CGRG Bibliography of Canadian Geomorphology
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Author : Cogley, J.G.; and Ecclestone, M.A.
Date : 2001.
Title : Spatial variation of melting on glaciers measured by orbiting radar.
Publication : Annual Scientific Meeting of the Canadian Geophysical Union. May 14-17, 2001, University of Ottawa, Ottawa.
Issue :
Page(s) :
Abstract
Direct, in-situ measurements of glacier mass balance are expensive. Remote sensing would be an attractive alternative if remotely-observable quantities could be interpreted in terms of mass gain or loss. A system developed recently for the analysis of Radarsat browse images is used here to explore spatial variations in the length of the melt season on selected glaciers on Axel Heiberg Island, Nunavut, Canada. The browse images have an effective spatial resolution of 2 km, are georeferenced to single-pixel accuracy, and number about 200 over the two study years, 1998 and 1999. Surface melting in the accumulation zone is readily recognized by the strong contrast in brightness between bright cold firn, which exhibits a microwave signal dominated by volume scattering from ice lenses and pipes, and dark wet firn, the signal from which is muted by either absorption or near-specular reflection at the surface. The time series of browse images allow us to estimate melt duration according to simple criteria. We quantify the rate of decrease of melt duration with elevation and show that it is in good agreement with point measurements of annual mass balance on two glaciers. Well-resolved, remotely-sensed estimates of melt duration are therefore useful proxies for total melt intensity as measured by traditional glaciological methods. In continuing work we are attempting to model melt intensity as well, and the prototype image analysis system used here shows promise of becoming a valuable tool for the remote estimation of glacier meltwater losses.
Bibliography of Canadian Geomorphology