基于风廓线仪等资料的珠江三角洲污染气象条件研究

利用珠江三角洲区域空气质量资料和珠海、南沙、增城的逐30 min风廓仪观测资料,以及清远探空站每天08时和20时的温度探空资料等,研究了2012年10月珠江三角洲出现的大范围持续性污染天气期间的大气边界层特征.结果表明:2012年10月珠江三角洲出现的大范围持续性污染天气主要是受到弱冷空气南下和台风外围下沉气流天气形势的影响;在污染日,增城、南沙和珠海低层风速普遍小于3 m·s-1,300m高度以下风速甚至小于2 m·s-1,增城和珠海观测站的通风量普遍小于5000~6000 m2·s-1;非污染日的通风量则远远大于污染日;在近海的南沙站和珠海站,海陆风等局地环流的的作用不利于污染物的扩散,海风约出现于下午6时,最大影响高度约600~800 m;逆温层是导致重污染的天气的重要原因,清远探空站频繁出现逆温层,甚至出现多层低空逆温,污染日的逆温层平均厚度和平均强度都较大.

Meteorological condition associated with poor air quality over Pearl River Delta based on the data of radar wind profiler

Based on the regional air quality data over Pearl River Delta (PRD), the wind profile data with 30 min time resolution in Zhuhai, Nansha, and Zengcheng, and the temperature sounding data at 8 a. m. and 8 p. m. in Qingyuan, the structure of atmospheric boundary layer associated with large-scale persistent pollution weather in October 2012 over PRD was studied. It was found that the large-scale persistent pollution weather was mostly influenced by the weather systems of weak southward moving cold air and the subsidence of tropical cyclone. During the poor air quality days, the ventilation indexes of Zengcheng and Zhuhai were smaller than 5000~6000 m²·s^-1 mostly, the wind speeds of Zengcheng, Zhuhai and Nansha were generally smaller than 3 m·s^-1 in the lower atmosphere, and the wind speeds below 500 m were even smaller than 2 m·s^-1. The ventilation indexes of clean days were significantly larger than those of poor air quality days. In the offshore stations of Nansha and Zhuhai, the influence of sea-land breezes was bad for the diffusion of pollutants, with the sea breeze emerging at about 6 p. m. and the maximum effect height about 600~800 m. Inversion layer is also a very important factor to poor air quality which occurred frequently in Qingyuan station. Multi-inversion layers sometimes even occurred. Furthermore, the mean thickness and intensity of inversion layer were quite large during pollution days.