13.3
A parameterization of sea spray contributions to mass and heat fluxes in hurricanes based on breaking wave properties
Christopher W. Fairall, NOAA/ESRL/PSD, Boulder, CO; and M. Desflots and S. S. Chen
Air-sea interaction is unquestionably a critical aspect of hurricane structure and evolution. Recent experiments with high resolution (km-scale) nested models have shown strong sensitivity to the representation of air sea fluxes – both the direct (interfacial) transfers and contributions of sea spray. With the advent of fully coupled (air-wave-ocean) models, it becomes possible to represent the surface fluxes in more physical detail (as opposed to simple wind-speed driven bulk flux algorithms). In this paper we describe a new representation of sea spray fluxes that is driven by the fundamental processes associated with blowing large droplets off the tops of breaking waves. The droplets are produced at the interface via a cascade of energy released by breaking waves and enter the atmosphere if they receive sufficient forward speed from wind gusts and the speed of the breaker to escape the surface. The actual contributions of this droplet spectrum to the sensible and latent heat fluxes are computed interactively as a balance of heat sources available to evaporate the droplets before they reenter the ocean. The parameterization uses input variables from the numerical model: energy lost to wave breaking, phase speed and slope of the breaking waves, and the surface stress. Examples of application in the RSMAS hurricane model will be shown.
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Session 13, New Parameterizations for Air-Sea Coupling
Thursday, 23 August 2007, 3:30 PM-5:00 PM, Broadway-Weidler-Halsey
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