2014—2020年河南省PM_(2.5)-O_(3)复合污染特征及气象成因分析

Analysis of PM_(2.5)-O_(3)Compound Pollution Characteristics and Meteorological Causes in Henan Province from 2014 to 2020

为了解河南省PM_(2.5)-O_(3)复合污染特征及气象成因,本文基于2014—2020年河南省18个地级市的空气质量国控点数据及常规地面气象观测数据,对河南省PM_(2.5)-O_(3)的复合污染时空特征及关键气象因子影响进行分析.结果表明:(1)在空间分布上,PM_(2.5)-O_(3)复合污染天数呈由河南省中北部向周围逐渐减少的特点,而O_(3)单污染和PM_(2.5)单污染高发区均主要集中于豫北地区.(2)在时间特征上,2014—2020年PM_(2.5)-O_(3)复合污染天数呈先增加后减少的特征,最多为12 d(2014年),2016—2017年未出现复合污染;PM_(2.5)单污染和O_(3)单污染天数均呈“M”型变化趋势,PM_(2.5)单污染天数的2个峰值分别出现在2015年和2019年,分别为174和93 d,O_(3)单污染天数的2个峰值分别出现在2017和2019年,分别为64和79 d.PM_(2.5)-O_(3)复合污染主要出现在4月、5月、6月、7月、10月;PM_(2.5)单污染天数呈“V”型变化趋势,8月污染天数最少,为2 d,O_(3)单污染主要集中在4—10月.PM_(2.5)-O_(3)复合污染时的O_(3)浓度日变化特征与O_(3)日最大滑动平均值(简称“O_(3)-8 h浓度”)均呈“单峰”型.PM_(2.5)-O_(3)复合污染时的O_(3)浓度在16:00达最大值,为171μg/m^(3).(3)PM_(2.5)-O_(3)复合污染频发时的气温较O_(3)单污染频发时的气温高,而较PM_(2.5)单污染频发时的气温低.PM_(2.5)-O_(3)复合污染频发时的相对湿度较单污染频发时的相对湿度低.当气温为13.7~23.4℃、相对湿度为40%~65%、风向为北或东北风、风速为2.7~3.1 m/s时有利于PM_(2.5)-O_(3)复合污染的发生.研究显示,2014—2020年河南省PM_(2.5)-O_(3)复合污染具有明显的时空特征且污染程度先减轻后加重的趋势,气温、相对湿度、风速和风向对PM_(2.5)-O_(3)复合污染影响显著.

In order to understand the characteristics of PM_(2.5)-O_(3)compound pollution and the meteorological contributing factors in Henan Province,this study analyzes the temporal and spatial characteristics of PM_(2.5)-O_(3)compound pollution and the impact of the key meteorological factors based on the data of national air quality control points and conventional ground meteorological observation from 18prefecture-level cities in Henan Province from 2014 to 2020.The results show that:(1)For the spatial distribution,the composite of PM_(2.5)-O_(3)pollution days decrease gradually from the central north of Henan Province to the surrounding areas,and the high incidence areas of single O_(3)pollution days and single PM_(2.5)pollution days are mainly concentrated in northern Henan Province.(2)In terms of the temporal characteristics,from 2014 to 2020,the days of PM_(2.5)-O_(3)composite pollution increase first and then decrease,with a maximum of 12 days(in 2014).From 2016 to 2017,there is no composite pollution.Both single PM_(2.5)and O_(3)pollution show‘M’type trends.The two peaks of single PM_(2.5)pollution appear in 2015 and 2019,with 174 and 93 days,respectively.The two peaks of single O_(3)pollution appear in 2017 and 2019,with 64 and 79 days,respectively.The monthly variation of PM_(2.5)-O_(3)composite pollution days is mainly concentrated in April-July and October.The single PM_(2.5)pollution shows a‘V’type trend with the minimum pollution days of two occurring in August.The single O_(3)pollution is mainly concentrated in April-October.The daily variation characteristics of PM_(2.5)-O_(3)composite pollution are consistent with the daily maximum running average value of O_(3)(referred to as‘O_(3)-8 h concentration’),which show a‘single-peak’distribution and reach the maximum of 171μg/m^(3)at 16:00.(3)The air temperature leading to PM_(2.5)-O_(3)composite pollution is higher than that of single O_(3)pollution and lower than that of single PM_(2.5)pollution,and the relative humidity is lower than that of single pollution.When the air temperature is 13.7-23.4℃,the relative humidity ranges from 40%to 65%,the wind direction is north or northeast,and the wind speed is 2.7-3.1 m/s,it is conducive to the occurrence of PM_(2.5)-O_(3)composite pollution.The results show that the PM_(2.5)-O_(3)compound pollution in Henan Province has obvious temporal and spatial characteristics from 2014 to 2020 and the pollution level first decreases and then increases.Temperature,relative humidity,wind speed,and wind direction have significant impact on the PM_(2.5)-O_(3)compound pollution.