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Stratified turbulence and ocean mixing

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Our blue oceans are chaotic and turbulent deep inside. Small scale nonlinear instabilities grow and collapse naturally, leading to bursts of energetic turbulence and vertical mixing. As a result, the oceans become biogeochemically ventilated!

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Despite their significant role in closing the large scale ocean circulation, these small scale “mixing agents” have been poorly characterized to the extent that their properties are grossly oversimplified in today’s climate models.

In this talk, I will discuss about some of the key findings of my doctoral thesis on ocean mixing and stratified turbulence. I will introduce and compare twomixing mechanisms in stratified shear flows, known as the Kelvin-Helmholtz and the Holmboe wave instabilities. Furthermore, I will demonstrate that the efficiency of ocean mixing has a non-trivial global distribution and that, surprisingly, mixing may become less efficient despite turbulence being too energetic!

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