长沙一次重污染天气过程成因分析

Reasons Analysis on Heavy Polluted Weather in Changsha

利用环境监测资料和常规气象资料对2014年6月13日长沙发生的空气重污染过程进行分析,结果表明,此次空气污染是人为与气象两方面因素共同作用的结果,人为因素是由于北方地面秸秆焚烧产生大量烟雾颗粒在中低层东北气流作用下向长沙地区输送;气象因素是高空天气形势配置有利于在中低层形成污染物输送通道,长沙地区受副热带高压控制,大气低层有稳定的等温层结,地面处于均压场中,静稳天气条件使污染源输送到长沙地区后不能得到有效稀释、扩散和清除,从而导致了重污染天气的发生。

The most serious air pollution occurred in June 13, 2014 in Changsha was analysed using the environment monitoring data and conventional meteorological data. The analysis result showed that the air pollution is caused by the human factor and the meteorological conditions. The human factor is due to the large amounts of smoke particles from burning, which was transported to Changsha area with the function of northeast flow in the lower layer; the meteorological factor is upper air weather situation configuration which is conducive to the formation of pollutant transport channel in the lower air flow. Meanwhile, Changsha area is controlled by the subtropical high, the lower atmosphere has a stable isothermal stratification, and the ground was in uniform pressure field. The pollution source which was transmitted to Changsha area cannot be diluted, diffused and cleaned effectively under the calm weather conditions, so leads to the heavy polluted weather.