Icetools: A full Stokes finite element model for glaciers

Detailed studies of glacier flow and deformation of ice require high-resolution numerical modeling. The model presented in this paper, icetools, solves the Stokes equation including all components of the stress tensor, termed full Stokes, with the finite element method to enable such detailed studies. Icetools is capable of running in parallel on computational clusters providing the computing power for large-scale simulations. Two different numerical tests were performed to demonstrate the capability of the model; (1) a comparison with the analytical solution for gravity driven plane flow down an inclined plane, and (2) flow over a Gaussian-shaped bed disturbance in comparison with the analytical transfer functions for this case. The second test involves time evolution of the surface geometry from an initially uniformly sloping surface. A linear rheology medium with a viscosity of 8 × 10 13 Pa s and a non-linear medium with Glen rheology exponent n = 3 and rate factor of A = 23 × 10 - 16 s - 1 kPa - 3 were studied. Both correlate well with the analytical solution and reach steady state, defined as when the maximum vertical movement drops below 5 × 10 - 5 times the mean ice thickness per year, after 282 years for the linear case and 135 years for the non-linear case, respectively.