臺灣博碩士論文加值系統

本研究為探討伴隨氣候長期變化的台灣地區降雨變化特性研究。根據台灣地區20 個傳統測站自1951-2008 年共58 的降雨資料進行空間上及時間上的降雨氣候分析。在分析降水氣候特性或變化時，主要是使用HHT這個自適性的分析方法，將降水變化的主時間序列依高頻至低頻分解成幾個子序列以及趨勢，並針對降水的趨勢以及低頻降水進行分析討論，進一步釐清台灣地區十年際以上的低頻降水之特性，例如時間的演化特性、空間分佈特性等等。研究結果顯示年累積降雨、暖季降雨及極端降雨之低頻分量的EOF分析第一模態特徵向量呈現全島同相位，而第二模態特徵向量則呈現東北-西南反相位兩極化的現象，與測站個別分析呈現東西分野降雨趨勢相反之現象結果一致。2000 年之後暖季降雨趨勢比起年累積降雨明顯增加，且越極端的低頻降雨增加趨勢幅度越大，東西分野反相位更加明顯且劇列。EOF及個別測站分析結果皆顯示低頻降雨最大時期發生於1955 年前，及2005年之後，而少雨期在1960-1965、1980、1995 年。
更近一步依溫度訊號顯示的暖化趨勢、MDV及PDO三個氣候變化趨勢，分別對降雨時序做迴歸，根據其結果可計算這些溫度氣候訊號對降雨影響的變化率，可知不同溫度波動訊號分別對台灣降水產生什麼影響而造成變化。整體而言暖化趨勢及MDV疊加的影響，使得台灣降雨在頭尾時間點(1955年之前、2000年之後)的降雨為最多的時期，中間期間因暖化趨勢及MDV的抵銷作用使降雨變動不大。在1985-1990年左右，暖化趨勢、MDV及PDO訊號對台灣降雨皆是正貢獻，疊加在一起的結果使得降雨開始有明顯的增加幅度，且越極端級別的降雨受之影響的變化率越大。

The aim of this study is discussing the precipitation variability and characteristics in Taiwan associated with inter-decadal and long-term trend climate changes. We analyze the 58 years (1951 to 2008) rainfall data temporally and spatially at 20 stations. When analyzing the precipitation characteristics and variability, we use
the adaptive method-HHT (Hilbert-Huang transform) to decompose the time series of rainfall variability to many sub-series and trend, focusing on the low frequency
component and trend to analyze and discuss. Furthermore, we intend to clarify the decadal and inter-decadal variability and characteristics of rainfall in Taiwan, ex: time series variability and spatial distribution…etc. The results show that the low frequency component of yearly cumulative rainfall, warm season rainfall and yearly
extreme rainfall, their eigenvectors of the first EOF display an island-wide synchronizing mode. However, the eigenvectors of the second EOF display the northeast-southwest dipole rainfall pattern. Reconstructed rainfall variability based on the two leading EOF modes is consistent with that of individual station analysis. Both
EOF analysis and individual station analysis show that after 2000, warm season rainfall increase much more significantly than yearly cumulative rainfall. The
increasing trend after 2000 is more evident in extreme rainfall, such that the more extreme, the more significantly rainfall increase and the more difference between east and west in Taiwan. Both EOF and individual station analyses show strong rainfall before 1955 and after 2005, weak rainfall during 1960-1965, 1980 and 1995.
We further perform a regression analysis of rainfall against the warming trend,MDV and PDO these three climate variability and trend signals that temperature
signals display. Based on the results, we calculate the rainfall change rate influenced by different temperature signals. Overall, warming trend together with MDV can
largely explain the low-frequency in yearly rainfall, warm season rainfall and the extreme rainfall before 1955 and after 2005.During the middle time, the offsets between warming trend and MDV make the little change in rainfall. Approximately 1985-1990, warming trend, MDV and PDO, all of them are positive contributions to Taiwan rainfall, therefore rainfall began to increase dramatically, the more extreme rainfall is, the more influenced by these temperature signals.

中文摘要..................I
英文摘要..................II
致謝......................IV
目錄.......................V
附表說明...................VI
附圖說明...................VII
第一章 緒論............... 1
1.1 前言............... 1
1.2 文獻回顧............... 1
1.3 研究動機............... 3
第二章 資料來源及研究方法...............4
2.1 使用資料............... 4
2.2 分析方法介紹............5
2.2.1 正交經驗函數(EOF)...............5
2.2.2 希爾伯特黃轉換(HHT)理論.........6
第三章 台灣降雨測站資料分析..........13
3.1 台灣低頻降雨之EOF分析結果.........13
3.2 台灣低頻降雨之個別測站分析結果.........17
第四章 與台灣降雨相關之氣候分析...........20
4.1大尺度溫度場..............20
4.2溫度變化訊號與降雨之迴歸分析.............21
第五章 結論與展望..............26
5.1總結.........................26
參考文獻........................28

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