南京一次典型雾霾天气气溶胶光学特性

利用太阳光度计测得的直射太阳辐射和天空扫描数据,对南京北郊2010年冬季一次雾霾天气过程中气溶胶的光学特性进行了反演研究.研究表明,雾霾影响期间气溶胶光学厚度(AOD)明显增加,在1020,870,675,440nm四个波段上,雾霾前AOD为0.16~0.43,雾霾影响期间为0.31~0.84,雾霾后为0.19~0.48;本次雾霾天气的局地气溶胶散射能力增强,单次散射反照率(SSA)由发生前的0.8~0.86增大到发生时的0.89~0.91,而复折射指数的虚部降低,气溶胶的吸收能力明显减弱;雾霾过程伴随了大尺度气溶胶的导入,同时也有人为排放的贡献.其中雾霾影响期间粗粒子模态的体积浓度是发生前的2.5倍,细粒子浓度也比发生前增长了90%.

Aerosol optical properties during the typical haze/fog event in Nanjing

The aerosol optical properties during haze/fog event were analyzed in the north suburb of Nanjing in the winter of 2010 by using direct solar irradiance and sky radiance of CE318 sun-photometer. Under the influence of haze/fog, the aerosol optical depth (AOD) showed a higher value. The values of AOD at 440, 675, 870 and 1020 nm varied from 0.16 to 0.43 before the haze and fog episodes, increased to 0.31~0.84 during the haze/fog influencing periods and reduced to 0.19~0.48 after the haze/fog process. The higher single scattering albedo (SSA) occurred in haze/fog influencing periods with value of 0.89~0.91. The imaginary part of complex refractive index decreased after the fog/haze days. These results suggests that the enhancement of scattering ability and the decrease of absorption ability of local aerosols. During the haze/fog episodes, the aerosol size distribution come from the addition of coarse aerosol particles and the contribution of the anthropogenic fine particles. The volume concentration of coarse mode increased by 2.5 times, with the lower value of 0.033 μm3/μm2 before the outbreak of the fog/haze process and 0.082 μm3/μm2 during the fog/haze influencing periods. The volume concentration of fine mode also increased by 90% compared to the before the events.