The thermomechanics of ice-stream margins

Jenny Sukale1,2 and James R. Rice1


Maps of the surface velocity of ice in West Antarctica show that flow localizes in narrow bands of fast flowing ice streams bordered by ridges of nearly stagnant ice. Despite the importance of ice streams for the stability of the West-Antarctic Ice Sheet, our understanding of the physical processes that determine their flow speed and width is incomplete. Here, we study the thermal and mechanical properties of ice-stream margins, where flow transitions from rapid to stagnant over a few kilometers. Our goal is to explore under which conditions the intense shear deformation in active ice-stream margins may lead to deformation-induced melting. We propose a 2D model that represents a cross-section through the ice-stream margin perpendicular  to the downstream flow direction. We include advection, latent heat and surface crevassing into our model and strive for a realistic description of the ice rheology. Our simulations suggest that a zone of temperate ice is likely to form in active shear margins.


1Harvard University; 2Stanford University