Simulation of energy and water budgets in aspen, black spruce and jack pine forests during winter using the Canadian Land Surface Scheme

In the boreal forest, snow covers the ground for six months of the year, and contributes about a third of the annual water budget. Its influence on surface albedo varies with vegetation type and height. Surface albedo strongly affects the surface energy budget, and is a major feedback mechanism in the climate system. Results from the BERMS (Boreal Ecosystem Research and Monitoring Sites) project have revealed that the timing of spring and the availability of liquid water in the soil can have a strong impact on the annual carbon budget of boreal forest stands. As such, realistic parameterizations of snow processes in surface schemes is important for the representation of boreal forests in climate models.

The Canadian Land Surface Scheme (version 3) contains a number of improved parameterizations of significance for surface simulations in the boreal forest, including improved treatment of snow processes and snow density in particular. Also, organic soils are now represented, canopy conductance varies with vegetation type, and different surface types within a grid-cell can be represented as patches in a mosaic.

Results are presented for surface simulations in three boreal forest stands for nine month model runs, including the winter of 2002-2003. The forest stands, Old Aspen, Old Jack Pine and Old Black Spruce, are part of the BERMS project, and are located in Central Saskatchewan. Components of the surface energy budget are evaluated using field measurements, with a focus on the accumulation and ablation of the snowpack, and its properties. The performance of CLASS version 3 is shown to be improved relative to version 2.7, the previous operational version.