安吉县PM2.5污染特征及后向轨迹分析

The Characters of Pollution and Back Trajectory Analysis of PM in Anji County

以湖州市安吉县的PM2.5为研究对象,利用安吉城东大气成分监测站的PM2.5污染物浓度数据分析2015年1月2日~2018年9月30日安吉地区的PM2.5污染物浓度变化特征。结果表明,安吉地区PM2.5日平均浓度频率分布呈指数衰减,PM2.5日平均浓度的年变化呈现明显周期特征,并且冬季PM2.5日平均浓度超标日数要多于夏季。利用HYSPLIT模型模拟安吉县100 m高度下气流后向轨迹,通过聚类分析方法分析5次中度到重度污染过程。结果表明,安吉地区PM2.5污染主要受华北和华中影响,通过西北和偏西路径进行中远距离传输,对安吉地区影响较大。

Aiming to study the concentration of PM2.5in Anji,Huzhou,this article analyzed its changes in Anji from January 2rd,2015 to September 30th,2018 using the data collected from atmosphere monitoring station in East Anji.The result shows that the frequency distribution of PM2.5in Anji is descending exponentially and the annual variation of daily average concentration displays obvious periodicity.Also,there are more days in winter when the daily average concentration is above the standard than that in summer.We conducted a back trajectory analysis under 100 meters in Anji,using HYSPLIT(hybrid single particle lagrangian integrated trajectory)model and analyzed the transition from medium to severe pollution level five times with clustering method.These data help us reach the conclusion that the high level of PM2.5in Anji was mainly caused by air pollution in North and Central China.Also,the pollution that took a medium-to-long distance journey from the direction of Northwest and West has great impact on Anji.