北京2010年10月一次典型灰霾过程光学特性分析

摘要

Based on the sounding data, NECP reanalysis data and AERONET aerosol retrieval data, the causes of one typical haze event in Beijing as well as the variation of aerosol optical properties parameters during this episode were analyzed. The analysis showed stable circulation pattern and high humidity environment together with inversion structure were responsible for the persistence and development of haze during this period. Due to the accumulation of local aerosols with the growing relative humidity, AOD and the concentration of PM2.5 were gradually on the increase, instead, visibility took on an opposite trend. Besides, particle extinction was enhanced at the same time. Aerosol volume spectrum exhibited bimodal structure, the peak concentration of fine aerosol particles increased day by day and was much greater than the coarse’s, the Angstrom exponent index varied from 1.2 to 1.4. These two parameters could indicate that the dominating particles were mainly contributed by fine aerosols during this episode. The increasing higher SSA suggested the enhancement of scattering ability. SSA changed with wavelength presenting two major trends, which was associated with the size of the dominating particles of the day. In addition, radiation flux reaching ground declined because of the existence of aerosols. These aerosol optical properties parameters provided references to explore the aerosol characteristics and climate effect during haze event in Beijing.%利用探空资料、NECP 再分析资料、AERONET 气溶胶反演资料等分析了北京地区一次典型灰霾天气过程的成因及气溶胶光学特性参数变化情况.结果表明：此次灰霾期间,稳定的环流形势、湿润的环境及逆温结构的存在是灰霾得以持续和发展的重要原因.灰霾期间AOD、PM2.5浓度逐渐增大,能见度逐渐降低,这可能与局地气溶胶的累积和相对湿度的增大有关,使气溶胶粒子的消光性增强.气溶胶的体积谱表现为双峰型结构,细粒子体积浓度峰值远大于粗粒子浓度峰值,且细粒子浓度峰值逐日增大,Angstrom波长指数在1.2~1.4之间,两参数均可表明此次灰霾过程的污染粒子以气溶胶细粒子为主；灰霾期间SSA逐日增大,表明气溶胶粒子的散射性逐渐增强,SSA随波长的变化主要呈现两种变化趋势,这与当日主控粒子的尺度有关.因气溶胶的作用,使到达地面的辐射通量减小.这些光学特性参量的变化为了解北京地区灰霾期间气溶胶特性及其气候效应提供了参考.