A physically-based method for mapping glacial debris-cover thickness from ASTER satellite imagery: development and testing at Miage Glacier, Italian Alps

摘要

Debris-covered glaciers (>50% of the ablation zone covered by debris) are common in many of the world's major mountain ran ges an d rep resent an imp ortant fres hwater resource. Previous studies have established that surface melt rates decrease strongly for an increase in supraglacial debris thickness from a fe wcmupto 20-30 cm, whereas, th in an d patchy debris cover enhances melt due to albedo reduction. It is therefore important to develop methods to map and monitor changes in debris cover to en able predictions of glacier responses to climate change through numerical modelling. It is not possible to achieve this from ground-based measurements alone. Therefore, a m ethod to estimate debris thickness from an ASTER thermal band surface temperature image, based on a physical solution of the energy balance at the debris surface, has been developed. The model performs well in comparison to previous em pirical methods showing good agreem ent with measured debris thicknesses.