2018-08-012024-05-18https://scholars.lib.ntu.edu.tw/handle/123456789/711988摘要：本計畫的研究目的是利用高解析度的數值模擬，探討梅雨鋒面上的中尺度對流系統 降水效率的演變，分析颱風於登陸過程降水效率之變化，並檢驗降水效率與環境水 氣傳輸間的非線性作用。經由高解析數值模擬結果診斷分析的中尺度對流系統與登 陸颱風的水氣輸送與降水效率，將與台美合作之台灣區域大氣水文觀測與預報實驗 (TAHOPE)大型觀測實驗分析結果做仔細比較，做為模式改進之參考。 梅雨期間中尺度對流系統內部對流胞間的碰撞可能增強冷池強度，而對流胞間 的合併有可能減慢冷池移速，導致強降雨所致的冷池移速突然減慢，導致降水時間 拉長使得累積雨量增加造成洪水，2017年6月2日北台灣的豪大雨事件即為一類似案 例。本計畫將使用高解析度數值模擬，探討梅雨期間中尺度對流系統之對流胞合併 物理機制，以及冷池移速突然減慢的原因為何？ 台灣地區另一類產生豪大雨的天氣類型即是颱風，以納莉(2001)颱風為例，我 們的研究指出，颱風登陸後其降水效率會增加10-20%。再以莫拉克(2009)颱風為例 ，我們的計算得出的降水效率與地面降雨強度有著高度相關，且當地面降雨強度高 於50 mm/h時，其降水效率將高於95%。本計畫將針對近年來的登陸颱風做類似的水 收支及降水效率計算，以確定之前對於納莉及莫拉克颱風的研究成果，是否可以延 伸至其他侵台颱風個案。<br> Abstract: The first purpose of this project is to investigate the evolution of precipitation efficiencies (PEs) within mesoscale convective systems (MCSs) embedded in Mei-Yu fronts and the landfalling typhoon circulations, using high-resolution model simulations. The second purpose is to examine the nonlinear interactions between the PEs and environmental moisture transport. The calculated moisture convergence from the environmental and PEs within MCSs and typhoons will be verified with those derived from the intense observations during the TAHOPE/PRECIP 2020 field experiment. During the Mei-Yu season (May and June), the collision between convective cells within the MCSs may enhance the cold-pool intensity, and the merger between convective cells may slow down the propagation of precipitation-induced cool pool, resulting in an unexpected movement or stagnation of cool pool embedded in Mei-Yu MCSs. This unexpected stagnation of cool pool embedded in Mei-Yu MCSs, such as those occurred in 2 June 2017, produced extremely heavy rainfall and severe flooding over northern Taiwan. Through cloud-resolving model simulations, this proposal plans to investigate the physical mechanisms responsible for the possible cell merger and the unexpected slowdown of the propagation of cold pool within the Mei-Yu MCSs. Another type of extreme weather producing heavy rainfalls on Taiwan is typhoon. For example, for the case of Typhoon Nari (2001), our results showed that the PE was increased by 10–20% after landfall. For Typhoon Morakot (2009), our calculated PE was highly correlated with the surface rain rate; in particular, the PE can reach more than 95% over southern Taiwan when the surface rain rate is greater than 50 mm/h. We would like to conduct similar vapor-budget and water-budget study of other landfalling typhoons and to examine how general the results from our previous studies on Typhoons Nari and Morakot can be applied to other landfalling typhoons in Taiwan.水收支降水效率中尺度對流系統颱風Water BudgetPrecipitation EfficiencyMCSTyphoon