HR: 10:50h
AN: T12B-03    [Abstracts]
TI: A Finite-Element Ice Flow Model for the Vicinity of Dome Fuji With Induced Anisotropy and Fabric Evolution
AU: * Seddik, H
EM: hakime@pop.lowtem.hokudai.ac.jp
AF: Institute of Low Temperature Science, Hokkaido University, Kita-19, Nishi-8, Kita-ku, Sapporo, 060-0819, Japan
AU: Greve, R
EM: greve@lowtem.hokudai.ac.jp
AF: Institute of Low Temperature Science, Hokkaido University, Kita-19, Nishi-8, Kita-ku, Sapporo, 060-0819, Japan
AU: Placidi, L
EM: luca.placidi@uniroma1.it
AF: Department of Structural and Geotechnical Engineering, "Sapienza" University of Rome, Via Eudossiana 18, Rome, 00184, Italy
AU: Zwinger, T
EM: thomas.zwinger@csc.fi
AF: CSC – Scientific Computing Ltd., P.O. Box 405, Espoo, 02101, Finland
AU: Gagliardini, O
EM: gagliar@lgge.obs.ujf-grenoble.fr
AF: Laboratory of Glaciology and Environmental Geophysics, CNRS, UJF-Grenoble I, BP 96, Saint-Martin d'Hères Cedex, Grenoble, 38402, France
AB: A three-dimensional, thermo-mechanically coupled flow model with induced anisotropy has been developed and applied to the vicinity of Dome Fuji, Antarctica. The model implements the full Stokes equations for the ice dynamics, and the system is solved with the finite-element method (FEM) using the open source multi-physics package Elmer (http://www.csc.fi/elmer/). The finite-element mesh for the computational domain has been created with two data sets, the fine resolution data obtained at Dome Fuji and the coarse resolution data sets RAMPDEM V2 and BEDMAP which cover the entire Antarctic ice sheet. The fine data which represent a 60 x 60 km area around the Dome Fuji station have been merged to the coarse data sets to create a single domain of about 200 x 200 km size. The mesh consists of a coarse resolution near the boundaries (20 km) and a mesh resolution refinement (up to 500 m) towards the position of the borehole located at the center of the domain. This procedure has been carried out in order to keep the lateral boundaries sufficiently far away from the dome, so that shallow- ice stresses can be prescribed there. At the base, no-slip conditions are assumed, and on the surface, the temperature is prescribed to be constant everywhere on the domain. A Continuum-mechanical, Anisotropic Flow model, based on an anisotropic Flow Enhancement factor (CAFFE model) is used for taking into account the flow-induced anisotropy in ice. The flow law is implemented in Elmer by means of second and fourth order orientation tensors that describe the c-axis orientation of the fabric. Similarly, the fabric evolution equation is written in terms of the evolution of the second order tensor, and it is solved with a Discontinuous Galerkin method using Picard type iterations for the non-linearity. Since the fabric evolution equation also depends on the fourth order orientation tensor, the IBOF (Invariant-Based Optimal Fitting) closure function is used for the computation of its components from the solution of the second orientation tensor. The questions to be investigated are (i) what is the evolution of the fabric over the last glacial cycle, (ii) how does the flow field change with the fabric, (iii) what is the effect of ice anisotropy at the site of the Dome Fuji ice core.
DE: 0774 Dynamics
DE: 0798 Modeling
DE: 8120 Dynamics of lithosphere and mantle: general (1213)
DE: 8138 Lithospheric flexure
DE: 8160 Rheology: general (1236, 8032)
SC: Tectonophysics [T]
MN: 2007 Fall Meeting