台灣與全球雨量長期變化研究（一）1920-1995變化趨勢

A Study on the Long-term Variations of Taiwan and Global Precipitation

盧孟明(Mong-Ming Lu) ； 麥如俊(Ru-Jiunn May)

《大氣科學》 31卷3期 (2003/09) Pp. 199-220

摘要

本報告分析了1920-95年這段期間台灣與全球雨量變化趨勢的特微。結果顯示，以台灣全年平均雨量而言，75年來沒有明顯的性變化趨勢。若以不同季節來看，夏季(六至八月)有明顯的減少趨勢，秋季(九至十一月)反有增加趨勢。以全球總降水量而言，最濕的年份出現在1965年左右，最乾的年份出現在1935年左右，自1950年以後夏半年(五至九月)降水總量有減少的趨勢，而冬半年(十至四月)降水總量是增加的。但是對台灣橋言，1965年左右卻是偏乾而1935年左右是偏濕的。台灣降水和全球平均降水距平的符號相似性在秋季和初冬(九至十二月)較高，夏季(七至九月)較底。
台灣和全球平均降雨的趨勢不盡相似顯示降雨長期變化趨勢的區域和季節特徵非常重要。東亞沿海區域的夏季降雨趨勢在南北方向的差異較大，秋季則在東西方向的差異較大。我們推測台灣和南方的菲律賓與北方的江淮流域距平符號在不同季節的相似程度很可能是受到西太平副高強度長期變化趨勢的控制，欲了解台灣氣候如何變化，必須要繼續研究東亞沿海區域的長期雨量變化趨勢和太平海溫與西太平副高特徵彼此之間的關系究竟如何。

關鍵字

台灣氣候 ； 雨量長期變化趨勢 ； 氣候年代際振盪影響

並列摘要

The characteristics of the long-term trends of Taiwan and global rainfall during the period of 1920-95 are studied. The results show that the annual total rainfall of Taiwan does not have clear linear trend. If separating the total rainfall to different seasons, we find negative trend in summer (June-August). In autumn (September-November), the trend is positive. The wettest year of the global mean annual total rainfalls appeared around 1965 , while the driest year appeared around 1935. In a contrast to the global mean rainfall, the years around 1965 is a dry period in Taiwan and around 1935 is a wet period . In addition, in the months of the northern summer (May-September) the global total rainfall shows a decreasing trend after 1950, the trend is opposite in winter months (October-April). Taiwan rainfall anomalies are in a better agreement with the sings of global rainfall anomalies in autumn and early winter months (September- December), but not during the summer months (July-September).
The main point emphasized by this study is that the regional and seasonal heterogeneity is a very important feature of the long-term trend of rainfall variability. In the coastal areas of East Asia, we find that the contrast in the north-south direction of the summer rainfall anomalies is large. In autumn, the contrast in east-west direction stands out. We hypothesize that such contrast as the anomalies in the Philippines, Taiwan and Yangtze River have different signs may result from the characteristic shape of the West Pacific Subtropical High (HPSH). The decadal-scale WPSH variations are modulated by the Pacific Decadal Oscillations (PDO). It is, therefore, of great importance to understand the relationship between WPSH and PDO in order to understand the causing mechanisms of the long-term trends of Taiwan rainfall.

並列關鍵字

Taiwan Climate ； Precipitation Long-term Trend ； pacific SST Decadal Varication Impacts