武汉地区夏季和秋冬季大气污染的天气概念模型

Research on Weather Conceptual Model of Air Pollution During Summer,Autumn and Winter in Wuhan Area

利用2013~2019年武汉市生态环境局监测数据、L波段雷达探空资料、NCEP/NCAR逐日再分析资料,对夏季和秋冬季武汉地区污染日的大气污染特征、边界层结构、环流形势、物理量场进行研究,建立了武汉地区大气污染的天气概念模型。主要结论如下:(1)武汉市空气质量具有季节性变化特征,大气污染程度四季分布表现为冬>秋>春>夏。夏季首要污染物是臭氧,冬季首要污染物是PM2.5。(2)比较挑选出的夏季清洁日和污染日的气象要素特征,污染日逆温的平均强度约为清洁日的一倍,逆温底高一般在600 m以下,空气质量一般为轻度-中度污染;静风频率(37.1%)明显高于清洁日的静风频率(2.9%);污染日平均风速小(0.8 m/s),边界层内相对湿度较低。同样比较秋冬季两类天气的气象要素特征,污染日逆温底高低、厚度小,不及清洁日的一半,不利于污染物的扩散,易出现重度污染天气。静风频率(20%)高于清洁日的静风频率(7.5%),风速小(1.6 m/s),污染日边界层内呈明显上干下湿的格局。(3)建立了夏季大气污染的天气概念模型,污染日副高偏弱位置偏东,长江流域易少雨干旱;地面我国东部大范围地区处于均压场中,武汉地区为偏东北异常小风,不利于大气污染物的扩散。(4)建立了秋冬季大气污染的天气概念模型,长江流域环流平直少波动,配合地面弱低压的天气形势和较强的逆温使得大气污染物聚集在近地面。蒙古冷高压强度偏弱,使得入侵我国的冷空气强度偏弱;武汉地区为偏北小风,对雾霾的移除和稀释扩散作用差。该研究结论可供大气污染预测预警研究和环境管理部门大气污染的联防联控参考。

This paper uses the monitoring data from Wuhan Ecology and Environment Bureau,L-band radar sounding,and NCEP/NCAR daily reanalysis data from 2013 to 2019 to analyze the atmospheric pollution characteristics,boundary layer structure,circulation situation,physical quantity field of the pollution days in Wuhan during summer,autumn and winter.A weather conceptual model of air pollution in Wuhan is established.The main conclusions are as follows:(1)The air quality in Wuhan has seasonal characteristics,and the seasonal distribution of air pollution is winter>autumn>spring>summer.The primary pollutant in summer is ozone,while the primary pollutant in winter is PM2.5.(2)Comparison of selected meteorological element on clean days and pollution days in summer,show that the average intensity of temperature inversion on pollution days is about twice that of clean days.The bottom height is generally below 600 m,and the air quality is generally mild to moderately polluted;the frequency of static wind on polluted days(37.1%)is significantly higher than the frequency of static wind on clean days(2.9%);the average wind speed on polluted days is small(0.8 m/s).The relative humidity in the boundary layer is low.Similarly,comparing the meteorological element characteristics of the two types of weather in autumn and winter,the height and thickness of the inversion on the pollution day are less than half of that of clean day,which is not conducive for diffusion of pollutants and is prone to severely polluted weather.The frequency of static wind(20%)is higher than the frequency of static wind(7.5%)on clean days,and the wind speed is low(1.6 m/s).There is a clear pattern of upper dry and lower wet in the boundary layer on the pollution days.(3)A weather conceptual model of atmospheric pollution in summer is established.The subtropical high of pollution is weak and eastward,and the Yangtze River Basin is prone to less rain and drought;On the ground,a large area in the eastern part is in the pressure equalization field,and the Wuhan area has an abnormally small wind from the northeast,which is not conducive for diffusion of air pollutants.(4)A weather conceptual model of atmospheric pollution in autumn and winter is established.The circulation in the Yangtze River Basin is flat and less fluctuating.In conjunction with the weather situation of weak ground pressure and strong temperature inversion,atmospheric pollutants accumulates near the ground.The intensity of the Mongolian cold high pressure is weak,which makes the intensity of the cold air invading China mainland weaker;the Wuhan area is a small northerly wind,which has a poor effect on the removal and dilution of the smog.The research conclusions of this paper can be used as references for air pollution prediction and early warning research and the joint prevention and control of air pollution by environmental management departments.