.