Constraining Sea Spray Heat Fluxes in High Winds Using Direct Covariance Heat Flux Observations

Upper ocean mixing is an important air-sea interaction process that impacts both the atmosphere and ocean during the passage of a tropical cyclone (TC). Along with storm-induced upwelling, mixing controls the sea surface temperature (SST) that drives surface heat fluxes that influence TC intensity, and it also determines the upper ocean structure that will persist and evolve for many days after a TC’s passage. Mixing is driven by many processes, including upper ocean vertical shear and buoyancy, but surface wave-related processes, such as wave breaking and Langmuir circulations, are often not addressed in models. In this study, we implement a one-dimensional turbulent kinetic energy-based scheme for upper ocean mixing with physics for wave breaking and Langmuir circulations into the Weather Research and Forecasting (WRF) model and evaluate its performance in TC simulations. We compare simulations in which wave effects are parameterized by surface winds to those in which they are modeled directly using wave properties obtained from coupled WRF-WaveWatch III simulations. We also compare our results to additional simulations using existing ocean mixing options available in WRF. We examine two TCs, namely Typhoon Fanapi (2010), which intensified in the open ocean to the northeast of the Philippines, and Hurricane Ian (2022), which crossed the southeastern Gulf of Mexico before making landfall in Florida, to contrast and improve model performance both in the open ocean (Fanapi) and during interaction with coastlines and shallow water (Ian).