Abstract

Ocean heat flux across the western Antarctic Peninsula (WAP) shelf is important in providing the energy required to drive the rapid melt rates observed in ice sheets and glaciers. There is however still significant uncertainty in the dominant processes controlling this heat flux, together with its overall magnitude. Two years’ of hydrographic data from ocean gliders identify a strong link between the bathymetry and the flow and mixing of deep water on the shelf. These localised mixing events occur at overflow locations where ridges partially block the flow of deep water along narrow glacially carved channels. Relatively shallow and cold water from the thermocline is mixed with warmer water in downward flows beyond the ridges. Understanding this process helps the interpretation of where and when heat is lost from the deep water on the shelf and highlights specific areas for further investigation of mixing and heat flux towards the coast. It also suggests a link between shallow waters, with noted seasonal and interannual variability linked to changing ice cover, and deeper waters that are otherwise more isolated from surface processes. The high resolution data shows isolated depressions with bottom temperatures cooler or warmer than surrounding areas of the same depth, with potential impacts on benthic diversity.