Parameterization of subgrid-scale energy injection in oceanic flows

Abstract

Dissipative terms are usually employed to parameterize subgrid fluxes of energy and enstrophy in turbulent flows. However, in certain flows, such as oceanic flows, when the dissipation is calculated self-consistently it turns out to be negative and hence numerically unstable. A solution to this problem is offered in this study in the form of a stochastic subgrid scale parametrization scheme. It is a spectral scheme employing matrices that generalize the classical eddy dissipation and stochastic forcing variance to include vertical transfers. Using a baroclinic model with typical oceanic parameters the scheme is able to maintain the resolved-scale spectra exceptionally well when the energy injection scale is in the subgrid scales. This work has implications for ocean climate modelling where the resolution is typically too coarse to resolve the energy injection due to baroclinic instability. References

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