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L. Zasova (IKI-Space Research Institute, Moscow, Russia), V. Formisano, D. Grassi, A. Maturilli (IFSI-CNR Area di Ricerca di Roma - Tor Vergata, Italy)
Martian atmosphere in the region of Great Volcanoes was investigated, using the IR thermal spectra, obtained by Mariner 9 Fourier spectrometer (IRIS). The data have been corrected for the instrumental effect. This effect distorted the spectra significantly, especially in the range n > 900 cm-1. It was analyzed 335 spectra in the Tharsis Volcanoes region, obtained for the period from Ls =314° to 348° in the latitude range j =20°S - 10°N and longitude range l = 90° - 150° in the afternoon between 13 and 18 H of local time. The temperature and aerosol profiles have been retrieved in a self-consistent way from each spectrum. A comparison of synthetic spectra, calculated for the retrieved parameters, to the measured ones shows that after correction for the instrumental effect a reasonable agreement may be reached in all spectral range from 200 to 2000 cm-1. It was found that the aerosol optical depth (near 1000 cm-1) varies in the range 0.05 < ta < 0.45. Atmospheric temperature depends on the dust loading in the atmosphere: the afternoon temperature at 0.1 mb level changes in the range of about 160-190K, when aerosol optical depth changes between 0.05 and 0.45. The highest surface temperature Ts >280K was found for the early afternoon. It was shown that the surface temperature correlates with local time and altitude. The water containing clouds, observed above the south slope of Arsia Mons, appear to have the optical depth 0.25±0.5.
The author(s) of this abstract have provided an email address for comments about the abstract: zasova@irn.iki.rssi.ru