台西海域冬季波浪之方向分佈

Abstract

海洋環境瞬息萬變，也直接影響近岸地區。因此如何能夠對各種不定 的海象狀況多所瞭解，以期更有效的運用海洋資源及對沿岸地區的開發利 用，一直是相關學者努力研究的課題。 波向是各種海洋物理現象之一 。至於波浪方向性的研究，無論是在海洋資源的開發或是海岸工程的規畫 設計方面，都具有一定的價值；而國內對於台灣四周海域的波向分佈研究 則並不普遍，因此本文利用台西外海的實測波浪資料加以分析研究，以期 瞭解該海域的波浪方向分佈特性。 本篇研究採用的台西海域實測資料 為94年10月至翌年3月間(東北季風作用下)的風浪資料，所採用的資料並 作過合理的篩選以確保分析結果的正確。再根據採用的資料，利用經由相 位差法驗證過的EMEP (Extension of the Maximum Entropy Principle Method) 方向頻譜模式計算出的方向頻譜，以作為波向分佈的分析之依據 。並運用光易型方向分佈函數中的方向分佈參數配合模式計算的結果，而 對台西海域的波向特性作具體的描述，最後以適合台西海域的方向分佈參 數對於無因次頻率之關係式作為最終研究的成果。同時希望整篇研究的成 果能夠在學術或工程上有少許的貢獻。 Oceanic environments are constantly changing which have direct impact on coastal conditions. It is therefore believed that how to expand our oceanographic knowledge to more effectively utilize oceanic resources for coastal development has always been an important subject of research for oceanographers. The direction of sea waves is one of the key phenomena of ocean. So the study of the direction of sea waves can not be overlooked for the development of oceanic resources and coastal engineering projects. Nevertheless,the directional distribution of different waves around Taiwan Island has not been widely acknowledged to be worth studying among local oceanographers. This research paper is therefore intended to determine the directional distribution of sea waves in the sea area near Taisi through field surveys. Data used in this research project were collected in the period from Octorber 1994 to March 1995 (under the influence of northeast seasonal wind). All data have been reasonally selected and verified to insure the reliable conclusion of analysis. Further according to the data thus selected, EMEP (Extension of the Maximum Entropy Principle Method) is verified by using phase difference method to obtain the directional spectrum upon which the directional distribution is based. Moreover, detailed description of the direction of sea waves in the subject area is given in characteristics by using the directional spreading parameter of the directional spreading function of the Mitsuyasu-type in keeping with EMEP. Finally, as a conclusion, the correlation between the directional spreading parameter suitable for Taisi sea area and frequency is given in equation form. It is hoped that this conclusion will be more or less useful in academic studies or civil engineering applications.