本研究使用WRF模式對凡那比(2010)颱風伴隨之豪雨進行分析，並探討台灣地形對颱風之影響。凡那比颱風於2010年9月 17日至20日期間影響台灣，颱風環流由東向西通過南台灣，並於侵台的12個小時內在南部降下近千毫米的累積降雨，瞬間的豪雨使得許多地區排水不及，造成淹水災情發生。
由WRF模式之降水物理參數測試結果顯示，積雲參數法相對於微物理過程對於模式表現有較顯著的影響。其中以使用Kain-Fritsch積雲參數法之模擬，颱風結構完整且降雨強度較強。使用BMJ scheme之模擬，颱風路徑較為南偏，導致降雨位置也較為南偏。使用Grell-Devenyi Ensemble scheme之模擬，颱風強度偏弱且無法掌握凡那比颱風所引發之降雨強度。使用Grell 3d scheme之模擬，颱風結構對稱，但颱風強度較觀測弱。因Kain-Fritsch積雲參數法對於颱風結構及強度的模擬結果較佳，故本研究以其為CTL組之參數設定。
　　研究結果顯示豪雨發生為颱風環流受地形影響有關，凡那比颱風侵台期間滿足多項利於地形豪雨發生之要素，強烈的低層風場、強風速帶之風向與台灣陡峭地形走向垂直、進入山區之氣流伴隨潮濕水氣及氣流具有極高的不穩定度等因素。由地形高度測試發現，台灣地形與颱風環流間的通道效應為颱風登陸前出現南偏的重要原因，地形高度越高則颱風登陸前南偏的情形越為顯著。當台灣山脈完整移除後，南部山區平均降雨僅剩原來之45%，若將地形高度減半，降雨亦顯著顯少，顯示地形對於豪雨發生扮演重要的角色。此外，地形高度的不同也會影響颱風出海後的移速，地形高度越高颱風移速越慢，因而造成颱風離台後較大的降雨發生。由垂直水氣通量與累積降雨之關係可見，各項利於降雨發生之要素間彼此相互影響，地形高度的提高能夠增強低層輻合、並增強對流，但亦會造成颱風強度減弱，導致迎風面地區的風速減弱及水氣減少，因此降雨強度並沒有明顯的改變。
關鍵字:凡那比颱風、豪雨、地形效應

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