Evidence of spray-mediated air-sea enthalpy flux within tropical cyclones

摘要

It has long been conjectured that spray ejected from the high-wind ocean surface enhances air/sea enthalpy fluxes, but a lack of observational data, particularly at wind speeds exceeding 20 m s~(-1), has prevented either confirmation or refutation of this hypothesis. The current study has two aims: first, to provide an estimate of surface enthalpy fluxes obtained from dropsonde data and second, to provide evidence of spray-mediated enthalpy transfer. These are accomplished first by assuming that Monin-Obukhov similarity is satisfied throughout the bottom 100 m of the high-wind boundary layer, then by focusing on the enthalpy flux HK rather than its transfer coefficient CK. The scaling of HK with wind speed in observational data sets reveals similarities to spray-mediated fluxes predicted by a newly developed surface flux model, in contrast with measurements made in a laboratory setting. This behavior supports the claim that surface enthalpy fluxes are dominated by spray within tropical cyclones.