Abstract
Abstract. A three-dimensional, thermo-mechanically coupled ice flow model with induced anisotropy has been applied to a ~200 × 200 km domain around the Dome Fuji drill site, Antarctica. The model ("Elmer/Ice") is based on the open-source multi-physics package Elmer (http://www.csc.fi/elmer/) and solves the full Stokes equations. Flow-induced anisotropy in ice is accounted for by an implementation of the Continuum-mechanical, Anisotropic Flow model, based on an anisotropic Flow Enhancement factor ("CAFFE model"). Steady-state simulations for present-day climate conditions are conducted. The main findings are: (i) the flow regime at Dome Fuji is a complex superposition of vertical compression, horizontal extension and bed-parallel shear; (ii) for an assumed geothermal heat flux of 60 mW m−2 the basal temperature at Dome Fuji reaches the pressure melting point and the basal melting rate is ~0.35 mm a−1; (iii) in agreement with observational data, the fabric shows a strong single maximum at Dome Fuji, and the age of the ice is decreased compared to an isotropic scenario; (iv) as a consequence of spatially variable basal melting conditions, the basal age tends to be smaller where the ice is thicker and larger where the ice is thinner. The latter result is of great relevance for the consideration of a future drill site in the area.
Highlights
Dome Fuji, situated at 77◦19 01 S, 39◦42 12 E, is the second-highest summit of the Antarctic ice sheet with an altitude of 3810 m a.m.s.l
The main findings are: (i) the flow regime at Dome Fuji is a complex superposition of vertical compression, horizontal extension and bed-parallel shear; (ii) for an assumed geothermal heat flux of 60 mW m−2 the basal temperature at Dome Fuji reaches the pressure melting point and the basal melting rate is ∼0.35 mm a−1; (iii) in agreement with observational data, the fabric shows a strong single maximum at Dome Fuji, and the age of the ice is decreased compared to an isotropic scenario; (iv) as a consequence of spatially variable basal melting conditions, the basal age tends to be smaller where the ice is thicker and larger where the ice is thinner
This was observed for the GRIP ice core in Greenland (Thorsteinsson et al, 1997), for the European Project for Ice Coring in Antarctica (EPICA) Dome C ice core in Antarctica (Wang et al, 2003) and for the first Dome Fuji ice core, for which Azuma et al (1999) report a strong vertical single maximum at 2500 m depth
Summary
Dome Fuji, situated at 77◦19 01 S, 39◦42 12 E, is the second-highest summit of the Antarctic ice sheet with an altitude of 3810 m a.m.s.l. (above mean sea level). The fabric (orientation distribution of the c-axes of the ice grains) of ice cores drilled near topographic domes typically evolves with depth from near-isotropic conditions close to the surface towards a single maximum. This was observed for the GRIP ice core in Greenland (Thorsteinsson et al, 1997), for the EPICA Dome C ice core in Antarctica (Wang et al, 2003) and for the first Dome Fuji ice core, for which Azuma et al (1999) report a strong vertical single maximum at 2500 m depth. Miyamoto (personal communication, 2009) extended the fabric measurements to 3024.5 m depth for the second Dome Fuji ice core.
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