Performance analysis of high-resolution ice sheet simulations

TL;DR

This paper evaluates the computational performance of high-resolution ice sheet simulations, analyzing how mesh resolution and solver algorithms impact simulation cost and stability, and compares explicit and implicit time-stepping methods.

Contribution

It provides a quantitative analysis of simulation costs at high resolutions and assesses the potential benefits of implicit schemes over explicit methods.

Findings

Explicit time-stepping models are limited by stability restrictions at high resolutions.

Implicit schemes have the potential to improve performance by relaxing stability constraints.

Algorithmic scaling of solvers significantly influences simulation efficiency.

Abstract

Numerical ice sheet models compute evolving ice geometry and velocity fields using various stress-balance approximations and boundary conditions. At high spatial resolution, with horizontal mesh/grid resolutions of a few kilometers or smaller, these models usually require time steps shorter than climate-coupling time scales because they update ice thickness after each velocity solution. High-resolution performance is degraded by the stability restrictions of such explicit time-stepping. This short note, which considers the shallow ice approximation and Stokes models as stress-balance end members, attempts to clarify numerical model performance by quantifying simulation cost per model year in terms of mesh resolution and the number of degrees of freedom. The performance of current-generation explicit time-stepping models is assessed, and then compared to the prospective performance of implicit schemes. The main result, Table 2, highlights the key roles played by the algorithmic scaling of stress-balance and implicit-step solvers.