Ocean circulation and ice-ocean interaction beneath the Amery Ice Shelf, Antarctica

Abstract

Simulations of the ocean dynamics in the cavity under the Amery Ice Shelf, Antarctica, were carried out using a three-dimensional numerical ocean model. Two different boundary conditions were used to describe the open ocean barotropic exchange at the ice front. The simulations show that the circulation in the ocean cavity is predominantly barotropic and is generally steered by the cavity topography. The circulation is driven by the density gradient in the cavity, which is strongly influenced by the heat and salt fluxes from melting and freezing processes at the ice-ocean interface, and by the horizontal exchange of heat and salt across the open ocean boundary at the ice front. The interaction at the ice-ocean interface allows the basal component of the mass loss of the Amery Ice Shelf to be estimated. In the two simulations the computed losses were 5.8 Gt yr-1 and 18.0 Gt yr-1, values consistent with observations. The bulk of the melting occurred near the southern grounding line of the ice shelf, although substantial melting also occurred in areas where heat transport by horizontal circulation was large. Accretion was restricted to areas where water, from upstream melting, became supercooled as it ascended the ice shelf base. Copyright 2001 by the American Geophysical Union.