2015年3月18-22日,云南省多个州市先后出现一次明显的污染天气过程,此次天气过程持续时间长、影响范围广.利用同期AQI指数、探空资料及常规气象观测资料等,分析此次污染天气事件的气象条件和出现持续大范围污染过程的成因.结果表明:过程前期,南支槽较活跃,多为“干性”弱南支槽活动,降水偏少,多大风,是污染物增多的主要气候背景;500 hPa云南一直处于弱高压脊区的均压场,700 hPa云南中部以东为西偏南暖湿气流,大气呈现高冷低暖,使近地边界层出现逆温层结,空气中颗粒物不断堆积且不易扩散;从污染源分析,空气质量下降的主要污染物是细颗粒物(PM2.5),本地源排放、境外污染物输送叠加的共同影响,是导致云南大部区域空气质量下降的重要人为原因之一,境外污染物影响相对较大.%An obvious process of pollution weather appeared in some cities in Yunnan province from 18 March to 25 March 2015,with characteristics of long duration and wide influential range.Based on AQI index,sounding data and meteorological observation data,the meteorological conditions of the pollution weather and the cause of this wide influential range of pollution had analyzed.Results show that:on the early stage of this process,the activities of southern trough were active that were dry and weak,the main climate background result in increased pollutants was the bigger wind and less precipitation.Yunnan province located in a weak high-pressure ridge at 500 hpa,and the east in central Yunnan province flowed the warm and moist of south west airflow at 700 hpa,it result in atmosphere pressure of high cold and low warm,appeared inversion layer near boundary layer,in the end,particulate matter piled up in the air and not easy to spread.For the pollution source analysis,the main pollutant of the deteriorated air quality was the particulate matter (PM2.5).One of the important human factor of the deteriorated air quality in most areas in Yunnan was the mutual influence of the local source emission and the outside pollutant transport,of which the outside pollutant affect relatively large.
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