台灣位於亞洲夏季季風區的海陸交接位置，深受季風所帶來之影 響，其中季內振盪的移動與發展對季風的肇始與中斷息息相關，因此 季內振盪的掌握優劣將直接的影響模式預報能力。但在過去數十年的 氣候模式研究中發現，模式普遍對季內振盪的模擬表現不佳，無法掌 握其訊號。因此，許多研究致力於如何改善模式的模擬能力，其中方 法之一為使用考慮海氣以及其他交互作用的耦合模式，但模擬能力優 劣仍有不一致的結論。
本研究選用 CMIP-5 資料，同時具備 Historical run 的耦合模式 模擬以及 AMIP run 單一大氣模式模擬，藉此比較 AGCM 以及 CGCM 模 擬的差異。模式分別為 CMCC-CM、CNRM-CM5、GFDL-CM3、IPSL-CM5A-MR、
MIROC-5、MPI-ESM-MR 以及 MRI-CGCM3。各模式評估時間相同，除降 水觀測資料為 1997 至 2008，其餘觀測與模式資料皆為 1995 至 2005。
所有模式水平解析度皆統一內插為 2˚x 2˚。本研究使用
Daubechies(1998)小波分析方法來濾波，並使用空間相關係數 (Pattern Correlation Coefficient)以及均方根誤差(Root Mean Square Error)來評估模式模擬的優劣。
在平均場以及總變異量的模擬中發現，除低解析度的模式外，
CMIP-5 的模式模擬表現要過去 CMIP-3 來得好，較能夠模擬出季內振 盪的訊號，無論是訊號的位置還是強度都較過去接近實際觀測，與 Kim et.al(2013)研究結果一致。整體表現上，系集平均(Ensemble mean)較單一模式模擬為佳，單一模式又以 CGCM 模擬較 AGCM 來得好。
AGCM 模式解析度越高有越容易高估季風區降水以及風場訊號的 趨勢，反之，低解析度 AGCM 模式容易低估訊號。考慮海氣以及其他 交互作用的中、高解析度模式 CGCM 模擬，能改善 AGCM 高估的問題，
讓結果更接近實際觀測，但是低解析度的模式則沒有太大的改善。模 式加入海氣以及其他交互作用的同時，也必須要兼顧模式的解析度在 一定水準之上，如此才能夠有較好的模擬。
在 EOF1(Empirical Orthogonal Function)分析中，大多數模式 都有不錯的表現，特別是風場的模擬優於降水及渦度。系集平均同樣 有相對最佳的模擬結果，無論強度還是訊號的空間分布，孟加拉灣、
南海以及西北太平洋都有非常好的表現。CGCM 整體優於 AGCM，CGCM 能改善 AGCM 模式在西北太平洋訊號過於偏東的現象。渦度場在所有 模式中都能夠模擬出位於降水場西北方的空間結構(Hsu and Weng 2001)。此空間配置將有利於對流向西北方移動發展，提供模式模擬 訊號北移的基本條件。
本研究利用風場 EOF-1 分析得到的特徵向量時間序列，將大於一
倍標準差以及小於負一倍標準差的資料取出，定義為 ISO 西風相位以 及東風相位時期，並分別比較模式的模擬結果。西風相位時期南海以 及西北太平洋有一大範圍的降水及正渦度訊號區域，如此的配置有利 於對流、颱風的生成以及提升季風的活耀度。東風相位時期則相反，
西北太平洋對流受到抑制，不利於降水的發生，與前人研究結果一致。
同樣無論在東風、西風相位時期，系集平均能有最佳的模擬，各別模 式也能夠模擬出此東、西風相位差異，但中、高解析度模式仍然較易 高估訊號強度，低解析度則明顯低估。在西北太平洋地區，AGCM 的 模擬訊號易過度向中太平洋延伸，CGCM 中能有一定程度的改善。在 空間相關係數以及 RMSE 的檢驗中也能看到同樣的結果，系集平均優 於個別模式，整體上 CGCM 的個別模式又優於 AGCM。
夏季 ISO 訊號向北移動的特性對東南亞以及台灣地區天氣有相 當大的影響。因此，本研究分析 ISO 北移模擬情形。觀測資料中 ISO 降水訊號從孟加拉灣赤道地區開始隨時間向東發展，走到南海以及菲 律賓海約 10˚N 時達到最強，隨後訊號開始轉為向北朝日本移動，或 向西北方移動通過台灣進入中國大陸並快速消散。觀測的波動自赤道 開始北傳至 30˚N 左右，週期約為 40 天。
AGCM 的模擬大多無法掌握出北傳特性，中、高解析度 CGCM 表現 則較佳，有較多模式能夠模擬出波動北傳的訊號。波動的訊號交替同
樣在 CGCM 有較好的表現，周期也與觀測相近，約為 40 天。AGCM 所 模擬的波動，則普遍沒有清楚的訊號交替特性，僅少數模式有模擬能 力並計算週期，其餘模式無法分析與討論。
綜合以上分析，考慮海氣以及其他交互作用的中、高解析度耦合 模式，模擬普遍優於單一大氣模式，與 Fu et al.(2002)研究結果一 致。但在本研究中所見，模式加入了海氣交互作用後，雖普遍有改善 ISO 總變異量及向北傳遞的模擬，但並非完全一致，模式的解析度必 須在一定水平之上，此時加入海氣以及其他交互作用才能夠產生明顯 的改善，模式解析度過低，海氣及其他交互作用所帶來的影響仍然非 常有限。未來模式若能適度的提升解析度並且加入海氣耦合系統，將 有利於夏季季內擾動的模擬，以及掌握其北傳特性，並有助於提升台 灣以及東南亞地區的預報準確度。
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Fig. 3.2 模式與觀測之平均場相關係數與 RMSE。(a)降水場 (b)u850
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Fig.3.4 模式與觀測之相關係數與 RMSE。(a)降水總變異量 (b) u850 總變異量。
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Fig.3.5 模式模擬 AGCM 與 CGCM 降水總變異量沿經度的變化，5˚N~30˚
N 地區平均，與 GPCP 觀測資料(黑色實線)比較。
(由上至下分別為：較高解析度模式、中解析度模式、較低解析度模式、
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Fig.3.7 模式與觀測之相關係數與 RMSE。(a) 降水 ISO 變異量 (b) u850 ISO 變異量。
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