季內振盪(ISO)為熱帶大氣系統的重要訊號，西太平洋地區ISO的活動與熱帶天氣及短期氣候變化相關。本篇研究除了探討颱風季七-九月西太平洋ISO與SST之年際關連外，亦利用高解玎度ECHAM4 T106與ECHAM5/MPI-OM海氣耦合模式來探討ISO年際變化模擬的情形。觀測場分析顯示，颱風季季內振盪氣候降水變異量最大值出現於熱帶風暴(TS)活動十分活躍之西北太平洋地區，而渦度變異量中心位於降水變異量中心的北/西北方。西北太平洋ISO的年際變化與七-九月NESO訊號具遙相關連，其中以西北太伴洋東南區域(WNPSE，150°-180E°, 0°-15°N)ISO活動與ENSO相關最顯著。暖年(Nino3.4 SSTA高於0.8個標準差)時，西太平洋暖海溫向東延伸至中太平洋，可能有利30-60天振盪沿赤道的東移。當30-60天振燙東移至換日線時，30-60天正渦度位於位於30-60天降水之西北前緣，對流由中歹錦洋地區轉向西北移行至臺灣降近。暖年沿ISO西北移行路徑上，30-60天對流活躍，有較多的TS發生。冷年(Nino3.4 SSTA小於0.8個標準差)時，熱帶地區ISO訊號微弱，WNPSE 30-60天振盪為負距平，TS發生頻率亦較低。 ECHAM4 T106及ECHAM5/MPI-OM耦合模式圾可模擬颱風季季內降水及渦度變異量之空間分佈，但ECHAM4 T106模式在定量上估低30-60天及10-20天降水變異量，海氣耦合模式模擬之降水變異量較接近觀測。ECHAM4 T106可模擬暖年沿赤導東移之30-6-天振盪 ，然而，自中太平洋向西北發展之30-60天ISO僅移行至155°E，10°N附近。ECHAM5/MPI_OM耦合模式模擬30-6-天振盪移行特徵與觀測較為接近。推測海氣交互作用可能是維持30-6-天振盪強度及持續向西北移行過程之重要關鍵。西太平洋地區10-20天振盪的年際變化與30-60天振盪強度及持續向西已移行過程之重要關鍵。西太平洋地區10-20天振盪的年際變化與30-60天不同，推測造成此兩頻段年際變化的機制可能不完全相同。而模式模擬10-20天振盪的能力有限，ECHAM$ T106及ECHAM5/MPI-OM均低估10-20天變異量距平值。

Intraseasonal oscillation (ISO) is an important signal in the tropical atmospheric system. the tropical weather and short-term climate variability over the western Pacific are related to the ISO activity. This study not only investigates the interannual correlation between ISO over the western Pacific and SST during typhoon season (July to September), but also examine the simulations of ISO interannual variations in high-resolution (T106) ECHAM$ atmospheric GCM and CEHAM5/MPI-OM air-sea coupled GCM. The analysis results from observation data show that the largest climatological variance of intraseasonal precipitation during typhoon season occurs over the western Pacific where the tropical strom (TS) activity is vigorous. The maximum variance of vorticity is located to the north/northwest of precipitation variance center. The interannual variation of ISO over the western Pacific has teleconnections with ENSO. The ISO shows the most significant correlation with ENSO signal in the southeastern region of western North Pacific (WNPSE，150°-180°E, 0°-15°N). During warm years (Nino3.4 SSTA greater than 0.8 standard deviation), the warm SST over the western Pacific extends eastward that might be beneficial for the 30-60 day ISO propagation eastward along equator. Once the 30-60 day ISO arrives at dateline, the 30-60 day positive vorticity appears to the northwest of 30-60 day precipitation. Meanwhile, ISO turns to migrate northwestward from central Pacific toward Taiwan. Along the route of northwestward-propagating ISO, during warm years, the 30-60 day convection is active and the TS frequency is also increased. During cold years (Nino3.4 SSTA smaller than 0.8 standard deviation), the ISO signals are weak in the tropics, 30-60 day ISO shows negative variance anomalies in WNPSE region, as well as the TS frequency is decreased. The spatial distributions of intrasesonal precipitation and vorticity during typhoon season cab be adequately simulated by ECHAM4 T106 and ECHAM5/MPI-OM. However, ECHAM4 T106 underestimates the variances of 30-6- day and 10-20 day precipitation. The ECHAM5/MPI OM produces a realistic intraseasonal precipitation variance. ECHAM5 T106 is able to simulate the eastward-propagating ISO along the equator. However, the northwestward-propagating ISO in ECHAM4 T106 can only propagate to 155°E, 10°N after it migrates from central Pacific. The propagation of 30-60 day ISO simulated by ECHAM5/MPI-OM is similar to observation. It suggests that the air-sea interaction is an important factor for maintaining the northwestward-propagating ISO. The mechanisms responsible for the interannual variability of 30-60 day and 10-20 day ISO might not be the same. Both ECHAM4 T106 and ECHAM5/MPI-OM models underestimate the variance anomalies of 10-20 day ISO.