isaac ginis il ju moon, tetsu hara, biju thomas university of rhode island and morris bender
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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)
Drag and Heat Exchange Coefficients vs Wind Drag and Heat Exchange Coefficients vs Wind Speed in the GFDL Operational ModelSpeed in the GFDL Operational Model
CdCd
ChCh
•Based on simple bulk Based on simple bulk parameterization. parameterization.
•States of growth of States of growth of wind waves relative to wind waves relative to local wind forcing is local wind forcing is neglected.neglected.
0185.0~.2*
0 constu
gz
• Near the peak : Near the peak : NCEPNCEP WAVEWATCH III wave modelWAVEWATCH III wave model..• High frequency part : High frequency part : Equilibrium spectrum modelEquilibrium spectrum model of Hara and of Hara and
Belcher (2002)Belcher (2002)
maxk0k
2k
1k
mink
1k
3k
2k 0k
012325 - max-1
vk
High frequency partNear peak
Coupled Wave-Wind (CWW) ModelCoupled Wave-Wind (CWW) Model
Wave Boundary Layer ModelWave Boundary Layer Model
Two dimensional wave spectrum:Two dimensional wave spectrum:
Wind profile and drag coefficientWind profile and drag coefficientover any given seasover any given seas
Explicitly calculates wave-induced stress
Full wave spectrum
Wave-Wind Simulations in Real Hurricanes Wave-Wind Simulations in Real Hurricanes
20 30 50
U10 (m /s)40
0
Powell et al. (2003) Large & Pond (1981)W W 3 (upper and lower bound)
3
1
Our results (upper and lower bound)
5
4
2C
D *
100
0
Bulk, 0.0185
• At high wind speeds, CAt high wind speeds, Cdd
levels off and even decrease levels off and even decrease with wind speedwith wind speed
• Under hurricane wind forcing Under hurricane wind forcing waves arewaves are extremely youngextremely young at at high wind speeds and the high wind speeds and the young waves produceyoung waves produce small small dragdrag..
Cd estimated from Cd estimated from CWW modelCWW modelhurricane simulationshurricane simulations
Upper and lower bounds from CWW model
GPS sonde observation under various GPS sonde observation under various hurricanes (Powell et al., 2003). hurricanes (Powell et al., 2003).
WAVEWATCH III
GFDL(WRF)Hurricane Model
NCEPWAVEWATCH III
Flux
Wind &Air Temp.
Atmosphere
Ocean Waves
Currents,
Wave Boundary Model
SST
Wave Spectra
Flux
POM(HYCOM)
Wind &Air Temp.
Flux
GFDLHurricane Model
POM
SST &Current
SST
Flux
Atmosphere
Ocean
Elevations, & SST
Operational GFDL/URI ModelOperational GFDL/URI Model Coupled Hurricane-Wave-Ocean ModelCoupled Hurricane-Wave-Ocean Model
Hurricane Ivan, Initial time: 00Z 12 SepHurricane Ivan, Initial time: 00Z 12 Sep
Hurricane Ivan, Initial time: 00Z 12 SepHurricane Ivan, Initial time: 00Z 12 Sep
880 900 920 940 960 980 1000 1020M inim um Sea Level P ressure (hPa)
1 0
2 0
3 0
4 0
5 0
6 0
7 0
8 0
Max
imum
Sur
face
Win
ds (
m/s
)P ressu re -W in d R e la tio n sh ip fo r Iv an
W ave-coupled
Uncoupled
Standard Relationship for Atlantic
• We have developed We have developed aa coupled hurricane-wave-oceancoupled hurricane-wave-ocean by by coupling the GFDL/URI hurricane-ocean model with the coupling the GFDL/URI hurricane-ocean model with the NCEP WAVEWATCH III wave model and a wave boundary NCEP WAVEWATCH III wave model and a wave boundary layer model.layer model.
• Preliminary Preliminary simulations indicate that the hurricane intensity simulations indicate that the hurricane intensity and structure can be significantly effected by explicit and structure can be significantly effected by explicit simulations of surface waves.simulations of surface waves.
• More rMore real-case simulations will be done in the nearest eal-case simulations will be done in the nearest future to assess the impact of wave coupling on hurricane future to assess the impact of wave coupling on hurricane predictions.predictions.
• Future work will be directed toward improving the heat flux Future work will be directed toward improving the heat flux parameterization in the coupled model and transitioning to parameterization in the coupled model and transitioning to the Hurricane WRF. the Hurricane WRF.
SummarySummary
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