摘要
对合肥2015—2017年的降水、风和PM_(2.5)、PM_(10)浓度观测数据统计研究发现,降水对PM_(2.5)、PM_(10)有一定的清除作用,尤其在秋冬季节.秋冬季节小雨、中雨分别导致PM_(2.5)和PM_(10)浓度降低23.1%、40.4%和32.0%、63.7%.雨日PM_(2.5)/PM_(10)比例上升8.4%,表明降水对PM_(10)清除作用更显著.降水前后PM_(2.5)浓度变化与降水前PM_(2.5)浓度、降水强度、降水时长密切相关.当降水强度大于4 mm·h^(-1)或PM_(2.5)初始浓度高于115μg·m^(-3)时,降水对PM_(2.5)产生明显清除作用;而降水强度小于1 mm·h^(-1)或PM_(2.5)初始浓度低于115μg·m^(-3)时由于吸湿增长作用极易造成PM_(2.5)浓度反弹升高;且持续3 h以上雨强介于1～4 mm·h^(-1)的降水也对PM_(2.5)产生清除作用.降水前后PM_(10)浓度变化与初始浓度密切相关,而与雨强相关性较弱.当PM_(10)初始浓度大于50μg·m^(-3),降水就对PM_(10)产生明显清除作用,且PM_(10)初始浓度越高,降水后PM_(10)浓度下降越多.风速大于2 m·s^(-1)可显著降低PM_(2.5)浓度,因此,当风速大于4 m·s^(-1)时合肥较少出现中度及以上污染,但易造成地面起尘,使PM_(10)浓度不降反升.合肥冬季严重污染主要出现在西北风向,夏季中度以上污染天气较少,主要出现在风速低于3 m·s^(-1)的东南风向.
The scavenging effects of rainfall and wind on PM2.5 and PM10 in Hefei were investigated using hourly data of ground level meteorological parameters and mass concentrations of PM2.5 and PM10 during 2015-2017.Statistical results show that rainfall played significant role on removing PM2.5 and PM10 in the air,especially in fall and winter.The light (moderate)rain decreased PM2.5 concentration by 23.1%(40.4%)and PM10 concentration by 32.0%(63.7%),respectively.Furthermore,the ratio of PM2.5 to PM10 increased by about 8.4% on rainy days,indicating that precipitation had a more significant effect on coarse particulate removal.The change of PM2.5 concentration before and after precipitation was closely related to the initial concentration of PM2.5,the intensity and duration of precipitation.When the precipitation intensity was greater than 4mm·h^-1,or the initial concentration of PM2.5 was higher than 115μg·m^-3,the precipitation had a significant clearance effect on PM2.5.However,when the precipitation intensity was weak (rainfall intensity<1mm·h^-1)or the initial concentration of PM2.5 was lower than 115μg·m^-3,the concentration of PM2.5 would rebound and rise due to the increasing hygroscopic growth.When the rainfall intensity was between 1-4 mm·h^-1 and precipitation lasted for more than 3hours,it also had a scavenging effect on PM2.5 if PM2.5 initial concentration was between 35μg·m^-3 and 115μg·m^-3.The change of PM10 concentration before and after precipitation was closely related to the initial PM10 concentration,but the correlation with rainfall intensity was weak.When the initial PM10 concentration was greater than 50μg·m^-3,it was obviously removed by precipitation,and the higher the initial PM10 concentration,the more PM10 concentration decreased after precipitation.The wind with a velocity over 2m·s^-1 could weaken the concentration of PM2.5 significantly,so the moderate or above pollution episode was rare when the wind speed exceeded 4m·s^-1.However,strong wind caused dust on the ground,resulting in PM10 concentration increase.Generally,heavy pollution events appeared primarily under northwest wind in winter and southeast wind with wind speed lower than 3m·s^-1 insummer.
作者
于彩霞
邓学良
石春娥
吴必文
翟菁
杨关盈
霍彦峰
YU Caixia;DENG Xueliang;SHI Chun'e;WU Biwen;ZHAI Jing;YANG Guanying;HUO Yanfeng(Key Laboratory of Atmospherie Science and Satellite Remote Sensing,Anhui Institute of Meteorology,Hefei 230031;Shouxian National Climate Observatory,Shouxian 232200)
出处
《环境科学学报》
CAS
CSCD
北大核心
2018年第12期4620-4629,共10页
Acta Scientiae Circumstantiae
基金
国家重点研发计划(N0.2016YFC0201903,2016YFC0201902)
中央引导地方专项资金科技惠民项目(No.2016080802D116)
中国科学院科技服务网络计划(STS计划)-区域重点项目(No.KFJ-STS-QYZD-022)
安徽省淮河流域气象开放研究基金(No.HRM201506)
安徽省气象科技发展基金(No.KM201809)。
关键词
降水
清除
初始浓度
雨强
PM2.5
PM10
合肥
rainfall
scavenging
initial concentration
rainfall intensity
PM2.5
PM10
Hefei
