Vertical and Lateral Mixing Processes Deduced from the Mediterranean Water Signature in the North Atlantic

Jan D. Zika Climate and Environmental Dynamics and Laboratory, School of Mathematics and Statistics, University of New South Wales, Sydney, New South Wales, and Wealth from Oceans Flagship, CSIRO Marine and Atmospheric Research, Hobart, Tasmania, Australia

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Trevor J. McDougall Wealth from Oceans Flagship, CSIRO Marine and Atmospheric Research, Hobart, Tasmania, Australia

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Abstract

The conservation equations of heat, salt, and mass are combined in such a way that a simple relation is found between the known volume flux of Mediterranean Water entering the North Atlantic Ocean and the effects of lateral and vertical mixing processes. The method is a form of inverse method in which the only unknowns are the vertical and lateral diffusivities. For each isohaline contour on each neutral density surface the authors develop one equation in two unknowns, arguing that other terms that cannot be evaluated are small. By considering several such isohaline contours, the method becomes overdetermined for each density layer, and results are found for both the vertical and lateral diffusivity that vary smoothly in the vertical direction, giving some confidence in the method.

Corresponding author address: Jan D. Zika, CSIRO Marine and Atmospheric Research, Castray Esplanade, Hobart, TAS 7000, Australia. Email: Jan.Zika@csiro.au

Abstract

The conservation equations of heat, salt, and mass are combined in such a way that a simple relation is found between the known volume flux of Mediterranean Water entering the North Atlantic Ocean and the effects of lateral and vertical mixing processes. The method is a form of inverse method in which the only unknowns are the vertical and lateral diffusivities. For each isohaline contour on each neutral density surface the authors develop one equation in two unknowns, arguing that other terms that cannot be evaluated are small. By considering several such isohaline contours, the method becomes overdetermined for each density layer, and results are found for both the vertical and lateral diffusivity that vary smoothly in the vertical direction, giving some confidence in the method.

Corresponding author address: Jan D. Zika, CSIRO Marine and Atmospheric Research, Castray Esplanade, Hobart, TAS 7000, Australia. Email: Jan.Zika@csiro.au

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  • Armi, L., and W. Zenk, 1984: Large lenses of highly saline Mediterranean water. J. Phys. Oceanogr., 14 , 15601576.

  • Baringer, M. O., and J. F. Price, 1997: Mixing and spreading of the Mediterranean outflow. J. Phys. Oceanogr., 27 , 16541677.

  • Ferrari, R., and K. L. Polzin, 2005: Finescale structure of the TS relation in the eastern North Atlantic. J. Phys. Oceanogr., 35 , 14371454.

    • Search Google Scholar
    • Export Citation
  • Ganachaud, A., and C. Wunsch, 2000: Improved estimates of global ocean circulation, heat transport and mixing from hydrographic data. Nature, 408 , 453457.

    • Search Google Scholar
    • Export Citation
  • Gouretski, V. V., and K. P. Koltermann, 2004: WOCE global hydrographic climatology. Berichte des Bundesamtes für Seeschifffahrt und Hydrographie Tech. Rep. 35/2004, 49 pp.

  • Griffies, S. M., 2004: Fundamentals of Ocean Climate Models. Princeton University Press, 518 pp.

  • Griffies, S. M., and Coauthors, 2005: Formulation of an ocean model for global climate simulations. Ocean Sci., 1 , 4579.

  • Hallberg, R. W., 2000: Time integration of diapycnal diffusion and Richardson number–dependent mixing in isopycnal coordinate ocean models. Mon. Wea. Rev., 128 , 14021419.

    • Search Google Scholar
    • Export Citation
  • Jackett, D. R., and T. J. McDougall, 1997: A neutral density variable for the world’s oceans. J. Phys. Oceanogr., 27 , 237263.

  • McDougall, T. J., 1984: The relative roles of diapycnal and isopycnal mixing on subsurface water mass conversion. J. Phys. Oceanogr., 14 , 15771589.

    • Search Google Scholar
    • Export Citation
  • McDougall, T. J., 1987: Thermobaricity, cabbeling, and water-mass conversion. J. Geophys. Res., 92 , 54485464.

  • McDougall, T. J., 1991a: Water mass analysis with three conservative variables. J. Geophys. Res., 96 , 86878693.

  • McDougall, T. J., 1991b: Parameterizing mixing in inverse models. Dynamics of Oceanic Internal Gravity Waves: Proc. ‘Aha Huliko‘a Hawaiian Winter Workshop, Honolulu, HI, University of Hawaii at Manoa, 355–386.

  • McDougall, T. J., 2003: Potential enthalpy: A conservative oceanic variable for evaluating heat content and heat fluxes. J. Phys. Oceanogr., 33 , 945963.

    • Search Google Scholar
    • Export Citation
  • McDougall, T. J., and A. B. Giles, 1987: Migration of intrusions across isopycnals, with examples from the Tasman Sea. Deep-Sea Res., 34A , 18511866.

    • Search Google Scholar
    • Export Citation
  • McDougall, T. J., and P. C. McIntosh, 2001: The temporal-residual-mean velocity. Part II: Isopycnal interpretation and the tracer and momentum equations. J. Phys. Oceanogr., 31 , 12221246.

    • Search Google Scholar
    • Export Citation
  • McDougall, T. J., and D. R. Jackett, 2005a: The material derivative of neutral density. J. Mar. Res., 63 , 159185.

  • McDougall, T. J., and D. R. Jackett, 2005b: An assessment of orthobaric density in the global ocean. J. Phys. Oceanogr., 35 , 20542075.

    • Search Google Scholar
    • Export Citation
  • McIntosh, P. C., and S. R. Rintoul, 1997: Do box inverse models work? J. Phys. Oceanogr., 27 , 291308.

  • Needler, G. T., and R. A. Heath, 1975: Diffusion coefficients calculated from the Mediterranean salinity anomaly in the North Atlantic Ocean. J. Phys. Oceanogr., 5 , 173182.

    • Search Google Scholar
    • Export Citation
  • Sloyan, B. M., and S. R. Rintoul, 2000: Estimates of area-averaged diapycnal fluxes from basin-scale budgets. J. Phys. Oceanogr., 30 , 23202341.

    • Search Google Scholar
    • Export Citation
  • Veronis, G., 1975: The role of models in tracer studies. Numerical Models of Ocean Circulation, National Academy of Science, 133–146.

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