Collaborative Research: Does Topography Control Mesocale Dissipation?

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The turbulent mechanical energy budget of the subsurface ocean has recently received considerable attention because it is key to understanding the global conveyor circulation. However, there exists a dissipation crisis in the mechanical energy budget. Energy is fed to the system and then dissipated by invoking eddy viscosities (the forms and values for which are dictated first and foremost by computational stability constraints). Essential oceanographic measures, like eddy kinetic energy, are determined by these parameterizations, and the implications of mesoscale dissipation are far reaching. This includes including diapycnal heat and tracer fluxes. To help clarify the issues surrounding the limitations of mesoscale energy loss, the parameterizations need to be developed from physical approaches and model calculations. In this study, researchers at the University of Rhode Island, Florida State University, and the University of California at Los Angeles will compute the energy losses to boundary dissipation, topographically induced unbalanced flows, and internal mesoscale dissipative mechanisms resulting from a topographically forced forward energy cascade to smaller scales. The team of scientists will conduct and analyze fine resolution primitive equation and non-hydrostatic model simulations of interactions of vortices and seamounts as a prototype for topographically induced loss-of-balance and dissipation. The principal tools will be analytical and process numerical models. The results gathered from this work will comment on the viability of their hypothesis that the interaction between the mesoscale and topography is important in controlling the mesoscale, principally through catalyzing transfers from balanced to unbalanced currents. If true, this information will impact the ocean sub-grid scale parameterization, from bottom boundary layers to interior mixing. In addition to the intellectual merit of the work, the research will train a graduate student and promote cooperation between scientists at URI, FSU, and UCLA. The results will be refereed to journals and presented at national and international scientific meetings and in seminars.