ARCUS | Arctic Research Consortium of the United States

7th Annual ARCUS Award for Arctic Research Excellence


Submitted by   Andreas Peter Ahlstrøm
Authors   Andreas P. Ahlstrøm, C. E. Bøggild, J. J. Mohr, O. B. Olesen, M. P. Hag, and K. Keller
Category   Physical Science
Title   Spatial Variability of Ice Sheet Ablation in West Greenland
Affiliation   Institute of Geography / Geological Survey of Denmark and Greenland, University of Copenhagen, Copenhagen, Denmark

Abstract

A distributed energy-balance model was forced with albedo derived from the Advanced Very High Resolution Radiometer (AVHRR) Polar Pathfinder (APP) data to evaluate the common assumption that ice sheet ablation can be considered a simple function of elevation. The model was applied to the western margin of the Greenland Ice Sheet between 67°N and 65°30’N because of the spatial heterogeneity of this area. Meteorological and glaciological observations from two transects were used to estimate input parameters and test the model, respectively. Results indicate that the ablation is mainly dependent on albedo which in turn depends on the spatial and temporal distribution of snow precipitation. The ablation was found to be highly variable near the margin irrespective of elevation, whereas a better correlation between ablation and elevation was found above the equilibrium-line altitude. The APP albedo was compared to in situ albedo measurements and found to be much too low, with a difference in ice albedo of more than 0.2, requiring adjustment if used for calculation of absolute ablation.