Capabilities and performance of Elmer/Ice, a new generation ice-sheet model

Gagliardini, Olivier; Zwinger, Thomas; Gillet-Chaulet, Fabien; Durand, Gaël; Favier, Lionel; Fleurian, Basile de; Greve, Ralf; Malinen, Mika; Martín, Carlos; Råback, Peter; Ruokolainen, Juha; Sacchettini, M.; Schäfer, Martina; Seddik, Hakime; Thies, Jonas

doi:10.5194/gmdd-6-1689-2013

Cited by 91 publications

(145 citation statements)

References 85 publications

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“…The last term in the heat transfer equation represents the amount of energy produced by the viscous deformation, which because of the low shear rates in our application has no significant contribution and hence is neglected. The complete set of equations is solved using the finiteelement method (FEM) using the open source software package Elmer/Ice (Gagliardini et al, 2013; http://elmerice. elmerfem.org), which has already been applied to glacier simulations of different kinds (Zwinger et al, 2007;Zwinger and Moore, 2009;Zhao et al, 2014), and we use similar numerical settings as discussed in Martín et.…”

Section: Modelmentioning

confidence: 99%

Influence of anisotropy on velocity and age distribution at Scharffenbergbotnen blue ice area

et al. 2014

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Abstract. We use a full-Stokes thermo-mechanically coupled ice-flow model to study the dynamics of the glacier inside Scharffenbergbotnen valley, Dronning Maud Land, Antarctica. The domain encompasses a high accumulation rate region and, downstream, a sublimation-dominated bare ice ablation area. The ablation ice area is notable for having old ice at its surface since the vertical velocity is upwards, and horizontal velocities are almost stagnant there. We compare the model simulation with field observations of velocities and the age distribution of the surface ice. No satisfactory match using an isotropic flow law could be found because of too high vertical velocities and much too high horizontal ones in simulations despite varying enhancement factor, geothermal heat flux and surface temperatures over large ranges. However, the existence of a pronounced ice fabric may explain the observed present-day surface velocity and mass balance distribution in the inner Scharffenbergbotnen blue ice area. Near absence of data on the temporal evolution of Scharffenbergbotnen since the Late Glacial Maximum necessitates exploration of the impact of anisotropy using prescribed ice fabrics: isotropic, single maximum, and linear variation with depth, in both two-dimensional and threedimensional flow models. The realistic velocity field simulated with a noncollinear orthotropic flow law, however, produced surface ages in significant disagreement with the few reliable age measurements and suggests that the age field is not in a steady state and that the present distribution is a result of a flow reorganization at about 15 000 yr BP. In order to fully understand the surface age distribution, a transient simulation starting from the Late Glacial Maximum including the correct initial conditions for geometry, age, fabric and temperature distribution would be needed. This is the first time that the importance of anisotropy has been demonstrated in the ice dynamics of a blue ice area and demonstrates the need to understand ice flow in order to better interpret archives of ancient ice for paleoclimate research.

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Section: Modelmentioning

confidence: 99%

Influence of anisotropy on velocity and age distribution at Scharffenbergbotnen blue ice area

et al. 2014

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“…The full Stokes solution that we use for comparison is obtained using the finite-element code Elmer/Ice (Gagliardini et al, 2013). The same mesh with the nodes on vertical lines was used for SIA, SOSIA and in Elmer/Ice.…”

Section: Methodsmentioning

confidence: 99%

“…In Sect. 5 we implement the SOSIA numerically and compute the accuracy of both the SIA and the SOSIA by comparing their solutions with the solution obtained with Elmer/ICE (Gagliardini et al, 2013), for varying . The same computations are repeated for a Newtonian fluid to verify that the comparison technique is reliable.…”

Section: Introductionmentioning

confidence: 99%

Accuracy of the zeroth- and second-order shallow-ice approximation – numerical and theoretical results

2013

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Abstract. In ice sheet modelling, the shallow-ice approximation (SIA) and second-order shallow-ice approximation (SOSIA) schemes are approaches to approximate the solution of the full Stokes equations governing ice sheet dynamics. This is done by writing the solution to the full Stokes equations as an asymptotic expansion in the aspect ratio , i.e. the quotient between a characteristic height and a characteristic length of the ice sheet. SIA retains the zeroth-order terms and SOSIA the zeroth-, first-, and second-order terms in the expansion. Here, we evaluate the order of accuracy of SIA and SOSIA by numerically solving a two-dimensional model problem for different values of , and comparing the solutions with a finite element solution to the full Stokes equations obtained from Elmer/Ice. The SIA and SOSIA solutions are also derived analytically for the model problem. For decreasing , the computed errors in SIA and SOSIA decrease, but not always in the expected way. Moreover, they depend critically on a parameter introduced to avoid singularities in Glen's flow law in the ice model. This is because the assumptions behind the SIA and SOSIA neglect a thick, high-viscosity boundary layer near the ice surface. The sensitivity to the parameter is explained by the analytical solutions. As a verification of the comparison technique, the SIA and SOSIA solutions for a fluid with Newtonian rheology are compared to the solutions by Elmer/Ice, with results agreeing very well with theory.

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“…Another limiting factor is the correct implementation of the retreat of marine-terminating glaciers in some ice flow models (Gagliardini and others, 2013).…”

Section: Introductionmentioning

confidence: 99%

Dynamic modelling of future glacier changes: mass-balance/elevation feedback in projections for the Vestfonna ice cap, Nordaustlandet, Svalbard

et al. 2015

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ABSTRACT. Future projections of the evolution of ice caps as well as ice sheets and consequent sealevel rise face several methodological challenges, one being the two-way coupling between ice flow and mass-balance models. Full two-way coupling between mass-balance models -or, in a wider scope, climate models -and ice flow models has rarely been implemented due to substantial technical challenges. Here we examine some coupling effects for the Vestfonna ice cap, Nordaustlandet, Svalbard, by analysing the impacts of different coupling intervals on mass-balance and sea-level rise projections. By comparing coupled to traditionally deployed uncoupled strategies, we prove that neglecting the topographic feedbacks in the coupling leads to underestimations of 10-20% in sea-level rise projections on century timescales in our model. As imposed climate scenarios increasingly change mass balance, uncertainties in the unknown evolution of the fast-flowing outlet glaciers decrease in importance due to their deceleration and reduced mass flux as they thin and retreat from the coast. Parameterizing mass-balance adjustment for changes in topography using lapse rates as a cost-effective alternative to full coupling produces satisfactory results for modest climate change scenarios. We introduce a method to estimate the error of the presented partially coupled model with respect to as yet unperformed two-way fully coupled results.

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Capabilities and performance of Elmer/Ice, a new generation ice-sheet model

Cited by 91 publications

References 85 publications

Influence of anisotropy on velocity and age distribution at Scharffenbergbotnen blue ice area

Influence of anisotropy on velocity and age distribution at Scharffenbergbotnen blue ice area

Accuracy of the zeroth- and second-order shallow-ice approximation – numerical and theoretical results

Dynamic modelling of future glacier changes: mass-balance/elevation feedback in projections for the Vestfonna ice cap, Nordaustlandet, Svalbard

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