Modeling the Effect of Ocean Spray on the Vertical Enthalpy and Momentum Transport in Hurricanes with a Multi-Fluid Approach

In-depth understanding and accurate modeling of air-sea heat, moisture, and momentum exchange is essential for reliable forecasting of hurricanes and severe tropical storms. These complex processes are influenced by factors such as wind speed, waves, and ocean spray. To describe the effect of ocean spray on the vertical fluxes, we have developed an Eulerian multifluid model of a hurricane's spray-laden marine atmospheric boundary layer (MABL). Unlike the mixture models traditionally used in this field, the multifluid model treats dry air, water vapor, and droplets of various sizes as separate interacting and interpenetrating turbulent continua. Each continuum is characterized by its velocity, temperature, and turbulent energy, and obeys mass, energy, and momentum conservation laws. Our findings reveal that the spray strongly affects important mechanical and thermodynamic characteristics of the hurricane’s MABL such as turbulence suppression rate, air-sea drag coefficient, wind speed, and magnitudes of heat fluxes. Furthermore, these spray effects depend sensitively on the droplet size and, consequently, on the droplet size distribution. We have demonstrated that predictions based on the multifluid model differ noticeably from those made using traditional mixture models.