Elmer/Ice News

Environmental influences on the calving behaviour of Helheim

Cook and co-authors present a flow-line model of Helheim glacier that has been tuned using observations (velocity, temperature distribution) including Benn's calving criterion. The model was forced with different melting scenarios at its face, different surface melt distributions and - in a simplistic way – also ice mélange in front of the terminus. According to the findings with this model, it is rather the changing surface mass balance than the expected increase in ocean induced melting or the disappearing ice mélange that have the highest impact on accelerating the downwasting of a Greenlandic tide-water glacier such as Helheim.

The picture shows the difference in stress distributions and obtained crevasse depths with respect to the undisturbed ice front for different values of applied back-stress (representing the effect of ice mélange).

Cook, S., I.C. Rutt, T. Murray, A. Luckman, T. Zwinger, N. Selmes, A. Goldsack, and T.D. James, 2014: Modelling environmental influences on calving at Helheim Glacier in eastern Greenland, The Cryosphere, 8, 827-841, doi:10.5194/tc-8-827-2014 [link to paper]

Elmer/Ice at EGU 2014

Second Elmer/Ice users meeting

The second Elmer/Ice users meeting will take place  at EGU this year (Tue, 29 Apr 2014, 12:15–15:00 / Room Y3).

Elmer/Ice talks and Posters

Monday, 28 Apr
17:30–19:00 / Blue Posters, CR3.5, Glaciers and ice caps under climate change  
- EGU2014-15062 : Spatially distributed reconstruction of the surface mass balance of Pasterze glacier, Austria, employing a full Stokes model. Daniel Binder, Thomas Zwinger, Beate Hauser, Bernhard Hynek, Wolfgang Schöner, and Gernot Weyss

Tuesday, 29 Apr
17:30–19:00 / Blue Posters, CR3.1, Changing dynamics and environmental services of glacierized low latitude catchments
- EGU2014-6131, Simulations of Glaciar Zongo (Bolivia, 16°S) changes over the 21th century using the full-Stokes Elmer/Ice model, Marion Réveillet, Antoine Rabatel, Fabien Gillet-Chaulet, and Alavaro Soruco

Wednesday, 30 Apr
08:30–10:00 / Room Y11, CR1.4, Subglacial Environments of Ice Sheets and Glaciers   
- 09:15–09:30, EGU2014-9668, Basal conditions of the Rhine Glacier at the Last Glacial Maximum: insights from high-resolution transient numerical models, Denis Cohen, Fabien Gillet-Chaulet, Wilfried Haeberli, and Urs H. Fischer

10:30–12:30 / Room Y1, CR3.4, State of the Cryosphere: Observations and Modelling (including Arne Richter Award for Outstanding Young Scientists Lecture)   
- 10:45–11:00: EGU2014-7098, Retreat of Pine Island Glacier controlled by marine ice-sheet instability, Gael Durand, Lionel Favier, Stephen Cornford, Hilmar Gudmundsson, Olivier Gagliardini, Fabien Gillet-Chaulet, Thomas Zwinger, Anthony Payne, and Anne Le Brocq

Thursday, 1st May
08:30–12:00 / Room Y1, CR7.2, Modelling ice sheets and glaciers   
- 09:45–10:00, EGU2014-8597, Estimations of the age of the ice beneath Dome A, Antarctica, Thomas Zwinger, Bo Sun, Liyun Liyun, John C. Moore, Daniel Steinhage, and Carlos Martin

17:30–19:00 / Blue PostersPosters, CR7.2, Modelling ice sheets and glaciers   
- EGU2014-7095, Sensitivity of Austfonna icecap transient behavior to model physics and basal boundary conditions, Yongmei Gong, Rupert Gladstone, Stephen Cornford, Martina Schäfer, Thomas Zwinger, John Moore, Thorben Dunse, and Ruth Mottram   
- EGU2014-5247, Recession of Thwaites Glacier: inferring relevant processes using the ice sheet model Elmer/Ice, Nacho Merino, Gael Durand, Fabien Gillet-Chaulet, Noel Gourmelen, Andre Stumpf, Thomas Lampert, and Olivier Gagliardini   
-  EGU2014-5390, Initialising ice sheet model using nudging, Cyrille Mosbeux, Fabien Gillet-Chaulet, Gaël Durand, and Olivier Gagliardini

Its the anisotropy!

Blue ice areas (BIA) cover about 1% of the Antarctic ice sheet. They are characterized by a local enhanced ablation zone leaving bare ice (hence the name) in a distinct ablation zone. BIAs are confined to the coastal areas, usually close to nunataks. The distinct ablation zone has the coinciding feature that isochrones get vertically aligned, making BIAs an attractive source for easy accessible climate data from maritime influenced regions by simply scratching an ice core horizontally from the SBB velo singlemax
surface. The huge drawback is, that - in comparison to the vertically drilled ice cores in the central regions of Antarctica - the dynamical evolution of the ice sheet is an even stronger determining input in order to interpret such horizontal ice cores. To that end, the well explored BIA at Scharffenbergbotnen, DML, East Antarctica was studied using Elmer/Ice. Being initially puzzled by a complete mismatch between computed and measured velocities with a standard Glen's flow law and by excluding all other possible reason, the authors came to the conclusion that the existence of a pronounced fabric at the glacier is the most likely explanation to correctly interpret the flow conditions at the BIA. Further, by studying the evolution of the age-depth horizons using a novel Semi-Lagrangian solver showed that the oldest ice is about the age of the Late GLacial Maximum (LGM) of about 15ka bp., leading to the conclusion that the BIA started to form after the LGM, when the surrounding ice sheet started to thin and the valley of Scharffenbergbotnen was decoupled from the main ice flow. The project behind this study was funded by the Finnish Academy.

Reference: Zwinger, T., M. Schäfer, C. Martín, and J.C. Moore, 2014. Influence of anisotropy on velocity and age distribution at Scharffenbergbotnen blue ice area, The Cryosphere, 8, 607-621, doi:10.5194/tc-8-607-2014 [link to paper]

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