北京夏末秋初不同天气形势对大气污染物浓度的影响

根据2007~2008年地面、850hPa和500hPa天气图,结合主要气象要素将夏末秋初(8月和9月)影响北京地区的主要天气系统分为高污染的积累天气型(包括槽前无降水、槽后脊前、脊、副高4种基本型)和清洁的清除天气型(包括槽或槽前有降水、槽后有降水或偏北风2种基本型).北京地区4站2007年在积累天气型控制时NOx、O3(日小时均值最大值)、PM2.5和PM10浓度分别为38.1×10-9(体积分数),115.2×10-9(体积分数),90.6μg/m3,212.5μg/m3,清除天气型控制时4种污染物浓度分别为36.3×10-9(体积分数),68.9×10-9(体积分数),39.3μg/m3,125.4μg/m3;2008年施行北京奥运空气质量保障措施期间,上述4种污染物在积累天气型控制时分别为19.3×10-9(体积分数),87.1×10-9(体积分数),66.3μg/m3,99.6μg/m3,清除天气型控制时分别为19.0×10-9(体积分数),62.5×10-9(体积分数),41.0μg/m3,65.2μg/m3;尽管施行了源减排措施,积累天气型控制时北京地区污染物浓度仍相对较高,因此需关注此天气形势下污染物的变化.

Relationship between different synoptic weather patterns and concentrations of atmospheric pollutants in Beijing during summer and autumn

Based on surface and 850,500hPa level synoptic maps and primary meteorological factors during summer and autumn from 2007 to 2008 in Beijing, two kinds of synoptic weather patterns were divided, one of which was helpful for accumulating pollutants with higher pollution including four basic types and the other was helpful for dispersing pollutants with lower pollution including two basic types. In 2007, concentrations of NOx, O3(hourly maximum), PM2.5 and PM10 averaged from four sites in Beijng were 38.1×10-9(V/V), 115.2×10-9(V/V), 90.6μg/m3, 212.5μg/m3 under accumulating synoptic pattern, respectively, while 36.3×10-9(V/V), 68.9×10-9(V/V), 39.3μg/m3, 125.4μg/m3 under dispersing synoptic pattern, respectively. The source control measures were carried out to ensure the air quality during 2008 Beijing Olympic Games, and concentrations of NOx、O3(hourly maximum)、PM2.5 and PM10 were 19.3×10-9 (V/V), 87.1×10-9(V/V), 66.3μg/m3, 99.6μg/m3 under accumulating synoptic pattern, respectively, while 19.0×10-9(V/V), 62.5×10-9(V/V), 41.0μg/m3, 65.2μg/m3 under dispersing synoptic pattern, respectively. Although the source control measures were carried out, higher pollutant concentrations were appeared under accumulating synoptic pattern; thus, researching pollutant changes under this synoptic pattern is very important for predicting severe pollutions and establishing effective source control measures.