Abstract
Abstract. A stationary, computationally efficient scheme ChAP 1.0 (Chemical and Aerosol Processes, version 1.0) for the sulfur cycle in the troposphere is developed. This scheme is designed for Earth system models of intermediate complexity (EMICs). The scheme accounts for sulfur dioxide emissions into the atmosphere, its deposition to the surface, oxidation to sulfates, and dry and wet deposition of sulfates on the surface. The calculations with the scheme are forced by anthropogenic emissions of sulfur dioxide into the atmosphere for 1850–2000 adopted from the CMIP5 dataset and by the ERA-Interim meteorology assuming that natural sources of sulfur into the atmosphere remain unchanged during this period. The ChAP output is compared to changes of the tropospheric sulfur 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 sulfur pollution, ChAP results are compared to other data, such as the CAMS reanalysis, EMEP MSC-W, and individual model simulations. Our model reasonably reproduces characteristics of the tropospheric sulfur cycle known from these information sources. In our scheme, about half of the emitted sulfur dioxide is deposited to the surface, and the rest is oxidised into sulfates. In turn, sulfates are mostly removed from the atmosphere by wet deposition. The lifetimes of the sulfur dioxide and sulfates in the atmosphere are close to 1 and 5 d, respectively. The limitations 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 sulfur pollution in the atmosphere at coarse spatial scales and timescales.
Highlights
Sulfur compounds in the troposphere are important pollutants and contribute both to the direct radiative effect, which is known as an aerosol–radiation interaction, and, owing to their hygroscopicity, are major contributors to the aerosol indirect effects on climate – the so-called aerosol–cloud interaction (Charlson et al, 1992; Boucher et al, 2013)
For the 1990 and 2000 time slices, annual mean sulfur dioxide burden exhibits maxima in the regions of the strong anthropogenic pollution – Europe, South-East Asia, and eastern North America, where BSO2 is typically larger than 2 mg S m−2 and in some grid cells is in excess of 5 mg S m−2 (Fig. 3b–e)
A stationary, computationally efficient scheme for the sulfur cycle in the troposphere, ChAP 1.0 (Chemical and Aerosol Processes, version 1.0), is developed. This scheme is designed to be implemented into Earth system models of intermediate complexity (EMICs)
Summary
Sulfur compounds in the troposphere are important pollutants and contribute both to the direct radiative effect, which is known as an aerosol–radiation interaction, and, owing to their hygroscopicity, are major contributors to the aerosol indirect effects on climate – the so-called aerosol–cloud interaction (Charlson et al, 1992; Boucher et al, 2013). A chemical reaction chain converts sulfur compounds into sulfur dioxide, which is further oxidised into sulfuric acid H2SO4 and sulfates SO24− (Seinfeld and Pandis, 2006; Warneck, 2000; Surkova, 2002) All of this has motivated researchers to implement interactive sulfur cycle into global climate models (or, more precisely, into Earth system models, ESMs). The goal of the present paper is to make a step beyond the Climber-2 and IAPRAS-MSU approaches and to allow for transport of sulfur species in the horizontal direction and the calculation of characteristics of the sulfur cycle directly This should be done in a computationally efficient manner in order not to destroy an important property of EMICs – their small turnaround time. A theoretical background for our scheme is presented and its offline performance is tested
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