柳州市空气污染特征及气象条件影响分析

Analysis of Air Pollution Characteristics and Met-eorological Conditions in Liuzhou City

利用广西2018年环境监测数据日均值和小时值对柳州市空气污染程度、污染物浓度季节变化和日变化特征进行分析,结合同期气象常规观测资料,探讨了气象要素与污染物浓度之间的关系,并利用NCEP 1°×1°再分析资料,对4个季节典型空气污染个例的天气形势进行分析,以进一步了解柳州各季节空气污染天气特征。结果表明:(1)柳州市首要污染物以PM_(2.5)为主,轻度污染最多,冬季污染最重,且集中在1月和2月;(2)O_(3)浓度变化为“夏高冬低”,主要与日照条件的季节变化有关,其余污染物浓度变化为“夏低冬高”,主要与冬季污染物排放量增大、扩散条件差、清除作用弱、微量降水日数多、增湿效果明显有关;(3)O_(3)浓度日变化为“单峰型”,峰值出现在15:00,其余污染物浓度日变化为“双峰型”,峰值分别出现在08:00~10:00和22:00~23:00,除O_(3)和SO_(2)外,其余污染物夜间浓度大于早间浓度;(4)PM_(2.5)、PM_(10)、NO_(2)与△P_(24)、T、Rh、P_(1)、V_(10)均呈负相关;O_(3)与T和V_(10)、SO_(2)与P_(24)、CO与Rh均呈正相关,与其他几种气象要素呈负相关。(5)典型个例分析表明,春季高空受偏北气流控制,低层有反气旋且风场较弱,地面处于变性冷高压后部;夏季受副热带高压控制,处于台风或低压外围并受下沉气流影响,地面位于低压带中;秋季处于副高边缘,低层受反气旋影响并受下沉气流控制,地面位于冷高压后部;冬季受槽后偏北气流或平直的西风控制,低层受偏西或偏南气流影响且风场较弱,地面受冷高压控制。这四种天气形势下,柳州天气晴好,无降水或只有弱降水,清除作用不明显,大气层相对稳定,污染物不易扩散,易造成污染天气。

Based on the daily and hourly environmental monitoring data of Guangxi in 2018,this paper analyzes the air pollution degree,seasonal and daily variation characteristics of pollutant concentration in Liuzhou City,discusses the relationship between meteorological elements and pollutant concentration,and analyzes the weather situation of typical air pollution cases in four seasons by using NCEP reanalysis data In order to further understand the characteristics of air pollution weather situation in Liuzhou.The results show that:(1) PM2.5 is the main pollutant in Liuzhou City,with the most light pollution and the heaviest pollution in winter,which are concentrated in January and February;(2) O3 concentration changes are "high in summ-er and low in winter",which are mainly related to the seasonal changes of sunshine conditions;(3) the other pollutants are "low in summer and high in winter",which are mainly related to the increase of pollutant emissions,poor diffusion conditions,weak scavenging effect and trace elements in winter The results showed that the diurnal variation of O3 concentration was "single peak type",with 3 the peak value at 15.00,and the diurnal variation of other pollutants was "double peak type",with the peak values at 08:00~10:00 and 22:00~23:00,respectively.Except for O3 and SO2,the nighttime concentration of other pollutants was higher than that in the morning;(4)PM2.5,PM10,NO2 and p24,T,Rh,,P1,V10 The results show that O3 is positively correlated with T and V10,SO2 and P24,CO and Rh,and negatively correlated with other meteorological factors;(5)typical case analysis shows that in spring,the upper air is controlled by northerly airflow,the lower level has anticyclone with weak wind field,and the ground is at the back of the denatured cold high;in summer,it is controlled by subtropical high,and it is at the periphery of typhoon or low pressure and affected by downdraft,and the ground level is low In autumn,it is at the edge of the subtropical high,the lower level is affected by anticyclone and controlled by downdraft,and the ground is behind the cold high;in winter,it is controlled by the northerly airflow behind the trough or the straight westerly wind,and the lower level is affected by the westerly or southerly airflow and the wind field is weak,and the ground is controlled by the cold high.Under these four weather conditions,Liuzhou has fine weather,no precipitation or only weak precipitation,and the removal effect is not obvious.The atmosphere is relatively stable,and the pollutants are not easy to spread,so it is easy to cause pollution weather.