The second Chinese glacier inventory: data, methods and results

The second Chinese glacier inventory was compiled based on 218 Landsat TM/ETM+ scenes acquired mainly during 2006–10. The widely used band ratio segmentation method was applied as the first step in delineating glacier outlines, and then intensive manual improvements were performed. The Shuttle Radar Topography Mission digital elevation model was used to derive altitudinal attributes of glaciers. The boundaries of some glaciers measured by real-time kinematic differential GPS or digitized from high-resolution images were used as references to validate the accuracy of the methods used to delineate glaciers, which resulted in positioning errors of 10m for manually improved clean-ice outlines and 30m for manually digitized outlines of debris-covered parts. The glacier area error of the compiled inventory, evaluated using these two positioning accuracies, was 3.2%. The compiled parts of the new inventory have a total area of 43 087 km, in which 1723 glaciers were covered by debris, with a total debris-covered area of 1494 km. The area of uncompiled glaciers from the digitized first Chinese glacier inventory is 8753 km, mainly distributed in the southeastern Tibetan Plateau, where no images of acceptable quality for glacier outline delineation can be found during 2006–10.