On the suitability of the SRTM DEM and ASTER GDEM for the compilation of topographic parameters in glacier inventories

Topographic parameters in glacier inventories are a requirement to analyze glacier characteristics and are of vital importance for several subsequent applications. To obtain the topographic information a digital elevation model (DEM) is required; however, in many regions of the world no national or local DEM of sufficient quality is available. With the SRTM DEM and the ASTER Global Digital Elevation Model (ASTER GDEM), two datasets of reasonable resolution and promising quality are freely available for nearly all glacierized mountain ranges in the world. However, both DEMs have artifacts and errors, caused by the different acquisition techniques and the challenges posed by the rough high-mountain terrain and the special surface characteristics of glaciers. In this study, topographic glacier parameters as derived from both DEMs were compared to reference values as derived from a high-quality Swiss national DEM. All DEMs were reprojected to the (metric) UTM system and resampled to a 25 m and a 100 m cell size. For each of the resulting DEM versions, seven topographic parameters (minimum, maximum, mean, and median elevation, mean slope, mean aspect, and mean aspect sector) were calculated for 1786 glaciers lager than 0.1 km2 in Switzerland.