Program     Turbulence and scaling processes in the ocean       0930 Mixing induced upwelling along a sloping boundary energized by the internal tide  (Invited) Tuesday 8th @ 0930-0950, Conference Room 4 Kraig Winters* , Scripps Institution of Oceanography University of California San Diego Presenter Email: kraig@coast.ucsd.edu Recent theories of ocean mixing (Ferrari et al; [2016], McDougall and Ferrari; [2017]), based on buoyancy and volume budget analyses, argue that deep ocean mixing is characterized by diapycnal upwelling along sloping boundaries and almost-compensating diapycnal downwelling in the ocean interior. This view contrasts rather sharply with the long-standing Abyssal Recipes model (Munk, 1966) of interior upwelling of cold waters balanced by a downward turbulent heat flux. Axiomatic in these new theories, however, is an idealized picture of turbulent ocean boundary layers that are nearly well mixed and are characterized by turbulent diapycnal fluxes that increase with height from the bottom within the well mixed layer before decreasing further above in the overlying stratified waters. While the underlying mathematics appears quite general, this spatial structure of the turbulent fluxes appears to be an essential precursor to the theoretical result. Recent high-resolution, deep ocean measurements of tidally-driven turbulent boundary layers on continental slopes and seamounts (e.g. van Haren, 2006), however, show active turbulent boundary layers that remain stably stratified. Moreover, the inferred diapycnal fluxes are maximal close to the boundary and decay with height, altogether different from the theoretical boundary layers envisioned. These boundary layers have been hypothesized to contribute a substantial fraction of the total mixing in their adjoining basins. The objective of this work is to try to reconcile the theoretical framework with the characteristics of observed tidally driven boundary layers and determine whether turbulence-driven upwelling along sloping boundaries is a generic process or one limited to idealized situations similar to that postulated for the theoretical model.

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