摘要或動機

Drought and inundation are two unusual natural disasters in Taiwan. The two natural disasters\r
have some relation of abnormal rainfall become more and more in Taiwan. So it let me think about\r
can climate vicissitudes make the chance of abnormal rainfall become more?\r
The study have researched the chance of abnormal rainfall by "rainfall duration" and "total\r
rainfall". It collect the day by day total rainfall from 1960 to July 2002, collect locals are Taipei,\r
Taichung, Kaohsiung and Hualien. Than enter the data into the computer, let computer calculation\r
total rainfall, rainfall days, heavy rain days, pouring rain days and torrential rain days. Then\r
analysis the tendency of long-term change.\r
According to the analysis, the chance of abnormal rainfall happened become more in Taipei,\r
Taichung, Kaohsiung and Hualien. The ratio of Hualien and Kaohsiung is the most obviously. It's\r
also find that there temperature and total evaporate became higher, the total sunshine duration\r
became lower. Then El Nino have some influence in abnormal rainfal. In El Nino year, total rainfall\r
will become lower. When La Nina year, the total rainfall will become more in Taipei and Hualien.\r
Then the long influence is clearly in Taipei.\r
乾旱與水災是台灣地區相當常見的二項天災，這二項災害的發生都與異常降水有直接的\r
關係。近年來台灣地區因異常降水造成的天然災害，似乎有逐年增加的趨勢。因此讓人聯想\r
到氣候變遷是否會導致異常降水頻率增加。\r
本研究主要由「降雨時數」與「降雨量」二方面探討異常降水發生頻率。先收集台北、\r
台中、高雄、花蓮四地自1960 年至2002 年七月三十一日之逐日雨量資料，將資料輸入電腦\r
後，統計各站歷年降雨量、降雨日數、大雨、豪雨、暴雨日數，並分析長期變化趨勢。\r
分析結果，台北、台中、高雄、花蓮四地異常降水發生機率，有增加的情形；其中以花\r
蓮及高雄變化的比例最高。再與其他各地氣象要素比較可發現，可能與氣溫及蒸發量數上升，\r
以及日照時數縮短有關。另外聖嬰現象也可能對異常降水有長期性的影響。一般而言聖嬰年\r
雨量減少，反聖嬰年台北、花蓮地區雨量反而會增加。而長期性的影響，以台北地區最顯著。