Analysis of Spatial and Temporal Variation Characteristics of Atmospheric Aerosol Optical Depth: A Case Study of Chongqing

Using EOS-Terra/MODIS in 2005-2007 to retrieve aerosol optical depth, spatial and temporal variations of aerosol optical depth in Chongqing was studied. The results show that the monthly distribution is characterized by double peak and double valley. The peak values appear in April, secondary peak in September, the minimum value in November and the other valley value in August. Seasonal change of aerosol optical depth in spring has a high level, comparatively stable in summer; peak appear in autumn, and the value keeps at low level in winter; annual variation shows the tendency to diminish in spring and increase gradually year by year; monthly change principle is basically identical; spatial distribution totally shows "high west , low east. " After going to summer from spring, the value mainly in the southeast, central area and west increases; going to autumn from summer, the value in most areas increases; going to winter from autumn, the value only in areas with decrease in autumn or with very little change increases slightly, mainly in the areas to the north of the Yangtz River and to the west of Wanzhou. Yearly average is characterized by that the value in western area is obviously higher than that in other areas, and in the southeast and in the area along Three-Gorge Reservoir higher.