Wave energy resources assessment for the multi-modal sea state of Hawaii

Abstract This paper describes development and validation of a 32-year wave hindcast for Hawaii as part of the energy resources assessment for the US and affiliated territories. The nested model system comprises structured WAVEWATCH III for the globe and unstructured SWAN around the Hawaiian Islands with wind forcing from the Climate Forecast System Reanalysis and its regional downscaling. The development effort follows the International Electrotechnical Commission (IEC) standards. The hindcast is first validated with buoy measurements in terms of the six IEC wave energy resources parameters. The comparison shows good overall agreement but with greater uncertainties for some of the parameters intended for narrowband spectra. The multimodal sea state of Hawaii includes a mix of short-period wind seas, long-period north and south swells as well as waves with moderate periods from multiple sources. We partition the hindcast spectra based on the respective period ranges and directions and validate the partitioned spectral energy and parameters with measured values. The partitioned hindcast spectra allow separate seasonal descriptions of dominate components from wind seas to swells for in-depth understanding of the wave climate and proper categorization of wave energy resources in terms of the six IEC parameters for Hawaii.