An Improved Version of the Atmospheric Sulfur Cycle Scheme for Earth System Model of Intermediate Complexity

The scheme of the atmospheric sulfur cycle ChAP (Chemical and Aerosol Processes), which is developed for Earth system models of intermediate complexity, is extended by taking into account the dimethylsulfide (DMS) emissions into the atmosphere and the differences of the sulfates washout efficiency between different kinds of precipitation. In addition, the transport scheme is slightly revised. To keep the scheme computationally efficient, the new version of the scheme, ChAP–1.1, still employs the stationary approximations and the prescribed vertical profiles for sulfur compounds in the atmosphere (as it was used in ChAP–1.0 as well), which is related to relatively short lifetimes of the sulfur dioxide and sulfates in the troposphere. As a result, the horizontal distributions of the tropospheric sulfur dioxide and sulfates burdens agree better (relative to those for ChAP–1.0) with the reanalysis data CAMS (Copernicus Atmosphere Monitoring Service) and with the ACCMIP (Atmospheric Chemistry and Climate Model Intercomparison Project) data for the late 20th–early 21st centuries. According to the ChAP–1.1 simulations, the global sulfur dioxide burden in the atmosphere in 1990–2000 is 0.2 TgS, and the respective value for sulfates is 0.6–0.7 TgS with the corresponding lifetimes 1 day and 6 days.