Vertical Distribution of the Aerosol Optical Characteristics during the 2008 Beijing Olympic Games

The effect of air pollution control in Beijing and its surrounding areas during the 2008 Beijing Olympic Games was evaluated by using the analysis of aerosols extinction vertical distribution (from lidar) and aerosol backward trajectory. The results indicated:1) In general，aerosol extinction coefficients decrease within various altitudes (notably below 600 m and within 1200－4000 m) in 2008 compared to trends in 2007. 2) Statistical analysis of the different types of the extinction coefficient showed that high pollutant concentrations in 2008 mainly occurred in the vicinity of the boundary layer confirming the decrease of the extinction coefficients near the ground. Description of the aerosols backward trajectory showed that the aerosols (mainly transported from Beijing surrounding areas) displayed the extinction coefficient decrease by about 18.1% below 400 m. This highlighted significant impact of air pollution control efficiency in the surrounding areas on the air quality improvement in Beijing.