Improving air-sea flux parameterization in the GFDL/URI Coupled Hurricane-Wave-Ocean Model for Transition to Operations Isaac Ginis Il Ju Moon, Tetsu Hara, Biju Thomas University of Rhode Island and Morris Bender NOAA/GFDL Collaborations: H. Tolman (EMC/NCEP) E. Walsh (ETL/NOAA) S. Belcher (UR, UK)

Drag and Heat Exchange Coefficients vs Wind Speed in the GFDL Operational Model Cd Ch Based on simple bulk parameterization.Based on simple bulk parameterization. States of growth of wind waves relative to local wind forcing is neglected.States of growth of wind waves relative to local wind forcing is neglected.

Near the peak : NCEP WAVEWATCH III wave model.Near the peak : NCEP WAVEWATCH III wave model. High frequency part : Equilibrium spectrum model of Hara and Belcher (2002)High frequency part : Equilibrium spectrum model of Hara and Belcher (2002) max High frequency part Near peak Coupled Wave-Wind (CWW) Model Wave Boundary Layer Model Two dimensional wave spectrum: Wind profile and drag coefficient over any given seas Explicitly calculates wave-induced stress Full wave spectrum

Wave-Wind Simulations in Real Hurricanes

At high wind speeds, C d levels off and even decrease with wind speed At high wind speeds, C d levels off and even decrease with wind speed Under hurricane wind forcing waves areextremely youngat high wind speeds and the young waves produce small drag. Under hurricane wind forcing waves are extremely young at high wind speeds and the young waves produce small drag. Cd estimated from CWW model hurricane simulations Upper and lower bounds from CWW model GPS sonde observation under various hurricanes (Powell et al., 2003). WAVEWATCH III

GFDL(WRF) Hurricane Model NCEP WAVEWATCH III Flux Wind & Air Temp. Atmosphere Ocean Waves Currents, Wave Boundary Model SST Wave Spectra Flux POM (HYCOM) Wind & Air Temp. Flux GFDL Hurricane Model POM SST & Current SST Flux Atmosphere Ocean Elevations, & SST Operational GFDL/URI Model Coupled Hurricane-Wave-Ocean Model

Hurricane Ivan, Initial time: 00Z 12 Sep

We have developed a coupled hurricane-wave-ocean by coupling the GFDL/URI hurricane-ocean model with the NCEP WAVEWATCH III wave model and a wave boundary layer model. We have developed a coupled hurricane-wave-ocean by coupling the GFDL/URI hurricane-ocean model with the NCEP WAVEWATCH III wave model and a wave boundary layer model. Preliminary simulations indicate that the hurricane intensity and structure can be significantly effected by explicit simulations of surface waves. Preliminary simulations indicate that the hurricane intensity and structure can be significantly effected by explicit simulations of surface waves. More real-case simulations will be done in the nearest future to assess the impact of wave coupling on hurricane predictions. Future work will be directed toward improving the heat flux parameterization in the coupled model and transitioning to the Hurricane WRF. Future work will be directed toward improving the heat flux parameterization in the coupled model and transitioning to the Hurricane WRF. Summary