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

Once the 10-m wind speed over the ocean reaches about 12 m/s, sea spray becomes an important agent for transferring heat and moisture across the air-sea interface. We confirm this fact using the two best high-wind-speed data sets available: HEXOS (the experiment to study Humidity Exchange over the Sea) and FASTEX (the Fronts and Atlantic Storm-Tracks Experiment). Using the COARE version 2.6 interfacial flux algorithm and a microphysical spray model, we partition the HEXOS and FASTEX measurements of sensible heat flux and latent heat flux into spray and interfacial contributions. This partitioning shows that, in most cases with wind speeds above 11–13 m/s, both the spray sensible and latent heat fluxes are at least 10% of the corresponding interfacial flux.

From the resolved spray flux components, we develop a fast bulk spray flux algorithm to combine with the COARE version 2.6 interfacial flux algorithm in a unified turbulent surface flux algorithm for use in large-scale ocean storm models. We highlight that, because the spray and interfacial fluxes scale much differently, they must be treated separately in models intended to predict air-sea fluxes in high winds.