Clara Henry: Numerical stabilisation schemes for ice-sheet modelling

Abstract: Ice-sheet modelling continues to be challenging because of the need to balance computational efficiency with model complexity, a trade-off that affects the accuracy of sea-level projections. A major reason for the computational efficiency bottleneck is that the system of PDEs describing ice flow is stiff, meaning that the time-step size is restricted by fast-decaying modes. Generally, restrictive time stepping can be alleviated by solving the system of PDEs implicitly rather than explicitly. However, without modification, the implicit treatment of both the momentum equations and the mass conservation equation is challenging.

To address these time-step restrictions, we develop numerical stabilisation schemes for ice-sheet models of varying complexity by modifying the gravitational force term in the momentum equations. In this talk, I will focus in particular on the numerical stabilisation of the Blatter-Pattyn Approximation, an intermediate-complexity approximation of the p-Stokes equations. These methods enable larger stable time steps and have the potential to significantly improve the computational efficiency of large-scale simulations of the Antarctic and Greenland ice sheets.