台灣梅雨季之中幅度降水與中幅度低壓研究

On the Mesoscale Rainfall and Mesolow in the Mei-Yu Season in Taiwan

陳泰然(George Tai-Jen Chen) ； 紀水上(Shui-Shang Chi)

《大氣科學》 7卷1期 (1980/05) Pp. 39-48

摘要

本文以0.5度經緯度網格分析1972－1977年台灣梅雨期內地面中幅度低壓及其與6小時平均降水量、6小時可能最大降水量以及不同降水強度產生之相對機率間之相關。分析結果提供了中幅度低壓於不同地區發生時之降水特徵分布之氣候參考值，此可做為短期降水預報之參考應用。同時，亦由降水特性分布推論地形效應、大幅度環境與中幅度低壓在決定降水所占的角色。結果顯示梅雨期中幅度降水分布特徵，主要係由地形效應與原已存在於雲帶內之對流雲羣決定。中幅度低壓僅在發生於新竹沿海時直接影響台灣北部地區之降水，當低壓發生於其他地區時，可能僅對地形與大幅度環境所決定的降水分布與降水強度做稍許改變，而不影響降水分布之大局。

並列摘要

Mesolows are analyzed at the 0.5-degree longitude-latitude square grid in the Mei-yu season in Taiwan for the year of 1972-1977. The relationships smong the mesolows, the 6-hour averaged rainfall amounts, the 6-hour maximum rainfalls, and the probabilities of various rainfall intensities are studied. Results provide the climatological values of rainfall distribution for the mesolows occurring in different regions. These can be used as reference values in the short range quantitative rainfall forecasting.Meanwhile, the characteristics of the rainfall distribution are studied to reveal the roles of topography, large-scale environment and mesolow in determining the various aspects of rainfall. Results show that the mesoscale rainfall systems in Mei-Yu season are mainly due to topographical effects and the pre-existing convective cloud clusters within the frontal cloud band. Mesolows are directly responsible for the rainfall in northern Taiwan only when they occur along the Hsinchu coast. As the mesolow occurs in other areas, it appears to be a modifier rather than a major factor in determining the rainfall characteristics.