颱風豪雨經常引發堤防潰堤導致河水氾濫，或是颱風豪雨碰到中央山脈陡峭地形經常引發土石流，使得橋樑損壞、建築崩塌及水庫淤積等，造成嚴重的複合型災害。本計畫擬研究侵台颱風的降水物理過程，透過高解析度WRF 模式數值模擬實驗，探討中央山脈如何改變或是加強颱風環流內的降水物理過程，以及探討颱風內核(inner core)及外圍雨帶(outer rainband)區域的降水效率如何受到台灣地形影響等科學議題。首先本計畫將以莫拉克(2009)颱風為主要研究個案，針對 WRF 模式模擬結果進行診斷分析及數值敏感度實驗，探討台灣地形如何改變莫拉克颱風的雲微物理過程，進而瞭解造成莫拉克颱風於高屏山區破紀錄豪雨（3 天累積雨量超過2700 mm）的主要雲微物理機制。此外，本研究另一目的在於比較WRF 模式中單矩量方案(僅預報降水粒子混合比）及雙矩量(two-moment)方案（預報降水粒子混合比及粒徑譜），對於颱風降水模擬結果的不同；期望透過系統性的比較分析，進而發展出最適合應用於台灣地區登陸颱風降水模擬的雲微物理參數化方案。 Heavy rainfalls brought by landfalling typhoons often induce severe fresh floods and mudslides, causing bridge collapse and building breakdown, which result in tremendous economical and property damages. This proposal will investigate the precipitation physical processes of landfalling typhoons, by using the high-resolution WRF model simulations. The scientific issues are to understand how the Taiwan Central Mountain Range modifies the microphysical processes within the typhoon circulation and to investigate how the precipitation efficiencies within the inner core and outer rainbands are changed by the terrain effects. This project will choose Typhoon Morakot (2009) as the target typhoon case to investigate how the steep Taiwan topography modifies the microphysical processes by conducting the control and sensitivity simulations with the high-resolution WRF model. The essential microphysical processes responsible for the record-breaking extreme rainfall (more than 2700 mm in 3 days) will be examined. In addition, the project will conduct systematic comparisons between the single-moment (predicting only the mixing ratio) and two-moment microphysics schemes (predicting both the mixing ratio and the number concentration) for typhoon simulations. Through systematic comparisons and detailed analyses, this proposal is aimed to find out the optimal microphysics parameterization scheme which is most appropriate for the precipitation simulations of landfalling typhoons over the Taiwan area. 研究期間：10008 ~ 10107
