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A parameterization of local and remote tidal mixing

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Friday, 19 July 2019, 10:30

Friday, July 19, 2019. 10:30AM. A parameterization of local and remote tidal mixing. Casimiar de Lavergne, Sorbonne University. Sponsored by NOAA GFDL. More information here.

 

Internal tides power much of the observed small-scale turbulence in the ocean interior. To represent mixing induced by this turbulence in climate-scale ocean models, energy routes from the generation to the dissipation of internal tides must be understood and mapped. Here we present a mixing scheme which accounts for the local breaking of high-mode internal tides and the distant dissipation of low-mode internal tides. The scheme relies on four static 2D maps of internal tide dissipation, constructed using mode-by-mode Lagrangian tracking of energy beams from sources to sinks. Each map is associated with a distinct dissipative process and a corresponding vertical structure. Applied to an observational climatology of stratification, the scheme produces a global 3D map of dissipation and mixing which compares well with available microstructure observations and with upper-ocean fine-structure mixing estimates. Implemented in the NEMO global ocean model, the scheme improves the representation of deep water-mass transformation and obviates the need for a fixed background diffusivity.

Location  Smagorinsky Seminar Room, Princeton University, Princeton, NJ.