1. A Sea-Spray Thermodynamic Parameterization Including Feedback C. W. Fairall *, J-W. Bao, and J. Wilczak NOAA Environmental Technology Laboratory (ETL) Boulder, CO 1.Background 2.Source strength 3.Feedback 4.Sensitivities 5.Model tests

3. Original Droplet Equations Fairall/Andreas circa 1990

5. S n Surface Source Strength for Sea Spray Droplets

6. Droplet Source Functions 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. 1994 Fairall, Banner, Asher Physical Model

7. Feedback

8. Partitioning of Droplet Contribution: Stages of cooling/evaporation Simplification: consider large droplets that are ejected, cool to wet bulb temperature and re-enter ocean with negligible change in mass Stages: –Cool from To to Tair = Qs –Cool from Tair to Twet = Ql_a –Evaporation while at Twet = Ql_b Total droplet enthapy transfer Qse=Qs+Ql_a Enthalpy Bowen ratio = Qs/Ql_a=(To-Ta)/(Ta-Twet) Qs=Qse*bowen/(1+bowen)

9. Feedback Characterization δT a Effect on the fluxes:

10. Turbulent Fluxes Above the Droplet Evaporation Layer

11. Direct Transfer Coefficients Assumed in Parameterization

12. Ratio of Transfer Coefficients With Droplet Enthalpy Flux

13. Feedback Sensitivity: Source Strength=0.3

14. Model Tests (Bao and Ginis) IVAN, ISABEL –GFDL operational –GFDL new zo, zt –WRF PLANS –HWRF at high resolution – matrix of tune values –Explicit droplet model (Kepert/ Fairall) in HWRF –Coordinate with Penn State LES work

15. Simulation with GFDL Operational Model: Isabel

16. But: Simulations with New Cd and Ce/Ch New Cd Ce/Ch Old Cd Ce/Ch