The problem at the terminus

It is difficult to use Nye's kinematic wave theory to study the details of the advance and retreat of real glaciers. This is, in part, because the mass flux, q, cannot go to zero at the terminus if the glacier is to respond to an increase in accumulation by advancing. However, Equation (14.4) suggests that u ^ 0as h ^ 0. To avoid this, Nye (1963b, p. 92) assumes that the glacier is sliding at the terminus so q = ub0(l0)h where ub0(£0) is the sliding speed, ub, at the terminus, l0, in the datum state. Here t0 is the length of the glacier, measured from the bergschrund. Then Co = d q/d h = ubo(lo).

In addition, the amount of advance, At, is sensitive to the assumed geometry of the terminus. As shown in Figure 14.8:

tan0o where hi (l0) is the perturbation in ice thickness at the terminus. Thus At depends on 0o.

0 0

Post a comment