| Budget Amount *help |
¥3,400,000 (Direct Cost: ¥3,400,000)
Fiscal Year 2005: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 2004: ¥2,600,000 (Direct Cost: ¥2,600,000)
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| Research Abstract |
It is difficult to accurately estimate a tsunami waveform within 5 minutes, because little information on the location and geometry of the earthquake source is available. In predicting tsunami waveforms, it is advantageous to use real-time measured surface current velocities of tsunami. In this research, the real-time prediction method of the tsunami waveform is developed by using the sea surface flow velocities acquired by HF ocean radar. As for the assimilation technique of the observational data, the execution is possible by the calculation of a large capacity by basically using the four dimensional data assimilation method. However, the memory of large capacity was necessary and there was a problem of taking the calculation time too much because it had to do the settling operation tens of or about hundreds of times to obtain a complete assimilation result. Then, the method by which the tsunami waveforms was able to be forecast in real time was developed in this research by a easier
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data assimilation technique by the use of the sea surface flow velocities observed with HF ocean radar.
A partial differential equation of elliptic type with respect to the sea surface elevation was derived by using the governing equations for the flow motions. The sea surface elevation at time can be obtained by solving the equation by the SOR method. It was found that the accuracy of the estimated water elevation did not decrease so much even when the average flow velocities of one minute at one minute interval were used. If the average flow velocities measured by HF ocean radar every minute were used, it was confirmed to be able to predict the tsunami waveforms in real time by the accuracy for practical use. In addition, the tsunami waveforms observed and estimated in real time at the locations near the coastline were compared to verify accuracy of this technique. As a result, it was shown that the correlation coefficient became 0.99 or more in all the points, and the standard deviation of the error became 0.2m or less. It was confirmed that the technique developed by this research was able to be applied to practical use. Less
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