在熱帶地區最明顯的氣候訊號就是聖嬰現象(ENSO)，週期大約是2-7年，對於全球的社會與經濟造成很大的影響。因為至今仍然還沒有一個方法能從觀測資料中萃取波動特徵，因此ENSO的起源和發展機制仍不清楚。在本文中我們利用經驗正交模分析從觀測資了中萃取出特定正交模震盪，對於ENSO現象有更近一步了解。
資料來源是採用NCEP/NCAR每日再分析資料，前置處理將每日資料作成五日平均資料，一方面節省空間又可以比月平均資料的解析度來得細密。資料時間長度從1979~2003年，共25年資料，分析範圍為60oS~60oN，水平解析度為2.5o*2.5o。垂直方向一共有4層(1000mb、850mb、500mb、200mb)。採用的變數有三個:重力位高度(hgt)、溫度場(tmp)、外逸長波輻射(OLR)。
本文利用結合SVD-CSD(奇值分解-餘弦正弦展開法)算出傳遞矩陣和POP(主要震盪型態)波動特徵兩種方法，而成經驗正交模分析(ENMA)方法，應用在NCEP/NCAR重新分析資料上，從觀測資料分解後的正交模震盪中，能夠算出正交模的波譜值與確認波動的傳播和變化的分布。
首先指出ENSO現象是由兩個明顯的波動所組成，一個波的週期約是60個月，在熱帶地區有明顯向東傳遞趨勢。另一個波是有43個月的週期，產生在南美洲沿岸，有向西傳遞的趨勢。結果顯示特定週期及ENSO相關發展能清楚表現出複雜的大氣-海洋調節過程。

no

黃玉旻，2003：NCEP重新分析資料中的有限時間不穩定與伴隨的奇異模。國立中央大學大氣物理研究所碩士論文，83頁。
Brockwell, P. J., and R. A. Davis, 1991: Time Series: Theory and Methods. Second ed. Springer-Verlag, 577 pp.
Farrell B. F., and P.J. Ioannou, 1996： Generallized stability theory. Part I：autonomous operators. Journal of the atmospheric sciences,14,2025-2040.
Fedorov, A. V., S. L. Harper, S. G. Philander, B. Winter, and A. Wittenberg, 2003: How predictable is El Nino? Bull. Am. Meteorol. Soc., 84, 911-919.
Golub, G. H. and C. F. Van Loan, 1996: Matrix computations. Johns Hopkins Univ. Press, Baltimore, 694 pp.
Harrison, D. E., and N. K. Larkin, 1998: El Nino-Southern Oscillation sea surface temperature and wind anomalies, 1946-1993. Reviews of Geophysics, 36, 353-399.
Hasselmann, K., 1988: PIPs and POPs: The reduction of complex dynamical systems using principal interaction and oscillation patterns. Journal of Geophysical Research, 93, 11015-11021.
Jin, F.-F., J. D. Neelin, and M. Ghil, 1994: El Niño on the devil’s staircase: Annual subharmonic steps to chaos. Science, 264, 70-72.
Lee Y.-A., 2002: A T-EOF based prediction method. Journal of Climate, 15, 226-234.
Lee Y.-A., 2004： Alternative approaches to estimating linear propagator and Finite-Time Growth Rates from data. Journal of Climate, (in revision).
Lee Y.-A., 2004： Observed normal mode characteristics of the El Niño-Southern Oscillation. Journal of Climate, (Submitted).
Neelin, J. D., D. S. Battisti, A. C. Hirst, F. Jin, Y. Wakata, T. Yamagata, and S. E. Zebiak, 1998： ENSO theory. Journal of Geophysical Research, 103, 14261-14290.
Penland, C., 1989: Random forcing and forecasting using principal oscillation pattern analysis. Monthly Weather Review, 117, 2165-2185
Penland C., and T.Magorian,1993： Prediction of Nino 3 sea surface Temperature using linear inverse modeling. Journal of Climate,6,1067-1076.
Penland C., and P.D.Sardeshmukh,1995： The optimal growth of tropical Sea Surface Temperature Anomalies. Journal of Climate,8,1999-2024.
Preisendorfer, R. W., and C. D. Mobley, 1988: Principal Component Analysis in Meteorology and Oceanography. Elsevier, Amsterdam, 425 pp.
Rasmusson, E. M., and T. H. Carpenter, 1982: Variations in tropical sea surface temperature and surface wind fields associated with the Southern Oscillation/El Nino. Monthly Weather Review, 110, 354-384.
von Storch, H., G. Buerger, R. Schnur, and J. von Storch, 1995: Principal oscillation patterns: a review. J. Climate, 8, 377-400.
von Storch, H., and F. W. Zwiers, 1999: Statistical analysis in climate research. Cambridge University Press, London, 484 pp.
Wallace, J. M., E. M. Rasmusson, T. P. Mitchell, V. E. Kousky, E. S. Sarachik, and H. von Storch, 1998: On the structure and evolution of ENSO-related climate variability in the tropical Pacific: lessons from TOGA. Journal of Geophysical Research, 103, 14241-14259.
Yu, J.-Y., C. R. Mechoso, J. C. McWilliams, and A. Arakawa, 2001: Impacts of the Indian Ocean on the ENSO cycle. Geophys. Res. Lett., 29, 10.1029/2001GL014098.