Cloud-radiation interactions amplify ozone pollution in a warming climate

Abstract. Ozone (O₃) pollution has recently become the most critical air quality issue in China, yet its underlying drivers related to climate change remain poorly understood. Using a regional atmospheric chemistry model, along with 10-year ground-level O₃ measurements and reanalysis data on low cloud cover (LCC) and surface downward shortwave radiation (SSRD), we found that O₃ production is strongly modulated by LCC and SSRD. Cloud-radiation interactions (CRI) play significant roles in regulating O₃ concentration, i.e., reduced LCC, increased SSRD, and weakened CRI are primarily responsible for the sharp increase in O₃ concentration observed during the warm season of 2022 in the Yangtze River Delta, China. Moreover, climate warming is likely to exacerbate future O₃ pollution via weakening CRI due to fewer clouds and more SSRD. To mitigate O₃ pollution, we thus propose implementing more stringent emission reduction measures on O₃ precursors, along with proactive strategies to address climate change.