The Cryosphere www.the-cryosphere.net 1994-0416 1994-0424 2 1 2008 10.5194/tc-2-67-2008 http://www.the-cryosphere.net/2/67/2008/ http://www.the-cryosphere.net/2/67/2008/tc-2-67-2008.html http://www.the-cryosphere.net/2/67/2008/tc-2-67-2008.pdf 67 76 2008-06-13 The ISMIP-HOM benchmark experiments performed using the Finite-Element code Elmer O. Gagliardini T. Zwinger LGGE, CNRS, UJF-Grenoble I, BP 96, 38402 Saint-Martin d'Hères Cedex, France CSC-Scientific Computing Ltd., Keilaranta 14, P.O. Box 405, 02101 Espoo, Finland 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 (<a href=''http://www.csc.fi/elmer'' target=''_blank''>http://www.csc.fi/elmer</a>). 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. Baiocchi, C., Brezzi, F., and Franca, L P.: Virtual bubbles and the Galerkin least squares method, Comp. Meths. Appl. Mech. Eng., 105, 125&ndash;141, 1993. Davis, T A.: A column pre-ordering strategy for the unsymmetric-pattern multifrontal method, ACM Trans. Math. Software, 30, 165&ndash;195, 2004. Donea, J. and Huerta, A.: Finite Element Methods for Flow Problems, John Wiley & Sons, 2003. Franca, L P. and Frey, S L.: Stabilized finite element methods: II. the incompressible Navier-Stokes equations, Comput. Methods Appl. Mech. Eng., 99, 209&ndash;233, 1992. Kelley, C.: Iterative methods for linear and nonlinear equations, Frontiers in Applied Mathematics, 16, SIAM, 1995. Les, P. and Wayne, T.: The NURBS Book, 646 pp., Springer-Verlag, New York, NY, Second Edition, ISBN 3-540-61545-8, 1997. Pattyn, F. and Payne, T.: Ice Sheet Model Intercomparison Project: Benchmark experiments for numerical Higher-Order ice-sheet Models, prefixhttp://homepages.ulb.ac.be/~fpattyn/ismip/, 2006. Pattyn, F., Perichon, L., Aschwanden, A., Breuer, B., de~Smedt, B., Gagliardini, O., Gudmundsson, G H., Hindmarsh, R., Hubbard, A., Johnson, J V., Kleiner, T., Konovalov, Y., Martin, C., Payne, A J., Pollard, D., Price, S., Rückamp, M., Saito, F., Souček, O., Sugiyama, S., and Zwinger, T.: Benchmark experiments for higher-order and full Stokes ice sheet models (ISMIP-HOM), The Cryosphere Discuss., 2, 111&ndash;151, 2008. Payne, A J., Huybrechts, P., Abe-Ouchi, A., Calov, R., Fastook, J L., Marshall, R. G. S J., Marsiat, I., Ritz, C., Tarasov, L., and Thomassen, M. P A.: Results from the EISMINT model intercomparison: the effects of thermomechanical coupling, J. Glaciol., 46, 227&ndash;238, 2000. Zwinger, T., Greve, R., Gagliardini, O., Shiraiwa, T., and Lyly, M.: A full Stokes-flow thermo-mechanical model for firn and ice applied to the Gorshkov crater glacier, Kamchatka, Ann. Glaciol., 45, 29&ndash;37, 2007.