Wave Coupling Sensitivity Investigations with a Coupled Hurricane-Ocean Model

Hyun-Sook Kim, IMSG at EMC/NCEP/NOAA, College Park, MD, United States, Jessica Meixner, Organization Not Listed, College Park, United States, Bin Liu, National Centers For Environmental Prediction-Environmental Modeling Center, College Park, MD, United States, Alan J Wallcraft, Center for Ocean-Atmospheric Prediction Studies, Florida State University, Tallahassee, FL, United States, Avichal Mehra, NOAA NWS NCEP Environmental Modeling Center, College Park, United States and Vijay Tallapragada, NOAA/NCEP/EMC, College Park, United States
Current operational two-way coupled Tropical Cyclone models include the first order approximation of complex, multi-scale air-interaction processes between atmosphere and the ocean, and one-way coupling to wave model. Our current efforts extend this coupling to three-way coupling of ocean-atmosphere-wave model components to help advance accurate representation of coupling processes by including wave-induced momentum and enthalpy flux in the wave boundary layer, and wave-induced circulation in the oceanic mixed layer. We use the Hurricane Weather and Research Forecast (HWRF) version coupled to the HYbrid Coordinate Ocean Model (HYCOM), to allow dynamic-interactions with the wave model component, WAVEWATCH III (WW3). In the current configuration, HWRF receives a set of the Charnock coefficients and misalignment angles between surface wind and stress from WW3, to modify the logarithmic wind profile in the surface layer, while WW3 provides a set of surface wave-averaged Stokes drift magnitude and wavelengths to HYCOM for simulations of Langmuir circulations and associated turbulent mixing. HYCOM has multiple options for parameterizing the Langmuir mixing, some of which consider buoyancy flux while others use refinement of diurnal SST simulations. This presentation focuses on the impact of these additional coupling processes and parameterizations on hurricane intensity forecasts, and Atlantic Hurricane Michael (2018) is chosen as an example for a case study.