AtmosphereOcean Interaction in Hurricanes Isaac Ginis.ppt
1,Progress Towards Developing a Coupled Atmosphere-Wave-Ocean Framework for Research and Operational Hurricane ModelsIsaac GinisB.Thomas,R.Yablonsky,T.HaraUniversity of Rhode IslandJ.-W.Bao,C.Fairall,L.BiancoNOAA/ESRL,Interdepartmental Hurricane Conference,2011,Miami,FL,Wind-Wave-Current Interaction,Image courtesy of Fabrice Veron,Hurricane model:air-sea fluxes depend on sea state(Moon et al.,2007)and sea spray(Bao et al,2011)and include surface current Wave model is forced by sea state dependent wind forcing and includes surface current(Fan et al.2009)Ocean model is forced by wind stress that is modified by growing or decaying wave fields(Fan et al.2010),Coupled Atmosphere-Wave-Ocean Framework,Red-atmospheric parameters,Green wave parameters,Blue-ocean parameters,4,Effect of Wave Coupling on Wind Stress,Surface Roughness,Drag Coefficient,Sea state dependence is parameterized based on Moon,Ginis&Hara(2007),Wind,Waves and Drag Coefficient in the Experimental GFDL Coupled Hurricane-Wave-Ocean Model,Wind at 35 m,Drag Coeff.at 35 m,Wave phase speed,SignificantWaveheight,Wind and Current Vectors Near the Hurricane Center,Wind/current ratio is not in a proper scale,-wind speed vector at a specific height-wind speed vector at the surface(=ocean current vector),Effect of Ocean Current on Wind Stress,U*vs.Wind Speed at 35 m,Case Study:Hurricane Earl Initial Time:00 UTC,30 August,2010,Effect of Ocean Current on Hurricane Intensity,Effect of Waves on Momentum Budget and Flux into Ocean,Wind stress,Wave Momentum flux,Momentum flux intoocean,Momentum Flux Reduction due to Wave Coupling,Relative reduction of the momentum flux to ocean depends on wind stress,which is not well constrained at high winds.Uncertainty of drag coefficientUpper bound:extrapolation of bulk parameterizationBlue:Moon et al.(2007)estimates from coupled wind-wave model Lower bound:observations by Powell et al.(2007),Upperbound of wind stressMoon et al.(2007)estimate of wind stress 8%reduction Lowerbound of wind Stress 15%reduction,Fan et al.(2010),Effect of Wave Momentum Budget on Hurricane Intensity,Case Study:Hurricane Earl Initial Time:00 UTC,30 August,2010,Sensitivity experiments with experimentation GFDL hurricane-wave-ocean model:Without effect of current and wave momentum budget2.With effect of current,without effect of wavesWith effect of current,with effect of wavesWithout effect of current,with effect waves,Case Study:Hurricane Earl Initial Time:00 UTC,30 August,2010,Spume production water droplets are ripped from wave crests by the wind when surface wind exceeds about 7 ms-1.Droplets range from 40m to 1mm in diameter.,Parameterization of Sea Spray Effect,NOAA/ESRL Sea Spray Parameterization(Fairall et al.2009,Bao et al.2011),Input parameters,Effect of Sea Spray on Momentum Flux,Sea Spray Effect on Drag Coefficient,Wave model component-WAVEWATCH III,WAVEWATCH III can accurately reproduce observed hurricane surface wave fields if:-Wind forcing is reduced at very high wind speeds.-Ocean current is explicitly included in the simulation.,WW3 significant wave height field(color)at Sept.15 2:00 UTC.The thick gray line is the flight track.,Significant wave height comparison between SRA measurements(during this flight)and WW3 results from experiments A,B(with modified wind stress)and C(with modified wind stress and including ocean currents).,Comparison between modeled and measured significant wave heights from all flights.,Fan et al.(2009),Extending WW3 to Finite/Shallow Water,.,*Previous version of WAVEWATCH III(v2.2.2)did not work well for water depth less than 30m(grey area below),New version of WAVEWATCH III(v3.1.4)includes improved physics in shallower water.*We are validating the WAVEWATCH III(v3.1.4)results in shallower water against observations(Scanning Radar Altimeter)in collaboration with Ed Walsh.,Hurricane Ivan(2004)significant wave height predictions,WW3 2.22,WW3 3.14,Difference,Extending the model to finite/shallow water,SRA aircraft track on 3 Oct 2002 during the landfall of Hurricane Lili(from Ed Walsh),Future Evaluation of WW3 in Shallow Waters using SRA Measurements,Summary and Future Work,Explicit representation of wind-wave-current interaction and sea spray indicate potential important effects on the air-sea momentum fluxes in hurricane conditions.Some components of the developed coupled atmosphere-wave-ocean interaction framework will be implemented into the HWRF and COAMPS-TC models for testing and evaluation in 2011.,
