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

本研究旨在开发适用于开阔海域边界的基于气-波-海耦合模式的海浪预报和后预报，为海洋设施的可靠性设计和性能规范提供高精度和高分辨率的海浪信息。主要研究结果如下：1.波后预报中开放边界资料同化伴随方法的发展研究结果表明，将开放边界上的方向谱作为代价函数的伴随WAM方法对波浪后向预报的精度有了很大的提高，计算量显著减小。2.风向海浪能量传输过程的研究和输入能量耗散源项的建立白帽与风浪能量传输密切相关。利用中尺度气象模式MM5对伊势湾海面风进行了高精度模拟。利用2001年全年的中尺度气象模式MM5对伊势湾海面风进行了模拟。将气象模式MM5用于计算海面风，波浪模式WAM和SWAN用于计算风浪，并将其应用于伊势湾和东京湾的高分辨率海浪后预报。5.对日本附近的WAM预报精度进行了检验。发展了任意点的伴随WAM同化波资料，其预报精度在日本周边地区有所提高。

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.