成都气象要素等级对大气污染的改善作用研究

Study on Improving Effect Of Meteorological Conditions on Air Pollution in Chengdu

为找到对成都空气质量有改善作用的气象要素等级,量化成都气象条件对大气污染物的影响,对2015—2018年成都环境监测站空气质量监测数据和温江国家气候观象台同时段的气象观测资料进行了研究分析。结果表明:(1)成都中部地区的空气质量污染较为严重,全年主要以PM_(2.5)和O_(3)污染为主,占比达75%,2015—2018年成都的PM_(2.5)污染呈下降趋势,而O_(3)污染虽有所波动但没有显著改善。(2)PM_(2.5)持续重污染过程中,过去12 h降水量和过去24 h降水量均大于1 mm,均为有效降水,大于2.5 mm对PM_(2.5)污染的改善作用显著增强;相对湿度低于70%对中度及以上PM_(2.5)污染的改善作用同步增加,低于40%对轻度PM_(2.5)污染的改善作用较为明显,优良天气的发生概率显著增加;风速大于1 m/s时PM_(2.5)浓度随风速的增大而减小,大于2 m/s对PM_(2.5)浓度的改善作用显著加强。(3)典型O_(3)污染过程中,当总辐射低于1 MJ/m^(2)、温度低于32℃、相对湿度高于50%、风速低于2 m/s时,O_(3)污染将得到显著改善。

In order to find the meteorological elements grade that can improve the air quality and quantify the impact of meteorological conditions on air pollutants in Chengdu,the observation data from environmental monitoring sites and Wenjiang national meteorological site in Chengdu from 2015 to 2018 were analyzed.The results indicated that the air pollution in the central area of Chengdu was relatively serious,mainly caused by PM_(2.5) and O_(3) pollution,accounting for 75%.From 2015 to 2018,PM_(2.5) pollution in Chengdu showed a downward trend,while O_(3) pollution fluctuated but did not improve significantly.In the process of continuous heavy PM_(2.5) pollution,the precipitation in the past 12 hours and the precipitation in the past 24 hours were more than 1 mm,which were both effective precipitation,and the improvement effect of more than 2.5 mm on PM_(2.5) pollution was significantly enhanced.The improvement effect of relative humidity lower than 70%on moderate and above PM_(2.5) pollution increased synchronously,and the improvement effect of relative humidity lower than 40%on light PM_(2.5) pollution was more obvious,and the probability of fine weather increased significantly.When the wind speed was greater than 1 m/s,the PM_(2.5) concentration decreased with the increase of wind speed,and the improvement effect of PM_(2.5) concentration was significantly strengthened when the wind speed was greater than 2 m/s.There was an obvious scavenging effect on O_(3) while the sun radiation was lower than 1 MJ/m^(2),the atmospheric temperature was lower than 32℃,the relative humidity was higher than 50%and the wind speed lower than 2 m/s.