2014年河北中南部两次重霾天气成因分析

利用河北省环保局环境监测站提供的污染物浓度数据及常规气象观测数据、NCEP再分析资料,结合HYSPLIT4.9后向轨迹模式,对2014年10月上旬发生在河北省的2次大范围的重霾天气特征和成因进行综合分析.结果表明,这2次重污染天气过程PM_2.5地面浓度最大值出现在邢台,为507μg/m³,水平能见度不足1km.均压场的分布和较为平稳的高空形势为2次霾天气提供了有利的气象背景.高湿,静小风以及较低的混合层高度不利于污染物扩散,是导致这两次重污染天气持续的主要原因.结合卫星火点及污染物来源分析表明,河北南部及周边省份的秸秆燃烧加重了第2次过程的污染,污染气团的输送对区域性重霾天气产生重要影响.

Formation mechanism of two severe haze episodes over central and Southern Hebei in 2014

The synoptic weather patterns and formation mechanisms of two large scale and severe haze episodes, which occured over Hebei province in early and middle October, was investigated by using pollutant concentration data from the Heibei environmental monitoring station, meteorological observations and NCEP reanalysis data, combining with the HYSPLIT4.9 backward trajectory model. The highest PM_2.5 concentration appeared in Xingtai, reached 507μg/m³. The visual range was less than 1km. The uniform pressure field and steady upper air circulation provided favorable meteorological conditions for two haze episodes. High relative humidity, small wind speed, and low mixing layer height result in an unfavorable meteorological condition for pollutant diffusion, which is the main cause of the two lasting haze episodes. Satellite fire map and air mass backward trajectory show that straw burning in southern Hebei and surrounding provinces exacerbated air pollution in two episodes. Transport of polluted air mass have significant impact on regional heavy haze weather.