曾文水庫集水區降水特性分析及颱風降水預報之研究

A Study on Characteristics of Precipitation Patterns and Typhoon Rainfall Forecasting over Tsengwen Watershed

吳宗堯(Tsung-Yao Wu) ； 謝信良(Shinn-Liang Shieh) ； 喬鳳倫(Feng-Lun Chiao) ； 陳正改(Cheng-Kai Chen) ； 黃清芬(Ching-Fen Hwang)

《大氣科學》 8卷1期 (1981/05) Pp. 1-18

摘要

本研究根據曾文水庫集水區自記測報雨量站過去十年之雨量記錄（民國59～68年），分析該集水區降雨之特性，發現年雨量有83%集中在5～9月；而導致日雨量達100公厘或以上之原因，以颱風（或熱帶性低氣壓）為主，梅雨次之。調查民國59～68年間影響曾文水庫集水區之颱風路徑與雨量之關係，得知西進而通過集水區以北之颱風對曾文水庫集水區之降水最有影響；暴雨發生時間甚短而強度最強；雨量尖峰平均出現在颱風最接近集水區時之前約2小時。應用一半經驗方法之颱風降水預測模式，考慮颱風環流之輻合作用及地形抬升兩種效應，模擬計算颱風以各種不同路徑侵襲集水區時之逐時雨量。結果顯示以西進颱風類之降水型態與實際情況最為接近，具有可預測性。故此一模式為曾文集水區颱風雨量預報之依據。

並列摘要

An intensive analysis of the rainfall data over Tsengwen Watershed for the period from 1970 to 1979 has been carried out. One of the results indicates that about 83% of the yearly rainfall occurs in the months from May to September. It is also seen that most cases of heavy rain with daily rainfall 100m or above were caused by typhoons or tropical depressions while a few occasions with the same daily rainfall were observed in Mei-Yu seasons.All typhoon tracks which affected the watershed during the years mentioned above have been classified into several categories according to their orientations. It is noted that the rainfall over the watershed was mostly introduced by typhoons which moved westward and passed in the north of the watershed; and thier peaks appeared at 2 hours in average before the typhoon reached the nearest position to the watershed.The rainfall forecasting model consists of two terms, namely, the topographical term and the typhoon circulation terms. Simulations of typhoon precipitations for variously oriented tracks reveal that the simulated west moving-typhoons give the rainfall patterns fairly close to the actual ones; hence it is reasonable to conclude that the said model is applicable to the typhoon rainfall forecasting over Tsengwen Watershed.