关中区域大气重污染年份气象条件分析

A conceptual model of regional pollution and meteorological conditions in Guanzhong region

利用关中区域环境污染监测数据和同时期气象数据,定义了区域重污染和区域污染天气过程,选择2017年为代表年,采用帕斯奎尔分类方法和国标法计算大气稳定度等级和混合层高度,着重分析了区域污染天气过程中稳定度等级等5个表征大气扩散能力的气象参数特征,建立了关中区域各强度污染天气气象条件概念模型。研究结果表明:2014—2018年关中区域年平均污染日为145.4 d,不同强度的污染日数均呈增加趋势,秋冬季是关中区域污染的多发季节,特别是当大气混合层高度≤300 m,稳定类频率60%,累积逆温厚度≥260 m,静小风频率≥55%和关中腹地出现风辐合区时,极不利于污染物的扩散和清除,易造成区域重污染天气。

Environmental pollution monitoring data and meteorological data from Guanzhong region were examined.We defined the regional heavy pollution and pollution weather processes,selecting 2017 as the representative year,and calculated the atmospheric stability level and mixed layer height using the Pasqual classification method and the national standard method.In addition,we analyzed the characteristics of six meteorological parameters that contribute to regional pollution weather and atmospheric diffusion ability:atmospheric stability,inversion intensity,inversion thickness,wind direction,and wind speed.In Guanzhong region,we found that regional pollution mostly occurs in autumn and winter,and an increasing trend of different strength pollution days from 2014 to 2018 was observed.In addition,when the height of the air mixing layer was≤300 m,the frequency of the atmosphere stable type was>60%,the accumulated inversion thickness was≥260 m,and the frequency of calm and light wind was≥55%.The hinterland of Guanzhong appears to be the wind convergence area,which is not conducive to the diffusion and removal of pollutants;on the contrary,severe regional pollution weather was observed in the area.