• 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
  • Blanke, B., and P. Delecluse, 1993: Variability of the tropical Atlantic Ocean simulated by a general circulation model with two different mixed layer physics. J. Phys. Oceanogr., 23 , 13631388.

    • Search Google Scholar
    • Export Citation
  • 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 , 21562179.

    • Search Google Scholar
    • Export Citation
  • da Silva, A. M., C. C. Young, and S. Levitus, 1994: Anomalies of Heat and Momentum Fluxes. Vol. 3, Atlas of Surface Marine Data, NOAA Atlas Series, NOAA Atlas NESDIS 7, 413 pp.

    • Search Google Scholar
    • Export Citation
  • Esbensen, S. K., and Y. Kushnir, 1981: The heat budget of the global ocean: An atlas based on estimates from the surface marine observations. Oregon State University Climate Research Institute Rep. 29, 27 pp.

    • Search Google Scholar
    • Export Citation
  • Janssen, G., and A. Kattenberg, 1993: On the role of mixing in a tropical ocean general circulation model. Ann. Geophys., 11 , 11161129.

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

  • Kraus, E. B., and J. S. Turner, 1967: A one-dimensional model of the seasonal thermocline. II: The general theory and its consequence. Tellus, 19 , 98106.

    • 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
  • Large, W. G., J. C. McWilliams, and S. C. Doney, 1994: Oceanic vertical mixing: A review and a model with a nonlocal boundary layer parameterization. Rev. Geophys., 32 , 363403.

    • Search Google Scholar
    • Export Citation
  • Large, W. G., G. Danabasoglu, J. C. McWilliams, P. R. Gent, and F. O. Bryan, 2001: Equatorial circulation of a global ocean climate model with anisotropic horizontal viscosity. J. Phys. Oceanogr., 31 , 518536.

    • Search Google Scholar
    • Export Citation
  • Latif, M., T. Stockdale, J. Wolff, G. Burgers, E. Maier-Reimer, M. M. Junge, K. Arpe, and L. Bengtsson, 1994: Climatology and variability in the ECHO coupled GCM. Tellus, 46A , 35366.

    • Search Google Scholar
    • Export Citation
  • Levitus, S., 1982: Climatological Atlas of the World Ocean. NOAA Prof. Paper No. 13, 173 pp. and 17 microfiche.

  • McPhaden, M. J., 1994: Moored time series measurements. Eos, Trans. Amer. Geophys. Union,71, 760.

  • Murtugudde, R., R. Seager, and A. B. Busalacchi, 1996: Simulation of the tropical oceans with an ocean GCM coupled to an atmospheric mixed-layer model. J. Climate, 9 , 17951815.

    • Search Google Scholar
    • Export Citation
  • Pacanowski, R. C., and S. G. H. Philander, 1981: Parameterization of vertical mixing in numerical models of the tropical oceans. J. Phys. Oceanogr., 7 , 952956.

    • Search Google Scholar
    • Export Citation
  • Pacanowski, R. C., and S. M. Griffies, 1998: MOM 3.0 manual. NOAA/Geophysical Fluid Dynamics Laboratory, 700 pp. [Available online at http://www.gfdl.gov/∼smg/mom/web/guide_parent/guide_parent.html.].

    • Search Google Scholar
    • Export Citation
  • Philander, S. G. H., W. J. Hurlin, and A. D. Seigel, 1987: Simulation of the seasonal cycle of the tropical Pacific Ocean. J. Phys. Oceanogr., 17 , 19862002.

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

  • Rothstein, L. M., R-H. Zhang, A. J. Busalacchi, and D. Chen, 1998: A numerical simulation of the mean water pathways in the subtropical and tropical Pacific Ocean. J. Phys Oceanogr., 28 , 322343.

    • Search Google Scholar
    • Export Citation
  • 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
  • Sterl, A., and A. Kattenberg, 1994: Embedding a mixed layer model into an ocean general circulation model of the Atlantic: The importance of surface mixing for heat flux and temperature. J. Geophys. Res., 99 , 1413914157.

    • Search Google Scholar
    • Export Citation
  • Stockdale, T., D. Anderson, M. Davey, P. Delecluse, A. Kattenberg, Y. Kitamura, M. Latif, and T. Yamagata, 1993: Intercomparison of tropical ocean GCMs. WRCP-79 and WMO/TD No. 545, 43 pp.

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

  • Zeng, Q-C., X-H. Zhang, and R-H. Zhang, 1991: A design of an oceanic-GCM without the rigid-lid approximation and its application to the numerical simulation of the Pacific Ocean circulation. J. Mar. Syst., 1 , 271292.

    • Search Google Scholar
    • Export Citation
  • Zhang, R-H., and M. Endoh, 1992: A free surface general circulation model for the tropical Pacific Ocean. J. Geophys. Res., 97 , 1123711255.

    • Search Google Scholar
    • Export Citation
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Effect of Penetrating Momentum Flux over the Surface Boundary/Mixed Layer in a z-Coordinate OGCM of the Tropical Pacific

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  • 1 International Research Institute for Climate Prediction, Lamont-Doherty Earth Observatory, Columbia University, Palisades, New York
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Abstract

A simple scheme is proposed for penetrating atmospheric momentum flux over the ocean surface boundary layer or mixed layer (BL/ML) and is tested in the z-coordinate NOAA/Geophysical Fluid Dynamics Laboratory Modular Ocean Model (MOM 3) for improving its performance. Analogous to the treatment in layered ocean models, wind stress is applied, as a body force, to the entire BL/ML whose depth is calculated from a nonlocal K-profile parameterization scheme. The penetrating scheme presents an explicit and effective way to distribute a priori momentum flux throughout the BL/ML that has varying depth in space and time, instead of just over the uppermost model level with fixed thickness. This additional procedure introduces an explicit mechanism that directly relates wind stress to the BL/ML formulation, which in turn controls current and thermal structure in the upper ocean and the interaction with the underlying thermocline. Two penetrating runs, one over the BL and the other over the ML, have similar results that differ systematically from those with the penetration over fixed depths (control run). It is demonstrated that, with coherent and systematic improvements, this penetrating scheme can have significant effects on simulated equatorial ocean currents and thermal structure not only in the surface layer, but also in the thermocline. Besides more reasonable ML depth simulation in the equatorial central basin, there is substantial reduction in the mean offset of simulated isotherm depths and warm bias in the thermocline, due to downward shift of the maximum upwelling zone in the equatorial central Pacific. Consistent with observations, the penetrating scheme realistically reproduces the springtime reversal of the South Equatorial Current and the corresponding surface warming in the central equatorial Pacific, with accompanying surfacing of the Equatorial Undercurrent Current in March–May.

Corresponding author address: Rong-Hua Zhang, IRI, Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY 10964. Email: rzhang@iri.ldeo.columbia.edu

Abstract

A simple scheme is proposed for penetrating atmospheric momentum flux over the ocean surface boundary layer or mixed layer (BL/ML) and is tested in the z-coordinate NOAA/Geophysical Fluid Dynamics Laboratory Modular Ocean Model (MOM 3) for improving its performance. Analogous to the treatment in layered ocean models, wind stress is applied, as a body force, to the entire BL/ML whose depth is calculated from a nonlocal K-profile parameterization scheme. The penetrating scheme presents an explicit and effective way to distribute a priori momentum flux throughout the BL/ML that has varying depth in space and time, instead of just over the uppermost model level with fixed thickness. This additional procedure introduces an explicit mechanism that directly relates wind stress to the BL/ML formulation, which in turn controls current and thermal structure in the upper ocean and the interaction with the underlying thermocline. Two penetrating runs, one over the BL and the other over the ML, have similar results that differ systematically from those with the penetration over fixed depths (control run). It is demonstrated that, with coherent and systematic improvements, this penetrating scheme can have significant effects on simulated equatorial ocean currents and thermal structure not only in the surface layer, but also in the thermocline. Besides more reasonable ML depth simulation in the equatorial central basin, there is substantial reduction in the mean offset of simulated isotherm depths and warm bias in the thermocline, due to downward shift of the maximum upwelling zone in the equatorial central Pacific. Consistent with observations, the penetrating scheme realistically reproduces the springtime reversal of the South Equatorial Current and the corresponding surface warming in the central equatorial Pacific, with accompanying surfacing of the Equatorial Undercurrent Current in March–May.

Corresponding author address: Rong-Hua Zhang, IRI, Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY 10964. Email: rzhang@iri.ldeo.columbia.edu

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