A full Stokes subgrid model for simulation of grounding line migration in ice sheets

TL;DR

This paper introduces a novel subgrid modeling approach using Nitsche's method for accurately simulating the dynamic movement of grounding lines in ice sheets with full Stokes equations.

Contribution

It presents a new subgrid model combined with Nitsche's method to improve grounding line simulation accuracy in ice sheet models.

Findings

Effective in simulating advancing and retreating grounding lines

Implemented in open source Elmer/ICE code

Demonstrates improved discretization near grounding lines

Abstract

The full Stokes equations are solved by a finite element method for simulation of large ice sheets and glaciers. The simulation is particularly sensitive to the discretization of the grounding line which separates the ice resting on the bedrock and the ice floating on water and is moving in time. The boundary conditions at the ice base are enforced by Nitsche's method and a subgrid treatment of the elements in the discretization close to the grounding line. Simulations with the method in two dimensions for an advancing and a retreating grounding line illustrate the performance of the method. It is implemented in the two dimensional version of the open source code Elmer/ICE.