[Spatial-temporal Variations and Driving Factors of Surface Ozone over the Qinghai-Xizang Plateau from 2015 to 2021]

The spatial-temporal distribution pattern of surface O₃ over the Qinghai-Xizang Plateau （QXP） was analyzed based on air quality monitoring data and meteorological data from 12 cities on the QXP from 2015 to 2021. Kolmogorov-Zurbenko （KZ） filtering was employed to separate the original O₃-8h series into components at different time scales. Then, multiple linear regression of meteorological variables was used to quantitatively isolate the effects of meteorology and emissions. The results revealed that the annual mass concentrations of surface O₃-8h from 2015 to 2021 in 12 cities over the QXP ranged from 78.7 to 156.7 μg·m^-3, and the exceedance rates of O₃ mass concentrations （National Air Quality Standard of grade II） ranged from 0.7%-1.5%. The monthly O₃-8h mass concentration displayed a single-peak inverted "V"-shape and a multi-peak "M"-shape. The maximum monthly concentration of O₃ occurred in April to July, and valleys occurred in July, September, and December. The short-term, seasonal, and long-term components of O₃-8hdecomposed by KZ filtering contributed 29.6%, 51.4%, and 9.1% to the total variance in the original O₃ sequence in 12 cities, respectively. From the whole region, the meteorological conditions were unfavorable for O₃ reduction on the QXP from 2015 to 2017, which made the long-term component of O₃ increase by 0.2-2.1 μg·m^-3. The meteorological conditions were favorable for O₃-8h reduction from 2018 to 2021, which led to the long-term component of O₃-8h decrease by 0.4-1.1 μg·m^-3. The meteorological conditions increased the long-term component of O₃-8h in Ngari, Lhasa, Naqu, Nyingchi, Qamdo, Haixi, and Xining, with an average contribution of 30.1%. The meteorological conditions decreased the long-term component of O₃-8h in Shigatse and Golog, with contributions of 359.0% and 56.5%, respectively. The increase in the long-term component of O₃-8h in Ngari, Shigatse, Nagqu, Haixi, and Xining could be due to the rapid decrease in the long-term component of PM_2.5 （4.04 μg·（m³·a）^-1）.