HR: 15:10h
AN: C43A-07 INVITED    [Abstracts]
TI: Dynamic/Thermodynamic Modeling of the Gorshkov Crater Glacier at Ushkovsky Volcano, Kamchatka
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: 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: LGGE CNRS-UJF Grenoble I, BP 96, St Martin d'Hères, 38402, France
AU: Isenko, E
EM: jorge@lowtem.hokudai.ac.jp
AF: Institute of Low Temperature Science, Hokkaido University, Kita-19, Nishi-8, Kita-ku, Sapporo, 060–0819, Japan
AU: Edelmann, E
EM: erik.edelmann@csc.fi
AF: CSC -- Scientific Computing Ltd., P.O. Box 405, Espoo, 02101, Finland
AU: Seddik, H
EM: hakime@lowtem.hokudai.ac.jp
AF: Institute of Low Temperature Science, Hokkaido University, Kita-19, Nishi-8, Kita-ku, Sapporo, 060–0819, Japan
AB: Glaciers which develop in volcano craters are unique systems because of their particular morphologies (large thickness-to-width ratio) and thermodynamic conditions (large geothermal heat flux). Here, we investigate the Gorshkov crater glacier, which is situated in the summit caldera of Ushkovsky volcano, Kamchatka, and fills the concave crater bed to a maximum depth of 240~m. The crater diameter is approx.\ 750~m. The glacier surface is gently inclined towards the northern crater rim, where the ice flows out of the crater and down the slope of the volcano. The geothermal heat flux at the crater rim is estimated to be as large as 10\;W m^-2 based on direct measurements. Furthermore, large parts of the glacier consist of firn rather than pure ice, which alters its rheological properties. We apply the three-dimensional, thermo-mechanically coupled, full-Stokes flow model "Elmer/Ice" (based on the open-source finite-element tool "Elmer") to the Gorshkov crater glacier. By assuming steady-state conditions and a spatial distribution of the geothermal heat flux obtained by an optimization procedure, the present-day density, velocity, temperature and age fields are simulated. We find that flow velocities are generally small (10's of centimeters per year). Horizontal and vertical velocities are of comparable magnitude, which shows that the shallow-ice approximation is not applicable. Owing to the spatially variable volcanic heat flux, the thermal regime at the ice base is cold in the deeper parts of the glacier and temperate in the shallower parts. The measured temperature and age profiles at the K2 borehole (close to the deepest point of the glacier) are reproduced quite well, and remaining discrepancies may be attributed to transient (non-steady-state) conditions.
DE: 0720 Glaciers
DE: 0766 Thermodynamics (1011, 3611, 8411)
DE: 0774 Dynamics
DE: 0798 Modeling
DE: 8440 Calderas
SC: Cryosphere [C]
MN: 2007 Fall Meeting