Modeling snow-cover heterogeneity over complex Arctic terrain for regional and global climate models

The small-scale (10 to 100 m) and local-scale (100m to 10 km) effects of topography (elevation, slope, and aspect) and snow redistribution by wind on the evolution of the snowmelt are investigated. The chosen study area is the 142 km² Upper Kuparuk River basin located on the North Slope of Alaska. Two land surface models (LSMs) designed for regional and global climate studies apply different techniques to resolve these additional processes and features and their effects on snowmelt. One model uses a distributed approach to simulate explicitly the effects of topography on snowmelt at a 131-m resolution across the entire Upper Kuparuk watershed. By contrast, the other LSM employs a simple parameterization to implicitly resolve the effects of wind-blown snow on the hydrology of the Upper Kuparuk basin. In both cases, the incorporation of these local- and small-scale features within the LSMs leads to significant heterogeneity in the 1997 end-of-winter spatial distribution of snow cover in the Upper Kuparuk watershed. It is shown that the consideration of subgrid-scale snow-cover heterogeneity over complex Arctic terrain provides a better representation of the end-of-winter snow water equivalent, an improved simulation of the timing and amount of water discharge of the Upper Kuparuk River, and an alteration of other surface energy and water budget components.