Meteorological assessment of ozone environment in Fenwei Plain based on superior guidance products

Based on the newly developed O₃ meteorological condition eval uation index and pollution source apportionment products by the National Meteorological Center,combined with ground meteorological observation data and pollutant monitoring data,the paper analyzed the O₃ pollution characteristics,verified the O₃ evaluation guidance product,and carried out further research on O₃ comprehensive environmental meteorological conditions and O₃ source apportionment in Fenwei Plain from April to October 2023.The results show that there are a total of 46 days of O₃ exceeding the standard from April to October 2023 in Fenwei Plain,with the first occurrence occurring earlier than from 2020 to 2022.All national control stations experience O₃ pollution,of which 25.5% reach severe pollution.The seasonal and daily variation of O₃ concentration show a unimodal distribution,with the monthly peak appearing in June,the highest frequency of hourly concentration peak occurring at 16:00,and the highest valley value at 07:00.The O₃ meteorological condition evaluation index and source apportionment products show good changes in O₃ concentration and have a good correlation with observed values,with correlation coefficients of 0.95 and 0.82,respectively.From April to October 2023,the meteorological conditions in Fenwei Plain are unfavorable for the decrease of O₃ concentration compared to the same period in 2020 and 2021,with an increase of 0.8% and 2.6% respectively.Compared to the same period in 2022 and the past three years,it is favorable for the decrease of O₃ concentration,with a decrease of 3.6% and 0.2% respectively.From May to July,the meteorological conditions are favorable for O₃ generation month on month,and from August to October,they are unfavorable for O₃ generation.From April to August,the contribution of atmospheric background values show a decreasing trend,while the contribution of local emissions and external transport show an increasing trend.Afterwards,the three show a reverse trend.NO_x contribute significantly to the generation of O₃ in Fenwei Plain,with external transport contributing more than local transport.Hubei and Shandong transport contribute the most to the O₃ concentration in Fenwei Plain,with 25% and 23% respectively,indicating that long-distance transport of pollutants is an important reason for O₃ pollution in Fenwei Plain.There are differences in the sources of O₃ in different types of processes.