中文摘要：

基于Lamb-Jenkinson天气分型方法对影响杭州四季的大气天气型进行频率划分,并结合杭州气候观测站的PM2.5观测数据分析各季典型天气型的污染特征.针对杭州秋冬季冷锋活动时PM2.5浓度值变化的不确定性,进一步分析了冷锋过程对杭州大气污染物的输送和清除特征.结果表明,冬季是杭州的主要污染季节,以高压控制和暖区发展天气型为主;春、秋季其次;夏季基本不发生高污染个例.其次,结合变温和风速气象要素特征发现,24h负变温范围在0~2℃之间或者平均风速低于2m/s条件下的弱冷锋环境以污染输送作用为主,而24h负变温幅度大于4℃以及平均风速大于4m/s的较强冷锋环境以污染清除作用为主.

英文摘要：

In this paper,the seasonal atmospheric circulation patterns over Hangzhou were classified,based on theLamb-Jenkinson weather classification method.Meanwhile,we summarized the seasonal air pollution characteristics ofthe typical atmospheric circulation patterns with the aid of PM2.5dataset from the national climate station in Hangzhou.Because the uncertainty of PM2.5levels were large under cold front synoptic condition,the pollution transport andpurification characteristics were analysed in autumn and winter.The results showed that in Hangzhou,winter,dominatedby anticyclone and warm zone in front of cold front,was the worst polluted season.Spring and autumn are secondary.Serious air pollution was almost impossibly occured in summer.In addition,identifying by the features of temperaturevariability and wind speed,we found that the weak cold front was favour of pollution transport in the conditions ofnegative temperature variability in24hours within0℃and2℃,or the average wind speed below2m/s.It was conduciveto purify the pollution for the strong cold front which was in the condition of negative temperature variability in24hourslarger than4℃,or the average wind speed higher than4m/s.