【摘要】 利用珠江三角洲56个环保监测站PM2.5浓度、广东省89个国家气象站的地面风向风速和2部风廓线雷达风、温廓线数据,分析了珠江三角洲PM2.5局地污染事件的时空变化特征及其背景环流特征。结果表明:1)珠江三角洲广州、佛山和肇庆为PM2.5污染中心,冬半年发生污染的频率高于夏半年,一天内夜间至次日凌晨发生的频次最高。2)PM2.5局地污染的天气形势可分为大陆冷高压底部型、海上变性高压脊性、副热带高压型和热带气旋外围偏北下沉气流等四种。3)PM2.5局地污染受局地环流影响大,山体、平原、海洋和城市的热力条件不同,地面风场发生变化,形成地面弱辐合线,阻止了污染的水平扩散,同时弱的偏北风从广东省北部山地倾泻下来,在珠江三角洲形成边界层内的下沉气流,抑制了污染的垂直输送,导致近地面的污染出现。更多还原

【Abstract】 In this paper, the spatial-temporal characteristics and the background circulations of local PM_2.5 pollution（LPP） episodes in the Pearl River Delta are analyzed by using the PM_2.5 data from 56 air quality monitoring stations and the meteorological data from 89 National Basic Weather Stations and 2 wind profile radars. The conclusions are as follows. First, the LPP episodes recorded in Guangzhou, Foshan and Zhaoqing are more than those in other cities. The LPP episodes occur more frequently in winter than in summer, and most of them occur during the period from night to the next morning. Second, the LPP episodes are caused by different background circulations, namely the continental cold high bottom, transformed sea high ridge, subtropical high and northly downdraft outside the tropical cyclone. Third, most typical LPP episodes are affected by the local circulations. Under the influence of mountains, plains and ocean thermal conditions, the surface wind changes, and the weak convergence line is formed, preventing the pollution from diffusing horizontally. At the same time, weak northerly winds from northern mountains of Guangdong Province arrive at the Pearl River Delta, causing downdrafts within the boundary layer, inhibiting the pollution from spreading vertically, resulting in the ground pollution.更多还原