Understanding the Dynamics of Ocean Heat Transport across the Antarctic Slope

Projections of the future Antarctic ice sheet stability suffer among others under uncertainties in basal melt rates of the ice shelves. The Antarctic continental shelf is usually characterised by very cold water, but observations show that intrusions of much warmer water provided by the deep ocean exist. If the warm water reaches the ice shelf cavity basal melt rates will respond. Such an onshore heat transport can also affect the global overturning circulation and local ecosystems. The physical system and the mechanisms that control a meridional circulation of warm water onto the continental shelf and close to the ice shelf cavity is not sufficiently understood. This is because the water on the continental shelf is actually separated from the Southern Ocean by the so-called Antarctic Slope Front (ASF). The ASF has a nearly circumpolar extent and acts as a dynamical barrier. The transport across this front will depend on local bathymetry, eddy dynamics as well as atmospheric and tidal forcing. Observations of this remote study area in the high southern latitudes, however, are scarce. Using the Regional Ocean Modelling System (ROMS), a process oriented idealised model of the Antarctic continental shelf coupled to an ice shelf, the shelf break and the deep ocean is developed. The aim is to investigate main forcing mechanisms of the system and to detect physical processes that allow a heat transport onto the Antarctic continental shelf and eventually to the vicinity of ice shelves. For this investigation we discuss the numerical requirements to capture relevant dynamics in the model and present preliminary results of sensitivity experiments that compare different states of the ASF.