台灣區域單日最大與月降雨量之變遷特性分析

本文探討區域降雨量受氣候變遷影響，採用蘭陽溪及南部地區共12站長期雨量站資料，分析1959～1990年、1991～2008年及1959～2008年單日最大降雨量資料，採用極端值第一型分布以推估其對應於不同重現期距之單日最大降雨量，並利用Mann-Kendall趨勢檢定分析其趨勢變化。結果顯示採用1991～2008年資料所推估之10年以上重現期距之降雨量值皆高於採用1959～1990年資料之推估值，亦即單日最大降雨量值有增加趨勢。隨測站高程上升與距海愈遠，各測站對應於重現期距之單日最大降雨量變化皆增加。50年資料顯示南北無明顯月雨量變化趨勢。然而1991～2008年資料分析顯示南部測站濕季除了八月之外，其他月份月降雨量幾乎全部呈現顯著增加的趨勢，乾濕交替月份（四月與十一月）亦有增加趨勢，說明南部乾濕季差別更為分明，降雨往濕季集中、雨量增加。

關鍵字

重現期距；降雨；極端值第一型分布； Mann-Kendall趨勢檢定

並列摘要

This study tried to discuss the effect of rainfall under climate change in both North and South of Taiwan. 50 years long term rainfall data consisting of 5 rainfall stations in LanYang basin in North of Taiwan and 7 rainfall stations in the South was analyzed. The extreme-value type I distribution was used to estimate the return period of the one day maximum rainfall in periods of year 1959 ~ 1990, 1991 ~ 2008 and the whole period 1959 ~ 2008. The Mann-Kendall trend test was used to analyze the trend of rainfall variation. The result showed that the interval value of return periods over 10 years in 1991 ~ 2008 were all higher than that in 1959 ~ 1990's. When the elevation and the distance to coastline of stations increased, the one day maximum rainfall of every station increased in return periods of 10, 20, 100 and 200 years, with especially obvious in the south of Taiwan. According to the analysis of Mann-Kendall method, there was no obvious trend in both north and south area with 50 years data. However, based on 1991 ~ 2008 record, the rainfall of the wet season of the south, showed significant trend of increase, except August. The trend of increase also appeared in the dry and wet alternate months (i.e., November, April). It is interpreted that the rainfall not only increases but also is converged toward wet season. As a result, the difference of rainfall between the wet and the dry season becomes more apparent in the south of Taiwan.

並列關鍵字

return period ； rainfall ； extreme-value type I distribution ； mann-kendall method

國際替代計量

台灣區域單日最大與月降雨量之變遷特性分析

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