Dynamically coupling the non-linear Stokes equations with the Shallow Ice Approximation in glaciology: Description and first applications of the ISCAL method

TL;DR

The paper introduces ISCAL, a novel method that dynamically couples full Stokes equations with the Shallow Ice Approximation for efficient and accurate large-scale ice sheet simulations, demonstrated on Greenland.

Contribution

ISCAL is the first method to automatically and dynamically couple FS and SIA equations, improving speed and accuracy in ice sheet modeling.

Findings

ISCAL is nearly ten times faster than monolithic FS with minimal accuracy loss.

ISCAL detects rapid dynamic changes in ice flow.

Application to Greenland shows practical utility.

Abstract

We propose and implement a new method, called the Ice Sheet Coupled Approximation Levels (ISCAL) method, for simulation of ice sheet flow in large domains under long time-intervals. The method couples the exact, full Stokes (FS) equations with the Shallow Ice Approximation (SIA). The part of the domain where SIA is applied is determined automatically and dynamically based on estimates of the modeling error. For a three dimensional model problem where the number of degrees of freedom is comparable to a real world application, ISCAL performs almost an order of magnitude faster with a low reduction in accuracy compared to a monolithic FS. Furthermore, ISCAL is shown to be able to detect rapid dynamic changes in the flow. Three different error estimations are applied and compared. Finally, ISCAL is applied to the Greenland Ice Sheet, proving ISCAL to be a potential valuable tool for the ice sheet modeling community.