Variation of atmospheric aerosol optical depth and its relationship with climate change in western China

Vsmg an indirect method, aerosol optical depths (AODs) are calculated based on atmospheric visibility and water vapor pressure measured at 94 key climate stations in western China (west of 100°E) over 1961-2005. Inferred AODs are compared with the MODIS satellite measurements for year of 2004. Results show that AODs averaged over 1961-2005 exhibit large values in southern Xinjiang basin and south of Tianshan mountains, and there is another high AODs in the eastern TP. Inferred AODs in western China show over southern Xinjiang basin and south of Tianshan mountains the strength of AODs increase during the period from 1960s to 1980s and decrease after 1990s. As far as AODs over the eastern TP are concerned, the strength decreases since 1960s and reach the minimum value during the turn of 21 century. Statistical analysis shows that variations in AODs correlate with the changes in precipitation and air temperature in western China from 1961 to 2005. The results show that the increases in AOD are coincident with the increases in rainfall and air temperature in the northern Xinjiang, drought in rainfall and the cooling in surface air temperature in the eastern TP.