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南海夏季降雨年際變化與侵台颱風之關係

Interannual Variability of the South China Sea Summer Rainfall and Typhoon Invading Taiwan

摘要


本文探討1979-2000年期間,亞洲夏季季風所屬南海降雨年際變化與侵台颱風之對應關係,及其對台灣夏季降雨的影響,主要研究結果陳述如下: 亞洲夏季季風二主要降雨區中,南海區(100°E-120°E-5°N-25°N降雨年際變化與侵台颱風變化存有明顯對應關係,南亞區(70°E-100°E-5°N-25°N)降雨則未見清楚的對應關係。 於南海夏季降雨顯著偏多年(1981、1984、1994、1995年),夏季侵台風傾向增加(平均5個),台灣地區平均降雨亦;於南海夏季降雨顯著偏少年1982、1998、1989、1993、1996、1998、年),侵台颱風傾向減少(平均2.7個),台灣地區平均降雨亦傾向減少。 當南海降雨顯著偏多時,日本區降雨偏少,580mb環流場於南海地區生成氣旋距平,日本地區生成反氣旋距平,上述降雨與環流場距平於南海降雨顯著偏少年時,呈現相反相位,顯示南海-日本間降雨與環流場南北振盪之年際變化SJ模態(SCS-Japan pattern)。 南海降雨偏多年時,西北太平洋區(包括南海地區)颱風生成位置西偏,密集於南海氣旋距平鄰近區域,颱風於此區生成後,主要移動路徑或西行往南海氣旋距平區前進,或順著南海氣旋距平與日本反氣旋距平交會處之南風距平導引,往北沿著中國東側沿海前,台灣恰位於此二主要移動路徑交會處,終致侵台颱風數增加;當南海降雨顯著偏少時,南海區出現反氣旋距平,颱風生成位置往東偏離南海,於西、中太平洋區明顯增加,此區颱風生成後,易往北朝日本區氣旋距平前進,偏離台灣地區,颱風侵台機會於是降。 南海降雨與侵台颱風年際變化對台灣降雨之影響有地域上的要別,三者之對應關係於受颱風較明顯影響的中央山脈東側沿岸與南側恆春地區較為顯著。

並列摘要


This study aims to examine the dynamic relationship among interannual variability of South China Sea (SCS) summer (June-August) rainfall, number of typhoon invading Taiwan, and summer rainfall of Taiwan for the period 1979-2000. Major findings of this study are as follows: Interannual variability of the Asian summer monsoon rainfall over the SCS region (100°E -120°E,5°N-25°N)contains a systematic dynamic relationship with the variability of number of typhoon invading Taiwan. During summers with excessive SCS rainfall (1981、1984、1994、1995), unmber of typhoon invading Taiwan tends to increase (in average 5), so does the averaged rainfall of Taiwan. During summers with suppressed SCS rainfall (1982,1988,1989,1993,1996,1998), number of typhoon invading Taiwan tends to decrease (in average 2.7),so does the averaged rainfall of Taiwan. Rainfall and 850 mb circulation anomalies exhibit opposite pattern between the SCS and Japan revealing the existence of a north-south oscillation mode associated with the interannual variability of summer SCS rainfall, which is referred to as the SCS-Japan (SJ) pattern. During summers with excessive SCS rainfall, typhoons tend to form in the vicinity of an anomalous low over the SCS. They show two major tracks: one is to move westward toward the anomalous low in the SCS, and one is to follow anomalous south winds over the conjunction region between the SCS anomalous low and Japan anomalous high to move northward along the east coasts of China. Since Taiwan is surrounded by these two major tracks, number and chance of typhoon to invade Taiwan thus Typhoon tend to form in the region east of the SCS. They tend to move northward toward the anomalous low in Japan, resulting in less chance to invade Taiwan. Dynamic relationship among interannual variability of SCS summer rainfall, number of typhoon invading Taiwan, and summer rainfall of Taiwan is more systematic and valid for the eastern part and southern tip of Taiwan, where typhoon activity is a major mechanism to affect variability of local rainfall.

被引用紀錄


陳姿彤(2011)。以臺灣中部雲杉樹輪重建三百年古氣候:利用傳統樹輪及總體經驗模態分解法〔碩士論文,國立臺灣大學〕。華藝線上圖書館。https://doi.org/10.6342%2fNTU.2011.01116

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