以動力降尺度資料評估氣候變遷下颱風降雨事件特性變異

Assessment of the Change of Typhoon Rainfall Event Characteristics Using Dynamic Downscaling Data under a Climate Change Scenario

蘇元風(Yuan-Fong Su) ； 劉俊志(Jun-Jih Liou) ； 鄭兆尊(Chao-Tzuen Cheng) ； 鬼頭昭雄(Akio Kitoh)

《農業工程學報》 60卷4期 (2014/12) Pp. 48-60

https://doi.org/10.29974/JTAE.201412_60(4).0005

摘要

颱風降雨對於農田水利設施規劃設計、水稻災損評估、水資源管理及淹水演算而言是最重要的因子，了解氣候變遷情境下颱風降雨事件特性於未來的改變對於前述農業與水文相關之工作是相當重要的。然而，過去有關氣候變遷對於降雨的研究中，受限於統計降尺度資料的時間解析度，大多以年、季節、或月降雨量為研究對象，幾乎沒有針對颱風事件特性變化的分析。國科會的「臺灣氣候變遷推估與資訊平台建置計畫（TCCIP）」與日本氣象廳合作取得動力降尺度資料（MRI），並進一步以美國的天氣研究與預報模式系統（WRF）降為5公里解析度，其時間解析度為小時，適合用以進行颱風事件特性變化的分析，本研究亦為國內首次使用動力降尺度資料探討颱風事件特性改變之研究。颱風事件特性包含事件延時、總降雨量、間隔時距等，研究中比較觀測資料與動力降尺度資料之差異，並進行偏差校正（Bias correction），最後比較氣候變遷情境下颱風事件特性於近未來（2015-2039）與世紀末（2075-2099）相較於基期（1979-2003）之變化情形。結果顯示，相對於基期而言，近未來與世紀末，在臺灣整體的颱風事件降雨延時減少，而總降雨量有明顯的增加趨勢，突顯出未來極端降雨強度增加的警訊。

關鍵字

氣候變遷 ； 動力降尺度 ； 颱風事件降雨特性

並列摘要

Typhoon rainfall is an important issue for many agricultural and hydrological practices, such as channel design, assessment of rice losses due to flooding, water resource management etc. However, the future change of typhoon rainfall patterns, in spatial and temporal, under climate change scenario is still unknown yet critical. Taiwan Climate Change Projection and Information Platform (TCCIP) project introduced a dynamic downscaling data set from Meteorological Research Institute (MRI) and further downscaled into 5 km grids by Weather Research and Forecasting modeling system (WRF). This research is the first research in Taiwan using the data set (hereafter, called WRF-MRI) with hourly rainfall for assessing the changes of typhoon rainfall event characteristics. We compared the typhoon rainfall characteristics including number of events, duration, total rainfall, and inter-event time, derived from observations and a dynamic downscaling data set. A bias correction of the dynamic downscaled data set was also conducted. After bias-corrected, the typhoon rainfall duration, in Taiwan, will generally decrease while the total rainfall amount will increase in the future under the climate change scenario. This indicated the rainfall intensity will increase in the future especially in central and southern parts of Taiwan and we should take this as a warming for future agricultural and hydrological practices.

並列關鍵字

Climate Change ； Dynamic Downscaling ； Typhoon Rainfall Characteristics