Modeling snowcover heterogeneity in polar regions

We investigate some of the physical representations of snowcover and the subsequent impact on a range of processes, including snowmelt, land/atmosphere interactions, and the surface energy and water budgets, that require consideration in the Arctic for regional and global climate models. Snow heterogeneity is identified as a critical feature that controls the hydrology of the Upper Kuparuk watershed, a 142 square kilometer basin on the Alaskan North Slope. Incorporation of subgrid-scale snow heterogeneity leads to improved simulations of the water and energy budgets during the spring transition period, including the timing and amount of water discharge. Two TOPMODEL-based hydrologic models are used to represent the snow heterogeneity. One model uses a distributed approach to simulate explicitly snowpack conditions at a 100-m resolution across the entire Upper Kuparuk watershed. It captures variations in the snowpack that arise from local differences in elevation and exposure to sunlight. By contrast, the other land surface model employs a simple parameterization to implicitly resolve the effects of wind-blown snow on the hydrology of the Upper Kuparuk Basin. We discuss how the distributed snowmelt simulations, supplemented by remote sensing data, provide constraints on developing a simple parameterization to implicitly resolve the effects of wind-blown snow in regional and global climate model simulations.