Inferring glacier mass balance using RADARSAT: Results from Peyto Glacier,Canada

The capability of RADARSAT synthetic aperture radar (SAR) for the purpose o f snow-line/accumulation area mapping For a temperate alpine glacier is exa mined. In agreement with other orbital C-band SAR studies, RADARSAT can dis criminate between firn and bare ice facies. Limited observations are report ed with respect to the electromagnetic variability of the ice facies in the ablation area, but they are inconclusive. Operational considerations are d iscussed with respect to reconciling the uncertainties of late-summer weath er and their possible impact on the dielectric and scattering properties of the glacier surface. Vagaries associated with other glacier settings, mass balance states aid their associated facies configurations are discussed in cluding the difficulty of using the transient snow-line to define the equil ibrium line and the lower extent of the accumulation area for glaciers wher e superimposed ice may form. The radar remote-sensing reconnaissance of equilibrium line altitude (ELA) and accumulation area ratio (AAR) for estimating glacier mass balance requi res serious consideration in those instances where traditional ground measu rements used in the direct glaciological method are absent. However, with r espect to the ELA, such estimates can vary depending on the accuracy of the reference digital elevation information. Moreover, for many glacier config urations, where mass balance variations due to altitude are influenced or i n some cases completely masked by local balance variations, defining the EL A may be an irreconcilable problem. Using the AAR may be more robust in thi s regard. It is further determined that the total error inherent in the rec onnaissance method would have serious implications for the confident estima tion of mass balance normals and climate-related trends if the method were to be utilized over the longer term.