Extended Abstract (40K)3A.5
Effects of sea spray in large-eddy simulation of the hurricane boundary layer
Mark Kelly, Penn State University, University Park, PA; and J. C. Wyngaard and W. Frank
The use of large-eddy simulation (LES) facilitates investigation of the role of sea spray and spume in the atmospheric boundary layer of a hurricane. We implement a generation function for spray and spume which depends on wind speed and varies in the horizontal according to estimated whitecap coverages. The resulting surface flux of spray and the associated sensible heat transfer are calculated locally and depend on droplet size. The spray also affects the turbulent atmosphere through condensation and evaporation, which are treated using a bulk microphysical model. Thus the thermodynamic air-spray interaction is two-way; we test the efficacy of several conserved temperature variables in representing this interaction when liquid-water mixing ratios are large. The modeled spray has a slip velocity, and hence exchanges momentum with the air; it also can fall back into the ocean or evaporate.
Through high-resolution LES we explore both the dynamic and thermodynamic effects of spray on the hurricane boundary layer. The LES results allow the assessment of the one-dimensional models of spray-mediated fluxes used in full-scale hurricane simulations. In particular, the results of LES offer insight into the thermodynamic feedbacks which the existing models attempt to parameterize, and facilitate the improvement of such models.
Session 3A, CBLAST III
Monday, 3 May 2004, 1:30 PM-2:45 PM, Le Jardin Room
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