Dynamics, heat transport, spectral composition and acoustic signatures of mesoscale variability in the ocean
Carvalho, Daniel Peixoto de
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The general circulation of the global ocean is turbulent rather than laminar. Mesoscale eddies contribute to the transport of tracers like heat, salt, and oxygen, and affect large-scale ocean dynamics. The problem of representing mesoscale variability stems from the nonlinear character of eddy dynamics that makes it difficult to predict equilibrated fluxes. The most intuitive solution is to apply a parameterization based on the eddy-driven transport observed in a global ocean that has been spinning up for centuries, which may not be feasible at present. An alternative approach involves constructing relatively simple analytically tractable equilibration models. In this study, the equilibration mechanism called the Growth Rate Balance (GRB) model proposes an explanation to the eddy dynamics as a competition between primary and secondary instabilities. The GRB model is validated in two configurations: in a two-layer model, and in a continuously stratified model. They identify the dependences of equilibrated fluxes on the characteristics of the background flow, and the applicability range of the GRB model. Finally, acoustic signatures of a fully developed eddy field predicted by the GRB model characterize the role of mesoscale variability in the important naval problem of acoustic propagation.
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