Meteorology with Omega and Spicam aboard Mars Express
Abstract
The combination of instruments aboard Mars Express allows us to observe new aspects of the Martian atmosphere (atmospheric circulation and composition, clouds, aerosols). Among Mars Express unprecedented measurements, we will foccuss on the first remote sensing observations of the upper atmosphere thermal structure by Spicam and the high resolution mapping of surface pressure variations by Omega. First, the occultation of numerous stars rising or setting through the Martian atmosphere as seen by the Spicam UV spectrometer allows to retrieve the CO2 density and thus the temperature from below 40 km to above 120 km. This part of the atmosphere was previously almost unknown since very few measurements were available (a few entry profiles). Moreover atmospheric models have shown that this part of the atmosphere presents a very active and interesting dynamic, but that simulation predictions are extremely model dependent. Preliminary analysis suggests that the lower nocturnal thermosphere is often colder than expected. Several hundreds profiles covering a wide range of latitude and season have now been obtained, and statistics on the seasonal evolution of the high atmosphere will be presented. Second, maps of surface pressure are retrieved by inverting the 2 microns CO2 absorption band. For this purpose, a fast and accurate radiative transfer model has been developed, with particular attention to atmospheric dust and surface spectra. The measured surface pressure is primarily sensitive to the surface altimetry. Using the accurate MOLA topography, we can retrieve a meteorological signature (e.g. mountain waves). Beyond Mars meteorology, since such a measurement is not possible on the Earth, it is of high interest for atmospheric science in general.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2005
- Bibcode:
- 2005AGUFM.P14A..06F
- Keywords:
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- 3329 Mesoscale meteorology;
- 3369 Thermospheric dynamics (0358);
- 5704 Atmospheres (0343;
- 1060)