临汾盆地一次持续性重污染天气过程分析

Analysis of a Severely Polluted Weather Process in Linfen Basin

该文研究了2018年12月临汾盆地一次持续性重污染天气过程,重点分析了重污染天气气象成因和污染物积累传输特征。重污染期间临汾市高层为平直偏西环流,低层为西南气流,冷空气势力较弱,湿度较大,风力较小,有利于静稳天气形成。08时在900 hPa到850 hPa上有逆温层出现,有利于近地层污染颗粒物的堆积和水汽积聚。地面市区相对湿度适中50%~70%、风速均<2 m/s、偏南风频率为53%,有利于将南部的污染物输送到市区。此次重污染天气过程包括几轮污染物积累-达到峰值-逐渐扩散的过程,整体主要受本地污染物积累的影响,期间在16日、17日、19日和21日凌晨左右的时段,在风力作用下存在浮尘传输、沉降过程。燃煤和机动车排放源等一次排放源的累积导致了前期污染发生,二次源是污染后期的主要贡献源类。

A continuous heavy pollution weather process which occurred in December 2018 in Linfen Basin was studied.This paper laid special stress on analysing the causes of meteorological and the accumulation and transport characteristics of pollutants.During the severe pollution period,the upper level of Linfen City is a straight westward circulation,and the lower level is a southwest air flow.The cold air is weak,the humidity is high,and the wind is small.All these that mentioned above are conducive to the formation of quiet and stable weather.The temperature inversion layer which appeared from 900 hPa to850 hPa at the time of 08 o’clock is beneficial to the accumulation of pollution particles and water vapor in the ground layer.The urban’s relative humidity on the ground is moderate 50%~70%,the temperature is high,the wind speed is less than 2 meters per second,and the frequency of southerly wind is 53%,which is conducive to transporting pollutants in the south to the urban area.Near the suiface,the relative humidity in the urban area is between 50%and 70%,the wind speed is less than 2 m/s,and the frequency of southerly wind is 53%,these meteorological conditions are favorable for the transport of pollutants from the south to the urban area.The process of this heavy pollution involves several cycles of accumulation、a spike and final gradual diffusion.During the periods around the morning of the 16 th,17 th,19 th,and 21 st,there are floating dust transmission and settlement processes under the action of wind.The pollution process is mainly caused by the accumulation of local pollutants,and there have processes of floating dust transmission and settlement around the early morning of 16 th,17 th,19 th and21 st due to the effect of wind.The accumulation of primary emission sources,such as coal burning and motor vehicle emission sources,leads to the occurrence of pollution in the early stage,while secondary sources are the main contribution sources in the late stage.