A thermomechanical model of ice flow in West Antarctica

This study uses a three-dimensional thermomechanical model to investigate t he internal flow dynamics of the West Antarctic Ice Sheet (WAIS). The model allows ice thickness, flow and temperature to interact freely. Its domain is prescribed as that of the present-day grounded WAIS. Realistic present-d ay climatic and topographical boundary conditions are employed. The analysi s of a series of experiments pays particular attention to the location and dynamics of concentrations of ice flow lice streams). Underlying topographi c troughs are crucial in determining the strength and location of these con centrations of flow. The flow pattern generated by subglacial troughs is ma de more distinct by the inclusion of ice flow/temperature coupling. The inc lusion of sliding leads to the generation of limit cycles in the ice flow. They are concentrated around the present-day ice streams B and C of the Sip le Coast and have a period of 5 to 10 ky. There appears to be competition b etween several preferred ice flow pathways in this area. The two end member s of the flow regime are a strong ice stream C with a weakened ice stream A /B complex, and strong ice streams A and B with a dormant ice stream C. Ice streams appear to require ice discharges above a certain threshold in orde r to maintain frictional heat generation and fast flow. Individual ice stre ams can therefore interact through changes in catchment-area size: a reduct ion in catchment area reduces the volume of ice entering a stream and can c ause stagnation as the amount of frictional heating falls.