Fracture-induced softening for large-scale ice dynamics

Published: Dec 1, 2014 by The PISM Authors

Surface velocity, calculated fracture density, and modeled flow results for Filchner Ice Shelf.

Fracture processes within ice shelfs have been observed to reduce the retentive forces of the shelves on the Antarctic ice sheet. This paper adds a continuum representation of fractures, and their evolution, to PISM, and applies it to several major ice shelves in Antarctica. A key addition is the introduction of a higher-order scheme for advecting the two-dimensional fracture density field. Fractures and ice flow are coupled through a reduction of modeled ice viscosity proportional to the fracture density, so fracture-induced softening can feed back to cause added shear and self-amplified fracturing. The results of the simulations are compared to observations. Observed sharp across-flow velocity gradients in fracture-weakened regions are reproduced. This fracture-softening model is a basis for a future model of enhanced fracture-based calving.