降水和风对苏州地区PM_(2.5)浓度影响分析  

Analysis on the Influence of Precipitation and Wind on PM_(2.5) Concentration in Suzhou

作　　者：吴玥 林惠娟[1] 曾晨 曹舒娅 韦芬芬[1] WU Yue;LIN Huijuan;ZENG Chen;CAO Shuya;WEI Fenfen(Suzhou Meteorological Bureau,Suzhou,Jiangsu 215131,China)

机构地区：[1]苏州市气象局,江苏苏州215131

出　　处：《环境监控与预警》2024年第3期86-90,共5页Environmental Monitoring and Forewarning

基　　金：江苏省气象局科研项目(KQ202320);苏州市气象局科研项目(SZKJ202201)。

摘　　要：为了解降水和风对苏州地区细颗粒物(PM_(2.5))质量浓度的影响,利用2018—2022年逐日降水量、风向风速和环境空气质量数据,分析苏州市降水和ρ(PM_(2.5))的月变化特征及日降水强度、降水时长和风向风速对ρ(PM_(2.5))变化的作用。结果表明,降水对PM_(2.5)存在一定湿清除作用,全年雨日ρ(PM_(2.5))平均值较非雨日低21%,1—2月和11—12月最为显著。降水的湿清除效率受日降水量级和日降水时长等因素的影响,当日降水量达到中雨及以上量级时,ρ(PM_(2.5))下降样本数超过总样本数的60%,降水的湿清除效率随着降水量级的增加而显著提高;当日降水时长>6 h时,降水对污染物浓度的改善作用明显,ρ(PM_(2.5))下降样本数超过总样本数的50%。不同风向、风速的清除作用也有差异,静风或微风状态下,高温高湿的西南风最易造成苏州地区的霾污染;当西北风速>4 m/s时,受到冷锋前的污染气团南下扩散影响,ρ(PM_(2.5))升高;对于东北风、西南风和东南风这3个风向,当风速达到5 m/s时,对污染物具有有效的干清除作用。In order to understand the impacts of precipitation and wind on PM_(2.5) concentration in Suzhou,daily data of precipitation,wind and air quality from 2018 to 2022 are used to analyse monthly variation characteristics of precipitation and PM_(2.5) concentration in Suzhou and the effects of daily precipitation intensity,durationwind direction and speed on PM_(2.5) concentration.The results indicate that precipitation has a certain wet removal effect on PM_(2.5).Average concentration of PM_(2.5) in rainy days throughout the year is 21%lower than that in non-rainy days,with the most significant effects in January,February,November and December.The magnitude and duration of daily precipitation affects its wet removal efficiency.When the magnitude of daily precipitation reaches the level of moderate rain or above,the number of samples ofρ(PM_(2.5))decreases more than 60%of the total number of samples,and the wet removal efficiency of precipitation significantly increases with the increase of the level.When precipitation duration exceeds 6 hours,the improvement effects on pollutant concentration is significant,with the number of samples ofρ(PM_(2.5))decreases more than 50%of the total number of samples.The clearance effect of different wind directions and wind speeds also varies.Southwest wind with high temperature and humidity is most likely to cause haze pollution in Suzhou in the case of low wind speed.When the northwest wind speed exceeds 4 m/s,PM_(2.5) concentration increases due to the southward diffusion of polluted air masses in front of the cold front.For the other three wind directions,namely,northeast,southwest,and southeast,it has an effective dry cleaning effect on pollutants when wind speed exceeds 5 m/s.

关 键 词：细颗粒物 降水 风 苏州 

分 类 号：P426.6[天文地球—大气科学及气象学] P425[环境科学与工程—环境工程] X513