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 of vital importance for several subsequent applications. In combination with digital elevation models (DEMs) with near global coverage, such parameters can in principle be derived for all digital glacier outlines. In this study we investigate the suitability of the SRTM DEM and the ASTER GDEM for the compilation of seven glacier-specific topographic parameters for a sample of 1786 Swiss glaciers. Both DEMs were applied in two different resolutions, and the obtained parameter values were compared to values derived from the Swiss national DEM (DHM25), which served as the reference. The analysis revealed that large differences of the values can occur on individual glaciers, but they average out for larger glacier samples. Parameters that depend on a single DEM value (e.g. minimum or maximum elevation) show a larger variability than parameters that are averaged over the entire glacier area (e.g. mean elevation or mean slope). Besides artifacts, also changes due to different acquisition dates and techniques (radar, optical) have an influence on the inventory parameters. Although the SRTM DEM yielded slightly better results than the ASTER GDEM, both DEMs are suitable for the compilation of topographic parameters in glacier inventories.