Near-inertial energy pathways: Collaborative research project with ESR and NWRA

PIs: Renellys C. Perez, and Rick Lumpkin

External PIs: Jonathan S. Lilly, Pascale Lelong, and Kathleen Dohan

Collaborators: Shane Elipot

Wind stress fluctuations acting at the surface of the ocean cause the mixed layer to ring with strong inertial oscillations. Some fraction of the energy is locally dissipated, either within the mixed layer or in the strongly stratified zone at its base. A large portion, however, makes its way into the ocean interior in the form of propagating near-inertial waves, which eventually break and drive small-scale mixing. The near-inertial energy pathways, far from being controlled by linear processes, appear to be shaped at first order by interactions with the mesoscale eddy field. The nature of these interactions may be more complex than previously thought, involving several distinct mechanisms of energy transfer.

We propose to investigate fundamental aspects of the near-inertial pathways through a combination of data analysis and numerical modeling. Our strategy is built around accessing and interpreting data from the Global Drifter Program network of surface buoys, now available with approximately hourly resolution since 2005. Analysis of the surface drifter dataset will quantify previously unobservable details of the near-inertial variability in the surface mixed layer. At the same time, outstanding dynamical questions of wave/eddy interactions will be explored with high-resolution numerical experiments and dynamical models. The net result will be an improved and quantitative understanding of the near-inertial energy flux from the mixed layer to the ocean interior, an important element of the ocean's energy budget.

A schematic detailing the processes by which energy input by the wind is converted into propagating internal waves (courtesy of Jonathan Lilly).

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