山地地形对喀左PM_(2.5)重污染事件的影响模拟  

Simulation analysis of the influence of mountainous terrain on heavy PM_(2.5)pollution events in Kazuo

作　　者：徐安宁 王咏薇[1,2] 吕亚宁 左天赐 戴泽凯 孟新杰 陈磊[1] XU Anning;WANG Yongwei;LÜYaning;ZUO Tianci;DAI Zekai;MENG Xinjie;CHEN Lei(School of Atmospheric Physics,Nanjing University of Information Science&Technology,Nanjing 210044;Yale-NUIST Center on Atmospheric Environment,Nanjing University of Information Science&Technology,Nanjing 210044)

机构地区：[1]南京信息工程大学大气物理学院,南京210044 [2]南京信息工程大学大气环境中心,南京210044

出　　处：《环境科学学报》2025年第2期380-393,共14页Acta Scientiae Circumstantiae

基　　金：国家自然科学基金项目(No.42305121)。

摘　　要：县域是我国大气污染格局的基本单位,往往人口稀少,工业及交通均不发达,污染物的排放偏少,但是其污染状况却未必乐观.研究其污染成因对于我国污染总体控制有重要意义.本文以辽宁省喀左县作为研究目标,使用WRF-Chem模式,模拟了喀左县2021年1月19日—26日一次长时间的PM_(2.5)重污染事件,分析了此次污染事件中PM_(2.5)的来源、时空分布特征以及当地独特山地地形条件的影响.结果表明:①喀左县城位于努鲁儿虎山脉及松岭山脉环绕的山谷之中,本地污染排放较少,1月19日—22日的污染来源为西北方向的凌源市以及内蒙古自治区,而1月23日—26日的污染来源为京津冀地区以及辽宁中部城市群.②山谷地形是污染物堆积的重要原因,风向的转变导致两股污染物在山谷内叠加、抬升,造成喀左县当地PM_(2.5)小时观测浓度连续26个时刻维持在150μg·m^(-3)以上.③山谷风是导致污染物堆积的另外一个重要原因.夜间山风使得喀左县PM_(2.5)污染聚集在谷中,一定程度上加剧了夜间的空气污染.④喀左县上空存在暖平流造成的逆温结构,夜间地表冷却以及山风吹来的冷空气进一步加深了逆温结构的稳定性,从而抑制了污染物的垂直扩散,使得当地夜间PM_(2.5)的浓度维持在较高水平.The county is the basic unit of air pollution patterns in China,characterized by a sparse population,underdeveloped industry and transportation,and low emissions of pollutants.However,the pollution situation in counties may still not be optimistic.Studying the causes of pollution in these areas is of great significance for the overall control of air pollution in China.This study used the WRF-Chem model to simulate a prolonged and severe air pollution event in Kazuo,Liaoning Province,from January 19 to 26,2021.The pollution sources,the spatial and temporal distribution of PM_(2.5),and the influence of the unique local mountainous terrain were analyzed.The results showed that:①Kazuo County is located in a valley surrounded by the Nulu'erhu Mountains and Songling Mountains,with low local pollution emissions.From January 19 to 22,pollution originated from Lingyuan and Inner Mongolia,and massive pollutants were transported to Kazuo under the influence of northwest winds.However,during January 23 to 26,pollution originated from the Beijing-Tianjin-Hebei region and the central Liaoning urban agglomeration.②The mountainous terrain was an important reason for the accumulation of pollutants.When the wind changed,pollutants from different sources mixed and rose in the valley,causing local PM_(2.5)concentrations to remain above 150μg·m^(-3)for 26 consecutive hours.③The mountain-valley wind was another important reason for the accumulation of pollutants.At night,mountain winds caused PM_(2.5)pollution to accumulate in the valley in Kazuo,exacerbating nighttime air pollution.④A temperature inversion caused by warm advection occurred in Kazuo,and the stability of this inversion was enhanced by surface radiation cooling and cold air from mountain winds at night.Therefore,the vertical diffusion of pollutants was suppressed,and PM_(2.5)concentrations remained high at night.

关 键 词：县城 山地地形 WRF-Chem PM_(2.5) 区域传输 

分 类 号：X513[环境科学与工程—环境工程]