For this week's special Tuesday seminar, let's welcome Dr. Giovanni Dematteis, visiting us from RPI. Dr. Dematteis will be presenting on the topic of developing a first-principles understanding of internal wave-driven mixing.
Diapycnal mixing in the ocean interior, largely due to breaking internal waves, is an important ingredient for understanding upwelling and horizontal circulation in the oceans. I will outline a first-principles quantification of the downscale energy fluxes in the internal-wave band, that ultimately feeds the wave-breaking, shear-instability conversion of energy into turbulent dissipation and mixing. The approach is based on the theory of wave-wave nonlinear resonant interactions. Although a seemingly well-established theory, it is just starting to reveal its 'hidden secrets' thanks to very recent theoretical and computational breakthroughs. Our results are consistent with the corroborated empirical formula for wave-induced mixing known as the finescale parameterization. This represents an essential benchmark, but also a fresh starting point. In general, the physical processes underlying internal wave energy transfers are still poorly understood. On the contrary, our calculation provides a detailed dynamical understanding of these processes. Firstly, supplemented with data assimilation, this offers an interpretation paradigm for the ever increasing amount of field data from global databases (e.g., ARGO and GMACMD). Secondly, this first-principles framework is the natural candidate for a much needed reformulation of internal wave-driven mixing as a dynamically interactive component of the ocean circulation, to be incorporated into the Global Circulation Models.
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