Sideswiping Typhoons Exacerbate Autumn Ozone Pollution in Coastal China

Abstract Ozone (O 3 ) pollution in coastal China exhibits a widespread increasing trend in autumn, coinciding with the active period of typhoons. Yet, the role of typhoons in autumn O 3 variations remains unclear. Here, we analyze autumn O 3 evolution during 63 typhoon episodes over 2014–2023, and illustrate diverse impacts of typhoons on O 3 variations over different coastal regions. We find that sideswiping typhoons, which move northward along the coasts, are more likely to trigger O 3 pollution, enhancing surface O 3 by 14.6∼39.5%. Model simulations show that O 3 enhancements over northern coastal regions are primarily resulted from chemical production and vertical transport (VTRA), while horizontal transport becomes the dominant factor responsible for elevated O 3 in southern regions during Typhoon “Muifa.” Impacts of typhoons on autumn O 3 under global warming are further investigated using a pseudo‐global‐warming simulation technique. If the typhoon occurred under a warmer background, substantial O 3 increases during typhoon days would be found, particularly in the northern regions, driven by stronger chemical processes and VTRA. Sensitivity simulations suggest that counteracting this warming‐induced O 3 amplification would require a joint reduction of NO x and VOCs emissions by 30%–75%. This study offers new insights on autumn O 3 variations impacted by typhoons based on observations and model projections, providing a scientific basis for surface O 3 formation and possible control strategy in the warming future.