全球暖化可能會改變地區的降雨頻率和強度，許多研究分析不同區域的觀測資料皆發現有中、小雨減少，強降雨增加的情形。本研究運用中央氣象局 (Central Weather Bureau, CWB)二十一個觀測站降雨資料及美國國家氣候中心 (National Climate Data Center, NCDC)的全球溫度距平資料分析臺灣的降雨強度隨全球溫度的變化。臺灣有許多的極端降雨是由颱風造成；因此，臺灣極端降雨的變化可能與侵襲臺灣颱風特性的變化有關係。本研究分析了十個不同強度的降雨隨全球溫度的變化，我們將降雨分為颱風降雨、非颱風降雨和季風降雨，並將颱風降雨以颱風的數目、日數和移動速度標準化。 分析結果發現不同類型的降雨變化在定性和定量的結果都很類似，皆呈現中小雨減少、強降雨增加的情形，且強降雨的增加幅度隨降雨強度越大則增加越多，而考慮侵襲臺灣颱風的特性變化後結果也無太大差異。顯示臺灣的降雨不論是否由颱風造成，其變化的主要原因應皆是因為全球暖化。其中最強的10%颱風、非颱風和季風降雨分別隨全球地表溫度增加一度而增加了約125 %、76 %和85 %；而最弱的10%降雨則分別減少了25 %、46 %和63 %。另外，為驗證臺灣降雨的改變是因水氣增加導致，我們也運用三個再分析資料計算了西北太平洋地區和沿侵襲台灣颱風路徑的可降水量變化，結果皆呈現顯著增加的趨勢。根據跨政府氣候變遷委員會第五次氣候變遷評估報告 (2013)，全球暖化非常可能會持續數十年以上且暖化速度會增加，使臺灣暴露於更嚴重的水旱災風險中。 ;Global warming can change the frequency and intensity of regional precipita-tion. Significant increase of heavy precipitation and decrease of light and moderate precipitation have been found in many areas of the world. Daily precipitation data from 21 stations of the Central Weather Bureau (CWB) in Taiwan and global surface temperature anomalies from the National Climate Data Center (NCDC) from 1961 to 2011 are analyzed in this study to characterize changes in the precipitation intensity in Taiwan. Located in a region of dense typhoon tracks, Taiwan’s precipitation extremes are greatly affected by typhoons. In this study, annual total precipitation is partitioned into categories of typhoon, non-typhoon and monsoon precipitation. In addition, each category of precipitation is divided into ten bins of equal amount of precipitation according to their precipitation intensity. We have found that all categories of precipitation change with global temper-ature in a consistent manner, which is characterized by decreases in light and moderate precipitation, but increases in heavy precipitation. The rate of increase is greater at heavier precipitation, suggesting that the observed significant increase of extreme heavy precipitation in Taiwan can be mainly attributed to global warming instead of changes in typhoon characteristics. Increases in the top 10%bins of typhoon, non-typhoon and monsoon precipitation are about 125%, 76%and 85%, while decreases in the bottom 10% bins are about 25%, 46% and 63%for each degree Kelvin (K) warming in global mean temperature, respectively. Moreover, analysis of precipitable water in the western North Pacific and along the tracks of typhoons affecting Taiwan also shows a significant increase in the past few decades. This provides further support for the theory of global warming as the cause of the increases in extremely heavy precipitation in all three catego-ries of precipitation.
