Towards binational concentration and deposition maps of nitrogen and sulphur with ADAGIO (Atmospheric Deposition Analysis Generated by optimal Interpolation of Observations)

Amanda Cole1, Alain Robichaud2, Mike D. Moran3, Mike Shaw4, Alexandru Lupu5, Guy Roy6, Vincent Fortin7 and Robert Vet8

The goal of Environment and Climate Change Canada’s ADAGIO project (Atmospheric Deposition Analysis Generated by optimal Interpolation of Observations) is to generate improved maps of wet, dry and total annual deposition of oxidized and reduced nitrogen (N) and sulphur (S) in Canada and the United States by combining observed and modeled data. Established measurements of wet deposition and/or air concentrations of deposited compounds provide the most accurate atmospheric deposition values in regions with dense coverage, but they are too sparse to provide reliable regional estimates of deposition for large areas of the continent and do not include all relevant species. Alternatively, atmospheric models that include meteorology, emissions, transport, chemistry and deposition of key N and S compounds provide complete spatial coverage and the ability to account for non-linear effects of meteorology and chemistry, but have varying degrees of bias and uncertainty in their predicted concentrations and fluxes. This project uses optimal interpolation techniques to combine the different advantages of measurements and models. Gridded seasonal precipitation amounts have been generated using the Canadian Precipitation Analysis (CaPA), in which all available precipitation data sets are used to adjust precipitation amounts predicted by Environment Canada’s Global Environmental Multiscale (GEM) numerical weather prediction model. Concentrations of N and S in precipitation are separately optimized using precipitation chemistry measurements from multiple Canadian and U.S. networks to perform optimal interpolation on concentration fields predicted by the in-line regional air quality model GEM-MACH (-Modelling Air quality and Chemistry). Similarly, surface air concentrations of particulate and gaseous N and S species will be optimized based on GEM-MACH output and network data. Effective dry deposition velocities will be obtained from GEM-MACH accumulated deposition amounts. The techniques are being developed using 2010 as a test year and will be applied to additional years in the future. Future directions may also include the incorporation of satellite measurements in the concentration analysis, and integration of ADAGIO methods and results with the USEPA’s Total Deposition (TDEP) program.


1Environment and Climate Change Canada,
2Environment and Climate Change Canada,
3Environment and Climate Change Canada,
4Environment and Climate Change Canada,
5Environment and Climate Change Canada,
6Environment and Climate Change Canada,
7Environment and Climate Change Canada,
8Environment and Climate Change Canada,