Analysis of Surface Ozone Pollution and Its Meteorological Causes in China during the Record Summertime Extreme Heat of 2022

In this study, the authors analyze surface ozone (O₃) pollution and its dominant meteorological drivers in China based on the record summertime extreme heat of 2022 using Chinese national air quality network measurements and EAR5 reanalysis meteorological fields. Spatially, the O₃ concentration across China remained high in the summer of 2022, with strong positive anomalies over northern China in June and southern China in July–August. For long-term trends, the O₃ concentration in the North China Plain (NCP) in June 2022 was the second highest in June since 2015, resulting in 21 regionally averaged ozone exceedance days. In July–August 2022, O₃ concentrations were the highest for these months since 2015 in the Yangtze River Delta (YRD) and Sichuan Basin (SCB). In terms of ozone precursor changes relative to 2019–2021, there was only a slight change in satellite-derived NO₂ columns in 2022, while the enhancement in satellite-derived HCHO over southern China was consistent with temperature changes. This suggests that the record-breaking summertime extreme heat of 2022 is the dominant driver of O₃ enhancement. Specifically, the spatial correlation coefficients between the O₃ and temperature anomalies in 2022 were 0.71, 0.64, and 0.49 for June, July, and August, respectively; additionally, O₃ sensitivity to temperature was relatively high in major clusters. Under the control of the subtropical high, the enhanced O₃ concentration exhibits a strong spatiotemporal consistency with stagnant weather conditions characterized by high temperature and low humidity. In particularly, the O₃–temperature relationship in 2022 was quite different from that of previous years, while the strong positive correlation observed for O₃–temperature was suppressed when reaching a high-temperature threshold in 2019–2021. This positive correlation persisted even at extremely higher temperatures in 2022 in the NCP and YRD. This study highlights the important role of extreme high-temperature events on O₃ pollution, which poses a pressing challenge for the synergistic control of complex air pollution issues in China.