A global evaluation of the JONSWAP spectra suitability on coastal areas

Wave spectra provide comprehensive information on wave energy for different directions and frequencies. Integrated sea state parameters, however, are more commonly used for wave climate characterization. Many engineering applications estimate spectral conditions from these parameters using theoretical spectra. One of the theoretical spectra of widest practical use is the JONSWAP. Here, the wave spectra for the hindcasted 30 years covering coastal areas worldwide are studied. We first compare the simulated historical spectra against measurements from 39 buoys. Several approaches are raised in order to provide different information, such as a directional and frequency distribution and climate evaluation. The suitability of the JONSWAP spectrum is then analysed by exploring the best fit of the peak-enhancement factor from hourly sea states. Results show a peak-enhancement factor below 2.4, lower than the standard JONSWAP (i.e a value of 3.3), in most coastal areas and especially in the east coast of the continents, even for energetic hourly sea states. Tropical areas on the west coasts provide values close to the standard JONSWAP. Seasonal and inter-annual variations in the peak parameter are also investigated.