| Summary: | 碩士 === 國立臺灣海洋大學 === 海洋環境資訊學系 === 100 === Sudden increase of wave height in a short time period can be dangerous to crafts, coastal fishery boats in particular, navigating in the ocean. This study investigated the rapid growth waves occurred at the sea off the Shinchu coast by analyzing the wave and meteorological information recorded by the Central Weather Bureau‘s Shinchu wave buoy. In the present study, the rapid growth waves were defined as those waves with significant wave height increased more than two times in the time span of 6 hours and their peak wave height is no less than 1.5 m at the end of their growth period. Based on this definition of the rapid growth waves, 144 wave events between 1997 and 2010 were identified. Among these 144 events, 53 events contained uninterrupted wave and wind data. These 53 events were used for detailed study to see the relationships between the wave height, wave period, wind direction, wind speed and atmospheric pressure.
The results showed that half of the 144 events occurred in the winter (72 events). There were 38 events happened in the spring and 32 events in the fall. Analysis from the 53 events, it was found that the growth of the wave height was accompanied by the increase of wind speed. After the rapid grow, the wind directions were from the NNE or NE directions. Mostly, it was found that about four hours before the growth of the wave the atmospheric pressure started to gradually increase. In addition, the wave period was found to decrease before the wave growth and then follwed by the increase in the wave period. The results also showed that most rapid growth events were related to the passage of meterorological front and severe winter high pressure.
This study also compared the rapid growth wave event found in the sea near theLongdong coast with that of the shinchu coast. It was found that for the same meterological system the rapid growth event occurred in Hsinchu was about 2-6 hours later than that of Longdong and the peak wave height in the growth event was smaller in Hsinchu than in Longdong.
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