Dependence of spray flux on breaking waves Fairall, C AF: NOAA / ETL, 325 Broadway, Boulder, CO United States M.Banner and Morison, R The University Of New South Wales, School of Mathematics, The University of New South Wales, Sydney, NSW 2052 Australia Peirson, W The University Of New South Wales, Civil Engineering, The University of New South Wales, Sydney, NSW 2052 Australia

Production and Removal at the sea-air interface Rate of change=Inputs-Removal=Source-Deposition For concentration n (#/volume) 1 Turbulent xport 2 Molecular diff. 3 Mean fall speed 4 Inertia 5 Source Number(r)/m^2/sec HOWEVER: At least one additional piece of information is required to characterize the soure. *Initial ejection velocity Wej *Effective height h

Source function whitecap scaling: A single whitecap produces sea spray distribution s whitecap [r]

Scaling Arguments

Source Scaling with Forcing Forcing = –Whitecap fraction –U 3 –U * 3 –DE 2/3 –DE Energy going into wave breaking –Л(c) length of breaking waves per unit area

Droplet Source Functions h Sig wave height/2 P energy wave breaking σ surface tension r droplet radius η Kolmogorov microscale f fraction of P going into droplet production V f =droplet mean fall velocity Fairall et al Fairall, Banner, Asher Physical Model

SPANDEX – SPUME Droplet Study Photograph of PDA and DMT probes for the Spray Production and Dynamics Experiment (Water Research Facility, Manly, Australia; January 2003). Bill Asher, Mike Banner, Chris Fairall, Bill Peirson

Droplet Source Strength: Deduced from droplet concentration data Above the source region, S n =0. Vertical transport balances fall velocity in equilibrium so constant=0 Within source region, S n ≈ V g n

Samples from Wind Tunnel Study SPANDEX Droplet spectra profiles Droplet spectra normalized by power law equation

Source Function Scaled by Friction Velocity Total near-surface droplet mass and the estimated mass flux near the surface (z=12.5 and 15.0 cm) as a function of u*. The SPANDEX data are indicated by circles. The red line represents the parameterization of Fairall et al. (1994) and the green solid line a recent update of that parameterization obtained from a physically-based model (Fairall et al., 2005).

Source Function Scaled by Small-Scale Wave Energy