兰州市冬春两季PM10重度污染的气象条件分析研究

Analysis of Meteorological Condition and Related Heavy Pollution of PM_(10) in Lanzhou City during Winter and Spring

根据兰州市环境监测站2001年1月1日～2005年12月31日兰州市区空气质量日报和同期兰州气象观测资料,分析了兰州市区可吸入颗粒物(PM10)和PM10重度污染季节分布特征。结果显示:5年间兰州市共出现108dPM10重度污染,其中97d分别出现在春季(3～4月)和冬季(12～2月)。其日平均浓度变化在春季和冬季分别表现为"陡峰型"和"缓慢累积型"。春季造成PM10重度污染的原因是强沙尘暴东移向下游的兰州输送大量尘土,主要由"外源"造成,污染日前后气象要素变化剧烈。冬季PM10重度污染由于地面连续处于地面高压和均压场影响之中,加之冬季近地面有逆温层结,抑制了污染物的扩散,地面气象要素表现为水平风速小、能见度差。

Based on the data of daily monitoring of PM10 concentrations and daily meteorological observation during the period from Jan. 1, 2001 to Dec.31, 2005 in Lanzhou City, this paper analyses the seasonal characteristics of heavy pollution of PM10, highlighting spring（Mar.-Apr.） and winter（Dec.-Feb.）. Results indicated there were 108 days of heavy pollution of PM10, during the five years and the seasonal pollution largely depends on the meteorological conditions, e.g., the close-to ground inversion temperature stratification in winter, which restrains pollution diffusion.