The Atmosphere’s Oxidizing Capacity in China: Role and Influence of different photochemical processes

With the drastic actions initiated by the Chinese authorities to improve air quality, the level of several secondary pollutants including near-surface ozone still has been increasing significantly between years 2013 and 2020, most notably in the Northern China Plain. Alleviating ozone pollution requires a quantitative understanding of the different processes that contribute to the photochemical formation and destruction of secondary species. It also requires that the budget of fast-reacting radicals that are directly involved in photochemical oxidation processes be investigated in detail. Here, we used a modified regional chemical transport model (the WRF-Chem) to analyze the influence of different photochemical processes on the entire geographical area covered by China. This analysis provides a quantitative estimate of the different factors that affect the oxidation capacity of the atmosphere in different regions of the country. Besides that, our model simulations will assess the relative importance of different photochemical processes that contribute to the budget of near-surface ozone in different chemical environments and provide some theoretical considerations on which our analysis is based. This study should support to reduction of ozone and other secondary pollutants in China.