基于气象条件指数的我国重点区域PM_(2.5)和臭氧复合污染气象影响评估

Meteorological Impact Assessment of PM_(2.5) and O_(3) Complex Pollution in Key Regions of China Based on Meteorological Conditions Index

气象条件变化对复合污染的发生发展起重要作用,基于PM_(2.5)和O_(3)不同的污染形成机制,利用污染气象长期观测数据,分别采用统计运算和深度学习方法,构建了PM_(2.5)和O_(3)气象条件指数,形成以气象条件指数开展区域大气复合污染气象特征和影响贡献的研究方法,并对剔除区域气象差异影响的污染分布与变化进行了量化分析.结果表明,2021年夏季我国中东部重点区域污染气象条件整体上呈北差南优(指数:“2+26”城市>苏皖鲁豫交界>长三角地区),6月最差、7月最好的分布特征,当区域内城市PM_(2.5)气象条件指数>30且O_(3)气象条件指数>100时,“双高”污染开始出现,随O_(3)气象条件指数增大,“双高”频率不断升高;与上年同期相比,各地区ρ(PM_(2.5))受气象条件改善影响分别降低3.9、3.3和1.4μg·m^(-3),平均占到各地ρ(PM_(2.5))降低的58.5%,O_(3)污染气象条件则呈北转好、南转差变化,在长三角地区带来ρ(O_(3))近2.8μg·m^(-3)的增长;剔除气象差异影响后的PM_(2.5)高值分布在沿渤海、省际交界及区域南部,O_(3)高值则集中在太行山沿线、泰山周边以及长三角部分地区,利用单个城市剔除气象差异后的逐日浓度变化可实现对临时管控措施执行情况的实时监督和调度.

Meteorological conditions play a key role in the occurrence and evolution of atmospheric complex pollution.Considering the different pollution formation mechanisms of PM_(2.5) and O_(3),statistical calculation and in-depth learning methods were used to construct the PM_(2.5) and O_(3) meteorological condition indexes based on long-term pollution meteorological observation data.A research method was developed to study the meteorological characteristics and impact contribution of atmospheric complex pollution by using the meteorological condition index,and quantitative analysis of the distribution and variation of pollution excluding the influence of regional meteorological differences was also conducted.The results showed that in the summer of 2021,the pollution meteorological conditions in the key regions in central and eastern China were generally worse in the north and better in the south(index:"2+26"cities>the border area of Jiangsu,Anhui,Shandong,and Henan>the Yangtze River Delta)and the worst in June and the best in July.The"double high"pollution began to appear when the PM_(2.5) meteorological condition index>30 and O_(3) meteorological condition index>100;meanwhile,the unfavorable meteorological conditions for O_(3) also promoted the increase in PM_(2.5) concentration,resulting in the frequency of"double high"increases with the increase in O_(3) meteorological condition index.Compared with that during the same period last year,ρ(PM_(2.5))of each region decreased by 3.9μg·m-3,3.3μg·m^(-3),and 1.4μg·m^(-3) due to the contribution of the improvement in the pollution meteorological conditions,which is nearly 58.5%on average of the total decrease in PM_(2.5) concentration.However,the change in O_(3) pollution meteorological conditions was better in the north and worse in the south,and the overall deterioration in the Yangtze River Delta Region led to approximately 2.8μg·m^(-3) growth for the O_(3) concentration.The PM_(2.5) and O_(3) concentrations after excluding the impact of meteorological differences showed different distribution characteristics from the air quality monitoring,in which the high concentrations of PM_(2.5) were distributed along the Bohai Sea,the inter-provincial border,and the south of the region,whereas the high concentrations of O_(3) were concentrated along the Taihang Mountains,around Mount Tai,and in parts of the Yangtze River Delta.The daily concentration variations in a single city during a specific pollution control period could be used as a basis for evaluating the effectiveness of local supervision and control,which will provide a reference for the dynamic supervision and daily scheduling of local control management.