A new satellite-derived glacier inventory for western Alaska

Glacier inventories provide the baseline data to perform climate-change impact assessment on a regional scale in a consistent and spatially representative manner. In particular, a more accurate calculation of the current and future contribution to global sea-level rise from heavily glacierized regions such as Alaska is much needed. We present a new glacier inventory for a large part of western Alaska (including Kenai Peninsula and the Tordrillo, Chigmit and Chugach mountains), derived from nine Landsat Thematic Mapper scenes acquired between 2005 and 2009 using well-established automated glacier-mapping techniques (band ratio). Because many glaciers are covered by optically thick debris or volcanic ash and partly calve into water, outlines were manually edited in these wrongly classified regions during post-processing. In total we mapped similar to 8830 glaciers (>0.02 km(2)) with a total area of similar to 16250 km(2). Large parts of the area (47%) are covered by a few (31) large (>100 km(2)) glaciers, while glaciers less than 1 km2 constitute only 7.5% of the total area but 86% of the total number. We found a strong dependence of mean glacier elevation on distance from the ocean and only a weak one on aspect. Glacier area changes were calculated for a subset of 347 selected glaciers by comparison with the Digital Line Graph outlines from the US Geological Survey. The overall shrinkage was,,similar to 23% between 1948-57 and 2005-09.