Modelling the dynamics of the Antarctic Slope Front

This thesis investigates the dynamics of the Antarctic Slope Front (ASF), which controls heat exchange across the Antarctic continental slope. The motivation comes from the need to advance the understanding of oceanic heat supply to the Antarctic ice shelf cavities which impacts the stability of the Antarctic Ice Sheet. To address this question, the ocean dynamics at the Antarctic continental shelf break system is explored using the Regional Ocean Modeling System (ROMS) which has been adapted for ocean/ice shelf interactions. The ASF is examined in two different model configurations, in an idealised channel domain and in a realistic circumpolar domain, with a focus on the sensitivity to surface forcing to understand how the ASF may change in a future climate. Firstly, an idealised model configuration of the Antarctic continental shelf break system in a zonally-symmetric periodic domain is developed. An intrinsic variability of the ASF that is driven by a deep bottom mixed layer is discussed in the case of a relatively fresh continental shelf. Secondly, the role of surface buoyancy forcing and wind for the strength and shape of the ASF is investigated by analysing sensitivity experiments using the idealised domain. Different frontal regimes and their thresholds are determined on the basis of the relative ratio between buoyancy forcing to mechanical forcing. Thirdly, perturbation experiments with artificially increased basal freshwater are performed in a realistic circumpolar domain. This work is motivated by the projected increase in freshwater supply to the ocean due to basal melting in a warmer climate. The response to the additional freshwater in the perturbed simulations is overall non-local. Findings between the idealised and realistic model agree in that the transport along the Antarctic continental slope increases for fresher continental shelves.