Elmer/Ice News

First online Elmer/Ice beginner's course

The first online Elmer/Ice beginner's course was taking place from November 23 to 27, ElmerIceCourse2020 Zoomwith a self-study preparation week based on instruction videos from 16. to 20. November. In total there were about 40 people from all over the world enrolled in this course, which was free of charge and supported by IGE, Grenoble and CSC in Espoo. The wide spread of timezones of the participants implied that every Zoom online session from the morning was repeated in the evening. The material (slides, videos and input files) is  still accessible via the course page and of course can be further used as reference or self-study material.

Besides some constructive suggestions on how to improve this course format, the feedback to the course was generally positive. A few quotes from the feedback form:

Thank you for the efforts and for a very well designed introduction course!

Thank you, you guys are the best!

I would like to thank you for the entire Elmer/Ice team for providing this great opportunity to learn the model. This was my first time with Elmer/Ice and I have found the model very important and useful in my research work. The course was detailed, informative and well structured. The training session was interactive and encouraged me to use the model in my research work. I am motivated to use the model in my current and future research.

Thank you very much for taking the time to run this course. It was fantastic to get an introduction to Elmer and to realise the possibilities it presents. I look forward to beginning to use Elmer in the near future.

 Encouraged by these positive reactions, the Elmer/Ice team is considering to provide courses of the same online format also in the post-pandemic future.

Elmer/Ice, Training

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Mapping the age of ice of Gauligletscher combining surface radionuclide contamination and ice flow modeling

jouvet2020In the 1950s and '60s, specific radionuclides were released into the atmosphere as a result of nuclear weapons testing. This radioactive fallout left its signature on the accumulated layers of glaciers worldwide, thus providing a tracer for ice particles traveling within the gravitational ice flow and being released into the ablation zone. For surface ice dating purposes, we analyze here the Plutonium and Uranium activity in more than 200 ice samples collected at the surface of Gauligletscher, Switzerland, and successfully identify the isochronal lines from 1960 and 1963. Hence this information is used to fine-tune an ice flow/mass balance model (Elmer/Ice), and to accurately map the age of the entire glacier ice (see picture). As an additional result, our results show that an airplane which crash-landed on the Gauligletscher in 1946 will likely soon be released from the ice close to the place where pieces have emerged in recent years, thus permitting the prognosis given in an earlier model to be revised considerably.

Read more: Jouvet G., S. Röllin, H. Sahli, J. Corcho, L. Gnägi, L. Compagno, D. Sidler, M. Schwikowski, A. Bauder and M. Funk, 2020. Mapping the age of ice of Gauligletscher combining surface radionuclide contamination and ice flow modeling, The Cryosphere, 14, 4233–4251, doi:10.5194/tc-14-4233-2020

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Quantifying the effect of ocean bed properties on ice sheet geometry over 40 000 years with Elmer/Ice

schanwell2020Simulations of ice sheet evolution over glacial cycles require integration of observational constraints using ensemble studies with fast ice sheet models. These include physical parameterisations with uncertainties, for example, relating to grounding-line migration. More complete ice dynamic models are slow and have thus far only be applied for < 1000 years, leaving many model parameters unconstrained. Here we apply a 3D thermomechanically coupled full-Stokes ice sheet model to the Ekström Ice Shelf embayment, East Antarctica, over a full glacial cycle (40 000 years). We test the model response to differing ocean bed properties that provide an envelope of potential ocean substrates seawards of today's grounding line. The end-member scenarios include a hard, high-friction ocean bed and a soft, low-friction ocean bed. We find that predicted ice volumes differ by > 50 % under almost equal forcing. Grounding-line positions differ by up to 49 km, show significant hysteresis, and migrate non-steadily in both scenarios with long quiescent phases disrupted by leaps of rapid migration. The simulations quantify the evolution of two different ice sheet geometries (namely thick and slow vs. thin and fast), triggered by the variable grounding-line migration over the differing ocean beds. Our study extends the timescales of 3D full-Stokes by an order of magnitude compared to previous studies with the help of parallelisation. The extended time frame for full-Stokes models is a first step towards better understanding other processes such as erosion and sediment redistribution in the ice shelf cavity impacting the entire catchment geometry.

Read more: Schannwell, C., R. Drews, T. A. Ehlers, O. Eisen, C. Mayer, M. Malinen, E. C. Smith and H. Eisermann, 2020. Quantifying the effect of ocean bed properties on ice sheet geometry over 40 000 years with a full-Stokes model, The Cryosphere, 14, 3917–3934, doi:10.5194/tc-14-3917-2020

 

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