Abstract
摘要:因應近年來大台北都會區極端對流暴雨(Extreme Convective Rainfall, ECR)事件頻仍,都會地區因
聚集大量人口及頻繁的經濟活動,更易造成嚴重災情,因此本研究針對雙北都會區ECR 事件進行科
學研究與防災應用,而本研究成果將來可延伸應用至其他都會地區,對於台灣防災應用將有很大助
益。因應台灣都會區防救災之需求,本計畫研究先以夏季午後暴雨為主要目標,ECR 定義為時降雨量
達40 mm 或3 小時累計雨量達100mm。
主要目標包含以下項目:(a)利用降水雷達監測網搭配高解析度衛星資料觀測ECR 事件、(b)了解
ECR 的動力過程,及其與大氣大尺度環流系統的交互作用、(c) 發展新的氣象與水文模式與系集預報
技術,改善ECR 預報能力、(d)了解ECR 之可預報度、(e) 建置及優化ECR 的視覺化產品,並建立氣
象水文資料平台應用於防災作業、(f) 外場觀測與預報實驗。我們將以降水雷達監測網搭配高解析度
衛星資料,結合包含新的冰晶物理的高解析度雲模式,水文模式,以及全球大尺度模式,用以研究ECR
跨尺度動力物理機制。我們的科學假說大尺度環流的水氣通量的傳送補給,有利於小尺度多胞型的對
流系統產生,多胞系統的合併以及冰雹物理過程,將導致ECR 發生。在東亞夏季季風區而大尺度水
氣傳送,常以數千公里長度數百公里寬度的環流結構源源不絕輸送水氣(大氣長河),本研究將以帶狀
化時間尺度及有效擴散率分析診斷工具來探討形成大尺度水氣輸送的動力機制。帶狀化時間尺度藉由
水氣通量場的拉伸變形,提供形成水氣梯度的時間,探討大氣長河生成動力,而有效擴散率則是反映
大尺度風場混合的過程。藉由以上這些研究,有利於我們了解ECR 和大尺度系統相關動力機制。進
一步改善ECR 短(0-6 小時)、中(天)及長時間(周)的預報,並研究這些不同時間尺度ECR 的可預報度。
計畫將結合雷達衛星資料,進行外場觀測實驗,以驗證發展氣象水文數值模式,了解ECR 動力物理
過程。外場實驗期間將和國際學界、氣象局與國內災防單位合作,進行預報實驗,驗證科學研究成果,
透過更多客觀引導資訊提供給防災減災決策者使用,希冀能有效減少ECR 的經濟損失。
Abstract: This proposal investigates the Extreme Convective Rainfall (ECR) events over Taipei metropolitan
area in Taiwan. The Taipei metropolitan area is chosen as the prototype ECR research because it has the
largest population and economic activities in Taiwan. Eventually, the research results can extend to other
metropolitan area in Taiwan. The ECR events in the study are defined as hourly rainfall exceeds 40 mm/hr
or three hour accumulated rainfall exceeds 100 mm. More often than not we will focus the ECR in the form
of the afternoon thunderstorms. The radar, satellite and meteorological observations, high resolution cloud
dynamics numerical model with a new cloud ice microphysics, flood hydrological model, and atmospheric
global large scale model will be used to monitor and study the origin and development of ECR events, and
to make better forecast for the ECR events.
The scientific hypotheses of the proposal is the presence of large scale water vapor transport support
the cloud scale multi-cells thunderstorm complex, and with significant ice hail process, which lead to the
ECR events through multi-scale interaction. The large scale water vapor transport in the form similar to
that of the atmospheric river (AR) in the East Asian summer monsoon will be studied with new dynamic
analysis of filamentation time and effective diffusivity. The filamentation time gives the information of AR
formation by water vapor field gradient tightening time scale. The effective diffusivity calculation
diagnosis the mixing effect of the large scale wind field. Through the research effort, the project will lead
to improved understanding of dynamical and physical processes associated with ECR events, its link to
large scale circulation, and improved capability of forecast of ECR events on short (0~6 hr), medium (days)
and extended-range (week) time scales. The predictability of ECR in these time scale will also be
investigated. We will conduct observation field experiments and forecast experiments to verify our research
results. The outcome of the research will include more accurate objective guidance so that decision-makers
can minimize the impacts and economic losses by ECR and reduce disaster on civilian activities.
In summary, the main thrusts are: a) better monitoring of ECR events, b) understanding the origin
and development of ECR events, and its scale interaction with large scale weather circulations, c)
improving the ECR prediction in hydro-meteorology with a new ensemble technique, d) understanding the
ECR predictability, e) visualization of ECR and constructing the platform that integrate
hydro-meteorological efforts for the disaster reduction, and f) observation field experiments and forecast
experiments for ECR events.
Keyword(s)
台北都會區
極端對流暴雨
大氣長河
可預報度
帶狀化時間尺度
有效擴散率
Metropolitan Taipei
extreme convective rainfall
atmospheric river
predictability,