Advances and Challenges in Understanding Atmospheric Oxidizing Capacity in China: Insights from Chemical Mechanisms and Model Applications.

The ability of the atmosphere to convert primary pollutants into secondary pollutants through atmospheric oxidants is referred to as the atmospheric oxidizing capacity (AOC). This study systematically reviews the generation mechanisms, influencing factors, and quantitative characterization methods of major oxidants, along with advances in chemical mechanisms and modeling. We provide a comparative analysis of AOCs across diverse environments, including urban, suburban, and rural regions, highlighting the distinct impacts of anthropogenic and biogenic emissions on oxidation regimes. Despite advancements in chemical transport models and machine learning, limitations such as sparse observations, imperfect parameterizations, and unresolved chemical mechanisms lead to significant underestimations of the AOC. Future research must prioritize multi-scale observational networks and the elucidation of key chemical processes to refine model accuracy and improve the effectiveness of pollution control strategies.