Long term variation trends of aerosol optical depth in China from MODIS and toms

摘要

TOMS AOD at 500nm (1980–2001), combined with MODIS data (2000–2008) at 550nm, are used to perform trend analysis of AOD, temporally and spatially, over eight typical regions in China. The variation trends are as follows: firstly no notable upward or downward tendencies in AOD during 1980–1992 for the relative low value (−0.0006/decade), then during 1996–2001 a discernible ascending tendency with larger magnitude at 0.0231/decade, and finally, since 2000, a weak downward trend with −0.0017/decade. The large increases during 1990's are presumably consequences of sharp increases in industrial and anthropogenic activities. In particular, in late 1990's, only in Taklimakan Desert a negative trend with a maximum magnitude of −0.04/decade is detected. However, over regions such as Jingjinji and Pearl River Delta influenced by industrial activities, positive tendencies at +0.01/decade are observed.