Elmer/Ice News

Two new papers in TC

Two new paper using Elmer/Ice just published in The Cryosphere !

In Gudmundsson et al. (2012), the ssnapshot4tability of grounding line on reverse slope is questioned for three-dimensonal geometries. As an important result, it is found that grounding line is not unconditionally unstable on reverse slope when considering the two horizontal dimensions. Retrograde bed slopes at the grounding lines of marine ice sheets, such as the West Antarctic Ice Sheet (WAIS), do not per se imply an instability, nor do they imply that these regions are close to a threshold of instability. This result clearly questions those estimates of the potential near-future contribution of WAIS to global sea level change based solely on the notion that WAIS, resting on a retrograde slope, must be inherently unstable.

In Gillet-Chaulet et al. (2012), we investigate with Elmer/Ice how current ice loss of the Greenland Ice Sheet may endure over the next century. This relies on three essential developments: the complete solution of the full system of equations governing ice deformation; an unstructured mesh to usefully resolve outlet glaciers and the use of inverse methods to better constrain poorly known parameters using observations. We show that the modelled ice discharge is in good agreement with observations on the continental scale and for individual outlets. By conducting perturbation experiments, we find that increasing ablation tends to reduce outflow and on its own has a stabilising effect, if destabilisation processes maintain themselves over time, current increases in the rate of ice loss are likely to continue. This work was performed using HPC resources from GENCI-CINES and from the Grenoble University High Performance Computing centre. This work is a contribution to the ice2sea project.

Elmer/Ice at AGU2012

Here is a list of the known Elmer/Ice talks and posters that will be presented at the forthcoming AGU in San Francisco,  3-7 Dec 2012. Please, if your talk/poster is not listed, contact me (OG) and I will add your presentation.

Wednesday, December 05, 2012

8:00 AM-12:20 PM, Hall A-C (Moscone South), C31B. Modeling of Glaciers and Ice Sheets I - Posters

  • C31B-0591. Capabilities and performance of the new generation icesheet model Elmer/Ice. O. Gagliardini; T. Zwinger; G. Durand; L. Favier; B. de Fleurian; F. Gillet-chaulet; H. Seddik; R. Greve; M. Mallinen; C. Martin; P. Raback; J. Ruokolainen; M. Schäfer; J. Thies
  • C31B-0592. Full Stokes or shallow ice approximation? Comparing the ice flow dynamics at the Shirase Drainage Basin, Antarctica. H. Seddik; R. Greve; T. Zwinger; S. Sugiyama
  • C31B-0597. Investigation of a new approach for the modelling of subglacial hydrology. B. de Fleurian; O. Gagliardini; G. Durand; E. Le Meur; D. Mair; T. Zwinger
  • C31B-0606. A simple method to assimilate both surface and bedrock data into an ice-sheet model. G. Durand; F. Gillet-chaulet

1:40 PM-3:40 PM, 3007 (Moscone West), C33E. Modeling of Glaciers and Ice Sheets II   

  • C33E-05. The dynamic response of Pine Island Glacier to a calving event inferred from two higher-order models. L. Favier; S.L. Cornford; G. Durand; O. Gagliardini; T. Zwinger

4:00 PM-6:00 PM, 3007 (Moscone West), C34A. Modeling of Glaciers and Ice Sheets III

  • C34A-01. Stable grounding lines on retrograde slopes. (Invited) G.H. Gudmundsson; J. Krug; L. Favier; G. Durand; O. Gagliardini

Thursday, December 06, 2012

3:55 PM-5:55 PM, 3002 (Moscone West), C43F. Cryospheric Contribution to Sea Level Rise: Current Estimates and Projections I (Video On-Demand)

  • C43F-06. Comparative forecast simulations of the Greenland icesheet using Elmer/Ice and GRISLI C. Ritz; F. Gillet-chaulet; O. Gagliardini; A. Quiquet; G. Durand; V. Peyaud

Friday, December 07, 2012

1:40 PM-6:00 PM, Hall A-C (Moscone South), C53B. Cryospheric Contribution to Sea Level Rise: Current Estimates and Projections II Posters

  • C53B-0840. Semi-empirical and process-based global sea level projections J.C. Moore; A. Grinsted; T. Zwinger; S. Jevrejeva




Parameterization of lateral drag in ice flowline models

cross section2Adhikari and Marshall (2012) employ Elmer/Ice model to identify two distinct sources of lateral drag (i.e., geometry-induced and slip-induced drag). Effects of both sources of lateral drag have been systematically parameterized for flowline models of glacier dynamics.

Abstract: Given the cross-sectional geometry of a valley glacier, effects of lateral drag can be parameterized in flowline models through the introduction of Nye shape factors. Lateral drag also arises due to lateral variability in bed topography and basal flow, which induce horizontal shear stress and differential ice motion. For glaciers with various geometric and basal conditions, we compare three-dimensional Stokes solutions to flowline model solutions to examine both sources of lateral drag. We calculate associated correction factors that help flowline models to capture the effects of lateral drag. Such parameterizations provide improved simulations of the dynamics of narrow, channelized, fast-flowing glacial systems. We present an example application for Athabasca Glacier in the Canadian Rocky Mountains.

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