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Coupled Atmosphere-Wave-Ocean Parameterizations for High-Winds

Shuyi S. Chen Joseph Tenerelli, Wei Zhao, Mark Donelan Rosenstiel School of Marine and Atmospheric Science University of Miami. Coupled Atmosphere-Wave-Ocean Parameterizations for High-Winds. Sponsored by the Office of Naval Research

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Coupled Atmosphere-Wave-Ocean Parameterizations for High-Winds

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  1. Shuyi S. ChenJoseph Tenerelli, Wei Zhao, Mark DonelanRosenstiel School of Marine and Atmospheric ScienceUniversity of Miami Coupled Atmosphere-Wave-Ocean Parameterizations for High-Winds Sponsored by the Office of Naval Research AMS 13th Conf on Interactions of the Sea and Atmos., Portland, 9-13 August 2004

  2. Coupled Atmosphere-Wave-Ocean Modeling System for Hurricane Predictions ATMOS. MODEL (MM5/COAMPS/WRF) OCEAN MODEL (HYCOM or 3DUOM) Surface fluxes and stress SST Param. of wave dissipation LES Sea Spray SSH & current velocity Wind-induced stress Wave-Induced stress Roughness length WAVE MODEL (WAVEWATCH III or WAM) Param. of spectral tail and drag coefficient Source function? Drop size distribution? Effects on turbulence? How do these affect exchange coefficients of enthalphy? What is the ratio of CK and CD?

  3. What is the ratio of CK and CD? LKB (1979)

  4. Coupled Modeling System • MM5 (PSU/NCAR) (vortex-following nests with 45, 15, 5, and 1.67 km grid spacing, NCEP analysis and AVHRR or TMI/AMSR-E SST) • WAVEWATCH III (NOAA/EMC) (1/12o, 25 frequency bands, 48 directional frequency bands) • HYCOM (UMiami/NRL) (1/12o, 22 vertical levels with 4-6 in the ocean mixed layer) • 3DUOM (Price’s 3-D Upper Ocean Circulation Models)

  5. MM5 Configuration • Model initialized on 00 UTC 11 Sep 1999 using the AVN analysis fields and the AVHRR Pathfinder SST • 30 vertical levels, lowest half-sigma level about 12 m above the surface • Four levels of nests, with grid spacing of 45, 15, 5, and 1.6 km, all but the coarsest mesh moving with the hurricane • Modified surface flux parameterization based on Garratt (1992) and Pagowski and Moore (2000)

  6. WAVEWATCH III Configuration • 4-D Spectrum Model [(x, y), (k, q)] • 1/6 degree grid spacing • 25 frequency bands (logarithmically spaced from 0.04-0.4 Hz) • 48 directional frequency bands (evenly spaced by 7.5o)

  7. Hybrid Coordinate Ocean Model (HYCOM) • one-way nested Western Atlantic-Gulf of Mexico-Caribbean Sea regional domain (with data assimilation of SSH prior to hurricane simulations) • 1/12 degree grid spacing • 22 Vertical layer, 4-6 layers in mixed layer with the 1st layer at 3 meter • MM5 atmospheric forcing, 8 September – 17 October 2002 (Hurricanes Isidore and Lili)

  8. Open Ocean (Northeast) Observed WW3

  9. Landfall (Southwest) Observed WW3

  10. Coupled MM5-WAVEWATCH III • Roughness Length (non-directional) t = tt + tw zo zo - wave-age dependent • Stress Vector (directional) Mx = - tx My = - ty tx , ty - components of stress from integral of momentum input to the wave spectrum. V t

  11. Wind-Wave Coupling Spectra Tail Parameterization: X-component of stress from integral of momentum input to the spectrum: Growth rate of each component from measurement of pressure-slope correlation Spectrum of long waves from WAVEWATCH III; spectrum of short waves from fit to tail given below. a is adjusted to fit the highest modeled wavenumbers. b is the spreading function for the short waves.

  12. 6 0 Z(cm) 6 0 0 10 20 30 40 x (cm) Figure 4. Vorticity contours obtained via Digital Particle Image Velocimetry (DPIV) in the air flow over wind driven waves [Reul, 1998]. Both wave and air flow are from left to right. (Top) waves of gentle slope – non-separated flow. (Bottom) waves of steep slope – separated flow. Drag coefficient in high-wind conditions (Donelan et al. 2004)

  13. Hurricane Floyd (1999)

  14. Emanuel (1995) found that Ck/Cd > 1 for intensifying storms. • CBLAST observed Ck/Cd < 1 (C. Fairall). Coupled Ck/Cd Uncoupled Ck/Cd

  15. Before Bonnie . . After Bonnie . . . . . . .

  16. Coupled Ocean Net Heat Flux Uncoupled Coupled Wave-Ocean

  17. Temperature Profiles Open Ocean Gulf Stream

  18. Hurricanes Isidore and Lili (2002) in tandem

  19. Hurricane Lili (2002)

  20. SST BeforeIsidore Satellite HYCOM

  21. SST Cooling After Isidore Satellite HYCOM

  22. SST Cooling After Lili Satellite HYCOM

  23. Gulf Common Water Loop Current Isidore Lili Isidore Lili

  24. CBLAST-Hurricane Coupled Atmosphere-Wave-Ocean Modeling Conclusions • Atmosphere-Ocean coupling improves tropical cyclone intensity forecasts, especially at very high resolution when eyewalls are explicitly resolved. • Wind-Wave coupling contributes to storm asymmetry that very significantly from storm-to-storm. • Simple 3DUOM+Satellite SST works well over the open ocean. However, full ocean model, e.g. HYCOM, is needed for the coastal regions and over the Gulf Stream and warm eddies.

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