[Meteorological Influences on Annual Variation and Trend of Autumn Surface Ozone in the Pearl River Delta]

Based on the ozone （O₃） monitoring data of the Pearl River Delta （PRD） from 2015 to 2022 and the reanalysis of meteorological data, the impact of meteorological conditions on the annual variation and trends of the maximum daily 8-hour average O₃ concentration （MDA8-O₃） were quantified using multiple linear regression （MLR） and LMG methods. The results indicated that the MLR model constructed using meteorological parameters from individual months in autumn better simulated the variation in MDA8-O₃ compared to that in the model built using meteorological parameters from the entire autumn season. The combined influence of total cloud cover, relative humidity, 2 m maximum temperature, and 850 hPa zonal wind led to a reduction of 34.1 μg·m^-3 in MAD8-O₃ in 2020 compared to that in 2019, with contributions of 31.3%, 45.2%, 15.8%, and 6.7%, respectively. The observed trends of MDA8-O₃ in the PRD for September, October, November, and the autumn season during 2015-2022 were 7.3, 5.2, 4.8, and 5.8 μg·（m³·a）^-1, respectively. Among these, the trends driven by meteorological factors were 3.6, 2.4, 2.4, and 3.1 μg·（m³·a）^-1. Overall, meteorological conditions contributed 53.4% to the variations in autumn MDA8-O₃ in the PRD from 2015 to 2022.