Biological and Environmental Research - Earth and Environmental System Sciences
Earth and Environmental System Modeling

A Comparison of Two Stokes Ice Sheet Models Applied to the Marine Ice Sheet Model Intercomparison Project for Plan View Models (MISMIP3d)

TitleA Comparison of Two Stokes Ice Sheet Models Applied to the Marine Ice Sheet Model Intercomparison Project for Plan View Models (MISMIP3d)
Publication TypeJournal Article
Year of Publication2017
AuthorsZhang, Tong, Price Stephen, Ju Lili, Leng Wei, Brondex Julien, Durand Gael, and Gagliardini Olivier
JournalCryosphere
Volume11
Pages179-190
Abstract / Summary

We present a comparison of the numerics and simulation results for two “full” Stokes ice sheet models, FELIX-S and Elmer/Ice. The models are applied to the Marine Ice Sheet Model Intercomparison Project for plan view models (MISMIP3d). For diagnostic experiments, the two models give similar results (<2% difference with respect to along-flow velocities) when using identical geometries and computational meshes, which we interpret as an indication of inherent consistencies and similarities between the two models. For prognostic experiments, we find that FELIX-S (Elmer/Ice) grounding lines are relatively more retreated (advanced), results that are consistent with minor differences observed in the diagnostic experiment results, and that we show to be due to different choices in the implementation of basal boundary conditions in the two models. While we are not able to argue for the relative favorability of either implementation, we do show that these differences decrease with increasing grid resolution and that grounding-line positions for FELIX-S and Elmer/Ice converge to within the estimated truncation error. Stokes model solutions are often treated as an accuracy metric in model intercomparison experiments, but computational cost may not always allow for the use of model resolution within the regime of asymptotic convergence. In this case, we propose that an alternative estimate for the uncertainty in the grounding-line position is the span of grounding-line positions predicted by multiple Stokes models.

URLhttps://doi.org/10.5194/tc-11-179-2017
DOI10.5194/tc-11-179-2017
Journal: Cryosphere
Year of Publication: 2017
Volume: 11
Pages: 179-190
Publication Date: 01/2017

We present a comparison of the numerics and simulation results for two “full” Stokes ice sheet models, FELIX-S and Elmer/Ice. The models are applied to the Marine Ice Sheet Model Intercomparison Project for plan view models (MISMIP3d). For diagnostic experiments, the two models give similar results (<2% difference with respect to along-flow velocities) when using identical geometries and computational meshes, which we interpret as an indication of inherent consistencies and similarities between the two models. For prognostic experiments, we find that FELIX-S (Elmer/Ice) grounding lines are relatively more retreated (advanced), results that are consistent with minor differences observed in the diagnostic experiment results, and that we show to be due to different choices in the implementation of basal boundary conditions in the two models. While we are not able to argue for the relative favorability of either implementation, we do show that these differences decrease with increasing grid resolution and that grounding-line positions for FELIX-S and Elmer/Ice converge to within the estimated truncation error. Stokes model solutions are often treated as an accuracy metric in model intercomparison experiments, but computational cost may not always allow for the use of model resolution within the regime of asymptotic convergence. In this case, we propose that an alternative estimate for the uncertainty in the grounding-line position is the span of grounding-line positions predicted by multiple Stokes models.

DOI: 10.5194/tc-11-179-2017
Citation:
Zhang, T, S Price, L Ju, W Leng, J Brondex, G Durand, and O Gagliardini.  2017.  "A Comparison of Two Stokes Ice Sheet Models Applied to the Marine Ice Sheet Model Intercomparison Project for Plan View Models (MISMIP3d)."  Cryosphere 11: 179-190.  https://doi.org/10.5194/tc-11-179-2017.