深圳城市气溶胶物理光学特性的观测研究

The Measurement of Aerosol Optical Properties Over Shenzhen

气溶胶是影响气候变化和空气污染的重要因子.在深圳地区展开气溶胶观测实验,可以获得可靠的光学物理特征,进而有助于准确评估气溶胶在新型超极城市区域的气像和环境效应.本文利用2010年12月至2011年8月太阳光度计、黑碳和浊度计等气溶胶观测资料,分析了新型超级城市深圳地区的气溶胶物理光学特性.深圳地区气溶胶呈明显季节变化,冬、春季由于城市污染性气溶胶的影响,气溶胶光学厚度和Angstrom波长指数都较大,夏季受海盐气溶胶的影响,光学厚度较小,Angstrom波长指数也较小.光学厚度与Angstrom波长指数对比表明城市综合性污染是引起深圳气溶胶高光学厚度的主要原因.深圳地区气溶胶的散射系数、吸收系数的平均值(标准偏差)分别为178.7×10-6 m-1(126.6×10-6 m-1)和32.5×10-6 m-1(18.1×10-6 m-1),均低于珠三角腹地多年观测平均值的二分之一和国内其他大型城市观测值.而单次散射反照率为0.81,与珠三角其他地区得到的结果接近.此外,气溶胶吸收、散射和单次散射反照率呈明显日变化,可能主要受大气边界层变化的影响.

Atmospheric aerosols is a key element of climate changes and air pollution, the analysis of the aerosol optical and physical properties can reduce uncertainties in the quantitative assessment of aerosol effects on regional climate and environmental changes, especially in the mega-city. In this study, from December 2010 to August 2011, in situ measurements of aerosol optical properties were conducted at rural and city sites of the mega-city Shenzhen in southeast China. The aerosol optical depth showed a seasonal cycle with the lowest values in summer, while the highest values occurred in winter and spring. The annual cycle of Angstrom wavelength exponent showed a summer minimum associated with sulfate aerosols, and a spring/winter maximum associated with heavy air pollution. The scatter grams of the optical thickness and Angstrom wavelength exponent also indicates that the high aerosol optical thickness mainly come from the city pollution. Mean values (standard deviation, S.D.) of scattering and absorption coefficients for the entire period are 178.7×10-6 m-1(126.6×10-6 m-1) and 32.5×10-6 m-1(18.1×10-6 m-1) respectively. These values are approximately half of the reported values obtained in the Guangzhou urban area. The mean single scattering albedo for the entire period was estimated as 0.81, which is similar to the values reported for the other urban area. The daily variations of aerosol absorption and scattering coefficients were strongly influenced by synoptic changes throughout the observation period.