Research and development of wave-forecasting models of the next generation

因此，本研究的目的不仅是开发技术，以改善波浪预报模式，而且还研究与波浪模型相关的风浪现象的广泛方面。因此，主要结果分为两类：（一）波浪预报模式的技术成就：1。RIAM模型与著名的WAM模型或其他模型的相互比较2。有限深度非线性能量传递计算方法的发展3.发展和测试的光谱演变（B）波动力学的发现和问题的辐射项的算法：1。在津崎站和日本海观测到的风浪统计2。波浪制动的实验研究，特别是其在能量再传递中的作用3.风浪谱的非线性频散关系和平衡谱研究结果如下：1）提出了一种计算“有限水深”波浪非线性能量传递的方法。该方法大大改进了增田（1980）或小松和增田（1996）的RIAM方法，是目前适用范围最广、最可靠的方法之一。然而，本研究中的实验清楚地表明，制动和非线性能量转移一样，在各分量波之间重新分配能量。3）长期数据分析表明，日本海有效波的陡度存在一个与风速季节无关的上限。有效波高和有效波周期在几天到几小时的时间内具有-5/3功率频谱。这些发现表明，存在一些更深层次的法律的变化“显着波”，这应该是一个后果，一些未知的动态。

The purpose of this research therefore was not only to develop technique for improving the wave-forecasting model, but also to study wide aspects of wind-wave phenomena associated with the wave model. Hence the principal results are classified into the two categories :(A) Technical achievements in the wave forecasting model :1. Intercomparison of the RIAM model and the well-known WAM model or others2. Development of the method for calculating nonlinear energy transfer at finite depths3. Development and test of algorithms for the radiation term of the spectral evolution(B) Wave-dynamical findings and problems :1. Statistics of wind and waves observed at the Tsuyazaki Station and in the Japan Sea2. Experimental study of wave braking especially on its role in redelivering energy3. Nonlinear dispersion relation and equilibrium spectra of wind-wave spectraResults of particular interest to be highlighted are as follows.1) A method was developed for calculating the nonlinear energy transfer among component waves at "finite depth". The method much improves the previous methods of Masuda (1980) or Komatsu and Masuda (1996, the RIAM method).the method developed here is probably is one of the most reliable with a widest applicability both in deep water and in shallow water.2) Wave breaking has so far been considered simply as an energy sink. The experiment made in this research, however, clearly indicated that braking redistributes energy among component waves just as nonlinear energy transfer does.3) The long-term data analysis revealed that the steepness of significant waves in the Japan Sea has an upper bound independent of the season of the wind speed. Also it was found that significant wave heights and significant wave periods have -5/3 power frequency spectra for periods from a few dayst to several hours. These findings suggest the presence of some deeper laws about the variability of "significant waves", which should be a consequence of some unknown dynamics.