The Finite-Element Method Applied to a Time-Dependent Flowband Model

The finite-element technique as applied to a 1-D flowband model of an ice sheet is described, as well as several modeling experiments to demonstrate the power of this technique.Based on the time-dependent continuity equation with ice velocity specified by a combination of flow and sliding laws, this fully time-dependent flowline-oriented finite-element model is used to: (1)compare computed steady-state and measured velocities in the Byrd Glacier in Antarctica, as well as to derive driving stress patterns, and estimates of the degree of sliding and creep deformation;(2)show the time evolution of an idealized flowband in which the ice hardness parameter undergoes a sudden 50% reduction;(3)show the time evolution of an idealized flowband in which the accumulation is doubled;(4)investigate the formation of an ice stream in a region originally dominated by sheet flow, and to display the time evolution of the surface elevation and the driving traction on various time scales as the ice stream forms, as well as to show the changing mass outflow at the grounding line.