Comparison of ice dynamics using full-Stokes and Blatter-Pattynapproximation: application to the central North East Greenland IceStream

• Main Authors: Rückamp, Martin, Kleiner, Thomas, Humbert, Angelika
• Format: Text
• Language: English
• Published: 2021
• Subjects: Greenland; East Greenland; Ice Sheet
• Online Access: https://doi.org/10.5194/tc-2021-193; https://tc.copernicus.org/preprints/tc-2021-193/

Full-Stokes (FS) ice sheet models provide the most sophisticated formulation of ice sheet flow. However, its applicability is often limited due to its high computational demand and its owing numerical challenges. To balance computational demand and accuracy, the so-called Blatter-Pattyn (BP) stress regime is frequently used. Here, we explore the dynamic consequences caused by solving FS and the BP stress regime applied to the central part of the North East Greenland Ice Stream (NEGIS). To ensure a consistent comparison, we use one single ice sheet model to run the simulations under identical numerical conditions. A sensitivity study to grid resolution reveals that velocity differences between the FS and BP solution emerge below ~1 km horizontal resolution and continuously increases with resolution. Generally, BP produces higher surface velocities than FS, at a resolution of 0.1 km up to 5.8 % on average. In an extreme case, estimated ice discharge rates are up to 8 % overestimated by BP; in a rather classical case, BP reveals up to 3 % more ice discharge. Based on these minor model disagreements and given other large uncertainties in ice sheet projections, we conclude that the use of FS seems not an urgent issue and takes a secondary role in narrowing uncertainties of current sea-level projections. However, the englacial advection schemes from both stress regimes indicate severe impacts on internal layers of ice sheets.