Seasonal variation of atmospheric aerosol optical properties in Beijing during 2009—2011

REN Tuanwei;GUO Zhaobing;LIU Weijia;School of Environmental Science and Engineering,Nanjing University of Information Science and Technology;School of Atmospheric Physics,Nanjing University of Information Science and Technology;Key Laboratory for Aerosol-Cloud-Precipitation of China Meteorological Administration;  

Using on the ground-based aerosol retrieval data of AERONET from 2009 to 2011,the seasonal properties of aerosol optical properties in Beijing were analyzed. Our study indicates that the aerosol optical thickness( AOT) and Angstrom exponent( α) had quite different daily variations in different seasons. Daily average AOT is mainly affected by local aerosol emission,atmospheric stability condition as well as solar radiation. α had a maximum value or exhibited a slight increasing trend after mid-day. The AOT showed significant seasonal variation,and increased in spring and summer while declined in autumn and winter with an annual average of 0.63. The seasonal variations are related to the typical characteristics of the monsoonal climate in Beijing. The α displayed a single peak in all seasons. Because of the discontinuous emission of dust aerosol in spring,α had widest probability distribution with maximum standard deviation and minimum value. The probability of α0.5 exceeded 10%,which indicates that coarse particles accounted for the largest fraction during thewhole year. α became greater than 1. 1 in summer and autumn,due to the typical urban-industrial aerosols during these two seasons. Furthermore,both seasonal average( greater than 0.9) and annual average( 1.07) of α indicate that aerosols in Beijing are dominated by fine particles throughout the whole year. Column content of water vapor showed clear seasonal variation,which is the same as that of the precipitation. It increased to a maximum value of 2. 33 cm in summer and decreased to a minimum value of 0.30 cm in winter,the values of spring and autumn varied between the two.

【Fund】： 国家自然科学基金(41373023);; 江苏省环保科研课题(2014t016)资助
【CateGory Index】： X513

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