ISMIP-HOM benchmark experiments using Underworld

Abstract. Numerical models have become an indispensable tool for
understanding and predicting the flow of ice sheets and glaciers. Here we
present the full-Stokes software package Underworld to the glaciological
community. The code is already well established in simulating complex
geodynamic systems. Advantages for glaciology are that it provides a
full-Stokes solution for elastic–viscous–plastic materials and includes
mechanical anisotropy. Underworld uses a material point method to track the
full history information of Lagrangian material points, of stratigraphic
layers and of free surfaces. We show that Underworld successfully reproduces
the results of other full-Stokes models for the benchmark experiments of the Ice Sheet Model Intercomparison Project for Higher-Order Models
(ISMIP-HOM). Furthermore, we test finite-element meshes with different
geometries and highlight the need to be able to adapt the finite-element
grid to discontinuous interfaces between materials with strongly different
properties, such as the ice–bedrock boundary.
