Mixing, dissipation and scale interactions in the oceanic circulation from an integrated theoretical and observational perspective

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Ocean circulation is the product of a myriad of processes operating at an enormous range of space and time scales. These range from basin-scale forcing patterns that drive the large-scale currents, to centimetre-scale turbulence that drives ocean mixing and dissipation. A major focus of recent research has been to quantify the large-scale forcing of the global circulation. However, the small-scale mechanisms of mixing and dissipation, as well as the multi-scale processes responsible for the transfer of energy from large to small scales, are of equal importance in governing ocean circulation and the ocean's role in the climate system. These processes remain poorly understood and, as a consequence, inadequately represented in climate models.***Through novel observational studies and closely-tied theoretical investigations, my research program will target a process-based understanding of the energy cascade and the turbulence that ultimately arrests it. It will investigate scale-interactions and scale-dependent mixing in idealised, actual and modelled oceanic flows. In this way, it will build an understanding of these processes step-by-step, produce global maps of their observed action and impact, and evaluate their representation in state-of-the-art climate models. Alongside these studies, I will build a unique observational program targeting turbulent dissipation and mixing rates and their underlying physical mechanisms. The focus will be on the role of these processes in driving exchange between the continental shelves and the deep basins off Canada's coasts. Enabled by state-of-the-art ocean observing technology, specifically an autonomous robotic observing platform equipped with turbulence-sensing instrumentation, my program will realise a step change in our ability to make the necessary multi-scale observations. Further it will do so in remote locations at a fraction of the cost of traditional observing platforms.***Physically-based parameterizations of scale interactions and the accurate representation of mixing and dissipation in ocean models are critical to improving confidence in our projections of future climate change. By applying a novel analysis technique to the study of these processes, my work has the potential to provide unique insight into how these processes work and suggest new ideas for model parameterizations. Shelf-basin exchange has critical implications for coastal circulation, ecosystems and ice cover. The advances my research program will bring about in the ability to observe the relevant processes, promise similar advances in our understanding of them. This research promises to be of significant benefit to Canadians by improving climate predictions, providing understanding critical for sustainable development in coastal regions undergoing rapid change, and strengthening Canada's standing at the forefront of oceanographic research.**