This research was supported by the National Oceanic and Atmospheric Administration (NOAA) Pan American Climate Studies (PACS) program through Grant NA17EC1483. The authors thank Mr. Eric Hackert for technical assistance with the Gent–Cane ocean model, Dr. William Kessler and an anonymous reviewer for helpful comments on the manuscript, and Dr. David Behringer for valuable input regarding the NCEP GODAS details and biases. The authors also acknowledge the SSM/I, NOAA/PMEL/TAO, and NOAA Climate Diagnostics Center (CDC) data distribution Web sites for providing the observational data used.
Behringer, D., , and Y. Xue, 2004: Evaluation of the global ocean data assimilation system at NCEP: The Pacific Ocean. Preprints, Eighth Symp. on Integrated Observing and Assimilation Systems for Atmosphere, Ocean, and Land Surface, Seattle, WA, Amer. Meteor. Soc., CD-ROM, 2.3.
Bengtsson, L., , M. Kanamitsu, , P. Kallberg, , and S. Uppala, 1982: FGGE 4-dimensional data assimilation at ECMWF. Bull. Amer. Meteor. Soc., 63 , 29–43.
Chen, D., , L. M. Rothstein, , and A. J. Busalacchi, 1994: A hybrid vertical mixing scheme and its application to tropical ocean models. J. Phys. Oceanogr., 24 , 2156–2179.
Deser, C., , and J. M. Wallace, 1990: Large-scale atmospheric circulation features of warm and cold episodes in the tropical Pacific. J. Climate, 3 , 1254–1281.
Eden, C., , and A. Timmerman, 2004: The influence of the Galápagos Islands on tropical temperatures, currents and the generation of tropical instability waves. Geophys. Res. Lett., 31 .L15308, doi:10.1029/2004GL020060.
Gent, P. R., , and M. A. Cane, 1989: A reduced gravity, primitive equation model of the upper equatorial ocean. J. Comput. Phys., 81 , 444–480.
Gordon, C. T., , A. Rosati, , and R. Gudgel, 2000: Tropical sensitivity of a coupled model to specified ISCCP low clouds. J. Climate, 13 , 2239–2260.
Harrison, M. J., , A. Rosati, , B. J. Soden, , E. Galanti, , and E. Tziperman, 2002: An evaluation of air–sea flux products for ENSO simulation and prediction. Mon. Wea. Rev., 130 , 723–732.
Hayes, S. P., , L. J. Mangum, , J. Picaut, , A. Sumi, , and K. Takeuchi, 1991: TOGA–TAO: A moored array for real-time measurements in the tropical Pacific Ocean. Bull. Amer. Meteor. Soc., 72 , 339–347.
Kessler, W. S., , L. M. Rothstein, , and D. Chen, 1998: The annual cycle of SST in the eastern tropical Pacific, diagnosed in an ocean GCM. J. Climate, 11 , 777–799.
Kessler, W. S., , G. C. Johnson, , and D. W. Moore, 2003: Sverdrup and nonlinear dynamics of the Pacific equatorial currents. J. Phys. Oceanogr., 33 , 994–1008.
Kiladis, G. N., , and H. F. Diaz, 1989: Global climatic anomalies associated with extremes in the Southern Oscillation. J. Climate, 2 , 1069–1090.
Kummerow, C., and Coauthors, 2000: The status of the Tropical Rainfall Measuring Mission (TRMM) after two years in orbit. J. Appl. Meteor., 39 , 1965–1982.
Levitus, S., , and T. P. Boyer, 1994: Temperature. Vol. 4, World Ocean Atlas 1994, NOAA Atlas NESDIS 4, 117 pp.
Lukas, R., 1986: The termination of the equatorial undercurrent in the eastern Pacific. Progress in Oceanography, Vol. 16, Pergamon Press, 63–90.
Luo, J-J., , S. Masson, , E. Roeckner, , G. Madec, , and T. Yamagata, 2005: Reducing climatology bias in an ocean–atmosphere CGCM with improved coupling physics. J. Climate, 18 , 2344–2360.
Marzeion, B., , A. Timmermann, , R. Murtugudde, , and F-F. Jin, 2005: Biophysical feedbacks in the tropical Pacific. J. Climate, 18 , 58–70.
Mechoso, C. R., and Coauthors, 1995: The seasonal cycle over the tropical Pacific in coupled ocean–atmosphere general circulation models. Mon. Wea. Rev., 123 , 2825–2838.
Mitchell, T. P., , and J. M. Wallace, 1992: The annual cycle in equatorial convection and sea surface temperature. J. Climate, 5 , 1140–1156.
Murtugudde, R., , R. Seager, , and A. Busalacchi, 1996: Simulation of the tropical oceans with an ocean GCM coupled to an atmospheric mixed-layer model. J. Climate, 9 , 1795–1815.
Murtugudde, R., , J. Beauchamp, , C. R. McClain, , M. Lewis, , and A. J. Busalacchi, 2002: Effects of penetrative radiation on the upper tropical ocean circulation. J. Climate, 15 , 470–486.
Nigam, S., 1997: The annual warm to cold phase transition in the eastern equatorial Pacific: Diagnosis of the role of stratus cloud-top cooling. J. Climate, 10 , 2447–2467.
Pacanowski, R. C., , and A. Gnanadesikan, 1998: Transient response in a Z-level ocean model that resolves topography with partial cells. Mon. Wea. Rev., 126 , 3248–3270.
Pacanowski, R. C., , and S. M. Griffies, 1999: The MOM3 manual. GFDL Ocean Group Tech. Rep. 4, NOAA/Geophysical Fluid Dynamics Laboratory, Princeton, NJ, 680 pp.
Price, J. F., , R. A. Weller, , and R. Pinkel, 1986: Diurnal cycling: Observations and models of the upper ocean response to diurnal heating, cooling, and wind mixing. J. Geophys. Res., 91 , 8411–8427.
Reynolds, R. W., , and T. M. Smith, 1994: Improved global sea surface temperature analyses using optimum interpolation. J. Climate, 7 , 929–948.
Ropelewski, C. F., , and M. S. Halpert, 1987: Global and regional scale precipitation patterns associated with the El Niño/Southern Oscillation. Mon. Wea. Rev., 115 , 1606–1626.
Schneider, E. K., , and Z. Zhu, 1998: Sensitivity of the simulated annual cycle of sea surface temperature in the equatorial Pacific to sunlight penetration. J. Climate, 11 , 1932–1950.
Stevenson, M. R., , and B. A. Taft, 1971: New evidence of Equatorial Undercurrent east of the Galápagos Islands. J. Mar. Res., 29 , 103–115.
Stockdale, T. N., , A. J. Busalacchi, , D. E. Harrison, , and R. Seager, 1998: Ocean modeling for ENSO. J. Geophys. Res., 103 , 14325–14356.
Sun, D-Z., , J. Fasullo, , T. Zhang, , and A. Roubicek, 2003: On the radiative and dynamical feedbacks over the equatorial Pacific cold tongue. J. Climate, 16 , 2425–2432.
Takahashi, T., and Coauthors, 1999: Net sea-air CO2 flux over the global oceans: An improved estimate based on the sea-air CO2 difference. Proc. Second Int. Symp. on CO2 in the Oceans, Tsukuba, Japan, Center for Global Environmental Research, National Institute for Environmental Studies, 9–15.
Vecchi, G., , M. Harrison, , A. Wittenberg, , and T. Rosati, 2005: Biases in ocean and coupled general circulation models. Proc. Workshop on the Application of EPIC2001 Data for Improving and Testing Coupled Atmosphere-Ocean Models, Seattle, WA, U.S. CLIVAR, 11–13.
White, W. B., 1973: An oceanic wake in the equatorial undercurrent downstream from the Galápagos Archipelago. J. Phys. Oceanogr., 3 , 156–161.
Xie, P., , and P. A. Arkin, 1996: Analyses of global monthly precipitation using gauge observations, satellite estimates, and numerical model predictions. J. Climate, 9 , 840–858.
Yulaeva, E., , and J. M. Wallace, 1994: The signature of ENSO in global temperature and precipitation fields derived from the Microwave Sounding Unit. J. Climate, 7 , 1719–1736.