Parameterization of Permafrost in the Canadian North

Permafrost is a phenomenon of growing interest in the science of global climate modelling. Global warming is projected to be amplified in northern high latitudes, with important implications for the future fate of currently frozen soils. This is of especial concern given the fact that the largest terrestrial store of organic carbon is located in permafrost, and is vulnerable to decomposition and release once thawing takes place. However, it has been shown that global climate models and earth system models display large differences in the extent of permafrost and the depth of the active layer that they simulate, even under current climate conditions. Results will be presented from an investigation into the interplay of different approaches to simulating the thermal and hydraulic regimes of permafrost areas. The model used for this purpose is "CLASS", the Canadian Land Surface Scheme, which is used operationally in the Canadian Earth System Model and Regional Climate Model. CLASS has been extensively tested in offline mode over single cell and regional domains in eastern and western Canada. Among the factors investigated will be soil discretization strategies, the treatment of snow cover and the role of wetlands. How the presence of permafrost is diagnosed, and the criteria for assessing the active layer depth, will be examined. Issues associated with the interpretation of data from the Canadian north, together with characteristic biases in the datasets, will be factored into the analysis.