秋強颱年代際變化之探討

Interdecadal Variability of the Strong Typhoon in Autumn

李佳容(Chia-Jung Lee)

指導教授 ： 鄒治華

國立臺灣師範大學/理學院/地球科學系/碩士(2007年)

摘要

本研究分析過去62年（1945?2006年）西北太平洋地區颱風活動之年代際（Interdecadal）變化，發現經過十一年滑動平均後，秋強颱呈現明顯的年代際變化，秋強颱活躍期（1990?1994年）颱風生成個數較多，且發展成強颱的比率（Ratio of strong typhoon, RST）較高，達33.8％，秋強颱非活躍期（1974?1978年）則相反，其RST僅19.6％。西北太平洋地區秋強颱活躍與否，和西北太平洋海溫較無明顯相關，反而強烈受到中?東太平洋地區海溫之影響。活躍期中?東太平洋海溫高，暖水厚度大，秋颱生成區向東南延伸至國際換日線一帶，生命期較長，非活躍期反之，秋颱均形成在160°E以西的區域，生命期較短。活躍期中?東太平洋暖海溫伴隨較高的環境水汽含量值，於暖水團的西北側低對流層出現氣旋式異常環流，高對流層出現反氣旋式異常環流，垂直風切減小，有利強烈颱風的生成與發展。

本文進一步藉由IPCC-AR4海氣耦合模式20C3M資料與現今實際觀測資料作比對，探討全球暖化後秋強颱強度變化的趨勢，顯示高解析度模式年代際變化大致和觀測相似，其變化趨勢和振幅相仿，可作為預測與秋強颱參考的指標。

關鍵字

年代際變化 ； 強颱

並列摘要

Tropical storm (TS) activity has strong impacts on the weather and climate over western North Pacific (WNP) Ocean. This study found that the activity of strong (categories 4-5) typhoon exhibits significant interdecadal variability, while the signal of interdecadal variability of categories 1-3 typhoon is not obvious. Since TS events in summer have received considerable attention, recently, this study focuses on the interdecadal variability of super typhoon activity in autumn. The ratio of the number of strong typhoon to the total number of typhoon (RST) in autumn is 29.3％. The RST during the strong typhoon active and inactive period are 33.8％ and 19.6％ respectively. The strong typhoon activity over the WNP Ocean in autumn is strongly influenced by the large-scale environment change over the central-eastern Pacific Ocean. During active period the warm sea surface temperature (SST) and high moisture content occur over the central-eastern Pacific Ocean. These conditions lead the formation of strong typhoon to extend south-eastward to the Date Line. On the contrary, the formation area of strong typhoon is restricted to the west of 160°E during inactive period. Thus, the strong typhoons have longer (shorter) journey and life span on the warm ocean during active (inactive) period. The interdecadal variability of the thermodynamic condition over the central Pacific is curial to the interdecadal change of strong typhoon in autumn over WNP Ocean. This study will further investigate the IPCC AR4 air-sea coupled model simulation to estimate the trend of strong typhoon after global warming.

並列關鍵字

interdecadal variability ； strong typhoon

參考文獻

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