Coastal Wave-Height Statistics during Hurricane Ike: Fid-Bau Portal

Coastal Wave-Height Statistics during Hurricane Ike

Nayak, Sashikant / Panchang, Vijay

The statistical behavior of wave heights obtained from short-term (i.e., 30-min) wave records during Hurricane Ike was investigated. Spectral data from seven temporary pressure gauges and one National Data Buoy Center (NDBC) buoy moored off the coast of Texas, covering a 12-day period, were used. The wave heights, based on time series reconstructed from the spectra, showed a very good fit to the form of the Rayleigh distribution with $H_{r m s}$ as the parameter of the distribution, whereas the use of the spectrally derived parameter $\sqrt{8 m_{0}}$ led to overprediction of the wave heights. Incorporating the spectral band width ( $α$ ) in the Rayleigh distribution reduced this overprediction. The empirical two-parameter Weibull distribution was also found to represent the wave-height distribution well, but with parameters different from a = 2.126 and b = 8.42. The Tayfun model, used as a representative of Rayleigh-like models, provided the best fit. When converting model-derived significant wave heights to other quantities, such as $H_{1 / 10}$ , $H_{1 / 100},$ and $H_{m a x}$ , the standard Rayleigh coefficients are often used in practice. These led to considerable errors in the present analysis, which also shows that the use of correction factor or $α$ can enhance the results. However, direct estimates of these quantities from a time series simulated using the model-derived spectrum may be an even better alternative to using the standard Rayleigh coefficients.