Wind Forcing and Eddy Killing in the Global Ocean

Shikhar Rai1, Matthew W Hecht2, Mathew E Maltrud2 and Hussein Aluie3, (1)University of Rochester, Rochester, NY, United States, (2)Los Alamos National Laboratory, Los Alamos, NM, United States, (3)University of Rochester, Rochester, United States
Wind forcing is the major source of energy for global ocean circulation which drives the Lorenz Energy Cycle. However, it is also known that such `relative wind' forcing is capable of extracting energy from the fluctuating flow, a process called `eddy killing.' Here, we utilize a coarse-graining approach to determine the length scales at which motion is impeded or ``killed'' by the wind. Using global data from scatterometry, altimetry, reanalysis, and a fully coupled 0.1-deg model, we find that eddy killing is most prominent in the scale band of 200 to 300 km and that it extracts 50 GW from the global ocean. In strongly eddying regions, such as Western Boundary Currents, the effect is drastic, channeling up to 30% of the wind energy input from the mesoscales back to the atmosphere.