Large-Eddy Simulation of the Spray-Laden Hurricane Boundary Layer: I. Spray Transport and Statistics

For decades, theoretical, observational, numerical, and experimental efforts have sought to quantify the behavior of sea spray in the high-wind boundary layer. A persistent problem, however, is that it is notoriously difficult to examine spray effects directly: observations are scarce, and numerical simulations are often idealized or lacking in a full representation of the physical processes involved. In this study, we provide the most complete treatment of spray transport and coupling with the hurricane boundary layer to-date by conducting high-resolution large-eddy simulations coupled with Lagrangian spray droplets across a range of wind speed using a GPU-accelerated model. In this first of a two-part work, we describe the turbulence, the impacts of spray on mean profiles, and the dispersion of spray throughout the boundary layer. Spray has minimal impacts on the velocity and turbulence statistics, while at the same time having a much more pronounced influence on profiles of temperature and water vapor. Droplet concentrations roughly follow the conventional power-law shape above the droplet injection layer, although almost universally over predict the droplet number concentrations. The Lagrangian lifetime statistics are computed as well, and it is shown that estimates based on a droplet falling at its Stokes terminal velocity from the significant wave height is inaccurate and cannot capture the wide range of possible droplet lifetimes.