The Utrecht Finite Volume Ice-Sheet Model: UFEMISM

<p>Improving our confidence in future projections of sea-level rise requires models that can simulate ice-sheet evolution both in the future and in the geological past. A physically accurate treatment of large changes in ice-sheet geometry requires a proper treatment of processes near the margin, like grounding line dynamics, which in turn requires a high spatial resolution in that specific region. This leads to a demand for computationally efficient models, where such a high resolution can be feasibly applied in simulations of 10<sup>5</sup> – 10<sup>7</sup> yr in duration. To solve this, we developed UFEMISM, a new ice-sheet model that solves the hybrid SIA/SSA approximation of the stress balance on a fully adaptive, unstructured triangular mesh. This strongly reduces the number of grid points where the equations need to be solved, making the model much faster than the square-grid models that are typically used in paleo-ice-sheet research. We will discuss some of the difficulties in developing such a model, and the solutions we came up with. We will show that the model successfully performs several common schematic benchmark experiments for ice-sheet models, and we will take a look at some preliminary results of realistic experiments.</p>

The Utrecht Finite Volume Ice-Sheet Model: UFEMISM (version 1.0)

Improving our confidence in future projections of sea-level rise requires models that can simulate ice-sheet evolution both in the future and in the geological past. A physically accurate treatment of large changes in ice-sheet geometry requires a proper treatment of processes near the margin, like grounding line dynamics, which in turn requires a high spatial resolution in that specific region. This leads to a demand for computationally efficient models, where such a high resolution can be feasibly applied in simulations of 105–107 yr in duration. Here, we present and evaluate a new ice-sheet model that solves the SIA and SSA approximations of the stress balance on a fully adaptive, unstructured triangular mesh. This strongly reduces the number of grid points where the equations need to be solved, increasing the computational efficiency. We show that the model reproduces the analytical solutions or model intercomparison benchmarks for a number of schematic ice-sheet configurations, indicating that the numerical approach is valid. Because of the unstructured triangular mesh, the number of vertices increases less rapidly with resolution than in a square-grid model, greatly reducing the required computation time for high resolutions. A simulation of all four continental ice sheets during an entire 120 kyr glacial cycle, with a 4 km resolution near the grounding line, is expected to take 100–200 wall clock hours on a 16-core system (1,600–3,200 core hours), implying that this model can be feasibly used for high-resolution paleo-ice-sheet simulations.

A Simple Method for Network Visualization

In this article, we present a simple method for network visualization. The proposed method is based on distmesh [P.O. Persson and G. Strang, A simple mesh generator in MATLAB, SIAM Review 46 (2004) pp. 329–345], which is a simple unstructured triangular mesh generator for geometries represented by a signed distance function. We demonstrate a good performance of the proposed algorithm through several network visualization examples.