Simulated ocean response to tropical cyclones: The effect of a novel parameterization of mixing from unbroken surface waves

Tropical cyclones dissipate large amounts of energy into the upper ocean, locally enhancing vertical mixing and cooling the sea surface. In this study, we investigate how the response of the ocean to tropical cyclones is affected by additional mixing from unbroken surface waves. This Surface Wave Mixing'' (SWM) is represented by a novel parameterization, in which the wave orbital motion contributes directly to the production of turbulent kinetic energy. The parameterization is implemented here as a modification to the k-epsilon turbulence scheme, used within an ocean model with 1/4 degrees horizontal resolution (MOM5). This model is forced with idealized tropical cyclone wind fields based on observed case studies. Relative to simulations without SMW, the inclusion of SWM leads to surface temperature differences of around 0.5 degrees C near the storm track, typically with warm anomalies on the side with the strongest winds and cool anomalies in other regions. This pattern is explained by an initial wave-induced deepening of the mixed layer, which can modify the subsequent shear-induced entrainment and upwelling. The temperature anomalies from SWM could potentially influence tropical cyclone intensity and structure.