Elmer/Ice News

Elmer/Ice used in ice core based accumulation reconstruction for the Caucasus

cp 20 237 2024 f03 webIn this study, is presented a seasonally resolved accumulation record spanning from 1750 to 2009 CE, based on a 181.8 m ice core obtained from the Elbrus Western Plateau in the Caucasus. Various methods are implemented to account for uncertainties associated with glacier flow, layer thinning, and dating. Particularly, the upstream effect is accounted for with the help of Elmer/Ice. Since the ice core includes layers that were deposited upstream of the drilling site, where annual snow accumulation conditions may differ from those at the drilling site, it is crucial to identify the ice core catchment area in order to investigate the connection between the ice core data and surface accumulation. To account for this upstream effect, were calculated the backward trajectories of the ice and firn particles positioned along a vertical line segment connecting the drill site and the bedrock. The trajectories are reconstructed based on the modeled glacier velocity field. The velocity field is simulated on the base of a 3-D full Stokes ice-flow model with the firn rheological law. A steady-state simulation with fixed glacier geometry is performed. The mathematical formulation of the ice-flow problem includes the Stokes and the volume balance evolution equations, the stress-free surface boundary condition, and the no-slip bedrock boundary condition. The model utilizes a smoothed vertical profile of density inferred from the 2009 Elbrus ice core. Based on the simulation, it was determined that the sources of the backward trajectories are located on the glacier surface close enough to the drill site. This result ascertains the representativeness of the ice core material as a proxy for surface accumulation rates.

Read more: Mikhalenko V., S. Kutuzov, P. Toropov, M. Legrand, S. Sokratov, G. Chernyakov, I. Lavrentiev, S. Preunkert, A. Kozachek, M. Vorobiev, A. Khairedinova and V. Lipenkov, 2024. Accumulation rates over the past 260 years archived in Elbrus ice core, Caucasus,Clim. Past 20, 237-255. doi:10.5194/cp-20-237-2024

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Controls on calving at a Greenland tidewater glacier

Choosing the location Sermeq Kujalleq (Store Glacier), the calving behaviour of a typical Greenlandic tidewater glacier  was Difference in first principal deviatoric stress for undercut ‘retreated’ configurations compared with the non-undercut case, and fractures modelled in HiDEMinvestigated using the crevasse-depth (CD) calving law in Elmer/Ice and compared to results with the discrete element model HiDEM as well as observational data. This particular glacier has a stable front position due to a compressive arch between lateral pinning points,  which regularly lets ice that advances seawards across this arch calve back, whereas any undercut land inwards is countered by a readvance to the stable front position, which acts as an attractor between unstable super-critical and sub-critical regimes. It turns out that such a self-organising critical system can be very well described with a CD calving law in combination with a position (rather than a rate-based) calving algorithm in a continuum ice-flow model (Elmer/Ice) that resolves the major stress components at the ice front.

Read more:

Benn, D.I., J. Todd, A. Luckman, S. Bevan, T.R. Chudley, J. Åström, T. Zwinger, S. Cook, P. Christoffersen, 2023. Controls on calving at a large Greenland tidewater glacier: stress regime, self-organised criticality and the crevasse-depth calving lawJournal of Glaciology 1-17. doi:10.5194/10.1017/jog.2023.81


Elmer/Ice

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A closer look on ISMIP6-Antarctica results

In this latest article on ISMIP6-Antarctica intercomparison (including contribution from Elmer/Ice),  a closer look is taken on the results for high carbon emission tc 17 5197 2023 avatar webscenarios. The work focuses on key glaciers around the Antarctic Ice Sheet in order to quantify their projected dynamic mass loss through increased ice discharge into the ocean in response to changing oceanic conditions. Particular attention is given to glaciers contributing the most to sea level rise, as well as their vulnerability to changes in oceanic conditions.  These key glaciers - alongside the whole ice-sheet - in the further are investigated for the different sources of uncertainty and their relative role in projections. The findings are that in addition to the "usual suspects" in W-Antarctic ice-sheet (that be Thwaites and Pine Island) also outlet systems in E-Antarctica (Moscow University and Totten) show high sensitivity to increased oceanic ice-melt. Further, the uncertainties of the choice of climate models and the parametrization of the ocean melt have been investigated. Yet, overall, the highest uncertainty in dynamic ice-loss seems to be coming from the choice of the ice-sheet model. 

Read more:

Seroussi, H., Verjans, V., Nowicki, S., Payne, A. J., Goelzer, H., Lipscomb, W. H., Abe-Ouchi, A., Agosta, C., Albrecht, T., Asay-Davis, X., Barthel, A., Calov, R., Cullather, R., Dumas, C., Galton-Fenzi, B. K., Gladstone, R., Golledge, N. R., Gregory, J. M., Greve, R., Hattermann, T., Hoffman, M. J., Humbert, A., Huybrechts, P., Jourdain, N. C., Kleiner, T., Larour, E., Leguy, G. R., Lowry, D. P., Little, C. M., Morlighem, M., Pattyn, F., Pelle, T., Price, S. F., Quiquet, A., Reese, R., Schlegel, N.-J., Shepherd, A., Simon, E., Smith, R. S., Straneo, F., Sun, S., Trusel, L. D., Van Breedam, J., Van Katwyk, P., van de Wal, R. S. W., Winkelmann, R., Zhao, C., Zhang, T., and Zwinger, T., 2023. Insights into the vulnerability of Antarctic glaciers from the ISMIP6 ice sheet model ensemble and associated uncertaintyThe Cryosphere 17. doi:10.5194/tc-17-5197-2023

ISMIP6, Elmer/Ice

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