鋒面與中尺度低壓在豪雨之角色：TAMEX第一階段之兩個個案

Role of Mei-Yu Front and Mesolow on the Heavy Rainfall Events: Two Cases in TAMEX Phase I (1986)

陳泰然(George Tai-Jen Chen) ； 俞家忠(Chia-Chung Yu)

《大氣科學》 18卷2期 (1990/06) Pp. 129-147

摘要

本文選取1986年5－6月TAMEX第一階段實驗之IOP2與IOP3豪雨個案，利用傳統觀測、雷達與衛星資料，分析探討豪雨之時空分佈特徵及梅雨鋒與中尺度低壓在豪雨所扮演之角色，並研究梅雨鋒特徵及中尺度低壓之結構與形成機制。結果顯示，梅雨鋒面為豪雨之重要因子，但鋒面之特徵差異無法解釋豪雨之時空分佈特徵，而中尺度低壓之強弱似為決定南部地區豪雨強弱之重要因子。此外，發現台灣西南部水平尺度約150公里之淺中尺度低壓（局限在5000呎以下）之形成，可能由中低對流層之氣流結構與中央山脈之冷卻效應而來（半地轉理論），唯亦無法排除積雲潛熱加熱、海陸摩擦差異、氣旋式海岸地形與地形阻檔之分流效應等過程在形成與加強之可能角色。

關鍵字

中尺度低壓 ； 豪雨 ； 梅雨鋒面 ； 台灣地區中尺度實驗計劃

並列摘要

Two cases of heavy rainfall events in TAMEX phase I of 1986 were selected. Conventional observation, radar and satellite data were used to study the spatial and temporal variations of heavy rainfall as well as the role of Mei-Yu front and mesolow in producing these variations. The characteristics of Mei-Yu front and the structure and formation of mesolow were also discussed.Results showed that the Mei-Yu front was an essential ingredient for producing heavy rainfall although it could not explain the spatial and temporal variations of the rainfall distribution. The mesolow over southwestern Taiwan appeared to be responsible for determining the intensity of heavy rainfall in southern Taiwan. In addition, the formation of shallow (limited below 5000 feet) mesolow (~150 km) over southwestern Taiwan could be explained by a non-linear semi-geostrophic theory under the prevailing northwesterlies and diabatic cooling of the Central Mountain Range. However, the roles of cumulus latent beating, land-sea frictional differential, cyclonically curved coastal line and diffluent flow of topographic blocking in the formation and maintenance of the mesolow should not be overlooked.

並列關鍵字

mesolow ； heavy rainfall ； Mei-Yu front ； TAMEX