凡那比颱風（2010）在西南台灣降水之颱風數值作業模式預報探討

A study on the prediction of the operational typhoon numerical model for Typhoon Fanapi (2010) rainfall over Southwestern Taiwan

葉天降(Tien-Chiang Yeh) ； 陳得松(Der-Song Chen) ； 蕭玲鳳(Ling-Feng Hsiao) ； 鄭浚騰(Chun-Teng Cheng) ； 黃康寧(Kang-Ning Huang)

《大氣科學》 48卷2期 (2020/12) Pp. 234-258

https://doi.org/10.3966/025400022020124802004

摘要

2010年侵台凡那比颱風（Fanapi）於9月18日中心由花蓮登陸、19日由臺南進入台灣海峽，並以偏西北西方向緩慢移動遠離，侵台期間除在高屏山區有劇烈降雨外，在高雄都會區亦有劇烈降雨帶造成災情。本研究利用中央氣象局當時之颱風數值預報模式，針對此個案特別是高雄都會區小尺度劇烈降雨帶之預報，分析以了解模式對此個案之預報能力，和探討造成劇烈降雨可能之機制。結果顯示，中央氣象局颱風數值預報模式，能相當程度掌握凡那比颱風侵台之路徑預報；最內層為5公里解析，於9月18日06UTC為起始之預報也對台灣地區特殊之降水有相當程度之掌握。移除地形之敏感度實驗結果顯示，移除地形後，原在山區地形強化之降雨及在高雄都會區特殊之降水不再發生，惟凡那比颱風本身結構與強度存有顯著降雨、降雨較大值並在中心南側之情形，能提供有利條件，加上其能維持受地形影響而又不至消散，在台灣西側重新組織，形成雨帶，同時颱風移動方向和雨帶方向大致平行，造成高雄都會區小尺度劇烈降雨。

關鍵字

颱風降雨量預測 ； 數值模式預測 ； 地形效應

並列摘要

In 2010, the Typhoon Fanapi made landfall from central Eastern Taiwan on September 18 and entered the Taiwan Strait from Tainan County the next day, and moved slowly in the west-northwest direction before made landfall in China. During the invasion, except for heavy rainfall in the Kaohsiung-Pingtung mountainous area, severe rains also caused disasters in the Kaohsiung metropolitan area. This study uses the TWRF (typhoon numerical forecast model) of the Central Weather Bureau to analyze the forecast of this case, especially the small-scale severe rain band in the Kaohsiung metropolitan area, to understand the forecasting capabilities of the model for this event, and to explore the possible mechanisms caused the severe rainfall. The results show that the TWRF model can will predict the track of Typhoon FANAPI to a considerable extent. The forecast of the innermost grid resolution of 5 kilometers, starting at 06UTC on September 18, is also useful for the special precipitation in Southern Taiwan. The results of the sensitivity experiment by removing the terrain show that both the enhanced rainfall in mountainous area and the special rainfall in the Kaohsiung metropolitan area no longer exist without terrain. The Typhoon FANAPI with significant rainfall and the rainfall is more intense in the south side of the system providing favorable conditions to the rainfall in southern Taiwan. Coupled with the condition that the FANAPI is affected by the terrain but is able to maintain and reorganize on the west side of Taiwan to form a rain band. Meantime, the moving direction of the reorganized system is roughly parallel to the orientation of the rain band, resulting in the special small-scale heavy rainfall in the Kaohsiung metropolitan area.

並列關鍵字

Typhoon rainfall prediction ； numerical model prediction ； terrain effect