Steady plane nonlinearly viscous flow of ice sheets on bedswith moderate slope topography

$epsilon$ , the aspect ratio of the ice sheet, , the maximum bed slope (), and one of either a, the maximum amplitude of the topography, or s, the span over which local topography extends. For steady plane flow of nonlinearly viscous ice the form of the leading order and two correction terms in the asymptotic expansion is deduced and the boundary value problems for the leading order and first correction terms are presented. As illustrations, the leading order and correction terms of the horizontal velocity are calculated and plotted for typical bed configurations. Comparison are then made with the three simpler cases of ice response: isothermal and nonlinearly viscous, then temperature dependent and linearly viscous, and finally isothermal and linearly viscous. It is found that for all three the correction terms in the horizontal velocity are very small. Received June 25, 2001 / Published online November 15, 2001