We are indebted to Stephane Raynaud for his help in setting up the ocean model at IRI. We thank D. Chen, D. DeWitt, Y. Tang, T. Barnston, P. Chang, A. J. Busalacchi, and R. Murtugudde for their comments. R. H. Zhang would like to thank P. Chang for his help in constructing the SVD-based statistical model. The ECHAM4.5 ensemble mean wind stress data are provided by Dr. M. Tippett at IRI, who is greatly appreciated. The authors wish to thank anonymous reviewers for their comments that helped to improve the original manuscript. This research is supported by the IRI and its sponsors, and by NSF Grant 25-74200-F0960 (RK) and NASA Grant 25-74200-F5044 (RK).
Barnett, T P., M. Latif, N. Graham, M. Flugel, S. Pazan, and W. White, 1993: ENSO and ENSO-related predictability. Part I: Prediction of equatorial Pacific sea surface temperature with a hybrid coupled ocean–atmosphere model. J. Climate, 6 , 1545–1566.
Barnston, A G., and C G. Ropelewski, 1992: Prediction of ENSO episodes using canonical correlation analysis. J. Climate, 5 , 1316–1345.
Barnston, A G., M H. Glantz, and Y. He, 1999: Predictive skill of statistical and dynamical climate models in SST forecasts during the 1997–98 El Niño episode and the 1998 La Niña onset. Bull. Amer. Meteor. Soc., 80 , 217–243.
Busalacchi, A J., and J J. O’Brien, 1980: The seasonal variability in a model of the tropical Pacific. J. Phys. Oceanogr., 10 , 1929–1951.
Chang, P., L. Ji, and R. Saravanan, 2001: A hybrid coupled model study of tropical Atlantic variability. J. Climate, 14 , 361–390.
Chen, D., S E. Zebiak, A J. Busalacchi, and M A. Cane, 1995: An improved procedure for El Niño forecasting: Implications for predictability. Science, 269 , 1699–1702.
Chen, D., M A. Cane, S E. Zebiak, R. Canizares, and A. Kaplan, 2000: Bias correction of an ocean–atmosphere coupled model. Geophys. Res. Lett., 27 , 2585–2588.
Ji, M., A. Leetmaa, and V E. Kousky, 1996: Coupled model forecasts of ENSO during the 1980 and 1990s at the National Meteorological Center. J. Climate, 9 , 3105–3120.
Jin, F-F., and S-I. An, 1999: Thermocline and zonal adjective feedbacks within the equatorial ocean recharge oscillator model for ENSO. Geophys. Res. Lett., 26 , 2989–2992.
Kang, I-S., and J-S. Kug, 2000: An El Niño prediction system using an intermediate ocean and a statistical atmosphere. Geophys. Res. Lett., 27 , 1167–1170.
Keenlyside, N., 2001: Improved modeling of zonal currents and SST in the tropical Pacific. Ph.D. thesis, Monash University, 193 pp.
Keenlyside, N., and R. Kleeman, 2002: Annual cycle of the zonal currents in the equatorial Pacific. J. Geophys. Res., 107 .3093, doi:10.1029/2000JC000711.
Kirtman, B., Y. Fan, and E K. Schneider, 2002: The COLA global coupled and anomaly coupled ocean–atmosphere GCM. J. Climate, 15 , 2301–2320.
Kleeman, R., 1993: On the dependence of hindcast skill on ocean thermodynamics in a coupled ocean–atmosphere model. J. Climate, 6 , 2012–2033.
Levitus, S., 1982: Climatological Atlas of the World Ocean. NOAA Prof. Paper 13, 173 pp. and 17 microfiche.
McCreary, J P., 1981: A linear stratified ocean model of the equatorial undercurrent. Philos. Trans. Roy. Soc. London, 298 , 603–635.
McCreary, J P., and D. L. T. Anderson, 1991: An overview of coupled ocean–atmosphere models of El Nino and the Southern Oscillation. J. Geophys. Res., 96 , 3125–3150.
Neelin, J D., and F-F. Jin, 1993: Modes of interannual tropical ocean–atmosphere interaction a united view. Part II: Analytical results in the weak-coupling limit. J. Atmos. Sci., 50 , 3504–3522.
Reynolds, R W., N A. Rayner, T M. Smith, D C. Stokes, and W. Wang, 2002: An improved in situ and satellite SST analysis for climate. J. Climate, 15 , 1609–1625.
Rosati, A., K. Miyakoda, and R. Gudgel, 1997: The impact of ocean initial conditions on ENSO forecasting with a coupled model. Mon. Wea. Rev., 125 , 754–772.
Schneider, E K., D G. DeWitt, A. Rosati, B P. Kirtman, L. Ji, and J J. Tribbia, 2003: Retrospective ENSO forecasts: Sensitivity to atmospheric model and ocean resolution. Mon. Wea. Rev., 131 , 3038–3060.
Stockdale, T N., D. L. T. Anderson, J. O. S. Alves, and M A. Balmaseda, 1998: Global seasonal rainfall forecasts using a coupled ocean–atmosphere model. Nature, 392 , 370–373.
Syu, H-H., and J D. Neelin, 2000: ENSO in a hybrid coupled model. Part II: Prediction with piggyback data assimilation. Climate Dyn., 16 , 35–48.
Syu, H-H., J D. Neelin, and D. Gutzler, 1995: Seasonal and interannual variability in a hybrid coupled GCM. J. Climate, 8 , 2121–2143.
Wang, W., and M J. McPhaden, 2000: The surface-layer heat balance in the equatorial Pacific Ocean. Part II: Interannual variability. J. Phys. Oceanogr., 30 , 2989–3008.
Zhang, R-H., and S. Levitus, 1997: Interannual variability of the coupled tropical Pacific ocean–atmospheric system associated with the El Niño–Southern Oscillation. J. Climate, 10 , 1312–1330.
Zhang, R-H., S E. Zebiak, R. Kleeman, and N. Keenlyside, 2003: A new intermediate coupled model for El Niño simulation and prediction. Geophys. Res. Lett., 30 .2012, doi:10.1029/2003GL018010.
Zhang, R-H., R. Kleeman, S E. Zebiak, N. Keenlyside, and S. Raynaud, 2005: An empirical parameterization of subsurface entrainment temperature for improved SST simulations in an intermediate ocean model. J. Climate, 18 , 350–371.