Abstract

Ice shelves play an important role in regulating the mass balance of ice sheets through their ability to buttress inland ice streams that drain to the ocean. When ice shelves thin, their buttressing capabilities are decreased, and the flow of ice mass to the ocean accelerates. In much of West Antarctica, relatively warm (above freezing) water accesses ice shelves near the grounding line—-the point where an inland ice stream transitions from a grounded glacier to a floating ice shelf—-creating a melt-water plume that rises along the underside of the ice shelf, entraining warm water and driving further melting. The characteristics of the large-scale sub-shelf circulation, and, in turn, the rate of ice-shelf thinning, depend heavily upon the characteristics of the near-grounding-line ocean. Here we present an adaptive-mesh finite-element model of ocean circulation within a few kilometres of the grounding line of an idealised ice shelf. Mesh spacing ranges from centimetres to meters, and subgrid-scale mixing effects are parametrised using a two-equation turbulence model. Flexure of the ice shelf due to tides is simulated using Fluidity’s moving mesh capabilities. Factors such as ocean temperature and tidal forcing are varied and resulting effects on sub-shelf ocean stratification, circulation, and melt rates are observed.