Spatial-temporal variability in solar radiation during spring snowmelt

Much of the spring landscape of arctic regions is dominated by a patchy snow cover with implications for both spring melt runoff and atmospheric fluxes. In addition to a variable end-of-winter snowpack, spatial differences in snowmelt energy terms play an important role in the development of this patchy snow cover. This paper focuses specifically on the influence of solar radiation on snowmelt by using a model to simulate the small-scale variability of solar radiation incident on the ground surface due to topographic influences over a small arctic catchment. The model only requires a digital elevation model (DEM) and measured global radiation. Despite the relatively low relief (average slope 3 degrees) of the study area, the results showed solar radiation differences of up to 10% of the area-wide mean over the melt period. This would result in differences in snowmelt amounts of up to 50 mm, a value similar in magnitude to the overall mean end-of-winter snow water equivalent in the study region. An analysis of the effects of changing model scale showed that the simulated variability decreased substantially for larger grid sizes. The results show that the small-scale variability of solar radiation contributes greatly to the mosaic patterns in melting snow covers of arctic regions, affects the timing and amount of meltwater release and influences the surface energy balance of these areas considerably.