Influence of atmospheric in-cloud aqueous-phase chemistry on the global simulation of SO<sub>2</sub> in CESM2

Abstract. Sulfur dioxide (SO2) is a major atmospheric pollutant and precursor of sulfate aerosols, which influences air quality, cloud microphysics, climate. Therefore, better understanding the conversion SO2 to essential simulate predict sulfur compounds more accurately. This study evaluates effects in-cloud aqueous-phase chemistry on oxidation in Community Earth System Model version 2 (CESM2). We replaced default parameterized reactions with detailed HOx, Fe, N, carbonate droplets performed global simulation for 2014–2015. Compared observations, results incorporating greatly reduced overestimation. overestimation was by 0.1–10 ppbv (parts per billion volume) most Europe, North America, Asia than 10 parts China. The biases annual simulated mixing ratios decreased 46 %, 41 22 % USA, China, respectively. Fe HOx contributed N chemistry. Higher concentrations soluble higher pH values could further enhance capacity. emphasizes importance SO2. These mechanisms can improve CESM2 deepen formation.