C34A-02
The dynamics of the Amerasian Basin ice shelf: ocean circulation in an immense ice cavity.
Wednesday, 16 December 2015: 16:30
3007 (Moscone West)
Johan Nilsson1, Martin Jakobsson2, Göran M Björk3, Christian Stranne2, Raymond Pierrehumbert4 and Nina Kirchner5, (1)Stockholm University, Department of meteorology, Stockholm, Sweden, (2)Stockholm University, Department of Geological Sciences, Stockholm, Sweden, (3)Göteborg University, Se-405 30 Göteborg, Sweden, (4)Univ of Chicago, Chicago, IL, United States, (5)Bert Bolin Center Climate Res, Stockholm, Sweden
Abstract:
Recent geological and geophysical data suggest that a one-kilometer thick ice shelf extend over the glacial Arctic Ocean and was partly grounded on the subsurface Lomonosov Ridge. The Amerasian Basin was then an immense ice cavity, which communication with the exterior ocean was restricted to a few sub-ice passages over the deepest parts of the Lomonosov Ridge. Using a one-dimensional ice shelf model, we find that back pressure from the re-grounding on the Lomonosov Ridge is essential for allowing a thick ice shelf at the upstream grounding line. Further, the back pressure serves to keep the shelf thickness uniform over Amerasian Basin. A simple model is developed to examine the ocean-ice shelf interactions in the ice cavity. It is found that the water exchange across the Lomonosov Ridge and the oceanic basal melting in the cavity are controlled chiefly by the turbulent mixing within the cavity. Rough estimates of the mixing yield basal melting rates in the range between 0.1 to 0.5 m year. This suggest that the ice shelf over Amerasian Basin could be maintained by surface accumulation and ice flow from the continents once it was formed.
