The Influence of Bathymetry Over Heat Transport Onto the Amundsen Sea Continental Shelf

Abstract

Ice streams such as Pine Island and Thwaites Glaciers which terminate at their ice shelves in the eastern Amundsen Sea, West Antarctica, are losing mass faster than most others about the continent. The mass loss is due to basal melting, which is influenced by a deep current that transports warm Circumpolar Deep Water (CDW) from the continental shelf break toward the ice shelves. This current and associated heat transport are controlled by factors such as bottom bathymetry, near-surface winds and meltwater. Using a realistic regional model as a reference, in this study we use idealized models to examine the role of bathymetric features in determining the shelf-wide circulation and in enabling heat transport from the deep ocean onto the continental shelf. We find that a ridge that blocks deep westward inflow from the Bellingshausen Sea enables a deep cyclonic circulation on the shelf with an eastward undercurrent immediately south of the shelf break. Inclusion of the ridge enhances heat transport onto the continental shelf; without the ridge the flow features an along-shelf break westward current that suppresses cross-shelf break fluxes. We also consider the effects of shifting the prescribed wind forcing profile to the south—a simplified representation of future potential changes to the winds—and we find that the continental shelf is warmer in this scenario. These fundamental investigations will help refine the aims of future fieldwork and modeling.