A comparison of box and plume model calculations for sulphur deposition and flux in Alberta, Canada

Two independently developed mathematical models are compared using meteorology and emissions from the province of Alberta, Canada, to observe similarities and differences in the model outputs with the aim of identifying those model components responsible. The Lagrangian box model and the plume expansion model use very different techniques to model the physical and chemical processes of atmospheric trassport and acidic deposition. Results show similarities in concentration of dry and wet deposition patterns, but differences in the magnitudes due primarily to differences in meteorological analysis and model parameterization. In general, the box model has more dispersion due to the instantaneous mixing within each grid box than the plume modelʹs puff expansion method except near large emission sources. The results indicate that patterns of mean pollutant concentrations across Alberta are dictated by source regions and meteorology but average pollutant concentrations are low overall when compared with populated and industrialized areas of eastern Canada and the United States. Total deposition patterns for Alberta are controlled by the wet deposition in the plume model but by dry deposition in the box model. Calculations of transboundary flux in both models reveal that 70% of the sulphur exiting Alberta enters the province of Saskatchewan.