Preprints
https://doi.org/10.5194/tc-2021-193
https://doi.org/10.5194/tc-2021-193

  16 Jul 2021

16 Jul 2021

Review status: this preprint is currently under review for the journal TC.

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

Martin Rückamp1, Thomas Kleiner1, and Angelika Humbert1,2 Martin Rückamp et al.
  • 1Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung, Bremerhaven, Germany
  • 2Faculty of Geoscience, University of Bremen, Bremen, Germany

Abstract. 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.

Martin Rückamp et al.

Status: open (until 10 Sep 2021)

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Martin Rückamp et al.

Martin Rückamp et al.

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Short summary
We present a comparative modelling study between the full-Stokes (FS) and Blatter-Pattyn approximation applied to the North East Greenland Ice Stream. Both stress regimes are implemented in one single ice sheet model to eliminate numerical issues. The simulations unveil that differences in flow velocity between both stress regimes are minor, even at a spatial resolution of 100m. Given other large uncertainties in ice sheet projections, the use of FS seems not an urgent issue.