Compilation of a glacier inventory for the western Himalayas from satellite data: methods, challenges, and results

Due to their sensitive reaction to changes in climatic conditions, glaciers have been selected as an essential climate variable (ECV). Although a large amount of ice is located in the Himalayas, this region is yet only sparsely represented in global glacier databases. Accordingly, a sound and comprehensive change assessment or determination of water resources was not yet possible. In this study, we present a new glacier inventory for the western Himalayas, compiled from Landsat ETM + scenes acquired between 2000 and 2002, coherence images from ALOS PALSAR image pairs, the SRTM digital elevation model (DEM) and the ASTER Global DEM (GDEM). Several specific challenges for glacier mapping were found in this region and addressed. They are related to debris cover, orographic clouds, locally variable snow conditions, and creeping permafrost features in cold-dry regions. Additional to seven topographic parameters that are obtained from the ASTER GDEM for each glacier, we also determined the relative amount of debris cover on the glacier surface. The inventory contains 11,400 glaciers larger than 0.02 km(2), which cover a total area of 9,310 km(2). Analysis of the inventory data revealed characteristic patterns of mean glacier elevation and relative debris cover amounts that might be related to the governing climatic conditions. The full dataset will be freely available in the GUMS glacier database to foster further analyses and modeling of the glaciers in this region. (C) 2012 Elsevier Inc. All rights reserved.