上海地区降雨清除PM_(2.5)的观测研究  

Observation of the wet scavenge effect of rainfall on PM_(2.5) in Shanghai

作　　者：许建明[1,2,3] 高伟[1,2,3] 瞿元昊 

机构地区：[1]上海市气象局,上海200030 [2]长三角环境气象预报预警中心,上海200030 [3]上海市气象与健康重点实验室,上海200030

出　　处：《环境科学学报》2017年第9期3271-3279,共9页Acta Scientiae Circumstantiae

基　　金：国家重点研发计划(No.2016YFC0203400);环保部行业专项(No.201509001)~~

摘　　要：分析2012—2016年上海徐家汇站的雨量和颗粒物(PM_1、PM_(2.5)、PM_(10))观测数据发现,降雨对PM_(2.5)的湿清除作用明显,降雨日的PM_(2.5)质量浓度较非降雨日平均降低约30%,在污染季节降低更加显著约50%.降雨时PM_1在PM_(2.5)中的占比明显下降,PM_1质量浓度下降幅度占PM_(2.5)下降幅度的84%,表明降雨对PM_1的有效清除是PM_(2.5)质量浓度下降的主要原因.降雨过程结束后PM_(2.5)质量浓度是否下降和降雨前PM_(2.5)的初始质量浓度关系密切,当初始浓度在冬季大于70μg·m^(-3)、在其他季节大于45μg·m^(-3)时,80%以上的降雨过程结束后PM_(2.5)质量浓度较降雨前下降,因此可作为研判降雨过程对PM_(2.5)湿清除影响的预报因子.The effect of wet scavenge of PM2.5 by rainfall in Shanghai, China is analyzed. The analysis includes the in-situ measurements of precipitation and particulate matter （ PM1 , PM2.5 and PM10 ） from 2012--2016 at Xujiahui in downtown Shanghai. The results show that precipitation plays an important role in reducing PM2.5 mass concentration. For example, the mean PM2.5 mass concentration on rainy days decreases about 30% compared with non-rainy days, with a maximum reduction of 50% in winter. The ratio of mass concentration between PM1 and PM2.5 also significantly decreases on rainy days. The reduced PMl mass concentration contributes 84% to the PM2.5 reduction, suggesting that wet scavenge is more effective for smaller particles than large particles. Therefore, the decrease in PM2.5 concentrations on rainy days is mostly attributed to the effective wet scavenge of PM1. The PM2.5 tendency related to rainfall is closely associated with the initial PM2.5 level prior to precipitation. There are about 80% of the rainfall processes leading to PM2.5 decreasing under the condition that the initial PM2.5 mass concentration is above 70μg·m-3 in winter and 45 μg·m-3 in other seasons, which could he considered as a predictor for forecasting the PM2.5 tendency due to precipitations.

关 键 词：湿清除 PM_(2.5) 降雨 

分 类 号：X513[环境科学与工程—环境工程]