A full-tensor approach for parameterising oceanic eddy tracer transport – Michael Haigh, Imperial College London

October 25, 2021 @ 1:00 pm – 2:00 pm
Dr. Jerome Neufeld

In numerical ocean models the effects of unresolved mesoscale eddies on large-scale tracer distributions are typically represented by a turbulent diffusion closure. Such a closure is characterised by a diffusivity coefficient for which scalars, diagonal tensors and full tensors have been proposed. We opt for the most general full-tensor approach applied to an eddy-resolving tracer simulation with no additional averaging or simplifications. The resulting ‘transport tensor’ exhibits new levels of spatio-temporal complexity and its properties — such as negative eigenvalues, non-uniqueness and its relationship with the large-scale flow — contrast those of eddy diffusion closures currently implemented in numerical ocean models. This work suggests a rethink of the role of mesoscale eddies and their representation in numerical models may be required in order to improve our ability to simulate large-scale tracer distributions.

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