台灣梅雨季之中尺度現象：中尺度低壓

Mesoscale Feature in the Taiwan Mei-Yu Season: Mesolow

陳泰然(George Tai-Jen Chen)

《大氣科學》 23卷1期 (1995/03) Pp. 1-17

摘要

台灣梅雨季之眾多中尺度現象中，中尺度低壓因與降水／豪雨關係密切，且其形成與發展與中央山脈之地形效應息息相關，故為近年來學者們非常熱衷的研究課題。本文除討論中尺度低壓之氣候特徵與中尺度低壓與降水／豪雨之關連之外，並回顧各區域中尺度低壓之形成機制，同時也探討中央山脈東西兩側中尺度低壓生命期內各階段之結構特徵。對中央山脈以西之中尺度低壓而言，近地層摩擦過程對其動力應扮演重要角色，使其增強速率減緩。不論豪雨發生於低壓區內或其南側，對流與降水強度在低壓出現時均顯著增強。東西兩側之中尺度低壓形成，雖可能導因於不同機制，但渦管拉伸效應均為使氣旋式環流增強之重要過程。最後，對未來中尺度低壓急待研究解決的問題，提出一些看法與建議。

關鍵字

中尺度低壓 ； 中尺度渦旋 ； 中尺度氣旋 ； 豪雨

並列摘要

Mesolow is one of the many mesoscale features observed in the Taiwan Mei-Yu season. Numerous researchers get interested in the mesolow study in recent years mainly because it is closely related to the heavy rainfall as well as to the topographical effects of the Central Mountain Range (CMR). In this paper, climatological characteristics, the mesolow-related heavy rainfall, and formation mechanisms of the mesolow are reviewed and discussed. The composite structure of the mesolows observed to the east and west of the CMR was investigated. It was found that the boundary layer frictional process plays an important role in the mesolow dynamics to slow down the intensification rate to the west of the CMR. Intensification of convection and rainfall rate over the mesolow and its immediate south is closely related to the formation of mesolow. Vortex stretching process is suggested to be an important mechanism for the circulation intensification over mesolow both to the east and the west of the CMR. Finally, the unresoloved issues related to the mesolow are proposed and discussed.

並列關鍵字

Mesolow ； Mesovortex ； Mesocyclone ； Central mountain range