西南氣流觀測與豪雨預報實驗(SoWMEX/TIMREX)是一台灣與美國的國際合作實驗計畫，此觀測實驗已順利的在2008 年5 月15 日至6 月30 日之間，成功的收集了九個密集觀測期的資料，其中包括從5 月30 日至6 月5 日的連續加強觀測期的密集觀測資料，此觀測實驗收集密集觀測資料以供台灣島地形對梅雨鋒系統、西南氣流、中尺度對流系統以及不穩定之副熱帶環境氣流下之降雨分布等科學問題之研究以及模式模擬之驗證。台灣島嶼地形不但會因阻塞以及地形抬升作用而影響西南氣流的減速、分流，甚至形成地形噴流，而且也會因為海陸分布以及山谷地形與平原之加熱日變化差異引發海陸風、山谷風等局部環流之發展，對對流之激發以及降雨的時空分布與變化會有明顯之影響，在有利的綜觀條件下，台灣西南部地區豪雨的發生與島嶼地形引發之氣流與地形作用關係密切，本研究將藉由TIMREX 之觀測資料收集診斷分析再搭配模式之模擬與敏感度實驗來探討島嶼地形作用對氣流、中尺度對流系統以及豪雨之生成與發展的影響。島嶼加熱日變化、海陸風之發展與島嶼引發之氣流與地形對豪大雨生成時間、位置之影響將特別深入探討研究。另一方面也將針對地形對降雨雲物理過程之影響進行觀測與模擬之研究，針對豪大雨個案之模擬將特別以三維變分方法測試雷達資料同化對降雨模擬之影響。TIMREX (Taiwan Island Monsoon Rainfall Experiment) is a joint Taiwan-US multiagency field program to be conducted during the period of 15 May to 30 June 2008. The proposed field campaign will provide the much needed data to study the effects of island terrain on Mei-Yu frontal system / LLJ, mesoscale convective systems (MCSs) and rainfall distribution in an unstable, subtropical environment and for model verifications. The island induced airflow (blocking, diurnal cycle, orographic lifting) plays an important role in determining rainfall distribution over a mountainous subtropical island. Under favorable synoptic settings, the heavy rainfall occurrence over southern Taiwan is affected by island- induced airflow and terrain, but is not well understood became of the lack of high temporal resolution island-scale data. The main goal of this project is to improve our basic understanding of island effects on airflow, front system / LLJ and heavy rainfall occurrences through collection, analysis and modeling of high spatial and temporal resolution data from the proposed SoWMEX/TIMREX filed program. The island-induced flow and orographic affects the timing, location of heavy rain occurrence will be the main focus of this study. 研究期間 : 9808 ~ 9907
