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| Titel |
A mechanical diagnosis of the ice flow around Dome C: Elmer/Ice 3D simulations constrained by measured surface velocities and radar isochrones. |
| VerfasserIn |
Olivier Passalacqua, Marie Cavitte, Massimo Frezzotti, Olivier Gagliardini, Fabien Gillet-Chaulet, Frédéric Parrenin, Catherine Ritz, Luca Vittuari, Duncan Young |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250141193
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| Publikation (Nr.) |
 EGU/EGU2017-4671.pdf |
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| Zusammenfassung |
| The Dome C region has been densely surveyed and studied for the last decades, in particular
to describe the shape of the ice surface, the bedrock relief, the surface velocity, the age and
fabric structure of the ice, and its vertical temperature profile. No comprehensive ice flow
modelling constrained by all of these field data has been done so far in this region. In
particular, the Dome C has recently been targetted as an oldest-ice area, so that we intend to
take advantage of a 2016 airborne radar survey that revealed the deep radar isochrones
south-west of Dome C, and provides unprecendented constraints for the ice flow
description.
The Stokes equations are solved with the Elmer/Ice finite element solver, on a 80x110 km2
3D domain, for three different values of the Glen exponent n (1, 3 and 4.5), and for different
fabric profiles. The goal of this study is threefold. First, as the range of stress types
(longitudinal, transverse, and vertical compression-only) are well covered around Dome C,
the observed surface velocities should efficiently constrain the possible values of the
rheological parameters (Glen exponent and fluidity), and the basal sliding. Then, we apply an
anisotropic flow law to correctly model the age structure, observed on the top 4/5th of the ice
thickness, so that we induce mechanically-correct ages for the basal layers. Finally,
once the ice mechanics is obtained, we compare the modelled vertical velocity
profiles with 1D synthetic profiles, to assess the validity conditions of 1D modelling
approaches, which are much more flexible tools for ensemble simulations or inversions. |
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