The temporal characteristics of atmospheric aerosol optical depth over Hefei

The atmospheric aerosols above Hefei were observed systemically and chromatically with a sun photometer CE318. The aerosol optical depth (AOD) was retrieved from the direct solar radiation data between January 2002 and December 2007, and the temporal characteristics of AOD above Hefei were analyzed. The statistic results show that there are 5 daily variation types of AOD. The AOD variation with the progression of months is wavy, reaching the maximum 0727 and the minimum 0192 in April and August respectively. The AOD in spring and summer is higher than that in summer and winter and it averages at 0636 and 0262 in Spring and Summer respectively. The AOD in winter has exhibited a steady increase from 2004 to 2007.