Wave-turbulence decomposition of particle trajectories.

The ocean surface flow controls air-sea fluxes of gas, heat, and momentum, and is characterized by wind-driven waves, and turbulence, among other processes. Decomposing the relative effects of waves and turbulence on velocity signals has long been of interest for Eulerian measurements. However, Lagrangian particle trajectories in this system have received relatively little attention. The decomposition of wave and turbulence motion in the frequency range in which they overlap continues to be a challenging problem. Many approaches limit their scope to irrotational waves and assume that waves and turbulence do not interact. We aim to develop a data-driven method using Dynamic mode decomposition (DMD) that does not make any of the assumptions mentioned, and additionally provides insight into the wave-turbulence interactions. We collected data from experiments in a wind-driven wave tank. Both the laboratory and synthetically-generated data were analyzed using conventional wave-turbulence decomposition methods and the proposed DMD method. This is a promising avenue that could have broad applications in the study of Lagrangian measurements.