Shallow shelf approximation as a “sliding law” in a thermomechanically coupled ice sheet model

The shallow shelf approximation, a balance of membrane stresses for ice flow, is an effective “sliding law” for ice sheet modeling. Our use of it as a sliding law becomes a standard model for ice stream flow when the sliding velocity is large (100 m a −1 and faster). Following Schoof (2006a), we describe the basal resistance as plastic till for which the yield stress is given by a Mohr‐Coulomb formula. Pore water pressure is related to basal melt rate. The velocity field used in the mass continuity and conservation of energy equations is an average of velocities from the shallow shelf approximation and the nonsliding shallow ice approximation. Using this scheme, our model has realistic, time‐dependent ice…