An Analysis of the Relation Between the Surface and Bedrock Profiles of Ice Caps

Abstract

Results art, presented of spectral analyses of the surface and bedrock profiles along a flow line of the Wilkes ice cap and the surface along the Greenland E.G.I.G. profile. Although the bedrock appears irregular over all was velengths studied, the ice-cap surface is typically characterized by a smooth curve with small-scale surface undulations superimposed on it. The following relations of Budd (1969, 19701 are confirmed. The “damping factor" or ratio of the bedrock amplitude to the surface amplitude is a minimum for wavelengths λ about 3.3 times the ice thickness. The surface lags the bed in the direction of motion by λ/4. The magnitude of the minimum damping factor φ_mis typically least near the coast, and increases inland depending on the ice thicknessZ, the velocityV, and the mean ice viscosityη(which is a function of stress and temperature) according to wherepis the mean ice density andgis the gravitational acceleration. Thus the determination of the damping factors provides a valuable means of estimating the ice flow parameterη.