Investigating Feedbacks Between Basal Sliding, Frictional Melting, and Longitudinal-Stress Transmission

Positive feedbacks between basal sliding, frictional melting, and longitudinal-stress transmission may allow for upstream migration of slow-to-fast sliding transitions, such as those occurring near to and upstream from ice stream onsets. We use a high-order, two-dimensional, thermomechanical flowband model to explore the potential for such feedbacks along an idealized ice stream tributary and onset region. The model, which includes a parameterization for the effects of lateral drag, incorporates basal sliding through shear deformation within a power-law viscous basal layer. The strength of this layer is assumed to decrease as the frictional melting rate increases. For a range of basal-layer rheologies (linear viscous to near plastic), we explore feedbacks between sliding, stress transmission, and melt-generation in order to understand how slow-to-fast sliding transitions may grow and migrate over time.