• Ayotte, K. W., P. P. Sullivan, J. C. McWilliams, J. C. Wyngaard, C.-H. Moeng, A. Andren, S. C. Doney, B. Holtslag, W. G. Large and J. J. Tribbia, 1996: An evaluation of neutral and convective planetary boundary layer parameterizations relative to large eddy simulations. Bound.-Layer Meteor.,79, 131–175.

  • Berliand, M. E., and T. G. Berliand, 1952: Measurement of the effective radiation of the earth with varying cloud amounts. Proc. Acad. Sci. USSR, Ser. Geophys., No. 1.

  • Bishop, J. K. B., and W. B. Rossow, 1991: Spatial and temporal variability of global surface solar irradiance. J. Geophys. Res.,96, 16 839–16 858.

  • Bryan, F. O., B. G. Kauffman, W. G. Large, and P. R. Gent, 1996: The NCAR CSM Flux Coupler. NCAR Tech. Note 424, 50 pp. [Available from NCAR, PO Box 3000, Boulder, CO 80305.].

  • Bryden, H. L., and E. C. Brady, 1989: Eddy momentum and heat fluxes and their effects on the circulation of the equatorial Pacific Ocean. J. Mar. Res.,47, 55–79.

  • Chen, D., L. M. Rothstein, and A. J. Busalacchi, 1994a: A hybrid vertical mixing scheme and its application to tropical ocean models. J. Phys. Oceanogr.,24, 2156–2179.

  • ——, A. J. Busalacchi, and L. M. Rothstein, 1994b: The roles of vertical mixing, solar radiation, and wind stress in a model simulation of the sea surface temperature seasonal cycle in the tropical Pacific Ocean. J. Geophys. Res.,99, 20 345–20 359.

  • Deardorff, J. W., 1970: A numerical study of three-dimensional channel flow at large Reynolds numbers. J. Fluid Mech.,41, 453–480.

  • ——, 1972: Numerical investigation of neutral and unstable planetary boundary layers. J. Atmos. Sci.,29, 91–115.

  • Fung, I. Y., D. E. Harrison, and A. A. Lacis, 1984: On the variability of the net longwave radiation at the ocean surface. Rev. Geophys. Space Phys.,22, 177–193.

  • Gent, P. R., 1991: The heat budget of the TOGA-COARE domain in an ocean model. J. Geophys. Res.,96, 3323–3330.

  • ——, and M. A. Cane, 1989: A reduced gravity, primitive equation model of the upper equatorial ocean. J. Comput. Phys.,81, 444–480.

  • Gill, A. E., 1982: Atmosphere–Ocean Dynamics. Academic Press, 662 pp.

  • Gregg, M. C., H. Peters, J. C. Wesson, N. S. Oakey, and T. J. Shay, 1985: Intensive measurements of turbulence and shear in the equatorial undercurrent. Nature,318, 140–144.

  • Hurrell, J., J. J. Hack, B. A. Boville, D. Williamson, and J. T. Kiehl, 1998: The dynamical simulation of the NCAR CCM3. J. Climate,11, 1207–1236.

  • Jerlov, N. G., 1976: Marine Optics. Elsevier, 231 pp.

  • Kalnay, E., M. Kanamitsu, R. Kistler, W. Collins, D. Deaven, L. Gandin, M. Iredell, S. Saha, G. White, J. Woollen, Y. Zhu, M. Chelliah, W. Ebisuzai, W. Higgins, J. Janowiak, K. C. Mo, C. Ropelewski, A. Leetmaa, R. Reynolds, and R. Jenne, 1996: The NCEP/NCAR 40-Year Reanalysis Project. Bull. Amer. Meteor. Soc.,77, 437–471.

  • Kraus, E. B., and J. S. Turner, 1967: A one-dimensional model of the seasonal thermocline; II. The general theory and its consequences. Tellus,19, 98–105.

  • 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, 363–403.

  • ——, G. Danabasoglu, S. C. Doney, and J. C. McWilliams, 1997: Sensitivity to surface forcing and boundary layer mixing in a global ocean model: Annual-mean climatology. J. Phys. Oceanogr.,27, 2418–2447.

  • Ledwell, J. R., A. J. Wilson, and C. S. Low, 1993: Evidence for slow mixing across the pycnocline from an open-ocean tracer-release experiment. Nature,364, 701–703.

  • McPhaden, M. J., and M. E. McCarty, 1992: Mean seasonal cycles and interannual variations at 0,110W and 0,140W during 1980–1991. NOAA Tech. Memo. ERL PMEL-95, U.S. Department of Commerce, Washington, DC, 118 pp.

  • McWilliams, J. C., P. P. Sullivan, and C.-H. Moeng, 1997: Langmuir turbulence in the ocean. J. Fluid Mech.,334, 1–30.

  • Moeng, C.-H., and J. C. Wyngaard, 1984: Statistics of conservative scalars in the convective boundary layer. J. Atmos. Sci.,41, 3161–3169.

  • ——, and ——, 1989: Evaluation of turbulent transport and dissipation closures in second-order modeling. J. Atmos. Sci.,46, 2311–2330.

  • Moum, J. N., and D. R. Caldwell, 1985: Local influences on the shear-flow turbulence in the equatorial ocean. Science,230, 315–316.

  • Pacanowski, R. C., and S. G. H. Philander, 1981: Parameterization of vertical mixing in numerical models of the tropical oceans. J. Phys. Oceanogr.,11, 1443–1451.

  • Paulson, C. A., and J. J. Simpson, 1977: Irradiance measurements in the upper ocean. J. Phys. Oceanogr.,7, 952–956.

  • Peters, H., M. C. Gregg, and J. M. Toole, 1988: On the parameterization of equatorial turbulence. J. Geophys. Res.,93, 1199–1218.

  • Philander, S. G. H., 1990: El Nino, La Nina, and the Southern Oscillation. Academic Press, 289 pp.

  • ——, W. J. Hurlin, and A. D. Siegel, 1987. Simulation of the seasonal cycle of the tropical Pacific Ocean. J. Phys. Oceanogr.,17, 1986–2002.

  • 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 temperature analyses using optimum interpolation. J. Climate,7, 929–948.

  • Rossow, W. B., and R. A. Schiffer, 1991: ISCCP cloud data products. Bull. Amer. Meteor. Soc.,72, 2–20.

  • Seager, R., S. E. Zebiak, and M. A. Cane, 1988: A model of the tropical Pacific sea surface temperature climatology. J. Geophys. Res.,93, 1265–1280.

  • Skyllingstad, E. D., and D. W. Denbo, 1995: An ocean large eddy simulation of Langmuir circulations and convection in the surface mixed layer. J. Geophys. Res.,100, 8501–8522.

  • ——, W. D. Smyth, J. N. Moum, and H. Wijesekera, 1999: Turbulent dissipation during a westerly wind burst: A comparison of large eddy simulation results and microstructure measurements. J. Phys. Oceanogr.,29, 5–28.

  • Wang, D., W. G. Large, and J. C. McWilliams, 1996: Diurnal cycling, eddy viscosity and horizontal rotation effects in equatorial ocean boundary layers. J. Geophys. Res.,101, 3649–3662.

  • ——, J. C. McWilliams, and W. G. Large, 1998: Large eddy simulation of the diurnal cycle of deep equatorial turbulence. J. Phys. Oceanogr.,28, 129–148.

  • Wyngaard, J. C., 1982: Lectures on the planetary boundary layer. Mesoscale Meteorology—Theories, Observations and Models, D. K. Lilly and T. Gal-Chen, Eds., NATO ASI Series, D. Reidel. 781 pp.

  • ——, and R. A. Brost, 1984: Top-down and bottom-up diffusion in the convective boundary layer. J. Atmos. Sci.,41, 102–112.

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Validation of Vertical Mixing in an Equatorial Ocean Model Using Large Eddy Simulations and Observations

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  • 1 National Center for Atmospheric Research, Boulder, Colorado
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Abstract

A nonlocal K-profile parameterization (KPP) of the upper-ocean boundary layer is tested for the equatorial regions. First, the short-term performance of a one-dimensional model with KPP is found to compare favorably to large eddy simulations (LES), including nonlocal countergradient heat flux. The comparison is clean because both the surface forcing and the large-scale flow are identical in the two models. The comparison is direct because the parameterized turbulent flux profiles are explicitly computed in LES. A similar comparison is less favorable when KPP is replaced by purely downgradient diffusion with Richardson-number-dependent viscosity and diffusivity because of the absence of intense convection after sunset. Sensitivity experiments are used to establish parameter values in the interior mixing of KPP.

Second, the impact of the parameterization on annual means and the seasonal cycle in a general circulation model of the upper, equatorial Pacific Ocean is described. The results of GCM runs with and without KPP are compared to annual mean profiles of zonal velocity and temperature from the TOGA-TAO array. The two GCM solutions are closer to each other than to the observations, with biases in zonal velocity in the western Pacific and in subsurface temperature in the eastern Pacific. Such comparisons are never clean because neither the wind stress and the surface heat flux nor the forcing by the large-scale flow are known to sufficient accuracy.

Finally, comparisons are made of the equatorial Pacific Ocean GCM results when different heat flux formulations are used. These include bulk forcing where prescribed air temperature and humidity are used, SST forcing where the use of such ocean-controlled parameters is avoided, and a fully coupled atmospheric general circulation model where there is no prescribed control over any surface fluxes. It is concluded, especially in the eastern Pacific, that the use of specified air temperature and humidity does not overly constrain the model sea surface temperature.

Corresponding author address: Dr. William G. Large, National Center for Atmospheric Research, 1850 Table Mesa Drive, P.O. Box 3000, Boulder, CO 80303.

Email: wily@ncar.ucar.edu

Abstract

A nonlocal K-profile parameterization (KPP) of the upper-ocean boundary layer is tested for the equatorial regions. First, the short-term performance of a one-dimensional model with KPP is found to compare favorably to large eddy simulations (LES), including nonlocal countergradient heat flux. The comparison is clean because both the surface forcing and the large-scale flow are identical in the two models. The comparison is direct because the parameterized turbulent flux profiles are explicitly computed in LES. A similar comparison is less favorable when KPP is replaced by purely downgradient diffusion with Richardson-number-dependent viscosity and diffusivity because of the absence of intense convection after sunset. Sensitivity experiments are used to establish parameter values in the interior mixing of KPP.

Second, the impact of the parameterization on annual means and the seasonal cycle in a general circulation model of the upper, equatorial Pacific Ocean is described. The results of GCM runs with and without KPP are compared to annual mean profiles of zonal velocity and temperature from the TOGA-TAO array. The two GCM solutions are closer to each other than to the observations, with biases in zonal velocity in the western Pacific and in subsurface temperature in the eastern Pacific. Such comparisons are never clean because neither the wind stress and the surface heat flux nor the forcing by the large-scale flow are known to sufficient accuracy.

Finally, comparisons are made of the equatorial Pacific Ocean GCM results when different heat flux formulations are used. These include bulk forcing where prescribed air temperature and humidity are used, SST forcing where the use of such ocean-controlled parameters is avoided, and a fully coupled atmospheric general circulation model where there is no prescribed control over any surface fluxes. It is concluded, especially in the eastern Pacific, that the use of specified air temperature and humidity does not overly constrain the model sea surface temperature.

Corresponding author address: Dr. William G. Large, National Center for Atmospheric Research, 1850 Table Mesa Drive, P.O. Box 3000, Boulder, CO 80303.

Email: wily@ncar.ucar.edu

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