The impact of detailed snow physics on the simulation of snow cover and subsurface thermodynamics at continental scales

The three-layer snow model of Lynch-Stieglitz is coupled to the global catc hment-based land surface model of the National Aeronautics and Space Admini stration's Seasonal to Interannual Prediction Project, and the combined mod els are used to simulate the growth and ablation of snow cover over the Nor th American continent for the period of 1987-88. The various snow processes included in the three-layer model, such as snow melting and refreezing, dy namic changes in snow density, and snow insulating properties, are shown (t hrough a comparison with the corresponding simulation using a much simpler snow model) to lead to an improved simulation of ground thermodynamics on t he continental scale. This comparison indicates that the three-layer model, originally developed and validated at small experimental catchments, does indeed capture the important snow processes that control the growth and the ablation of continental-scale snowpack and its snow insulation capabilitie s.