Aerosol component of the Martian atmosphere and its variability from the results of infrared radiometry in the Termoscan/Phobos-2 experiment

Two thermal infrared images taken by the Termoscan/Phobos-2 radiometer at the morning and evening limbs of Mars are analysed. The retrieval of aerosol extinction coefficients from about 400 cross-limb brightness profiles yielded a two-dimensional distribution of the aerosol with a spatial resolution of ∼ 2 km. The aerosol vertical structure in the morning consists of two components: one is an exponentially increasing extinction from about 20 km down to the surface and the other is an aerosol layer located at 20–35 km altitude. In contrast, no aerosol layers were observed at the evening limb. In addition, the aerosol extinction in the evening showed a trend to decrease in the lower 5 km near the surface. The differences between the morning and evening observations were interpreted as an indication of the formation of the ice hazes at 20–35 km and near the surface at night on Mars.