Southern Ocean Pathways to Deep Ocean Ventilation

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Two of the main environmental challenges of the coming century will be the response of global sea levels and marine ecosystems to rapid ocean warming, particularly in the polar regions. Recently, large increases in surface temperature and ice melt have been recorded at many locations in the Arctic Ocean and Greenland, while Antarctica has seen cooling with increase in ice volume at some locations and decrease at others. Understanding the reasons behind this asymmetric inter-hemispheric trend lies in understanding the ocean circulation patterns.The possibility of sudden catastrophic polar ice loss has raised fears over its potential impact on altering Europe's moderate climate in addition to threatening its coastlines due to global sea level rise. There is still insufficient knowledge about the pathways and mechanisms by which heat and carbon are transferred between atmosphere and ocean interior, and between polar regions and the rest of the globe. Progress in our understanding has been hindered by our lack of full grasp of ocean turbulence. Furthermore, the increase in ocean temperature and the reduction in sea ice in the polar regions are likely to have significant impacts on the operation of the Arctic and Antarctic ecosystems, particularly for populations of fish, krill and penguins. Understanding the mechanisms that cause heat, carbon and nutrients to be mixed both laterally and vertically in polar oceans is vital to interpreting the regional physical, chemical and biological changes that are occurring. Mixing if facilitated by turbulence generated by winds and eddies in the upper ocean as well as tides in the abyssal ocean, among other factors. Turbulent mixing mixes tracers (such as heat and carbon) in the ocean just like stirring mixes heavy cream in a coffee cup. The key project objectives are therefore:1. To quantify, describe and understand the spatial and time-varying patterns of lateral turbulent mixing in the Southern Ocean and vertical mixing over the global ocean.2. To employ our findings to reconstruct more accurate ocean circulation patterns by using a combination of observational data and state of art climate models,3. To employ the climate models to study the climate variability over the next decades to centuries and to evaluate its impact on regional climate.