全球暖化對聖嬰的影響看法仍相當分歧，目前尚無一致結論。本研究透過比較CMIP3模式中GFDL-CM2.1模式及UKMO-HADCM3模式對不同氣候情境模擬，探討暖化對聖嬰的影響，旨在歸納影響(1)兩類型聖嬰(即，中太平洋聖嬰與東太平洋聖嬰)出現頻率與(2)極端強聖嬰振幅的關鍵因子。研究中選擇GFDL-CM2.1模式及UKMO-HADCM3模式的原因是，兩個模式在現今氣候模擬(20C3M)對赤道東太平洋海溫的統計特徵(如平均態、變異度與偏度)皆與觀測非常相似，但在未來氣候模擬(A1B)則出現完全相反的結果。
在工業革命前控制實驗(pre-industrial control experiment，PICTL)長期模擬顯示，GFDL-CM2.1模式與UKMO-HADCM3模式皆顯示或中太平洋聖嬰(Central Pacific El Niño，簡稱CP-EN)偏多時期，赤道東太平洋平均場之斜溫層深度(或海溫、海水高度)變淺(小)，東太平洋聖嬰(Eastern-Pacific El Niño，簡稱EP-EN)偏多時期則反之。此外，研究發現平均場的計算若移除聖嬰與反聖嬰年，與不移除聖嬰年與反聖嬰年的結果相反(即，CP-EN偏多時期赤道東太平洋斜溫層深度變深)。此結果表示，聖嬰對平均場的調整作用不容忽略。
A1B模擬與PICTL實驗比較發現，平均場在赤道西－東太洋斜溫層厚度的斜率變化對兩類型聖嬰出現頻率具關鍵性影響。相較於PICTL實驗，UKMO-HADCM3模式在A1B模擬，平均場之赤道西－東太平洋斜溫層厚度之斜率明顯變小，由於赤道中太平洋斜溫層厚度變淺，有利於斜溫層－海溫回饋，CP-EN出現頻率明顯增多。然而，上述平均場變化在GFDL-CM2.1模式並不明顯，CP-EN出現頻率，因此未明顯增多。
至於暖化對極端強聖嬰振幅的影響，GFDL-CM2.1在A1B模擬顯著減弱，但UKMO-HADGEM1模式反而增強。GFDL-CM2.1極端強聖嬰振幅減弱，歸納原因為：(1)風-海溫回饋機制，(2)斜溫層-海溫回饋機制與(3)IOD-ENSO回饋機制的減弱。UKMO-HADGEM1模式，極端強聖嬰振幅在A1B模擬增加則歸納與赤道大西洋海溫變冷有關。

The change of ENSO (El Niño and Southern Oscillation) in future climate projection is still an open question. The change of the frequency of two types El Niños, the central Pacific El Nino (CP-EN), and eastern Pacific El Nino (EP-EN) and the amplitude of El Niño in future climate under the global warming was investigated by diagnosing the CMIP3 simulations. The GFDL-CM2.1 and UKMO-HADCM3 simulations are particularly selected for diagnosis because that both models successfully capture the behaviors of El Niño (e.g., SST variance and skewness) in present simulation (20C3M run), but shows a widely distinction in the future climate (A1B run).
In the pre-industry control experiment (PICTL), both models showing consistent results, reveals that that the occurrence of two type El Niños tightly related with the mean state of the depth of thermocline (i.e., D20, depth at 20oC, which is substantially modified by the ENSO events, in the equatorial eastern Pacific (EEP). The frequency of CP-EN increases substantially during the period when the mean state of D20 in EEP deepens, and vice versa. The change of the frequency of the two type El Niños in future climate (A1B) exhibits a characteristic of model dependent: the frequency of CP-EN increases significantly in UKMO-HADCM3, but does not have essential change in GFDL-CM2.1, which the D20 in EEP does not shows remarkable deepening in A1B.
As the amplitude of El Nino, the GFDL-CM2.1 shows significant decrease in A1B, but the El Niño amplitude remains unchanged and even shows a bit stronger in A1B than that in 20C3M. It shows that the change of the El Niño amplitude is primarily dominated by the following factors: 1) wind-evaporation-SST feedback, 2) thermocline-SST feedback, 3) IOD (Indian Ocean Diploe)-ENSO feedback, and 4) TA(tropical Atlantic)-ENSO feedback. The decrease of El Niño amplitude in GFDL-CM2.1 is due to the weakening of Bjerkness feedback (factor 1 and 2), and the weakening of IOD-ENSO feedback. Conversely, the enactment of El Niño amplitude in UKMO-HADCM3 is due to the enhancement of TA-ENSO feedback.

An S-I, Wang B., 2000: Interdecadal changes of the structure of the ENSO mode and impact on the ENSO frequency. J Climate, 13, 2044–2055.
An, Z. Ye, and W. W. Hsieh, 2006: Changes in the leading ENSO modes associated with the late 1970s climate shift:Role of surface zonal current. Geophys. Res. Lett., 33, L14609, doi:10.1029/2006GL026604
An, S.-I., J.-S. Kug, Y.-G. Ham, and I.-S. Kang, 2008: Successive modulation of ENSO to the future greenhouse warming. J. Climate, 21, 3–21.
Angell, J. D., and J. Korshover, 1978: Global temperature variation, surface-100 mb: An update into 1977. Mon. Wea. Rev., 106, 755–760.
Ashok, K., Z. Guan, and T. Yamagata, 2003: Influence of the Indian Ocean Dipole on the Australian winter rainfall. Geophys. Res. Lett., 30, 1821, doi:10.1029/2003GL017926.
Ashok, K., Z. Guan, N. H. Saji, and T. Yamagata, 2004: Individual and combined influences of ENSO and Indian Ocean dipole on the Indian summer monsoon. J. Climate, 17, 3141–3155.
Ashok, K., S. K. Behera, S. A. Rao, H. Weng, and T. Yamagata, 2007: El Niño Modoki and its possible teleconnection. J. Geophys. Res., 112, C11007, doi:10.1029/2006JC003798.
Boer, G.J., 2009: Changes in Interannual Variability and Decadal Potential Predictability under Global Warming. J. Climate, 22, 3098-3109. DOI 10.1175/2008JCLI2835.1
Berlage, H. P., 1966: The Southern Oscillation and world weather. K. Ned. Meteor.Inst. Meded. Verh., 88, 135–152.
Capotondi, A., A. Wittenberg, and S. Masina, 2006: Spatial and temporal structure of tropical Pacific interannual variability in 20th century coupled simulations. Ocean Modell., 15, 274–298.
Collins, M., 2000a: The El Niño-Southern Oscillation in the second Hadley Centre coupled model and its response to greenhouse warming. J. Climate, 13, 1299–1312.
Collins, M., 2000b: Understanding uncertainties in the response of ENSO to greenhouse warming. Geophys. Res. Lett., 27, 3509–3512.
Collins, M., 2005: El Niño - or La Niña-like climate change? Climate Dyn., 24, 89–104.
Collins M., S.-I. An, W. Cai, A.Ganachaud, E.Gguilyardi, F.-F. Jin, M. Jochum, M. Lengaigne, S. Power, A. Timmermann, G.Vecchi, and A. Wittenberg, 2010: The impact of global warming on the tropical Pacific ocean and El Niño. Nature Geoscience, 3, 391-397, DOI:10.1038/NGEO986
Delworth T L, Broccoli A J, Rosati A et al., 2006: GFDLs CM2 global coupled climate models (Part 1): Formulation and simulation characteristics. J. Climate, 19(5), 643–674.
Fedorov, A. V., and S. G. Philander, 2000: Is El Niño changing? Science, 288, 1997–2002.
Flügel, M., P. Chang, and C. Penland, 2004: The role of stochastic forcing in modulating ENSO predictability. J. Climate, 17, 3125–3140.
Gu D, Philander S G H, 1995: Secular changes of annual and interannual variability in the tropics during the past century. J Climate, 8(4), 964–876.
Hoerling, M. P., A. Kumar, and M. Zhong, 1997: El Niño, La Niña, and the nonlinearity of their teleconnections. J. Climate, 10, 1769–1786.
Jin, F. F., 1997a: An equatorial ocean recharge paradigm for ENSO. Part I: Conceptual model. J. Atmos. Sci., 54, 811–829.
Jin, F. F., 1997b: An equatorial ocean recharge paradigm for ENSO. Part II: A stripped-down coupled model. J. Atmos. Sci., 54, 830–847.
Kang I.-S. and J.-S. Kug, 2002: El Niño and La Niña SST Anomalies: Asymmetric Characteristics Associated with Their Wind Stress Anomalies. J. Geophy. Rea., 107(D19), 4372, doi:10. 1029/2001JD000393.
Kao, H.‐Y., and J.‐Y. Yu, 2009: Contrasting eastern‐Pacific and central‐Pacif ictypes of El Niño. J. Climate., 22, 615–632, doi:10.1175 /2008JCLI2309.1
Kirtman, B. P., K. Pegion, and S. Kinter, 2005: Internal atmospheric dynamics and climate variability. J. Atmos. Sci., 62, 2220-2233.
Kug, J. S., & Kang, I. S., 2006: Interactive feedback between ENSO and the Indian Ocean. Journal of Climate, 19(9), 1784–1801.
Kug, J. S., Li, T., An, S. I., Kang, I. S., Luo, J. J., Masson, S., 2006: Role of the ENSO-Indian Ocean coupling on ENSO variability in a coupled GCM. Geophysical Research Letters, 33(9), doi:10.1029/2005gl024916
Knutson, T. R., and S. Manabe, 1995: Time-mean response over the tropical Pacific to increased CO2 in a coupled ocean-atmosphere model. J. Climate, 8, 2181–2199.
Knutson, T. R., and D. Gu, 1997: Simulated ENSO in a global coupled ocean-atmosphere model: Multidecadal amplitude modulation and CO2 sensitivity. J. Climate, 10, 138–161.
Kug, J.‐S., F.‐F. Jin, and S.‐I. An, 2009: Two types of El Niño events:Cold tongue El Niño and warm pool El Niño, J. Clim., 22, 1499–1515,doi:10.1175/2008JCLI2624.1.
Larkin, N.-K., and D. E. Harrison, 2001: ENSO warm (EL Niño) and cold (La Niña) event life cycles: ocean surface anomaly patterns, their symmetries, asymmetries, and implications. J. Climate, 15, 1118–1140.
Larkin, N.K., and D.E. Harrion, 2005a: Global seasonal temperature and precipitation anomalies during El Niño autumn and winter. Geophys. Res. Lett., 32, L16705, doi:10.1029/2005GL022860.
Larkin, N. K., and D. E. Harrison, 2005b: On the definition of El Niño and associated seasonal average U.S. weather anomalies. Geophys. Res. Lett., 32, L13705, doi:10.1029/2005GL022738.
Lau, N. C., & Nath, M. J., 1996: The role of the ''atmospheric bridge'' in linking tropical Pacific ENSO events to extratropical SST anomalies. Journal of Climate, 9(9), 2036–2057.
Lau, N.-C., A. Leetma, and M.J. Nath, 2008: Interactions between the responses of North American climate to El Niño–La Niña and to the secular warming trend in the Indian–Western Pacific Oceans. J. Climate, 21(3), 476–494.
Lee, T., and M. J. McPhaden, 2010: Increasing intensity of El Niño in the central‐equatorial Pacific. Geophys. Res. Lett., 37, L14603, doi:10.1029/2010GL044007.
Li, T., B. Wang, C.-P. Chang, and Y. Zhang, 2003: A theory for the Indian Ocean dipole-zonal mode. J. Atmos. Sci., 60, 2119–2135.
Li, T., P. Liu, X. Fu, B. Wang, and G. Meehl, 2006: Spatiotemporal structures and mechanisms of the tropospheric biennial oscillation in the Indo-Pacific warm ocean regions. J. Climate., 19, 3070–3087.
Manabe, S., and R. T. Wetherald, 1975: The effects of doubling the CO2 Concentration on the climate of a general circulation model. J. Atmos. Sci., 32, 3–15.
Meehl, G. A., G. W. Branstator, and W. M. Washington, 1993: Tropical Pacific interannual variability and CO2 climate change. J. Climate, 6, 42–63.
Meehl, G.A., and H. Teng, 2007: Multi-model changes in El Niño teleconnections over North America in a future warmer climate. Clim. Dyn., 29, 779–790. doi:10.1007/s00382-007-0268-3
Meyers, G., P. Mcintosh, L. Pigot, and M. Pook, 2007: The years of El Niño, La Niña and interactions with the tropical Indian Ocean, J. Climate .
Müller, W.A. and E. Roeckner, 2008: ENSO teleconnections in projections of future climate in ECHAM5/MPI-OM. Clim. Dyn., 31, 533–549. doi:10.1007/s00382-007-0357-3
Nitta, T., and S. Yamada, 1989: Recent warming of tropical sea surface temperature and its relationship to the Northern Hemisphere circulation. J. Meteor. Soc. Japan, 67, 375–383.
Okumura, Y., and C. Deser, 2010: Asymmetry in the duration of El Nin˜o and La Nin˜a. J. Climate, 23, 5826–5843.
Picaut, J., Masia, F., and du Penhoat, Y., 1997: An advective-reflective conceptual model for the oscillatory nature of the ENSO. Science, 277, 663–666.
Ramanathan, V., and J. A. Coakley, Jr., 1978: Climate modeling through radiative-convective models. Rev. Geophys. Space Phys., 16, 465–689.
Schneider, E.K., M.J. Fennessy, and J.L. Kinter III, 2009: A Statistical/Dynamical Estimate of Winter ENSO Teleconnections in a Future Climate. J. Climate.
Schneider, S. H., 1975: On the carbon dioxide-climate confusion. J. Atmos. Scl., 32, 2060–2066.
Suarez M J, Schopf P S., 1988: A delayed action oscillator for ENSO. J. Atmos. Sci., 45, 3283–3287
Saji, N. H., B. N. Goswami, P. N. Vinayachandran, and T. Yamagata, 1999: A dipole mode in the tropical Indian Ocean. Nature, 401, 360–363.
Saji, N. H., and T. Yamagata, 2003: Structure of SST and surface wind variability during Indian Ocean dipole mode events: COADS observations. J. Climate, 16, 2735–2751.
Terray, P., & Dominiak, S., 2005: Indian Ocean sea surface temperature and El Niño-Southern Oscillation: A new perspective. Journal of Climate, 18(9), 1351–1368.
Timmermann, A.,J. Oberhuber, A. Bacher, M. Esch, M. Latif, and E. Roeckner, 1999: Increased El Niño frequency in a climate model forced by future greenhouse warming. Nature, 398, 694–697.
Trenberth, K. E., 1990: Recent observed interdecadal climate changes in the Northern Hemisphere. Bull. Amer. Meteor. Soc., 71, 988–993.
Trenberth, K.E., 1997: The Definition of El Niño. Bull. Amer. Met. Soc., 78, 2771–2777.
Trenberth, K.E., and L. Smith, 2009: Variations in the Three-Dimensional Structure of the Atmospheric Circulation with Different Flavors of El Niño. J. Climate., 22, 2978-2991. DOI 10.1175/2008JCLI2691.1
van Oldenborgh, G. J., S. Philip, and M. Collins, 2005: El Niño in a changing climate: A multi-model study. Ocean Sci., 1, 81–85.
Vecchi, G. A., B. J. Soden, A. T. Wittenberg, I. M. Held, A. Leetmaa, and M. J. Harrison, 2006: Weakening of tropical Pacific atmospheric circulation due to anthropogenic forcing. Nature, 441, 16 doi:10.1038/nature04744
Vecchi, G. A., and A. T. Wittenberg, 2010: El Niño and our future climate: Where do we stand ? Wires climate change. 1, 260–270.
Wang B, Wang Y., 1996: Temporal structure of the Southern Oscillation as revealed by waveform and wavelet analysis. J Climate, 9, 1586—1598.
Wang, C., Weisberg, R. H., and Virmani, J. I., 1999: Western Pacific interannual variability associated with the El Niño-Southern Oscillation. J. Geophys. Res., 104, 5131–5149.
Wang, G., and H. H. Hendon, 2007: Sensitivity of Australian rainfall to inter‐El Niño variations, J. Clim., 20, 4211–4226, doi:10.1175/JCLI4228.1.
Webster, P. J., A. M. Moore, J. P. Loschnigg, and R. R. Leben, 1999: Coupled ocean-atmosphere dynamics in the Indian Ocean during 1997-1998. Nature, 401, 356–360.
Weisberg, R. H., and Wang, C., 1997: A western Pacific oscillator paradigm for the El NiñoSouthern Oscillation. Geophy. Res. Lett., 24, 779–782.
Weng, H., K. Ashok, S. K. Behera, S. A. Rao, and T. Yamagata, 2007: Impacts of recent El Niño Modoki on dry/wet conditions in the Pacificrim during boreal summer. ClimateDynamics, 29, 113–129, doi:10.1007/s00382-007-0234-0.
Weng, H., Wu, G. Liu, Y., Behera, S. K. and T. Yamagata, 2011: Anomalous summer climate in China influenced by the tropical Indo-Pacific Oceans. Clim Dyn., 36, 769–782, doi:10.1007/s00382-009-0658-9.
Wu, R. G., & Kirtman, B. P., 2004a: Impacts of the Indian Ocean on the Indian summer monsoon-ENSO relationship. Journal of Climate, 17(15), 3037–3054.
Wu, R. G., & Kirtman, B. P., 2004b: Understanding the impacts of the Indian ocean on ENSO variability in a coupled GCM. Journal of Climate, 17(20), 4019–4031.
Yang, H., and Q. Zhang, 2008: Anatomizing the ocean role in ENSO changes under global warming. J. Climate, 21, 6539–6555.
Yeh, S.-W., and B. P. Kirtman, 2005: Pacific decadal variability and decadal ENSO amplitude modulation. Geophys. Res. Lett., 32, L05703, doi:10.1029/2004GL021731.
Yeh, S.‐W., J.‐S. Kug, B. Dewitte, M.‐H. Kwon, B. Kirtman, and F.‐F. Jin, 2009: El Niño in a changing climate, Nature, 461, 511–514,doi:10.1038/nature08316.
Yu, J. Y., Weng, S. P., & Farrara, J. D., 2003: Ocean roles in the TBO transitions of the Indian-Australian monsoon system. Journal of Climate, 16(18), 3072–3080.
Yu, J. Y., 2005: Enhancement of ENSO's persistence barrier by biennial variability in a coupled atmosphere-ocean general circulation model. Geophysical Research Letters, 32(13), –. doi:10.1029/2005gl023406
Yu, J.-Y., and Kao, H.-Y., 2007: Decadal Changes of ENSO Persistence Barrier in SST and Ocean Heat Content Indices: 1958-2001. J. Geophys. Res., 112, D13106, doi:10.1029/2006JD007654.
http://www.pmel.noaa.
http://nomads.gfdl.noaa.gov