Ocean Heat Delivery Mechanisms Beneath Antarctic Ice Shelves

Ocean currents around Antarctica are responsible for transporting heat under the Antarctic ice shelves and exporting cold melt-water out into the open ocean. These ocean currents are important for the determining the melt rates beneath the Antarctica ice shelves. This thesis explores the three modes of melting beneath Antarctic ice shelves using laboratory experiments, analysis of field observations, and both of complex and simple numerical models.;In Chapter 1, we construct a laboratory experiment to simulate the density driven circulation under an idealized Antarctic ice shelf (mode 1). Results confirm that the ice front can act as a dynamic barrier that partially inhibits fluid from entering or exiting the ice shelf cavity, away from two wall-trapped boundary currents. The strength of the dynamic barrier is sensitive to changes in the ice shelf geometry and changes in the buoyancy fluxes which drive the flow.;Chapter 2 explores how instabilities in topographically steered jets could be responsible for the exchange of warm Circumpolar Deep Water across the continental shelf break in West Antarctica (mode 2). Results show that the majority of mixing occurs in discrete mixing events which coincide with the shelf break jet becoming baroclinically unstable. The largest instability events display a intermittent low frequency variability with instabilities occurring up to 50 years apart.;Chapter 3 uses observational data to study the summer intrusion of surface waters below McMurdo Ice Shelf (mode 3). A six month temperature record collected below the ice shelf in 2011-2012 shows the temporal and spatial structure of the summertime warm water signal that penetrates beneath the ice shelf. A Ross Sea numerical model demonstrates a seasonal warm water pathway leading from the west side of the Ross Sea Polynya (RSP) towards McMurdo Sound.