梅雨季發生大雨之綜觀預報法

Synoptic Method for Predicting the Occurrence of Heavy Rain in Mei-Yu Season

曲克恭(Ko-Kung Chu) ； 任立渝(Li-Yu Jen)

《大氣科學》 14卷1期 (1986/09) Pp. 17-32

摘要

台灣梅雨季中之大雨，大多導於中尺度天氣系統及地形作用。由於對中尺度系統之瞭解不夠與偵察技術之欠缺，目前尚難達到何處、何時及何量之理想大雨預報境界，若能改善綜觀尺度分析及預報作業方式，確實掌握引發中尺度大雨系統之環境，則對梅雨季中之大雨預報或可有所助益。本研究即以此為目的，完成兩部份工作：（一）整理國內過去研究梅雨之文獻，找出已被發現導致大雨之綜觀尺度大氣因子，直接引用其圖表，或根據其數據製成圖表。（二）應用1967～1984年，五、六月份台灣北部22個及南部36個大雨個案資料分析大雨發生24、12及6小時前與大雨當時之重要徵候及變化，製成預測參考圖表，供預報作業時用。根據以上二項分析，按地面、高空綜觀系統、濕度分布狀況及穩定度之順序，並加入NWP（日本JMA）之預測，製成梅雨季大雨預報檢查表，供預報人員應用。本研究雖只能獲得大雨發生或不發生之定性預測，但極適合實際作業之時效要求。

並列摘要

The purpose of this study is to find out an operational method of synoptic analysis for predicting the occurrence of heavy rain in Taiwan during the Mei-Yu Season. Two approaches were taken in this study. At first, we selected the synoptic factors which were found and recognized as the principal causes of heavy rain in Mei-Yu Season by other authors. These selected papers were reviewed and some charts and diagrams in the papers which can be used in the routine works of weather forecast were selected directly or simplified in order to meet forecasters' need. Secondly, using the meteorological data of 22 heavy rain cases in the northern Taiwan and 36 cases in the southern Taiwan in May and June from 1967 to 1984, we analyzed the characteristics of some synoptic factors, which appeared 6 hours, 12 hours and 24 hours before the heavy rain: the results were also summarized into simple charts which can be used by forecasters directly and quickly. A checking form listing the meteorological factors which were considered as the important indications of the occurrence of heavy rain in the Mei-Yu Season in Taiwan was also prepared. It only includes the products of daily weather analysis and prediction, such as the factors obtained from the surface and upper air charts and in the thermodynamic diagram. Besides, some products from the NWP of JMA are also included as the factors in the prepared check list.