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J.C. Pearl, M.D. Smith (NASA/GSFC), B.J. Conrath (Cornell University), P.R. Christensen (Arizona State University)
The Mars Global Surveyor spacecraft has been in its mapping orbit for nearly a martian year. Infrared spectra returned by the Thermal Emission Spectrometer (TES) provide information on the thermal structure and the distribution of aerosols in the martian atmosphere. Combined nadir- and limb-viewing observations allow global monitoring of the atmosphere up to 0.01 mbar (65 km). We report here on the atmospheric thermal structure and the horizontal and vertical distribution of aerosols determined thus far during the mapping phase of the MGS mission. Zonal and temporal mean cross sections are used to investigate the seasonal evolution of atmospheric temperatures and zonal winds during a period extending from northern hemisphere mid-summer through the winter. Temperature maps at several pressure levels allow characterization of the winter polar vorticies and associated planetary-scale waves. Retrieved maps of atmospheric infrared dust opacity show the formation and evolution of regional dust storms during southern hemisphere summer. An immediate strong response in the atmospheric thermal structure to the changing dust loading is observed. Maps of water ice opacity as determined from the thermal infrared show numerous orographic clouds, as well as strong seasonal development and decay of the low latitude aphelion cloud belt, as prominent a feature of northern summer as dust storms are of southern summer.