利用拉曼米散射偏振激光雷达对2009年11月珠江三角洲地区出现的一次灰霾天气过程进行了观测研究,对颗粒物 的光学性质和物理参数进行了分析。灰霾发生期间,颗粒物主要分布在1.5 km以下,其中0.6~1 km高度的浓度 较大。灰霾发生前期,颗粒物在532 nm波长退偏比为0.2, Angstrom指数和雷达比分别为1±0.4和 40±8 sr, 表明灰霾颗粒物中有大量非球形粒子,粒径大,符合一次污染源排放的颗粒物特征; 11月25日后,颗粒物在532 nm波长 退偏比逐渐变小至0.07±0.02, Angstrom指数为1.5±0.6,激光雷达比为56±12 sr,说明颗粒物 多为球形粒子,细粒子占比较大。观察结果表明,前期轻度灰霾天气期间,颗粒物主要为人为源污染源排放,为大 气复合污染提供了条件,随着污染物不断聚集,25日后二次颗粒物大量生成,加剧了灰霾污染。

Aerosol optical and microphysical parameters of particles under severe haze polluted condition in the Pearl River Delta (PRD) in Southern China in November 2009 were observed by using Raman-Mie polarized lidar. It was found that the haze layer was distributed below 1.5 km, and the concentration of haze layer was comparatively thicker at the heigh of 600~1000 m, the characteristics of dust haze were analyzed and discussed. In the beginning, the depolarization ratio in 532 nm wavelength is 0.2, Angstrom exponent and lidar ratio of the haze were 1±0.4 and 40±8 sr, respectively. It meant that there was a large number of non-spherical particles and large size particles in the haze particles, it was in line with characteristics of anthropogenic emissions particles. After November 26, 2009, the depolarization ratio in 532 nm wavelength of haze particles gradually decreases to 0.07 ± 0.02, Angstrom exponent and lidar ratio also changed to 1.5±0.6 and 56±12 sr, respectively. It was proved that there was a larger proportion of fine particles in haze, and the particles were mostly spherical particles. It meant that a large number of the second particles were generated after November 25, which aggravated the haze pollution. The result indicated that at the beginning, some artificial particles resulted in the light haze, these artificial source provided the condition for compound air pollution, with the second particle generating, the haze pollution was further aggravated.