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Modeling the Controls on the Front Position of a Tidewater Glacier in Svalbard

Written by Olivier Gagliardini on .

Calving is an important masOtero Fig8s-loss process at ice sheet and marine-terminating glacier margins, but identifying and quantifying its principal driving mechanisms remains challenging. Hansbreen is a grounded tidewater glacier in southern Spitsbergen, Svalbard, with a rich history of field and remote sensing observations. The available data make this glacier suitable for evaluating mechanisms and controls on calving, some of which are considered in this paper. We use a full-Stokes thermomechanical 2D flow model (Elmer/Ice), paired with a crevasse-depth calving criterion, to estimate Hansbreen’s front position at a weekly time resolution. The basal sliding coefficient is re-calibrated every 4 weeks by solving an inverse model. We investigate the possible role of backpressure at the front (a function of ice mélange concentration) and the depth of water filling crevasses by examining the model’s ability to reproduce the observed seasonal cycles of terminus advance and retreat. Our results suggest that the ice-mélange pressure plays an important role in the seasonal advance and retreat of the ice front, and that the crevasse-depth calving criterion, when driven by modeled surface meltwater, closely replicates observed variations in terminus position. These results suggest that tidewater glacier behavior is influenced by both oceanic and atmospheric processes, and that neither of them should be ignored.

More information: Otero J, F.J. Navarro, J.J. Lapazaran, E. Welty, D. Puczko and R. Finkelnburg, 2017. Modeling the Controls on the Front Position of a Tidewater Glacier in Svalbard. Front. Earth Sci. 5:29. doi:10.3389/feart.2017.00029.

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Evidence of an unusually warm 21st century Arctic

Written by Olivier Gagliardini on .

adrien GRL2017

As a remnant of the Laurentide Ice Sheet, Barnes Ice Cap owes its existence and present form in part to the climate of the last glacial period. The ice cap has been sustained in the present interglacial climate by its own topography through the mass balance-elevation feedback. A coupled mass balance and ice-flow model, forced by Coupled Model Intercomparison Project Phase 5 climate model output, projects that the current ice cap will likely disappear in the next 300 years. For greenhouse gas Representative Concentration Pathways of +2.6 to +8.5 W/m2, the projected ice-cap survival times range from 150 to 530 years. Measured concentrations of cosmogenic radionuclides 10Be, 26Al, and 14C at sites exposed near the ice-cap margin suggest the pending disappearance of Barnes Ice Cap is very unusual in the last million years. The data and models together point to an exceptionally warm 21st century Arctic climate.

More information: Gilbert, A., G. E. Flowers, G. H. Miller, K. A. Refsnider, N. E. Young, and V. Radić, 2017. The projected demise of Barnes Ice Cap: Evidence of an unusually warm 21st century Arctic, Geophys. Res. Lett., 44, doi:10.1002/2016GL072394.

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Elmer/Ice @EGU2017

Written by Olivier Gagliardini on .

egu plainThe fourth Elmer/Ice users splinter meeting will take place during EGU 2017 (Wednesday 25 April 2017, from 12:15 to 15:00, Room 0.51). The provisional agenda is here.

Don't miss the 15 Elmer/Ice related posters and orals that will be presented during EGU 2017:

Monday, 24 Apr

Eva de Andrés, Jaime Otero, Francisco Navarro, Agnieszka Prominska, Javier Lapazaran, and Waldemar Walczowski, A fjord-glacier coupled system model. Mon, 24 Apr, 13:30–13:45, Room G2

Joe Todd, Poul Christoffersen, Thomas Zwinger, Peter Råback, Nolwenn Chauché, Alun Hubbard, Nick Toberg, Adrian Luckman, Doug Benn, Donald Slater, and Tom Cowton. A 3D Full-Stokes Calving Model Applied to a West Greenland Outlet Glacier. Mon, 24 Apr, 14:30–14:45, Room G2

Tuesday, 25 Apr
Yongmei Gong, Thomas Zwinger, Jan Åström, Rupert Gladstone, Thomas Schellenberger, Bas Altena, and John Moore. Basal friction evolution and crevasse distribution during the surge of Basin 3, Austfonna ice-cap – offline coupling between a continuum ice dynamic model and a discrete element model. Tue, 25 Apr, 16:30–16:45, Room -2.32

Yasmina M. Martos, Carlos Martin, and David G. Vaughan. New basal temperature and basal melt rate maps of Antarctica. Tue, 25 Apr, 17:30–19:00, Hall X5

Wednesday, 26 Apr
Johannes J. Fürst, Thorsten Seehaus, Björn Sass, Kjetil Aas, Toby J. Benham, Julian Dowdeswell, Xavier Fettweis, Fabien Gillet-Chaulet, Geir Moholdt, Francisco Navarro, Christopher Nuth, Rickard Petterson, and Matthias Braun. A two-step mass-conservation approach to infer ice thickness maps: Performance for different glacier types on Svalbard. Wed, 26 Apr, 17:30–19:00, Hall X4

Thursday 27 Apr
Shahbaz Memon, Dorothée Vallot, Thomas Zwinger, and Helmut Neukirchen. Coupling of a continuum ice sheet model and a discrete element calving model using a scientific workflow system. Thu, 27 Apr, 08:45–09:00, Room L2

Doug Benn, Jan Åström, Thomas Zwinger, Joe Todd, and Faezeh Nick. Modelling tidewater glacier calving: from detailed process models to simple calving laws. Thu, 27 Apr, 08:45–09:00, Room G2

Mauro A. Werder, Basile de Fleurian, Timothy T. Creyts, Anders Damsgaard, Ian Delaney, Christine F. Dow, Olivier Gagliardini, Matthew J. Hoffman, Julien Seguinot, Aleah Sommers, Inigo Irarrazaval Bustos, and Jakob Downs. Subglacial Hydrology Model Intercomparison Project (SHMIP). Thu, 27 Apr, 09:45–10:00, Room G2

Olivier Passalacqua, Marie Cavitte, Massimo Frezzotti, Olivier Gagliardini, Fabien Gillet-Chaulet, Frédéric Parrenin, Catherine Ritz, Luca Vittuari, and Duncan Young. A mechanical diagnosis of the ice flow around Dome C: Elmer/Ice 3D simulations constrained by measured surface velocities and radar isochrones. Thu, 27 Apr, 17:30–19:00, Hall X5

Dorothée Vallot, Rickard Pettersson, Adrian Luckman, Douglas I. Benn, Thomas Zwinger (presenting), Ward van Pelt, Jack Kohler, Martina Schäfer, Björn Claremar, and Nicholas R. J. Hulton. Influence of surface changes on spatio-temporal variations of basal properties for Kronebreen, Svalbard. Thu, 27 Apr, 17:30–19:00, Hall X5

Rupert M. Gladstone, Thomas Zwinger (presenting), Fabien Gillet-Chaulet, and John C. Moore. Basal shear stress and choice of sliding relation in Antarctic Ice Sheet simulations. Thu, 27 Apr, 17:30–19:00, Hall X5

Denis Cohen, Thomas Zwinger, Wilfried Haeberli, and Urs H. Fischer. Did permafrost modify basal conditions during the Last Glacial Maximum? The case of the Rhine glacier, Swiss Alps. Thu, 27 Apr, 17:30–19:00, Hall X2

Fabien Gillet-Chaulet, Laure Tavard, Nacho Merino, Vincent Peyaud, Julien Brondex, Gael Durand, and Olivier Gagliardini. Anisotropic mesh adaptation for marine ice-sheet modelling. Thu, 27 Apr, 17:30–19:00, Hall X5

Lenneke Jong, Rupert Gladstone, and Ben Galton-Fenzi. Coupled ice sheet-ocean modelling to investigate ocean driven melting of marine ice sheets in Antarctica. Thu, 27 Apr, 17:30–19:00, Hall X5

Friday, 28 Apr
Reinhard Drews, Christoph Mayer, Olaf Eisen, Veit Helm, Todd A. Ehlers, Frank Pattyn, Sophie Berger, Lionel Favier, Ian H. Hewitt, Felix Ng, Johannes J. Fürst, Fabien Gillet-Chaulet, Nicolas Bergeot, and Kenichi Matsuoka. Fun at Antarctic grounding lines: Ice-shelf channels and sediment transport. Fri, 28 Apr, 08:52–08:54, PICO spot 3

Frédéric Parrenin, Marie Cavitte, Donald Blankenship, Jérôme Chappellaz, Hubertus Fischer, Olivier Gagliardini, Fabien Gillet-Chaulet, Valérie Masson-Delmotte, Olivier Passalacqua, Catherine Ritz, Jason Roberts, Martin Siegert, and Duncan Young. Is there 1.5 million-year old ice near Dome C, Antarctica? Fri, 28 Apr, 10:48–10:50, PICO spot 3

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