• 关键词：武汉城市圈  污染天气分型  大气层结  逆温

• 基金项目：湖北省气象局科技发展基金项目（No.2019Z02，2020Y01）；国家重点研发计划项目（No.2017YFC0212603）

• 陈璇
• 武汉中心气象台，武汉 430074

• 王晓玲
• 武汉中心气象台，武汉 430074

• 陈赛男
• 武汉中心气象台，武汉 430074

• 董良鹏
• 武汉中心气象台，武汉 430074

• 章翠红
• 武汉中心气象台，武汉 430074

• 祝波
• 湖北省环境监测中心站，武汉 430072

• 柳草
• 武汉中心气象台，武汉 430074

• 岳岩裕
• 金沙国家大气本底站，武汉 430074;武汉区域气候中心，武汉 430074

• 摘要：利用2015—2019年PM_2.5和气象要素观测资料、NCEP和ERA5再分析资料，分析不同天气型下武汉城市圈PM_2.5区域污染时空分布、天气尺度环流和大气层结特征.结果表明，城市圈污染以武汉为中心，多为轻度-中度污染，西部重于东部.造成武汉城市圈区域污染增长的天气形势包括4类，分别为冷高压底前部型、高压后部型、均压场型和低压倒槽型.4类污染天气型均有较低的混合层高度和地表通风系数，且边界层 存在弱下沉运动和逆温，抑制污染垂直扩散.但气象要素影响PM_2.5污染的机理各异：冷高压底前部型主要为大气压梯度引导偏北大风带来 污染物远程输送，边界层冷平流导致低温、锋面逆温和浅薄高湿层（65%~80%），强输入性污染配合吸湿性累积增长造成严重污染，逆温厚度对PM_2.5增幅作用明显；低压倒槽型东南风输入污染弱，但高温、低压引起气流辐合导致本地污染汇积，边界层暖平流带来平流逆温和深厚湿层（1000~750 hPa），逆温层底高偏低、厚度偏厚，促进污染物在近地面吸湿增长；高压后部和均压场型均为浅薄湿层（1000~975 hPa）、湿度中等（56%~75%），污染物吸湿增长相对较弱，高压后部型主要为偏东风短程输入污染为主；均压场型则为小风静稳天气，多晴空辐射逆温，逆温 强度大，大气扩散能力差，污染主要为弱北风的输入和本地累积.

• Abstract：Based on PM_2.5 and meteorological observations data， NCEP and ERA5 reanalysis data from 2015 to 2019， the temporal and spatial distribution of PM_2.5 pollution event， synoptic-scale circulation， and atmospheric stratification characteristics in Wuhan metropolitan area under different weather patterns are analysed. The results show that the pollution events in the metropolitan area are concentrated in Wuhan， with mostly mild to moderate pollution， and heavier pollution in west than that in east. There are four types of weather conditions causing the heavier pollution in Wuhan Metropolitan Area， which are cold-high-pressure front type， high-pressure rear type， uniform pressure field type and low-pressure inverted trough type. There is the lower mixing layer height， smaller surface ventilation coefficient， weak subsidence movement and temperature inversion in the boundary layer in all these four types of pollution weather， which inhibits the vertical diffusion of pollution. However， the influence mechanism of meteorological elements on pollutions are different. The cold-high-pressure front type is accompanied by long-distance transportation of pollutants caused by the northerly gale guided by the atmospheric pressure gradient. The cold advection of the boundary layer leads to low temperature， frontal inversion and shallow high humidity layer （65%~80%）. The strong transportation of pollutants combined with the aerosol hygroscopic growth leads to the occurrence of heavy pollution. The thicker inversion layer would increase the PM_2.5 concentration significantly. The transportation of pollutants by southeast wind is weak in the low-pressure inverted trough type. The airflow convergence caused by high temperature and low pressure leading the accumulation of pollutants. Warm advection of boundary layer brings advection inversion and deep wet layer （1000~750 hPa）. The height of inversion base is low， with the thicker depth， promoting hygroscopic growth of aerosol near the ground. There is shallow wet layer （1000~975 hPa） in both of the high-pressure rear and the uniform pressure field types， with medium humidity （56%~75%）， showing the relatively weak hygroscopic growth of aerosol. The high-pressure rear type is accompanied by short-distance transportation of pollutants by the easterly winds. The uniform pressure field type is with a stable atmospheric stratification， showing the weak wind. Stronger radiation inversion is more common. The pollutants would be accumulated by the poor diffusion ability of atmosphere， and the transportation of pollution by the weak north wind.

• Key words：Wuhan metropolitan area  pollution weather classification  atmospheric stratification  temperature inversion

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