2018—2021年京津冀及周边地区“2+26”城市PM2.5与O3污染特征及气象影响

为了解《打赢蓝天保卫战三年行动计划》期间(2018—2020年)以及之后(2021年)我国重点污染区域空气质量情况，并区分排放源控制与气象条件的贡献，本文利用逐小时监测的PM_2.5、O₃浓度以及气象要素数据，研究了2018—2021年京津冀及周边地区“2+26”城市PM_2.5与O₃污染特征，结合KZ (Kolmogorove Zurbenko)滤波方法定量分析了排放源与气象条件对PM_2.5与O₃浓度长期趋势的贡献. 结果表明:①2018—2021年“2+26”城市PM_2.5浓度年均值与O₃-8 h-90th浓度(O₃日最大8 h平均浓度的第90百分位数)均呈逐年下降趋势. 2018—2021年PM_2.5浓度年均值分别为60、57、51和45 μg/m3，河北省南部、河南省与山东省南部PM_2.5浓度年均值均较高；O₃-8 h-90th浓度分别为198、195、179和171 μg/m3，2018年保定市、石家庄市、聊城市与晋城市的O₃-8 h-90th浓度(>210 μg/m3)均较高，而2021年太原市O₃-8 h-90th浓度(192 μg/m3)较高. ②PM_2.5与O₃-8 h浓度(O₃日最大8 h平均浓度)的长期分量在大部分城市受气象条件影响较为明显. 受气象条件影响的PM_2.5浓度长期分量在2018—2020年无明显趋势，在2021年呈下降趋势；受排放源影响的PM_2.5浓度长期分量在2018—2020年呈下降趋势，在2021年无明显趋势. 受气象条件影响的O₃-8 h浓度长期分量在2018—2020年呈下降趋势，在2021年呈上升趋势；受排放源影响的O₃-8 h浓度长期分量在2018年呈下降趋势，在2019—2021年无明显趋势. ③11个气象因子中，温度和相对湿度对PM_2.5与O₃-8 h浓度变化的影响较大，当温度与相对湿度均比前一天升高时，更有利于PM_2.5与O₃-8 h浓度的同时升高. 研究显示，“2+26”城市PM_2.5与O₃污染受气象条件影响显著，温度与相对湿度的变化对判定PM_2.5与O₃-8 h浓度同时升高的现象有一定积极意义. 

Characteristics of PM2.5 and O3 Pollution and Related Meteorological Impacts in ‘2+26’ Cities of Beijing-Tianjin-Hebei and Its Surrounding Areas from 2018 to 2021

In order to understand the air quality in key polluted areas in China, fine particulate matter (PM_2.5) and ozone (O₃) were studied during the Three-Year Action Plan to Win the Blue Sky Defense from 2018 to 2020 and in 2021. Specifically, the characteristics of PM_2.5 and O₃ compound pollution were analyzed using hourly monitoring data of PM_2.5 and O₃ in the ‘2+26’ cities of Beijing-Tianjin-Hebei and its surrounding areas. In addition, the contributions of emission sources and meteorological factors to the long-term trend of PM_2.5 and O₃ concentrations were quantified based on the KZ filter method. The results showed that in recent years, the annual mean PM_2.5 and the 90th quantile of maximum daily 8-hour average ozone (O₃-8 h-90th) concentrations decreased in the ‘2+26’ cities. The annual mean values of PM_2.5 concentration from 2018 to 2021 were 60, 57, 51 and 45 μg/m3, respectively. The higher concentration of annual mean PM_2.5 appeared in southern Hebei, Henan and southern Shandong provinces; O₃-8 h-90th concentrations were 198, 195, 179 and 171 μg/m3, respectively. In 2018, O₃-8 h-90th concentration was higher in Baoding, Shijiazhuang, Liaocheng and Jincheng (greater than 210 μg/m3), while Taiyuan O₃-8 h-90th concentration was higher (192 μg/m3) in 2021. Furthermore, the long-term trend of PM_2.5 and O₃-8 h (maximum daily 8-hour average ozone) concentrations were more significantly influenced by meteorology. The long-term component of PM_2.5 concentration affected by meteorology showed no obvious trend from 2018 to 2020 and a downward trend in 2021, while the long-term component of PM_2.5 concentration affected by emissions showed a decreasing trend from 2018 to 2020 and no significant trend in 2021. The long-term component of O₃-8 h concentration affected by meteorology showed an upward trend from 2018 to 2020 and a downward trend in 2021, while the long-term component of O₃-8 h concentration affected by emissions showed a downward trend in 2018 and had no obvious trend from 2019 to 2021. Moreover, temperature and relative humidity had the greatest effect on both the concentration of PM_2.5 and O₃-8 h among the 11 meteorological factors. When the temperature and relative humidity increased together, it was more conducive to the simultaneous increase of PM_2.5 and O₃-8 h. The research shows that PM_2.5 and O₃ pollution in the ‘2+26’ cities are significantly affected by meteorology, and the changes in temperature and relative humidity are important in determining the simultaneous increase of PM_2.5 and O₃-8 h concentrations.