[Simulation and Analysis of Ozone Pollution Process in Shijiazhuang Based on CMAQ-ISAM Model].

Abstract

In Shijiazhuang City, ozone （O₃） pollution occurs frequently in June every year. In June 2023, the average O₃ 8 h concentration （O₃-8h） pollution exceeded 80% of the days in the month, and O₃ was the primary pollutant, accounting for 100%. For an O₃ heavy pollution process from June 11 to 18, the air quality model WRF-CMAQ was used for simulation, and the average error data MFB and MFE were -10.47% and 17.96%, respectively, which was within the ideal error range. The CMAQ process analysis module was used to simulate the physical and chemical processes in Shijiazhuang City, and the dry deposition （DDEP） contribution concentration was -23.88 μg·m^-3, which was the main process of O₃ consumption, whereas the transport process （TRAN） was the main source of O₃, among which the contribution was more significant in vertical transport （VTRA）. At the same time, the source analysis module （ISAM） was used to analyze the O₃ contribution of local and surrounding areas in Shijiazhuang City. The results showed that the contribution rate of local industry sources in Shijiazhuang City was as follows： traffic source （12.54%） > industrial source （6.94%） > residential source （6.56%） > power source （4.75%）. The long-distance transmission source （BCON） continued to be in the first place with a high contribution rate of 63.31%. In the heavy pollution period under stable weather, the contribution concentration of BCON in the D02 layer of the nested domain to Shijiazhuang City was lower than the sum of the marked area. Among the surrounding cities, Baoding City had the highest contribution rate under stable weather, accounting for 26.21%. In the late period, the contribution concentration of Xingtai City increased rapidly under the action of high-value southwest wind. To effectively reduce O₃ pollution, it is necessary to reduce emissions in the city and to control the upwind cities in advance, and the implementation of inter-regional joint prevention and control is the key.