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Characteristics of Rapid Growth Waves off the Longdon Coast
Rapid growth wave
|Issue Date: ||2017-01-04T06:02:18Z
|Publisher: ||第 35 屆海洋工程研討會論文集|
|Abstract: ||海上的風浪急速的變化易造成從事海上活動的人與船隻嚴重的威脅，因此有需要探討波浪急速成長的現象。本文將急速成長波定義為在時間間距為六小時內的情況下，示性波高成長 2倍以上且達到 1.5 公尺以上。本文使用的是龍洞浮標站資料，首先從波浪資料中找出急速成長波浪，然後並分析急速成長波發生時海氣象的特性。從 1998-2012 年間的資料找到 671 筆急速成長波個案。這些個案顯示急速成長波發生於春、秋與冬季比例最高，且大多是受到大陸冷高壓南下的天氣系統影響。另發現個案平均的示性波高從急速成長波開始發生後平均示性波高於四小時後即成長至開始時的兩倍，在急速成長期間個案平均週期與平均風速也顯著增加，在波浪開始急速成長前後 8 小時風向皆以北北西至東北風象限為主，但此象限風的比例由急速成長波發生前的約 65%增加到約 85%。
Abstract: Sudden increase of wave height poses dangers to marine crafts. This study investigated the rapid growth waves by analyzing the waves recorded by the Longdon wave bouy. The rapid growth waves were defined as those with significant wave height increased more than two times in the time span of 6 hours and their significant 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, 671 wave events between 1998 and 2012 were identified. The results showed that over half of the events occurred in the fall, winter and spring. Our analysis showed that the growth of the wave height was accompanied by the increase of wind speed. The wind directions were mainly from the NNW to NE directions. However, the percentage of wind in the NNW to NE diections increasded from about 65% before the start of rapid growth to about 85% after. 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 mainly related to the passage of severe winter high pressure system.
|Appears in Collections:||[海洋環境資訊系] 演講及研討會|
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