Topographic controls on the surface energy balance of a high Arctic valley glacier

This paper presents the results of a distributed, two-dimensional surface energy balance model used to investigate the spatial and temporal variations in the surface energy balance of Midre Lovenbreen, a small valley glacier in northwest Spitsbergen, Svalbard, over the summer of 2000. We utilize high-resolution airborne lidar data to derive a digital elevation model of the glacier and surrounding topography, on which a surface energy balance is computed, driven by meteorological data obtained from a meteorological station located on the glacier and a synoptic station maintained at the nearby Ny-Alesund research base. Given the high-resolution topographic data, we focus particularly on whether the long duration of sunshine at high latitudes compensates for the higher solar zenith angles on the season-long energy balance and whether shading by the surrounding topography plus glacier surface slope and aspect play an increased role in the patterns of solar radiation receipt (and hence melt) over the glacier surface. The model results are validated using a combination of mass balance data from the glacier, measured surface lowering at the glacier meteorological station, and by comparing a derived energy balance component from the model with a measured energy flux. Overall, the model performance is very good. Glacier topography is found to play a fundamental role in determining the surface energy balance; topographic shading, slope, and aspect and correction of the surface albedo for high solar zenith angles are found to play a crucial role in determining spatial patterns of surface energy balance and therefore melt.