Improving airsea flux parameterization in the GFDLURI Coupled HurricaneWaveOcean Model for Transitio

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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)
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Drag and Heat Exchange Coefficients vs Wind Speed
in the GFDL Operational Model

• Based on simple bulk parameterization.
• States of growth of wind waves relative to local
  wind forcing is neglected.

Cd
Ch
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Coupled Wave-Wind (CWW) Model

• Near the peak NCEP WAVEWATCH III wave model.
• High frequency part Equilibrium spectrum model
  of Hara and Belcher (2002)

Two dimensional wave spectrum
Full wave spectrum
Near peak
High frequency part
Wave Boundary Layer Model
Explicitly calculates wave-induced stress
0
1
2
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25
- max
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Wind profile and drag coefficient over any given
seas
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Wave-Wind Simulations in Real Hurricanes
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Cd estimated from CWW model hurricane simulations
WAVEWATCH III

• At high wind speeds, Cd levels off and even
  decrease with wind speed
• Under hurricane wind forcing waves are extremely
  young at high wind speeds and the young waves
  produce small drag.

Upper and lower bounds from CWW model
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Operational GFDL/URI Model
Coupled Hurricane-Wave-Ocean Model
Atmosphere
Atmosphere
GFDL Hurricane Model
GFDL(WRF) Hurricane Model
Wind Air Temp.
Flux
Wind Air Temp.
Flux
SST
Wave Boundary Model
SST
SST Current
Wave Spectra
Flux
Flux
Currents,
NCEP WAVEWATCH III


POM (HYCOM)
POM
Elevations, SST
Ocean
Ocean
Waves
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Hurricane Ivan, Initial time 00Z 12 Sep
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Hurricane Ivan, Initial time 00Z 12 Sep
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Summary

• 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.
• 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.