摘要
大尺度環流的突然轉變與降雨的迅速增強是亞洲夏季季風肇始的明顯特徵，除季節變化影響外，季內振盪低值到達時間亦是關鍵。本研究的目的即在分析季內振盪與季風環流之互動關係。並探討台大波普模式(NTU GCM)模擬亞洲季風區內季內振盪與季風環流之動力關係，我們採用Daubechies(1988)之波列轉換進行濾波，因其在處理區域性波動時能會保有原波動的區域性特徵。結果顯示，夏季熱帶地區出現三個強對流，分別在印度西岸、孟加拉灣與南海地區，其中南海地區的OLR變化主要是以30~60天波動為主。南海地區氣候平均值在五月中突然下降，30~60天振盪負值亦在相同時間由赤道向北傳遞，南亞高壓北移、南海高層風場反轉與30~60天振盪負值到達時間一致。此外，南海季內振盪可能是影響南亞高壓北移與高層東風的重要因素。NTU GCM模式可以模擬東亞夏季季風之爆發性突變，而模擬之季風肇始與模擬之30~60 天波動北傳的關係密切。NTU GCM所模擬之高壓北移、南海高層風場反轉時間亦與30~60天振盪負值到達時間一致。此結果顯示，以氣候平均觀點，模式中季內振盪之結構與與季風環流之間動力連結一致。
為探討東亞季風與東太平洋海平面溫度之相互關係，我們根據Nino3地區6~8月海溫距平區分SST冷年及SST暖年，結果顯示Nino3地區海溫與南海地區對流，無論在強度或肇始時間皆呈負相關，即在SST暖年，南海地區對流發生時間延遲，對流強度減弱，而其影響直接反應在30~60天振盪上。此外，受到OLR呈南北振盪的影響，長江流域(日本)與Nino3地區海溫呈正(負)相關。模式模擬之季風肇始在SST冷年較SST暖年早，與實際相符，且模式在SST冷年之OLR 及30~60天振盪均較SST年強，顯示模式在南海季風之季風肇始及強度的年際變化，確實受到模式本身之30~60 天振盪影響。

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