Abstract. A stationary, computationally efficient scheme ChAP-1.0 (Chemical and Aerosol Processes, version 1.0) for the sulphur cycle in the troposphere is developed. This scheme is designed for Earth system models of intermediate complexity (EMICs). The scheme accounts for sulphur dioxide emissions into the atmosphere, its deposition to the surface, oxidation to sulphates, and dry and wet deposition of sulphates on the surface. The calculations with the scheme are performed forced by anthropogenic emissions of sulphur dioxide into the atmosphere for 1850–2000 adopted from the CMIP5 dataset and by the ERA-Interim meteorology assuming that natural sources of sulphur into the atmosphere remain unchanged during this period. The ChAP output is compared to changes of the tropospheric sulphur cycle simulations: with the CMIP5 data, with the IPCC TAR ensemble, and with the ACCMIP phase II simulations. In addition, in regions of strong anthropogenic sulphur pollution, ChAP results are compared to other data, such as the CAMS reanalysis, EMEP MSC-W, and with individual model simulations. Our model reasonably reproduces characteristics of the tropospheric sulphur cycle known from these information sources. In our scheme, about half of the emitted sulphur dioxide is deposited to the surface and the rest in oxidised into sulphates. In turn, sulphates are mostly removed from the atmosphere by wet deposition. The lifetime of the sulphur dioxide and sulphates in the atmosphere is close to 1 day and 5 days, respectively. The limitation of the scheme are acknowledged and the prospects for future development are figured out. Despite its simplicity, ChAP may be successfully used to simulate anthropogenic sulphur pollution in the atmosphere at coarse spatial and time scales.
State-Dependence of the Climate Sensitivity in Earth System Models of Intermediate Complexity
