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. Here, we use 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) to investigate the impacts of variations in LCC, SSRD, and cloud–radiation interactions (CRIs) on O3 production. We design six numerical experiments and specifically modify parameters related to cloud radiation effects in the chemistry module to find out the underlying cause for O3 increase during the warm season of 2022 in the Yangtze River Delta (YRD), China. Results show that O3 production is strongly modulated by LCC and SSRD. CRI plays a significant role in regulating O3 concentration; i.e., reduced LCC, increased SSRD, and a weakened CRI are primarily responsible for the sharp increase in warm-season O3 concentration observed in 2022 in the YRD, 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.