中国主要城市群在灰霾污染下的近地面风场特征

Characteristics analysis on near-surface wind field under haze pollution conditions in major urban agglomerations of China

利用2015—2016年全国PM 2.5质量浓度站点资料及CCMP(Cross Calibrated Multi-Platform)风场再分析资料,对中国华北、长三角、珠三角以及四川盆地主要城市在PM 2.5污染下的近地面风场及其影响进行统计分析。结果表明:(1)近地面风速与PM 2.5质量浓度表现为负相关,低风速有利于PM 2.5的积累,但是该相关关系并不完全显著,体现出“冬强夏弱”的季节性差异;(2)不同地区PM 2.5质量浓度对不同风向的反应不同,华北地区在偏南风主导下PM 2.5质量浓度较高,长三角则是在偏西风主导下PM 2.5质量浓度较高,而珠三角地区冬季PM 2.5质量浓度较高,主导风向为偏北风;(3)通过分析地面散度场发现不同地区主导的污染类型不同,华北地区、长三角以及珠三角污染类型主要为区域性污染,四川盆地主要为局地型污染。

Based on the observed PM 2.5 concentration data and the wind field obtained from CCMP(Cross Calibrated Mulit-Platform)reanalysis data from 2015 to 2016,the characteristics and effects of near-surface wind field in North China,Yangtze River Delta,Pearl River Delta and Sichuan Basin under PM 2.5 pollution conditions were investigated.Results show that:(1)near-surface wind speed is negatively correlated with PM 2.5 concentration.Low wind speed contributes to the accumulation of PM 2.5,but the correlation is not completely significant,which reflects the“strong in winter and weak in summer”seasonal difference.(2)Different regions have different responses to PM 2.5 concentrations under different wind directions.In North China,PM 2.5 concentration is high when southerly wind dominates.While the PM 2.5 concentration in the Yangtze River Delta is high dominated by the westerly wind.In the Pearl River Delta,the dominant wind direction in winter is northerly.(3)By analyzing the characteristics of surface convergence and divergence field,it is found that the type of pollution in different regions are various.The pollution types in North China,Yangtze River Delta and Pearl River Delta are mainly regional pollution while the pollution in Sichuan Basin is mainly local and the external transportation has little influence on it.