ATMOSPHERIC RADIATION, OPTICAL WEATHER, AND CLIMATE On Results of Studies of Atmospheric Aerosol Optical Depth in Arctic Regions

We discuss the characteristics of the spectral aerosol optical depth (AOD) of the atmosphere mea� sured using sun photometers in highlatitude regions (Spitsbergen, Tiksi, Yakutsk). The seasonal variations are characterized by a decrease in AOD from spring to fall by approximately a factor of 2 in Yakutia and by a factor of 1.5 in the region of Spitsbergen. It is shown that the high selectivity of the spectral AOD dependence in warm period (with Angstrom parameters varying from 1.3 to 1.8) was caused by low content of coarsely dis� persed aerosol. Multiyear data of MODIS satellite observations are used to estimate the spatial distribution of turbidity; it is shown that satellite observations systematically overestimate AOD over Arctic seas.