Monitoring of seasonal glacier mass balance over the European Alps using low-resolution optical satellite images

Abstract

We explore a new method to retrieve seasonal glacier mass balances (MBs) from low-resolution optical remote sensing. We derive annual winter and summer snow maps of the Alps during 1998-2014 using SPOT/VEGETATION 1 km resolution imagery. We combine these seasonal snow maps with a DEM to calculate a 'mean regional' altitude of snow (Z) in a region surrounding a glacier. Then, we compare the interannual variation of Z with the observed winter/summer glacier MB for 55 Alpine glaciers over 1998-2008, our calibration period. We find strong linear relationships in winter (mean R2 = 0.84) and small errors for the reconstructed winter MB (mean RMSE = 158 mm (w.e.) a-1). This is lower than errors generally assumed for the glaciological MB measurements (200-400 mm w.e. a-1). Results for summer MB are also satisfying (mean R2 and RMSE, respectively, 0.74 and 314 mm w. e. a-1). Comparison with observed seasonal MB available over 2009-2014 (our evaluation period) for 19 glaciers in winter and 13 in summer shows good agreement in winter (RMSE = 405 mm w.e. a -1) and slightly larger errors in summer (RMSE = 561 mm w.e. a-1). These results indicate that our approach might be valuable for remotely determining the seasonal MB of glaciers over large regions.