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Comparing SIA and Stokes on a large Antarctic basin

Written by Thomas Zwinger.

Full Stokes (FS) formulation and the most Seddik Shiraze ElmerIceWebsimplified shallow ice approximation (SIA) are implemented in the ice flow model Elmer/Ice, which enables the authors to compare them by applying the model to the East Antarctic Shirase drainage basin. Using the control inverse method to infer the distribution of basal friction with FS, they compare FS and SIA by simulating the flow of the drainage basin under present-day conditions and for three scenarios 100 years into the future defined by the SeaRISE (Sea-level Response to Ice Sheet Evolution) project. To no big surprise, FS reproduces the observed flow pattern of the drainage basin well, in particular the zone of fast flow near the grounding line, while SIA generally overpredicts the surface velocities. Looking at transient scenarios, the ice volume change (relative to the constant-climate control run) of the surface climate experiment is nearly the same for FS and SIA, while for the basal sliding experiment (halved basal friction), the ice volume change is  ∼  30 % larger for SIA than for FS. This confirms findings of earlier studies that, in order to model ice sheet areas containing ice streams and outlet glaciers with high resolution and precision, careful consideration must be given to the choice of a suitable force balance.

Read more: Seddik, H., R. Greve, T. Zwinger, and S. Sugiyama, 2017. Regional modeling of the Shirase drainage basin, East Antarctica: full Stokes vs. shallow ice dynamics, The Cryosphere, 11, 2213-2229, doi:https://doi.org/10.5194/tc-11-2213-2017.

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