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Rapid growth waves off the coast of Hsinchu
|Authors: ||Shu-Jun Chen|
|Contributors: ||NTOU:Department of Marine Environmental Informatics|
Significant wave height;Period;Winter high pressure;Meterorological front
|Issue Date: ||2013-10-07T02:53:41Z
|Abstract: ||本文研究新竹海域發生之急速成長波浪，資料取自中央氣象局的新竹資料浮標測站。本文所謂之急速成長波浪係指在時間間距為六小時內的情況下，示性波高成長2倍以上，成長後並達到1.5公尺以上者。急速成長波浪的發生，容易造成海上作業船隻的風險。據此定義找出在1997-2010年間有144個急速成長波事件，但因資料缺值的關係，本文僅能將海氣象資料皆完整之急速成長波浪之53個急速成長波事件作進一步分析比較示性波高與週期、氣壓、風速、風向之間的關聯性。 資料顯示急速成長波浪的發生時機，在新竹海域以12月至翌年2月冬季(72個案)為主，其次在春(38個案)與秋季(32個案)。在本研究中，發現在53個急速成長波浪事件中風速有隨波浪成長時間持續增加的趨勢；新竹海域之急速成長波浪發生前後風向皆以北北東至東北為主，尤其是急速成長波浪發生後，其北北東與東北向的風向比例有增加的趨勢；急速成長波浪發生前四小時開始氣壓逐漸升高。另在急速成長波浪發生前週期逐漸變小，而在急速成長波浪發生後，週期則有逐漸增大的趨勢。 另外，分析新竹海域六個急速成長波浪的個案中，發現鋒面過境、冷高壓南下等天氣條件，對急速成長波浪的發生有明顯的影響。總體來看，新竹海域急速成長波浪的發生，皆伴隨鋒面通過、大陸冷高壓南下的天氣條件。 另本文將新竹海域的急速成長波浪與龍洞的急速成長波浪比較，在同一天氣系統下，新竹急速成長波浪比龍洞晚了2~6小時，成長後的示性波高也不及龍洞。|
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.
|Appears in Collections:||[海洋環境資訊系] 博碩士論文|
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