A finite element multigrid-framework to solve the sea ice momentum equation

We introduce a geometric multigrid method as a preconditioner to the GMRES iteration for accelerating the solution of the linear problems. We show that the convergence rate of the multigrid method is robust with respect to mesh refinement. This makes it an appealing method for high resolution simulations. We validate the robustness of the linear solver and compare the multigrid with ILU preconditioning. In particular on fine meshes (∼16 km-2 km), multigrid preconditioning can substantially reduce the computational effort and decreases iteration counts by 80%.