2026/04/08 by Isabelle Giddy, Daniel Whitt, Ilker Fer +4
Earth and Planetary Sciences · Engineering · #Ocean Waves and Remote Sensing #Oceanographic and Atmospheric Processes #Fluid Dynamics and Turbulent Flows
paper · doi:10.1175/jpo-d-25-0076.1
Abstract We investigate the turbulence kinetic energy (TKE) budget of the upper ocean and its response to wind and wave forcing in the Southern Ocean, using realistically forced large-eddy simulations (LESs) and in situ microstructure shear observations. The widely used law of the wall similarity scaling assumes that shear production of TKE is balanced by its dissipation. However, our findings reiterate that this assumption is violated under wave forcing: Dissipation is primarily balanced by local Stokes shear production, augmented by almost equal contributions from local Eulerian shear production and nonlocal convergence of TKE transport. Despite this, the canonical law of the wall scaling reasonably describes the vertical distribution of dissipation rates in the boundary layer in both realistically forced LES and observations, even though the underlying physical reasoning does not hold. We propose a modified scaling to account for the nonlocal component of the TKE budget that yields accurate predictions of the TKE budget as well as an interpretation accounting for wave effects. These insights have important implications for interpreting turbulence dissipation rate observations. Significance Statement This study provides and evaluates a physical model of turbulence in the near-surface layer of the Southern Ocean under strong winds and waves. This turbulence model quantifies how the vertical transport and dissipation of turbulence relate to the production of turbulence due to winds and waves. This model of turbulence is valuable because the Southern Ocean plays a key role in regulating climate through the uptake of heat and carbon from the atmosphere, which is mediated by small-scale turbulent motions that generally must be estimated without turbulence observations in global ocean and climate simulations. In addition, this model provides insight into dissipation rate observations, which are generally collected without observations of the corresponding turbulence production and transport.