Eddies, mixing and recent climate change

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To assess the future impact of man's activities on the climate system, we need to run climate prediction models. These models depend heavily on processes that cannot be resolved explicitly, either because the computer power is simply not available, or because the models would be too complex, making it impossible to judge their reliability. An example is the representation of clouds. It is almost impossible to imagine representing the physics of each cloud explicitly in a model, yet clouds are known to play a fundamental role in the Earth's radiation balance. Here we are concerned with the representation of unresolved processes in the ocean; in particular time dependent fluctuations ("eddies") with spatial scales from kilometres to tens of kilometres. Our ability to represent eddies in climate models is currently quite limited, yet we are beginning to realise the fundamental role played by eddies in the budgets of heat, freshwater, carbon and other tracers, issues central to the climate change problem. The proposed research is aimed at improving the ability of climate models to represent the effect of eddies, building on our past work in this field. We also address the issue of recent climate change in an attempt to unravel the role played by the tropical oceans and the upper atmosphere (e.g. the stratosphere) within the context of the increasing concentration of greenhouse gases in the atmosphere. These activities combined should lead to improvements in our ability to predict future climate, and the likely impact of climate change as it affects Canadians.