15D.6
Numerical simulations of the hurricane directional wave spectra in the open ocean and at landfall
Isaac Ginis, Univ. of Rhode Island, Narragansett, RI; and I. J. Moon, T. Hara, E. J. Walsh, and H. Tolman
The Hurricane Bonnie (1998) directional wave spectra obtained from NASA Scanning Radar Altimeter (SRA) on 24 August 1998 in the open ocean, and on 26 August when the storm was approaching Wilmington, NC are compared with results of a third-generation ocean wave model, WAVEWATCH-III. This is the first detailed comparison of the spatial distribution of the sea surface directional wave spectra in surface wave model simulations with observations in both open ocean and landfall hurricane cases.
The simulated maximum wave height in the open ocean case reaches 12 m, agreeing well with the SRA observations and buoys. It was gradually reduced by the distributed wave energy dissipation across the shelf as the hurricane approached the shore. The variation of the hurricane translation speed from 2 m/s at 06 UTC, 24 August to 8.1 m/s prior to landfall affected the distributions of the wave height as well as the directional spectrum. The effect of bathymetry at landfall was also an important factor determining the wave fields. The model and SRA spectra are in a good agreement in the open ocean. The peak wave direction and frequency and the spatial variation of spectra in all four quadrants relative to the storm center are simulated quite well. For the landfall case, however, the simulated peak frequencies displayed noticeable disagreement with the SRA observations, probably due to the model’s limitations of resolving shallower depths.
Session 15D, Tropical Cyclone Air-Sea Interaction II (Parallel with Sessions 15A and 15B)
Thursday, 2 May 2002, 4:00 PM-5:30 PM
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