Ocean Turbulence

Flyer.pdf

Agenda.pdf (Updated 5/20)

Conference Program.pdf

Summary

The world’s oceans exhibit phenomena at multiple length and time scales whose effects accumulate to produce the large scale circulation responsible for the heat and tracer transport that so greatly affects global climate, as well as the more local ocean currents that affect such things as fishing, regional climate and energy. Two very different examples of seemingly turbulent phenomena are:

1. Baroclinic instability and mesoscale eddies. Baroclinic instability creates eddies at the scale of the deformation radius that not only have many of the characteristics of turbulent flow (chaos, multiple scales) but that lead to important changes in the stratification, especially at high latitudes in the Southern Ocean.

2. Mixing at small scales. When dense water spills over oceanic ridges Kelvin-Helmholtz instability leads to strong, perhaps explosive, turbulent mixing, and when tides and mesoscale eddies force water over topography gravity waves are generated and break, again giving rise to mixing. Recent results further suggest that turbulent mixing can arise when internal waves propagate through the strain generated by mesoscale eddies or through geostrophic instabilities that develop close to topographic corrugations. Not only does such mixing help set the stratification locally, but it greatly affects the meridional overturning circulation and hence the flow at global scales. Evidently, small-scale turbulence is not just a passive consequence of the larger scales: rather, the feedbacks on the large-scale flow are of first-order importance.

This conference will address the inter-relation of these and other phenomena through theory, modeling, observation, and experiment. Mixing seems to play a central role, but is this a consequence of turbulence, a definition, or what? And is mixing truly important, or is the ocean interior adiabatic at first order? Is the concept of an ‘eddy diffusivity’ still useful? How does energy pass through the system from the large scales to the Kolmogorov scale? Are mesoscale eddies genuinely turbulent, and what is their relation to mixing and to the small scales, if any? Finally, what can we learn from looking at the mathematical properties of the fluid equations? Is the lack or the presence of regularity in the equations important from a physical standpoint? Can the mathematical structure help us in understanding the dynamics or building parameterizations? Put simply, the conference will address the most fundamental questions in ocean turbulence. Since today’s models are built upon the understanding of yesterday, this conference seeks to bring together new science and mathematics to build the understanding required for tomorrow’s models.