The influence of basal disturbances on the velocity fields of glaciers is investigated numerically in two dimensions. This is done for finite-amplitude perturbations in bedrock topography and in basal slipperiness for both linear and non-linear rheology. The effects of nonlinear rheology on the velocity fields are mainly quantitative consisting essentially in a concentration of the anomalous flow near the base and in a reduction of the horizontal velocity perturbation near the surface. At small wavelengths (< 3 ice thicknesses) and small perturbation amplitudes, a recirculation forms in the velocity pattern for both types of perturbations. The anomalous flow increases with the wavelength of the perturbation and reaches a maximum at around 10 ice thicknesses for sufficiently high slip ratios.
|Number of pages
|Mitteilungen der Versuchsanstalt fur Wasserbau, Hydrologie und Glaziologie an der Eidgenossischen Technischen Hochschule Zurich
|Published - 1 Dec 2007