• Anderson, D. L. T., E. S. Sarachik, P. J. Webster, and L. M. Rothstein, 1998: The TOGA decade. J. Geophys. Res, 103 , 1416714510.

  • Atlas, R., R. Hoffman, S. Bloom, J. Jusem, and J. Ardizzone, 1996: A multiyear global surface wind velocity dataset using SSM/I wind observations. Bull. Amer. Meteor. Soc, 77 , 869882.

    • Search Google Scholar
    • Export Citation
  • 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 , 15451566.

    • Search Google Scholar
    • Export Citation
  • Cane, M. A., and S. E. Zebiak, 1985: A theory for El Niño and Southern Ocillation. Science, 228 , 10841087.

  • Chang, P., L. Ji, and R. Saravanan, 2001: A hybrid coupled model study of tropical Atlantic variability. J. Climate, 14 , 361390.

  • Chen, D., S. E. Zebiak, A. J. Busalacchi, and M. A. Cane, 1995: An improved procedure for El Niño forecasting. Science, 22 , 16991702.

    • Search Google Scholar
    • Export Citation
  • 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 , 25852588.

    • Search Google Scholar
    • Export Citation
  • Goldenberg, S., and J. O'Brien, 1981: Time and space variability of the tropical Pacific wind stress. Mon. Wea. Rev, 109 , 11901207.

  • 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 , 723732.

    • Search Google Scholar
    • Export Citation
  • Ji, M., D. W. Behringer, and A. Leetmaa, 1998: An improved coupled model for ENSO prediction and implications for ocean initialization. Part II: The coupled model. Mon. Wea. Rev, 126 , 10221034.

    • Search Google Scholar
    • Export Citation
  • Jin, F-F., and S-I. An, 1999: Thermocline and zonal advective feedbacks within the equatorial ocean recharge oscillator model for ENSO. Geophys. Res. Lett, 26 , 29892992.

    • Search Google Scholar
    • Export Citation
  • Kalnay, E., and Coauthors, 1996: The NCEP/NCAR 40-Year Reanalysis Project. Bull. Amer. Meteor. Soc, 77 , 437471.

  • Kessler, W. S., and M. J. McPhaden, 1995: Oceanic equatorial waves and the 1991–93 El Niño. J. Climate, 8 , 17571774.

  • Kleeman, R., 1993: On the dependence of hindcast skill on ocean thermodynamics in a coupled ocean–atmosphere model. J. Climate, 6 , 20122033.

    • Search Google Scholar
    • Export Citation
  • Large, W. G., and P. R. Gent, 1999: Validation of vertical mixing in an equatorial ocean model using large eddy simulations and observations. J. Phys. Oceanogr, 29 , 449464.

    • Search Google Scholar
    • Export Citation
  • Latif, M., and Coauthors, 2001: ENSIP: The El Niño simulation intercomparison project. Climate, Dyn, 18 , 255276.

  • Lau, N-C., S. G. H. Philander, and M. J. Nath, 1992: Simulation of ENSO-like phenomena with a low-resolution coupled GCM of the global ocean and atmosphere. J. Climate, 5 , 284307.

    • Search Google Scholar
    • Export Citation
  • Levitus, S., 1982: Climatological Atlas of the World Ocean. NOAA Prof. Paper 13, 173 pp. and 17 microfiche.

  • McCreary, J. P., and D. L. T. Anderson, 1991: An overview of coupled ocean–atmosphere models of El Niño and the Southern Oscillation. J. Geophys. Res, 96 , 31253150.

    • Search Google Scholar
    • Export Citation
  • Meehl, G. A., P. R. Gent, J. M. Arblaster, B. Otto-Bliesner, E. Brady, and A. P. Craig, 2001: Factors that affect the amplitude of El Niño in global coupled climate models. Climate Dyn, 17 , 515526.

    • Search Google Scholar
    • Export Citation
  • 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 , 35043522.

    • Search Google Scholar
    • Export Citation
  • Neelin, J. D., and Coauthors, 1992: Tropical air–sea interactions in general circulation models. Climate Dyn, 7 , 73104.

  • Pacanowski, R. C., and S. M. Griffies, 1998: MOM 3.0 Manual. NOAA/Geophysical Fluid Dynamics Laboratory, 700 pp.

  • Philander, S. G. H., 1990: El Niño, La Niña, and the Southern Oscillation. International Geophysics Series, Vol. 46, Academic Press, 283 pp.

    • Search Google Scholar
    • Export Citation
  • Philander, S. G. H., N-C. Lau, R. C. Pacanowski, and M. J. Nath, 1992: Simulation of ENSO with a global atmospheric GCM coupled to a high-resolution, tropical Pacific Ocean GCM. J. Climate, 5 , 308329.

    • Search Google Scholar
    • Export Citation
  • Rasmusson, E. M., and T. H. Carpenter, 1982: Variations in tropical sea surface temperature and surface wind fields associated with the Southern Oscillation/El Niño. Mon. Wea. Rev, 110 , 354384.

    • Search Google Scholar
    • Export Citation
  • Reynolds, R. W., and T. M. Smith, 1994: Improved global sea surface temperature analysis using optimum interpolation. J. Climate, 7 , 929948.

    • Search Google Scholar
    • Export Citation
  • Rosati, A., and K. Miyakoda, 1988: A general circulation model for upper ocean simulation. J. Phys. Oceanogr, 18 , 16011626.

  • Seager, R., M. Blumenthal, and Y. Kushinir, 1995: An advective atmospheric mixed layer model for ocean modeling purposes: Global simulation of surface heat fluxes. J. Climate, 8 , 19511964.

    • Search Google Scholar
    • Export Citation
  • Stockdale, T. N., A. J. Busalacchi, D. E. Harrison, and R. Seager, 1998: Ocean modeling for ENSO. J. Geophys. Res, 103 , 1432514355.

  • Suarez, M. J., and P. S. Schopf, 1988: A delayed action oscillator for ENSO. J. Atmos. Sci, 45 , 32833287.

  • Syu, H-H., and J. D. Neelin, 2000: ENSO in a hybrid coupled model. Part I: Sensitivity to physical parameterization. Climate Dyn, 16 , 1934.

    • Search Google Scholar
    • Export Citation
  • Syu, H-H., J. D. Neelin, and D. Gutzler, 1995: Seasonal and interannual variability in a hybrid coupled GCM. J. Climate, 8 , 21212143.

    • Search Google Scholar
    • Export Citation
  • Zebiak, S. E., and M. A. Cane, 1987: A model El Niño/Southern Oscillation. Mon. Wea. Rev, 115 , 22622278.

  • 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 , 13121330.

    • Search Google Scholar
    • Export Citation
  • Zhang, R-H., and S. E. Zebiak, 2002: Effect of penetrating momentum flux over the surface boundary/mixed layer in a z-coordinate OGCM of the tropical Pacific. J. Phys. Oceanogr, 32 , 36163637.

    • Search Google Scholar
    • Export Citation
  • Zhang, R-H., and S. E. Zebiak, 2003: Embedding a SST anomaly model into a z-coordinate OGCM for producing El Niño oscillation in the tropical Pacific climate system. Geophys. Res. Lett.,30, 1176, doi:10.1029/2002GL015428.

    • Search Google Scholar
    • Export Citation
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An Embedding Method for Improving Interannual Variability Simulations in a Hybrid Coupled Model of the Tropical Pacific Ocean–Atmosphere System

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  • 1 International Research Institute for Climate Prediction, The Earth Institute at Columbia University, Columbia University,Palisades, New York
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Abstract

An embedding approach is developed and tested to improve El Niño–Southern Oscillation (ENSO) simulations in a hybrid coupled model (HCM), focusing on the ocean thermocline effects on sea surface temperature (SST) in the eastern equatorial Pacific. The NOAA/GFDL Modular Ocean Model (MOM 3) is coupled to a statistical atmospheric model that estimates wind stress anomalies based on a singular value decomposition (SVD) of the covariance between observed wind stress and SST anomalies. Analogous to the Cane–Zebiak (CZ) coupled model, a separate SST anomaly model is explicitly embedded into the z-coordinate ocean general circulation model (OGCM). The three components exchange predicted anomalies within the coupled system: The OGCM provides anomalies of ocean currents in the surface mixed layer and the thermocline depth, which are used to calculate SST anomalies from the embedded SST model; wind anomalies are then determined according to the statistical atmospheric model, which in turn force the OGCM. Results from uncoupled and coupled runs with and without the embedding are compared. With the standard coupling, the system exhibits similar behavior to previous HCMs, including interannual variability with a dominant quasi-biennial oscillation and a westward propagation of SST anomalies on the equator. These characteristics suggest that the horizontal advection is playing a more important role than the vertical advection in determining SST changes over the eastern equatorial Pacific. Incorporating the embedded SST anomaly model, with which the thermocline effects on SST can be enhanced in the eastern equatorial Pacific, has a significant impact on performance of the HCM. The embedded HCM exhibits more realistic SST variability and coupled behavior, characterized by 3–4-yr oscillations and a more standing SST pattern along the equator.

The results support the hypothesis that current physical parameterizations in the OGCM provide insufficient thermal linkage between the thermocline and the sea surface in the eastern equatorial Pacific. It is demonstrated that the long-known deficiency of some OGCMs in their depiction of the thermocline and its interactions with SST may contribute to unrealistic coupled variability in HCMs of ENSO. The embedding approach not only provides a diagnosis for parameterization deficiencies in current OGCMs but, pending progress on this difficult problem, provides a straightforward means to bypass it and improve coupled model performance.

Current affiliation: Earth System Science Interdisciplinary Center, University of Maryland, College Park, College Park, Maryland

Corresponding author address: Dr. Rong-Hua Zhang, ESSIC, University of Maryland, College Park, Computer and Space Science Building #224, College Park, MD 20742. Email: rzhang@essic.umd.edu

Abstract

An embedding approach is developed and tested to improve El Niño–Southern Oscillation (ENSO) simulations in a hybrid coupled model (HCM), focusing on the ocean thermocline effects on sea surface temperature (SST) in the eastern equatorial Pacific. The NOAA/GFDL Modular Ocean Model (MOM 3) is coupled to a statistical atmospheric model that estimates wind stress anomalies based on a singular value decomposition (SVD) of the covariance between observed wind stress and SST anomalies. Analogous to the Cane–Zebiak (CZ) coupled model, a separate SST anomaly model is explicitly embedded into the z-coordinate ocean general circulation model (OGCM). The three components exchange predicted anomalies within the coupled system: The OGCM provides anomalies of ocean currents in the surface mixed layer and the thermocline depth, which are used to calculate SST anomalies from the embedded SST model; wind anomalies are then determined according to the statistical atmospheric model, which in turn force the OGCM. Results from uncoupled and coupled runs with and without the embedding are compared. With the standard coupling, the system exhibits similar behavior to previous HCMs, including interannual variability with a dominant quasi-biennial oscillation and a westward propagation of SST anomalies on the equator. These characteristics suggest that the horizontal advection is playing a more important role than the vertical advection in determining SST changes over the eastern equatorial Pacific. Incorporating the embedded SST anomaly model, with which the thermocline effects on SST can be enhanced in the eastern equatorial Pacific, has a significant impact on performance of the HCM. The embedded HCM exhibits more realistic SST variability and coupled behavior, characterized by 3–4-yr oscillations and a more standing SST pattern along the equator.

The results support the hypothesis that current physical parameterizations in the OGCM provide insufficient thermal linkage between the thermocline and the sea surface in the eastern equatorial Pacific. It is demonstrated that the long-known deficiency of some OGCMs in their depiction of the thermocline and its interactions with SST may contribute to unrealistic coupled variability in HCMs of ENSO. The embedding approach not only provides a diagnosis for parameterization deficiencies in current OGCMs but, pending progress on this difficult problem, provides a straightforward means to bypass it and improve coupled model performance.

Current affiliation: Earth System Science Interdisciplinary Center, University of Maryland, College Park, College Park, Maryland

Corresponding author address: Dr. Rong-Hua Zhang, ESSIC, University of Maryland, College Park, Computer and Space Science Building #224, College Park, MD 20742. Email: rzhang@essic.umd.edu

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