珠三角一次重空气污染过程特征分析及数值模拟

以珠江三角州地区(珠三角)2009年11月23-29日一次重空气污染过程为例,利用常规观测资料及中尺度气象模式(MM5)、污染源排放模式(SMOKE)和空气质量模式(CMAQ)的模拟,研究此次重空气污染过程的特征.结果表明,造成此次重污染的主要原因有:①前期高压脊带来的稳定层结和静小风条件使得大气污染物逐日累积,难以扩散;②西太平洋台风向南海附近发展移动时,其外围下沉气流导致珠三角大气污染物向低层输送并积累.珠三角区域污染分布特征表明,广州和佛山的本地贡献明显,而肇庆等地受外地源输送的影响更为显著.

Characteristics Analysis and Numerical Simulation Study of a Severe Air Pollution Episode over the Pearl River Delta

Based on conventional observations and simulation results by the MM5/SMOKE/CMAQ model, the characteristics of a severe regional air pollution episode which occurred over the Pearl River Delta (PRD) during 23^rd to 29^th November 2009 were analyzed. It was found that there were two main reasons for this event: one is the stable stratification and calm winds controlled by an anticyclone which led to the accumulation of air pollutants which were difficult to diffuse. Another is the descent airflow over the PRD brought by a strong tropical storm moving from the West Pacific to the South China Sea, which led to air pollutants over the PRD migrating to the ground and accumulating. From analysis of the spatial distribution features of the pollutants, it can also be seen that local sources are more significant in Guangzhou and Foshan, but regional sources play a more important role in Zhaoqing and other areas.