An observationally validated theory of viscous flow dynamics at the ice-shelf calving front
An analytical theory is developed for ice flow velocity in a boundary layer couplet at
the calving front. The theory has simple quantitative characteristics that relate ice front velocity to
thickness, strain rate and shelf width, matching one set of empirically derived relationships (Alley and
others, 2008) and implying that these relationships predict ice velocity rather than calving rate. The
two boundary layers are where longitudinal and transverse flow fields change from the interior flow to
patterns consistent with the calving-front stress condition. Numerical simulations confirm the analytical
theory. The quantitative predictions of the theory have low sensitivity to unmeasured parameters and to shelf plan aspect ratio, while its robustness arises from its dependence on the scale invariance of the governing equations. The theory provides insights into calving, the stability of ice-shelf calving fronts, the stability of the grounding line of laterally resisted ice streams, and also suggests that the calving front is an instructive dynamical analogue to the grounding line.