Profiling the Martian Atmosphere with Solar Occultations in the UV (Mars Express/SPICAM)
Résumé
We have analyzed MEx/SPICAM solar occultations in the ultraviolet. We retrieve middle atmosphere vertical profiles of the abundance of gaseous species (CO2, O3), aerosol optical depth, and the particle size with vertical resolution of 500m or less. Recently, the SPICAM technical team has provided new corrections for the data, giving access to previously unused orbits, and new, more precise geometry files, and we have developed a method to correct for oscillations induced by the MARSIS radar antennae. We have analyzed about 700 occultations spanning 4 Mars Years (MY27-30). The results reveal the lower atmosphere dust haze, and detached layers at high altitudes. Large seasonal and interannual variations in the thickness of the near-surface dust layer are observed, particularly during the dust storm of MY28. The high-altitude detached layers show large variability, and the highest layers are found during the dust storm of MY28. We can also retrieve the particle size of the aerosols in the radius range 30-500 nm. We observe ozone profiles at certain seasons and we compare them to the LMD Mars GCM simulations. We will present a global overview of the results and some specific cases of interest.