The column total sulfate mass loading with a geographical distribution (figures below) is specified and vertically distributed with a homogeneous mixing ratio in the lowest 740 m thickness of the atmosphere. The temporal variation is included with multiplying a weighting time-series based on the historical emission record. Only the direct effect for shortwave radiation is included in the model. The sulfate mass loading data is from Mitchell and Johns (1997) and provided by T. C. Johns (personal communication).
The upper panels show geographical distribution of anthropogenic sulfate aerosol for (a) 1990 and (b) 2050, based on IPCC-IS92a scenario. Unit is 10?3 gm?2 in column total. Temporal change is the linear combination of (a) and (b) with respective weights plotted in the lower panel.