The influence of topography on ice-ocean interactions in coastal Antarctica

Abstract

Interactions between various water masses and ice shelves along the Antarctic coastline impact the global climate and sea level. This thesis focuses on how geometric features such as troughs and fast ice affect cross-shelf exchange in dense water formation regions of the Antarctic continental shelf. In Chapter 2, we use an idealized, eddy-resolving model to examine how an outflow of Dense Shelf Water (DSW) drives an inflow of warmer Circumpolar Deep Water (CDW) in a narrow, prograde trough. We find that the trough organizes mesoscale, cyclonic eddies in the dense outflow into a chain pattern. These cyclones then, as an efficient group, entrain filaments of CDW towards the coast. In Chapter 3, we use the same model to investigate buoyancy-driven cross-shelf exchange in a wide, retrograde trough. We find that the dynamics of the CDW intrusion change near the shelf-break. Here, the DSW outflow excites Topographic Vorticity Waves which interact with the DSW outflow to drive onshore intrusions of CDW. Onshore of the shelf-break, CDW intrudes further poleward due to a mean flow driven by eddy rectification. In Chapter 4, we switch to a realistic model of Prydz Bay, East Antarctica, to test the impact of local icebergs on cross-shelf exchange, dense water formation, and ice shelf basal melt rates. We find that removing the Cape Darnley Ice Barrier increases CDW intrusions and decreases dense water formation due to changes to the sea ice cover and wind-driven circulation. Conversely, removing the tabular Iceberg D-15 has little impact on heat transport and only slightly decreases dense water formation. Thus, the location of grounded icebergs greatly influences their impact on regional hydrography and ice shelf melt. In all, this thesis uses numerical models to examine the dynamics of cross-shelf exchange in coastal Antarctica. Understanding these dynamics is imperative for projecting how the Antarctic margins will impact the globe in a changing climate.