A bulk air-sea flux algorithm for high-wind, spray conditions, version 2.0

When sea spray proliferates in high winds, the droplets essentially increase the ocean’s surface area and, thereby, provide new routes for the air-sea transfer of sensible and latent heat. Newly created spray droplets also accelerate almost immediately to the local wind speed and, thus, extract momentum from the wind. When they ultimately crash back into the surface, they deliver this momentum to the sea. In short, when sea spray is present in copious amounts, it alters air-sea coupling through the turbulent fluxes.

In this presentation, I will describe Version 2.0 of a bulk air-sea flux algorithm that I have developed to compute both interfacial and spray fluxes of sensible heat, latent heat, and momentum. The ultimate application is in large-scale, coupled air-sea interaction models. The algorithm relies on microphysical theory and a reliable expression for the spray generation function; I validate it with heat flux data from HEXOS, the experiment to study Humidity Exchange over the Sea. Version 2.0 improves on previous versions of the algorithm by incorporating a more realistic dependence on surface temperature and a better parameterization for very high relative humidity.