Is there turbulence in the deep ocean?

Short answer: Yes.

One might imagine the deep ocean as a dark, silent world, largely untouched by the restless motion seen at the surface, where winds raise waves and storms stir the sea. However, just as surface waves exist along the sharp density interface between the ocean and the atmosphere, internal waves are supported by smooth vertical gradients in density far beneath the ocean's surface. The turbulence of these waves plays a central role in ocean mixing and circulation.

I will introduce surface and internal waves as examples of dispersive wave systems, and explain how their long-time dynamics can be described using the theory of weak wave turbulence. I will then present our recent work, which addresses a long-standing problem in geophysical fluid dynamics: deriving the observed broadband oceanic spectrum of internal waves, known as the Garrett-Munk spectrum, directly from the governing equations.

The central message of the talk is that the weak-rotation limit is singular, and that it is precisely this singular limit that allows the oceanic spectrum to emerge from first principles.

No background in geophysical fluid dynamics will be assumed.