Abstract. We present the results of the first ice sheet model intercomparison project for higher-order and full-Stokes ice sheet models. These models are compared and verified in a series of six experiments of which one has an analytical solution obtained from a perturbation analysis. The experiments are applied to both 2-D and 3-D geometries; five experiments are steady-state diagnostic, and one has a time-dependent prognostic solution. All participating models give results that are in close agreement. A clear distinction can be made between higher-order models and those that solve the full system of equations. The full-Stokes models show a much smaller spread, hence are in better agreement with one another and with the analytical solution.

Abstract. We present the results of the first ice sheet model intercomparison project for higher-order and full Stokes ice sheet models. These models are validated in a series of six benchmark experiments of which one has an analytical solution under simplifying assumptions. Five of the tests are diagnostic and one experiment is prognostic or time dependent, for both 2-D and 3-D geometries. The results show a good convergence of the different models even for high aspect ratios. A clear distinction can be made between higher-order models and those that solve the full system of equations. The latter show a significantly better agreement with each other as well as with analytical solutions, which demonstrates that they are hardly influenced by the used numerics.

[1] A mathematical model for polythermal glaciers and ice sheets is presented. The enthalpy balance equation is solved in cold and temperate ice together using an enthalpy gradient method. To obtain a relationship between enthalpy, temperature, and water content, we apply a brine pocket parameterization scheme known from sea ice modeling. The proposed enthalpy formulation offers two advantages: (1) the discontinuity at the cold-temperate transition surface is avoided, and (2) no treatment of the transition as an internal free boundary is required. Fourier's law and Fick-type diffusion are assumed for sensible heat flux in cold ice and latent heat flux in temperate ice, respectively. The method is tested on Storglaciären, northern Sweden. Numerical simulations are carried out with a commercial finite element code. A sensitivity study reveals a wide range of applicability and defines the limits of the method. Realistic temperature and moisture fields are obtained over a large range of parameters.Citation: Aschwanden, A., and H. Blatter (2009), Mathematical modeling and numerical simulation of polythermal glaciers,

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