The built-in inversion capabilities of Elmer/Ice have been used to determine the change of basal friction coefficients below the glacier at Basin 3, Austfonna, during the acceleration phase of its recent surge. This time series, showing the unplugging of the stagnant ice front, was made possible by a highly temporal and spatial resolved set of satellite observations.
Observations also provided information on the crevasse field at the glacier, which was used to compare with the results obtained by the discrete element model, HiDEM, which was used to determine the instantaneous fractures as a reaction to the changing inverted basal friction. Identifying those crevasses that are deep enough to act as a path for surface water towards the bed and using a simplified hydraulic model, the possible mechanisms that lead to the surge of Basin 3 in early 2013 are discussed in this paper.
The picture shows the basal sliding velocities computed by Elmer/Ice as well as the flow path according to the hydraulic potential of water entering the deepest crevasses (red dots) that have been computed with HiDEM.
Read more: Gong, Y., Zwinger, T., Åström, J., Altena, B., Schellenberger, T., Gladstone, R., and Moore, J. C., 2018. Simulating the roles of crevasse routing of surface water and basal friction on the surge evolution of Basin 3, Austfonna ice cap. The Cryosphere, 12, 1563-1577, doi:10.5194/tc-12-1563-2018
Elmer/Ice contributed to the ISMIP6 initMIP-Greenland intercomparison exercice.
Earlier large-scale Greenland ice sheet sea-level projections (e.g. those run during the ice2sea and SeaRISE initiatives) have shown that ice sheet initial conditions have a large effect on the projections and give rise to important uncertainties. The goal of this initMIP-Greenland intercomparison exercise is to compare, evaluate, and improve the initialisation techniques used in the ice sheet modelling community and to estimate the associated uncertainties in modelled mass changes. initMIP-Greenland is the first in a series of ice sheet model intercomparison activities within ISMIP6 (the Ice Sheet Model Intercomparison Project for CMIP6), which is the primary activity within the Coupled Model Intercomparison Project Phase 6 (CMIP6) focusing on the ice sheets. Two experiments for the large-scale Greenland ice sheet have been designed to allow intercomparison between participating models of (1) the initial present-day state of the ice sheet and (2) the response in two idealised forward experiments. The forward experiments serve to evaluate the initialisation in terms of model drift (forward run without additional forcing) and in response to a large perturbation (prescribed surface mass balance anomaly); they should not be interpreted as sea-level projections. We present and discuss results that highlight the diversity of data sets, boundary conditions, and initialisation techniques used in the community to generate initial states of the Greenland ice sheet. We find good agreement across the ensemble for the dynamic response to surface mass balance changes in areas where the simulated ice sheets overlap but differences arising from the initial size of the ice sheet. The model drift in the control experiment is reduced for models that participated in earlier intercomparison exercises.
More information: Goelzer, H., S. Nowicki, T. Edwards, M. Beckley, A. Abe-Ouchi, A. Aschwanden, R. Calov, O. Gagliardini, F. Gillet-Chaulet, N. R. Golledge, J. Gregory, R. Greve, A. Humbert, P. Huybrechts, J. H. Kennedy, E. Larour, W. H. Lipscomb, S. Le clec'h, V. Lee, M. Morlighem, F. Pattyn, A. J. Payne, C. Rodehacke, M. Rückamp, F. Saito, N. Schlegel, H. Seroussi, A. Shepherd, S. Sun, R. van de Wal and F. A. Ziemen, 2018. Design and results of the ice sheet model initialisation experiments initMIP-Greenland: an ISMIP6 intercomparison, The Cryosphere, 12, 1433-1460. doi:10.5194/tc-12-1433-2018
Don't miss the 7 Elmer/Ice related posters and orals that will be presented during EGU 2018:
Monday, 9 Apr 2018
Johannes Fürst, Francisco Navarro, Fabien Gillet-Chaulet, Geir Moholdt, Xavier Fettweis, Charlotte Lang, Thorsten Seehaus, Matthias Braun, Douglas Benn, Toby Benham, Julian Dowdeswell, Mariusz Grabiec, Jack Kohler, Katrin Lindbäck, Rickard Pettersson, and Heïdi Sevestre. The ice-free topography of Svalbard, Mon, 09 Apr, 14:00–14:15, Room N1
Tuesday, 10 Apr 2018
Joe Todd, Jan Åström, Doug Benn, Thomas Zwinger, and Poul Christoffersen. 3D Calving Modelling of Store Glacier and Rink Isbrae using Elmer/Ice and HiDEM, Tue, 10 Apr, 17:30–19:00, Hall X4, X4.20
Wednesday, 11 Apr 2018
Lionel Favier, Nicolas Jourdain, Nacho Merino, Gael Durand, Olivier Gagliardini, and Fabien Gillet-Chaulet. Ice/Ocean coupled model based recommendations for sub-shelf melting parameterisations in standalone ice-sheet modelling, Wed, 11 Apr, 17:30–19:00, Hall X5, X5.377
Carlo Licciulli, Pascal Bohleber, Josef Lier, Olivier Gagliardini, Martin Hoelzle, Olaf Eisen, and Dietmar Wagenbach. Full Stokes ice-flow modeling of the high -Alpine glacier saddle Colle Gnifetti, Monte Rosa,Wed, 11 Apr, 17:30–19:00, Hall X5, X5.377
Clemens Schannwell, Reinhard Drews, Christoph Mayer, Olaf Eisen, Emma C. Smith, Todd A. Ehlers, Fabien Gillet-Chaulet, and Olivier Gagliardini. Fully-coupled 3D modelling of Hal, vfarryggen Ice Rise, Dronning Maud Land, East AntarcticaWed, 11 Apr, 09:00–09:15, Room L3
Thursday, 12 Apr 2018
Sainan Sun, Reinhard Drews, Frank Pattyn, Keith Nicholls, and Sophie Berger. Basal melt rate variability across ice-shelf channels in Dronning Maud Land, Antarctica, Thu, 12 Apr, 10:44–10:46, PICO spot 4
Friday, 13 Apr 2018
Sophie Berger, Reinhard Drews, Veit Helm, Niklas Neckel, Sainan Sun, Frank Pattyn, and Olaf Eisen. Detecting high spatial variability of ice-shelf basal mass balance, Fri, 13 Apr, 11:30–11:45, Room N1