颱風壯度與大小對台灣風雨之影響

The influence of typhoon strength and size on Taiwan's wind and rainfall

周昆炫(Kun-Hsuan Chou) ； 吳聖宇(Sheng-Yu Wu) ； 林書正(Shu-Jeng Lin)

《大氣科學》 46卷3期 (2018/09) Pp. 222-246

https://doi.org/10.3966/025400022018094603001

摘要

2015年及2016年共有4個路徑、對流結構相似，但是不同強度的颱風登陸台灣，分別為2015年蘇迪勒颱風、杜鵑颱風，以及2016年尼伯特颱風、梅姬颱風。不過這四個颱風的風雨表現狀況並非跟颱風強度呈現正相關，因此讓我們想要探討除了強度之外的因素對台灣風雨的影響。本研究利用NCEP-GFS (The National Centers for Environmental Prediction Climate Forecast System Reanalysis - Global Forecast System)全球模式的初始分析場資料及CFSR (Climate Forecast System Reanalysis)的全球再分析資料分別計算颱風的壯度及大小，發現颱風壯度跟大小之間有良好的正相關性，颱風強度跟壯度、大小之間的相關性較差。颱風強度、壯度、大小這三個因素之間有不同的變化情況，包括三者變化一致、強度巔峰過後壯度跟大小仍持續增加以及颱風大小最大值出現在強度巔峰之前等三種類型。過去研究發現颱風對台灣風雨的影響因素包括颱風路徑、結構、颱風移速及綜觀環境等，本研究則著重於探討颱風強度、壯度、大小以及颱風移速跟台灣風雨的關係。針對台灣整體風雨的分析結果發現颱風壯度及大小跟風雨指標之間的相關性最好，其次則是颱風移速跟風雨指標的相關性，強度跟風雨指標的相關性則較低。針對不同路徑的分析則發現，第二類路徑(自宜蘭到花蓮間登陸並向西穿越台灣陸地)颱風的強度、颱風移速跟風雨指標間的相關性較好。第三類路徑（自花蓮到台東間登陸並向西穿越台灣陸地）颱風的大小、颱風移速跟風雨指標間的相關性較好，雨量指標尤其明顯。針對不同測站在不同路徑下的分析結果發現，接近颱風內核區的測站風雨指標跟颱風強度的相關性較好，位於颱風外圍區域的測站其風雨指標跟颱風大小的相關性較好。

關鍵字

颱風壯度 ； 颱風大小 ； 颱風風雨預報

並列摘要

In 2015 and 2016, there were four typhoons with different intensities landed in Taiwan, including severe typhoon Dujuan (2015) and Nepartak (2016) and moderate typhoon Soudelor (2015) and Megi (2016). Although the first two were stronger typhoons, the associated wind and rainfall impacts on the island were much less than the latter two storms. This situation didn't in line with the traditional impression that the stronger landfalling typhoon which could lead to more damages over the island. Not only the tropical cyclone (TC) intensity, this study also investigates the relationship between the others TC parameters and associated wind and rainfall distributions during landfall. The NCEP-GFS and CFSR model analysis data are utilized to calculate TC strength and size. It is found that there is a good correlation between strength and size, while the correlations between the intensity and size, as well as intensity and strength, are not obvious. There are three different types of changes between the three factors, (1) change of three factors are the same; (2) intensity reaches the peak but strength and size continue to increase; and (3) the maximum TC size appears before the intensity reaches the peak. In the past studies, the influence factors of TC on Taiwan's wind and rainfall were analyzed, including TC path, structure, speed, and environment. This study specially focuses on the relationship between the strength, size, speed, and Taiwan's wind and rainfall. According to the analysis of the overall wind and rainfall in Taiwan, it is found that the correlation between TC strength, size, speed and wind, rainfall indexes is better than TC intensity. According to the analysis of different types of path, it is found that the TC intensity, speed of the second type appears better correlations in wind and rainfall indexes. The correlation between the size, speed of the third type, and wind, rainfall indexes is better than intensity, especially the rainfall index is obvious. According to the analysis results of different stations under different paths, it is found that the wind and rainfall indexes of stations near the storm core area reveal a better correlation with the TC intensity, and the wind and rainfall indexes of stations over the outer-core area of storm appear a better relationship with the TC size.

並列關鍵字

typhoon strength ； typhoon size ； Taiwan's wind and rainfall