Elmer/Ice News

Influence of high-order mechanics on climatic response of a glacier

adhikari2013Evolution of glaciers in response to climate change has mostly been simulated using simplified dynamical models. Because these models do not account for the influence of high-order physics, corresponding results may exhibit some biases. For Haig Glacier in the Canadian Rocky Mountains, we test this hypothesis by comparing simulation results obtained from 3-D numerical models that deal with different assumptions concerning physics, ranging from simple shear deformation to comprehensive Stokes flow. In glacier retreat scenarios, we find a minimal role of high-order mechanics in glacier evolution, as geometric effects at our site (the presence of an overdeepened bed) result in limited horizontal movement of ice (flow speed on the order of a few meters per year). Consequently, high-order and reduced models all predict that Haig Glacier ceases to exist by ca. 2080 under ongoing climate warming. The influence of high-order mechanics is evident, however, in glacier advance scenarios, where ice speeds are greater and ice dynamical effects become more important. Although similar studies on other glaciers are essential to generalize such findings, we advise that high-order mechanics are important and therefore should be considered while modeling the evolution of active glaciers. Reduced model predictions may be adequate for other glaciologic and topographic settings, particularly where flow speeds are low and where mass balance changes dominate over ice dynamics in determining glacier geometry.

Reference: Adhikari, S. and S. J. Marshall, 2013. Influence of high-order mechanics on simulation of glacier response to climate change: insights from Haig Glacier, Canadian Rocky Mountains, The Cryosphere, 7, 1527-1541, doi:10.5194/tc-7-1527-2013. [pdf]

Spatial sensitivities of Greenland

Fig06-a-d from Nowicki etal 2013b JGRF
Fig06-colour-bars from Nowicki etal 2013b JGRF

The Sea-level Response to Ice Sheet Evolution (SeaRISE) effort explores the sensitivity of the current generation of ice sheet models to external forcing to gain insight into the potential future contribution to sea level from the Greenland and Antarctic ice sheets. All participating models (including Elmer/Ice) simulated the ice sheet response to different types of external forcings. In Insights into spatial sensitivities of ice mass response to environmental change from the SeaRISE ice sheet modeling project II: Greenland, an analysis of the spatial response of the Greenland ice sheet is presented, and the impact of model physics and spin-up on the projections is explored. As one of the results, Figure 6 from the paper shows the ensemble mean thickness change from the (a) control and (b) standard deviation resulting from the S2 experiment (doubled basal sliding) after 100 simulated years, along with the thickness contribution from the (c) maximum (Elmer/Ice) and (d) minimum (PISM) models.

Reference: Nowicki et al., 2013. Insights into spatial sensitivities of ice mass response to environmental change from the SeaRISE ice sheet modeling project II: Greenland. Journal of Geophysical Research: Earth Surface 118 (2), 1025-1044, doi:10.1002/jgrf.20076. [link to paper]

Elmer/Ice description paper

GMDIn Capabilities and performance of Elmer/Ice, a new-generation ice sheet model, published in Geoscience Model Development, we summarise the almost 10 yr of development performed by different groups. We only focus on the past developments that are relevant for simulations of three-dimensional ice sheets. This paper presents the governing equations implemented in Elmer/Ice, the associated boundary conditions, other useful equations (such as the equation to evaluate the age of the ice), the inverse methods implemented in Elmer/Ice, some technical aspects related to the resolution of these equations in the framework of the FE method, some standard convergence and scalability tests to verify the efficiency of Elmer/Ice and finally, we provide some insights into the future planned developments.

Reference: Gagliardini, O., T. Zwinger, F. Gillet-Chaulet, G. Durand, L. Favier, B. de Fleurian, R. Greve, M. Malinen, C. Martín, P. Råback, J. Ruokolainen, M. Sacchettini, M. Schäfer, H. Seddik,  and J. Thies, 2013. Capabilities and performance of Elmer/Ice, a new-generation ice sheet model, Geosci. Model Dev., 6, 1299-1318, doi:10.5194/gmd-6-1299-2013.

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