Study on wave forecasting and hindcasting method based on air-wave-sea coupled model adaptable for open sea boundary

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This study was performed to develop the wave forecasting and hindcasting based on air-wave-sea coupled model adaptable for open sea boundary, that can supply ocean wave information with high accuracy and resolution essential to reliability design and performance specification for ocean facilities. The primary results are summarized as follows :1.Development of the adjoint method for open-boundary date assimilation in wave hindcasting and forecastingIt was shown that the accuracy of the wave hindcasting and forecasting using the adjoint WAM that treats the directional spectra on the open-boundary as a cost function was greatly improved and the computation area was remarkably reduced.2.Investigation on the energy transfer process from winds to waves and formulation of the source term of input energy and dissipationWhite caps were found to be closely related to the transferred energy from winds to waves. On the basis of the results, the formulation considering the influences of the white caps was made on the input and dissipation terms of energy.Highly accurate simulation of sea surface winds using the mesoscale meteorological model MM5The simulation of sea surface winds over Ise bay using, the mesoscale meteorological model MM5 was performed for the whole year of 2001, and its accuracy was validated with observations at a marine tower station in Ise bay.Wave hindcasting and forecasting based on the coupled atmosphere and wave modelA model coupling the meteorological model MM5 to compute sea-surface winds and the wave models WAM and SWAN to compute wind waves was developed and was applied to high-resolution wave hindcasting in Ise bay and Tokyo bay. Its accuracy and utility were validated with observations.5.Examination on prediction accuracy of WAM around JapanAdjoint WAM assimilating wave data at arbitrary points was developed, and its accuracy was shown to improve around Japan.