Elmer/Ice News

Basal traction mainly dictated by hard-bed physics over grounded regions of Greenland

On glaciers and ice sheets, identifying the relationship between velocity and traction is critical to constrain the bed physics that controls ice flow. We determine the spatial relationship between velocity and traction in all eight major drainage catchments of Greenland. We find the relationships are consistent with our current understanding of basal physics in each catchment.

We identify catchments that predominantly show Mohr–Coulomb-like behavior typical of deforming beds or significant cavitation, as well as catchments that predominantly show rate-strengthening behavior typical of Weertman-type hard-bed physics.

Overall, the traction relationships suggest that the flow field and surface geometry of the grounded regions in Greenland is mainly dictated by Weertman-type hard-bed physics up to velocities of approximately 450m/yr, except within the Northeast Greenland Ice Stream and areas near floatation.

The results and analysis serve as a first constraint on the physics of basal motion over the grounded regions of Greenland and provide unique insight into future dynamics and vulnerabilities in a warming climate.

 

 

Read More: Maier, N., Gimbert, F., Gillet-Chaulet, F., Gilbert, A., 2021. Basal traction mainly dictated by hard-bed physics over grounded regions of Greenland. The Cryosphere 15, 1435–1451. https://doi.org/10.5194/tc-15-1435-2021

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A new tool for ice-ocean coupling

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Understanding ice sheet-ocean interaction is a key-point to quantify future sea level rise.  A recently published article presents FISOC (Framework for Ice Sheet-Ocean Coupling), which is an open-source tool based on ESMF (Earth System Model Framework) that allows for coupling different ice-sheet model and ocean model components. FISOC allows fully synchronous coupling, in which both ice and ocean run on the same time step, or semi-synchronous coupling in which the ice dynamic model uses a longer time step. Multiple regridding options are available, and there are multiple methods for coupling the sub-ice-shelf cavity geometry. Also, thermodynamic coupling is an option.The approach is modular, meaning that any ESMF-compliant ice-sheet or ocean model can be coupled using FISOC. Elmer/Ice includes an application interface (API) to FISOC and has been used in the current article to demonstrate the capabilities of the framework along the lines of simplified setups.

More details under:  Gladstone, R., Galton-Fenzi, B., Gwyther, D., Zhou, Q., Hattermann, T., Zhao, C., Jong, L., Xia, Y., Guo, X., Petrakopoulos, K., Zwinger, T., Shapero, D., and Moore, J., 2021. The Framework For Ice Sheet–Ocean Coupling (FISOC) V1.1.Geosci. Model Dev.,14,889–905. doi:10.5194/gmd-14-889-2021 (or direct link at GMD)

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Results from the Ice Thickness Models Intercomparison eXperiment Phase 2 (ITMIX2)

J. Fürst has participated to ITMIX2 with Elmer/Ice!

Knowing the ice thiITMIX2ckness distribution of a glacier is of fundamental importance for a number of applications, ranging from the planning of glaciological fieldwork to the assessments of future sea-level change. Across spatial scales, however, this knowledge is limited by the paucity and discrete character of available thickness observations. To obtain a spatially coherent distribution of the glacier ice thickness, interpolation or numerical models have to be used.

Whilst the first phase of the Ice Thickness Models Intercomparison eXperiment (ITMIX) focused on approaches that estimate such spatial information from characteristics of the glacier surface alone, ITMIX2 sought insights for the capability of the models to extract information from a limited number of thickness observations. The analyses were designed around 23 test cases comprising both real-world and synthetic glaciers, with each test case comprising a set of 16 different experiments mimicking possible scenarios of data availability. A total of 13 models participated in the experiments.

Read More: Farinotti, D., Brinkerhoff, D.J., Fürst, J.J., Gantayat, P., Gillet-Chaulet, F., Huss, M., Leclercq, P.W., Maurer, H., Morlighem, M., Pandit, A., Rabatel, A., Ramsankaran, R., Reerink, T.J., Robo, E., Rouges, E., Tamre, E., van Pelt, W.J.J., Werder, M.A., Azam, M.F., Li, H., Andreassen, L.M., 2021. Results from the Ice Thickness Models Intercomparison eXperiment Phase 2 (ITMIX2). Front. Earth Sci. 8. https://doi.org/10.3389/feart.2020.571923

 

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