Field research on hydraulic problems concerning coasts and harbors facing oceans and development of data sharing system

在研究期间，我们在赤羽港附近的太平洋沿岸进行了三次波浪观测，时间分别为97年9月7日、96年10月19日、96年9月10日、97年10月30日和98年9月5日至10月1日。我们获得了从港口附近经过的几艘大船提供的大浪记录。在部分台风靠近港口时，进行了港内波浪和海流的测量，在此基础上，研究了近岸波浪和港内振荡的特征，特别是长周期波浪，研究了其放大和传播特性。本文还建立了模拟港内强迫振荡的有限元模型，并将数值计算结果与实测结果进行了对比，研究了港内强迫振荡的特性。主要结果如下：（1）长周期波的振幅随波高的增加而增大。长周期波的振幅几乎与有效波高和波周期的乘积成正比。(2)近海长周期波由量级相近的近岸波和近岸波组成。通过分析两测点之间的波浪记录的互相关，可以区分各分量波中的入射波和反射波。(3)赤羽港存在100S、300s和800s的多个频率响应。针对数值模拟中假定线性长波的线性响应与观测结果不一致的问题，开发了WWW服务器，实现了波浪数据的共享，所有的波浪数据都可以在Internet上公开。除波浪资料外，还包括风场、气压场和台风路径等资料。据统计，对数据库的访问次数约为数百次。

During the research period, we carried out wave observations three times for the periods of Sep.7, '96 - Oct.19, '96, Sept.10, '97 - Oct.30'97 and Sept.5'98 - Oct.1'98 on the Pacific coast off Akabane harbor using two wave and current meters. We obtained high wave records provided by several typoons passing near the harbor. We also carred out wave and current measurements in the harbor when some of the typhoon became close to the harbor.On the basis of the wave data, we investigated the characteristics of offshore waves and oscillation in the harbor, where we especially focused on long period waves and studied its amplification and propagation properties. We also developed FEM model to simulate forced oscillation in the harbor, by which we studied oscillation characteristics comparing numerical and observed results. The main results are as follows : (1) The magnitudes of long period waves increase as wave heights increase. The amplitude of long period waves is almost proportional to the product of significant wave height and wave period. (2) Long period waves in offshore zone are comprised of on-offshore components and longshore components at similar degree of magnitudes. By analyzing cross correlations of wave records between two measuring points, we can distinguish incident and reflected waves in each component waves. (3) In Akabane harbor, there exist multiple frequency responses with 100S, 300s and 800s. The numerical simulation, where linear response to linear long waves is assumed, does not give sufficient agreemet with observations.We developed WWW server to give the service of wave data sharing, where all the wave data are open to public on the internet. In addition to wave data, the data of wind, atomospheric pressure distribution and typhoon trajectories are also involved. About several hundreds times of access to the database have been counted.