The shallow shelf approximation as a "sliding law" in a thermomechanically coupled ice sheet model

TL;DR

This paper introduces a thermomechanically coupled ice sheet model using the shallow shelf approximation as a sliding law, which accurately simulates ice streams and is computationally efficient.

Contribution

It develops a new sliding scheme based on plasticity and Mohr-Coulomb yield stress, improving ice sheet modeling accuracy and stability.

Findings

Produces realistic ice streams in simulations

Balances driving stress with membrane stresses

Stable across parameter variations

Abstract

The shallow shelf approximation is a better ``sliding law'' for ice sheet modeling than those sliding laws in which basal velocity is a function of driving stress. The shallow shelf approximation as formulated by \emph{Schoof} [2006a] is well-suited to this use. Our new thermomechanically coupled sliding scheme is based on a plasticity assumption about the strength of the saturated till underlying the ice sheet in which the till yield stress is given by a Mohr-Coulomb formula using a modeled pore water pressure. Using this scheme, our prognostic whole ice sheet model has convincing ice streams. Driving stress is balanced in part by membrane stresses, the model is computable at high spatial resolution in parallel, it is stable with respect to parameter changes, and it produces surface velocities seen in actual ice streams.