Distribution of aerosol optical depth and possible factors influencing dust optical depth over arid and semi−arid Eurasia

In this paper, long-term temporal and spatial distribution characteristics of aerosols in arid and semi-arid regions of Eurasia (30° N - 60° N, 25° E - 90° E) from 2001 to 2021 were studied by combining Moderate−resolution Imaging Spectroradiometer (MODIS), Cloud−Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) (2007-2021) and Ozone Monitoring Instrument (OMI) observations.  Aerosol types over Eurasia were studied based on aerosol optical depth (AOD), Ångström exponent (AE), and aerosol single scattering albedo (SSA). The results show that the average AOD (obtained from MODIS) is high in the Taklimakan, Tar, Kizikom, and Syria deserts. Seasonal aerosol concentrations in Xinjiang, Iraq, Iran, Kazakhstan, Uzbekistan, and Turkmenistan were the highest in spring, the second-highest in summer, and the lowest in autumn and winter. Clean marine and mixed aerosols are the primary aerosol types in the Eurasia. The relative contribution of meteorological factors to dust optical depth (DOD) and its long-term variation have been quantified by stepwise regression model. The model results show that the contribution of humidity at 500 hPa (H500) to the change of DOD is 28%, the contribution of wind speed (WS) to the change of DOD is 19%, and the contribution of temperature (T) to the change of DOD is 12%.  The spatial distribution of the correlation coefficient between DOD and meteorological factors is higher under the bare surface compared to complex terrain. This result highlights the sensibility of meteorological factors on the distribution of DOD in the desert. The results presented in is paper are helpful for understanding the interaction between DOD and meteorological factors.

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