Wind-driven surface gravity waves interacting with flow-induced turbulence

Wave-turbulence interaction is a complex multi-scale coupling process in the surface ocean that strongly influences vertical energy transport and mixing. In this work, controlled laboratory experiments with high-precision measurements were conducted to investigate the interaction between wind-driven surface gravity waves and turbulence induced by a submerged jet. Using the Holo-Hilbert spectral analysis (HHSA), we confirm the existence of wave-turbulence interactions, which facilitates wave spectral energy attenuation by 18% and drifts flow centerline upward over 5∘. Energy released from wave attenuation is redistributed vertically through two pathways: direct transfer from waves to high-frequency turbulence in the near-surface region, and indirect mean-flow-mediated transfer from low-frequency motions near the surface into deeper layers. Finally, we classify the types of wave-turbulence interactions and four characteristic regimes were identified, ranging from dominant wave-flow coupling near the surface to strong overlap, weak mean-flow-mediated coupling, and minimal interaction at depth. Simplified phenomenological models were developed to represent the typical flow responses in each regime. These findings give new experimental evidence on the mechanisms of wave-turbulence coupling and provide guidance for improving parameterisations of surface wave energy dissipation and vertical energy transport in the upper ocean.