Modeling Wave-Induced Stress for Non-Equilibrium Surface Waves in the Marine Atmospheric Boundary Layer

Swells influence air–sea momentum exchange by introducing a wave-induced upward component of surface stress, which modifies the turbulence structure within the atmospheric boundary layer. Under low-wind conditions, this interaction can give rise to a wave-induced low-level jet: a feature not captured by conventional models that rely on a fixed roughness length and Monin–Obukhov similarity theory to estimate surface stress. Additionally, kinematic effects associated with vertical wave motions pose a challenge for wall-modeled large-eddy simulations (LES) due to the absence of vertical surface displacements, leading to an underestimation of wave-induced stresses. In this study different theoretical and empirical wind–wave models are tested in a single column modeling framework by solving the dynamic Ekman equations and a new parameterization for the wave-induced stress is proposed. An augmented flux-layer model, which incorporates the vertically varying wave-induced stresses, is subsequently implemented and tested in Large Eddy Simulation of airflow over wind-waves and swell.