福州市PM2．5、PM2．5/PM10分布特征及与气象条件关系的初步分析

PRELIMINARY ANALYSES ON DISTRIBUTION CHARACTERISTICS OF PM_(2.5)、PM_(2.5)/PM_(10) AND ITS RELATIONSHIP WITH METEOROLOGICAL CONDITIONS IN FUZHOU

利用福州市PM2.5、PM10和气象资料,分析PM2.5、PM2.5/PM10的分布特征及与气象条件的关系。结果表明:福州市细粒子污染程度较轻,春季PM2.5和PM2.5/PM10值均是四季中最高的,其次是冬季,夏季最低;影响PM2.5浓度出现高值的天气系统有:暖区辐合与高空槽前、大陆高压后部和暖区降水三种系统,其中暖区降水天气形势下的PM2.5平均浓度最高,超标率为25.5%;影响PM2.5浓度出现低值的天气系统有:冷高压脊、高压底部和高空槽后,副热带高压及边缘,台风(热带辐合带)及外围系统,在后两种天气系统影响下的PM2.5平均浓度最低,超标率为0;剔除因降水、雾等低能见度个例,PM2.5浓度与能见度的相关系数为-0.626,冬春季的相关系数是夏秋季的1.4倍;PM2.5浓度与单一气象要素(如温度、相对湿度、风速等)相关性不明显,但不同季节、不同气象要素变化的组合对PM2.5浓度有直接影响。

Based on the PM2.5, PM10 and meteorological data of Fuzhou, the distribution of PM2.5 and main characteristics of PM2.5/PM10 and their relationship with weather conditions are analyzed. The results showed that ambient fine-particle pollution in Fuzhou is relative light. The greatest season of PMzs is spring, followed by winter. The weather patterns favorable for high PMz5 are warm-sector convergence, the passage of the front part of an upper-level trough and the rear portion of a continental high pressure, or a warm-zone precipitation system. The PM2.5 value under warm-zone precipitation systems is higher than with any other weather patterns and the proportion exceeding the standard value is 25.5%. The weather situation with low PM2.5 concentration can be attributed to a cold-high ridge, a high pressure, the rear part of an upper-level trough, a subtropical high and its edge, or a typhoon （the ITCZ）. The proportion exceeding the standard value of PMz5 average concentration under the subtropical high or the typhoon is zero. The correlation between PMzs and visibility （excluding some low-visibility events induced by precipitation or fog） is -0.626 and the correlation in winter and spring is 1.4 times that of summer and autumn. The correlation between PMz5 and single weather factors, such as temperature, relative humidity and wind speed, is not significant. However, combined weather factors in different seasons have a direct effect on PM2.5 concentration.