The ISMIP-HOM benchmark experiments performed using the Finite-Element code Elmer

Abstract. The aim of this paper is to describe in detail how the benchmark tests ISMIP-HOM (Ice Sheet Model Intercomparison Project-Higher-Order ice-sheet Model) have been performed using the open source finite element (FE) code Elmer (http://www.csc.fi/elmer). The ISMIP-HOM setup consists of five diagnostic and one prognostic experiments, for both 2-D and 3-D geometries. For all the tests, the full-Stokes equations are solved. Some technical points concerning FE, such as mesh characteristics, stabilisation methods, numerical methods used to solve the linear system and parallel performance are discussed. For all these setups, the CPU time consumption in relation to the accuracy of the solution is analysed. Based on these findings, some general rules on optimising the computing time versus the accuracy of the results are deduced.