The aerosol optical depth retrievals from ground sunphotometer measurements in Yangtze River Delta of China

The aerosol optical depth was affected by the chemical composition, the particle size and the shape of aerosol as well as the water vapor in the atmosphere; it is an important indicator for air pollution. The special and temporal characteristics of aerosol optical depth (AOD) was measured by CE318 sun-photometer, Angstrom wavelength exponent (α) and the aerosol turbidity coefficient (β) were calculated in Shanghai, and Lin'an in Yangtze River Delta from 2007 to 2008. We also analyzed the relationship between AOD and Angstrom wavelength exponent (α) in these stations. The results show that there are different pattern of AOD in this gradient of urban and suburban region. Lin'an station had two peaks of AOD, but Shanghai stations had single peak of AOD in measurement year. The difference of AOD seasonal pattern exists in two sites. The Angstrom wavelength exponent (α) analysis suggests that the aerosol sizes in two stations various from fine particle in autumn to coarse particle in spring. The seasonal patterns show that spring air pollution is serious, summer is relatively clean, and autumn and winter are relative serious in two stations.