• Abernathey, R., , J. Marshall, , M. Mazloff, , and E. Shuckburgh, 2010: Enhancement of mesoscale eddy stirring at steering levels in the Southern Ocean. J. Phys. Oceanogr., 40 , 170184.

    • Search Google Scholar
    • Export Citation
  • Böning, C. W., , A. Dispert, , M. Visbeck, , M. Rintoul, , and F. Schwarzkopf, 2008: Antarctic circumpolar current response to recent climate change. Nat. Geosci., 1 , 864869.

    • Search Google Scholar
    • Export Citation
  • Chelton, D. B., , M. Schlax, , M. Freilich, , and R. Millif, 2004: Satellite measurements reveal persistent small-scale features in ocean winds. Science, 303 , 978983.

    • Search Google Scholar
    • Export Citation
  • Cisewski, B., , V. Strass, , and H. Prandke, 2005: Upper-ocean vertical mixing in the Antarctic Polar Front Zone. Deep-Sea Res. II, 52 , 10871108.

    • Search Google Scholar
    • Export Citation
  • Cushman-Roisin, B., 1987: Subduction. Dynamics of the Oceanic Surface Mixed Layer: Proc. ‘Aha Huliko’a Hawaiian Winter Workshop, Honolulu, HI, University of Hawaii at Manoa, 181–196.

    • Search Google Scholar
    • Export Citation
  • Danabasoglu, G., , and J. Marshall, 2007: Effects of vertical variations of thickness diffusivity in an ocean general circulation model. Ocean Modell., 18 , 122141.

    • Search Google Scholar
    • Export Citation
  • de Boyer Montégut, C., , G. Madec, , A. Fischer, , A. Lazar, , and D. Iudicone, 2004: Mixed layer depth over the global ocean: An examination of profile data and a profile-based climatology. J. Geophys. Res., 109 , C12003. doi:10.1029/2004JC002378.

    • Search Google Scholar
    • Export Citation
  • Dong, S., , J. Sprintall, , S. Gille, , and L. Talley, 2008: Southern Ocean mixed- layer depth from Argo float profiles. J. Geophys. Res., 113 , C06013. doi:10.1029/2006JC004051.

    • Search Google Scholar
    • Export Citation
  • Ferreira, D., , J. Marshall, , and P. Heimbach, 2005: Estimating eddy stresses by fitting dynamics to observations using a residual mean ocean circulation model and its adjoint. J. Phys. Oceanogr., 35 , 18911910.

    • Search Google Scholar
    • Export Citation
  • Fine, R. A., , K. A. Maillet, , K. F. Sullivan, , and D. Willey, 2001: Circulation and ventilation flux of the Pacific Ocean. J. Geophys. Res., 106 , (C10). 2215922178.

    • Search Google Scholar
    • Export Citation
  • Follows, M. J., , and J. C. Marshall, 1994: Eddy-driven exchange at ocean fronts. Ocean Modell., 102 , 59.

  • Gent, P., , and J. McWilliams, 1990: Isopycnal mixing in ocean circulation models. J. Phys. Oceanogr., 20 , 150155.

  • Gille, S. T., 2002: Warming of the Southern Ocean since the 1950s. Science, 295 , 12751277.

  • Gille, S. T., 2003: Float observations of the Southern Ocean. Part I: Estimating mean fields, bottom velocities, and topographic steering. J. Phys. Oceanogr., 33 , 11671181.

    • Search Google Scholar
    • Export Citation
  • Grist, J. P., , and S. A. Josey, 2003: Inverse analysis adjustment of the SOC air–sea flux climatology using ocean heat transport constraints. J. Climate, 16 , 32743295.

    • Search Google Scholar
    • Export Citation
  • Hallberg, R., , and A. Gnanadesikan, 2006: The role of eddies in determining the structure and response of the wind-driven Southern Hemisphere overturning: Results from the Modeling Eddies in the Southern Ocean (MESO) Project. J. Phys. Oceanogr., 36 , 22322252.

    • Search Google Scholar
    • Export Citation
  • Hanawa, K., , and L. Talley, 2001: Mode waters. Ocean Circulation and Climate, G. Siedler et al., Eds., International Geophysics Series, Vol. 77, Academic Press, 373–386.

    • Search Google Scholar
    • Export Citation
  • Huang, R. X., 1991: The three-dimensional structure of wind-driven gyres: Ventilation and subduction. Rev. Geophys., 29 , (Suppl.). 590609.

    • Search Google Scholar
    • Export Citation
  • Iudicone, D., , K. Rodgers, , R. Schopp, , and G. Madec, 2007: An exchange window for the injection of Antarctic Intermediate Water into the South Pacific. J. Phys. Oceanogr., 37 , 3149.

    • Search Google Scholar
    • Export Citation
  • Jenkins, W. J., 1982: On the climate of a subtropical gyre: Decadal timescale variations in water mass renewal in the Sargasso Sea. J. Mar. Res., 40 , 265290.

    • Search Google Scholar
    • Export Citation
  • Jenkins, W. J., 1987: 3H and 3He in the Beta Triangle: Observations of gyre ventilation and oxygen utilization rates. J. Phys. Oceanogr., 17 , 763783.

    • Search Google Scholar
    • Export Citation
  • Joyce, T. M., , and W. J. Jenkins, 1993: Spatial variability of subducting water in the North Atlantic: A pilot study. J. Geophys. Res., 98 , (C6). 1011110124.

    • Search Google Scholar
    • Export Citation
  • Joyce, T. M., , J. R. Luyten, , A. Kubryakov, , F. B. Bahr, , and J. S. Pallant, 1998: Meso- to large-scale structure of subducting water in the subtropical gyre of the eastern North Atlantic Ocean. J. Phys. Oceanogr., 28 , 4061.

    • Search Google Scholar
    • Export Citation
  • Karsten, R., , and J. Marshall, 2002: Constructing the residual circulation of the ACC from observations. J. Phys. Oceanogr., 32 , 33153327.

    • Search Google Scholar
    • Export Citation
  • Karstensen, J., , and D. Quadfasel, 2002: Formation of Southern Hemisphere thermocline waters: Water mass conversion and subduction. J. Phys. Oceanogr., 32 , 30203038.

    • Search Google Scholar
    • Export Citation
  • Lapeyre, G., , and P. Klein, 2006: Dynamics of the upper oceanic layers in terms of surface quasigeostrophic theory. J. Phys. Oceanogr., 36 , 165176.

    • Search Google Scholar
    • Export Citation
  • Ledwell, J., , A. Watson, , and C. Law, 1998: Mixing of a tracer in the pycnocline. J. Geophys. Res., 103 , (C10). 2149921529.

  • Levitus, S., , J. I. Antonov, , T. P. Boyer, , and C. Stephens, 1998: Warming of the world. Ocean. Sci., 287 , 22252229.

  • Lumpkin, R., , and K. Speer, 2007: Global ocean meridional overturning. J. Phys. Oceanogr., 37 , 25502562.

  • Luyten, J., , J. Pedlosky, , and H. Stommel, 1983: The ventilated thermocline. J. Phys. Oceanogr., 13 , 292309.

  • Marsh, R., , A. Nurser, , A. Megann, , and A. New, 2000: Water mass formation in the Southern Ocean in a global isopycnal coordinate GCM. J. Phys. Oceanogr., 30 , 10131045.

    • Search Google Scholar
    • Export Citation
  • Marshall, D., 1997: Subducting of water masses in an eddying ocean. J. Mar. Res., 55 , 201222.

  • Marshall, D., , and J. Marshall, 1995: On the thermodynamics of subduction. J. Phys. Oceanogr., 25 , 138151.

  • Marshall, J., , and T. Radko, 2003: Residual mean solutions for the Antarctic Circumpolar Current and its associated overturning circulation. J. Phys. Oceanogr., 33 , 23412354.

    • Search Google Scholar
    • Export Citation
  • Marshall, J., , A. Nurser, , and R. Williams, 1993: Inferring the subduction rate and period over the North Atlantic. J. Phys. Oceanogr., 23 , 13151329.

    • Search Google Scholar
    • Export Citation
  • Marshall, J., , D. Jamous, , and J. Nilsson, 1999: Reconciling thermodynamic and dynamic methods of computation of water mass transformation rates. Deep-Sea Res. II, 46 , 545572.

    • Search Google Scholar
    • Export Citation
  • Marshall, J., , H. Jones, , R. Karsten, , and R. Wardle, 2002: Can eddies set ocean stratification? J. Phys. Oceanogr., 32 , 2638.

  • Marshall, J., , E. Shuckburgh, , H. Jones, , and C. Hill, 2006: Estimates and implications of surface eddy diffusivity in the Southern Ocean derived from tracer transport. J. Phys. Oceanogr., 36 , 18061821.

    • Search Google Scholar
    • Export Citation
  • McDougall, T. J., 1989: Streamfunctions for the lateral velocity vector in a compressible ocean. J. Mar. Res., 47 , 267284.

  • McDougall, T. J., 1991: Parameterizing mixing in inverse models. Dynamics of Oceanic Internal Gravity Waves: Proc. Sixth. ‘Aha Huliko’a Hawaiian Winter Workshop, P. Müller and D. Henderson, Eds., Honolulu, HI, University of Hawaii at Manoa, 355–386.

    • Search Google Scholar
    • Export Citation
  • Montgomery, R., 1937: A suggested method for representing gradient flow in isentropic surfaces. Bull. Amer. Meteor. Soc., 18 , 210.

  • Morrow, R., , G. Valladeau, , and J. Sallée, 2008: Observed subsurface signature of Southern Ocean decadal sea level rise. Prog. Oceanogr., 77 , 351366.

    • Search Google Scholar
    • Export Citation
  • Naveira-Garabato, A. C., , J. Allen, , H. Leach, , V. Strass, , and R. Pollard, 2001: Mesoscale subduction at the Antarctic Polar Front driven by baroclinic instability. J. Phys. Oceanogr., 31 , 20872107.

    • Search Google Scholar
    • Export Citation
  • Paci, A., , G. Caniaux, , M. Gavart, , H. Giordani, , M. Levy, , L. Prieur, , and G. Reverdin, 2005: A high-resolution Simulation of the ocean during the POMME experiment: Simulation results and comparison with observations. J. Geophys. Res., 110 .doi:10.1029/2004JC002712.

    • Search Google Scholar
    • Export Citation
  • Qiu, B., , and R. Huang, 1995: Ventilation of the North Atlantic and North Pacific: Subduction versus obduction. J. Phys. Oceanogr., 25 , 23742390.

    • Search Google Scholar
    • Export Citation
  • Rhines, P. B., , and W. R. Young, 1982: Homogenization of potential vorticity in planetary gyres. J. Fluid Mech., 122 , 347367.

  • Ridgway, K., , J. Dunn, , and J. Wilkin, 2002: Ocean interpolation by four-dimensional weighted least squares—Application to the waters around Australasia. J. Atmos. Oceanic Technol., 19 , 13571375.

    • Search Google Scholar
    • Export Citation
  • Rintoul, S., , and M. England, 2002: Ekman transport dominates air–sea fluxes in driving variability of subantarctic mode water. J. Phys. Oceanogr., 32 , 13081321.

    • Search Google Scholar
    • Export Citation
  • Rio, M., , P. Schaeffer, , F. Hernandez, , and J. Lemoine, 2005: The estimation of the ocean mean dynamic topography through the combination of altimetric data, in-situ measurements and GRACE geoid: From global to regional studies. Proc. GOCINA Int. Workshop, Luxembourg, Geoid and Ocean Circulation in the North Atlantic, 171–177.

    • Search Google Scholar
    • Export Citation
  • Robbins, P. E., , J. Price, , W. B. Owens, , and W. Jenkins, 2000: The importance of lateral diffusion for the ventilation of the lower thermocline in the subtropical North Atlantic. J. Phys. Oceanogr., 30 , 6789.

    • Search Google Scholar
    • Export Citation
  • Robinson, A. R., , and H. Stommel, 1959: The oceanic thermocline and the associated thermohaline circulation. Tellus, 11 , 295308.

  • Rupolo, V., 2007: A Lagrangian-based approach for determining trajectories taxonomy and turbulence regimes. J. Phys. Oceanogr., 37 , 15841609.

    • Search Google Scholar
    • Export Citation
  • Sallée, J., , N. Wienders, , R. Morrow, , and K. Speer, 2006: Formation of Subantarctic Mode Water in the southeastern Indian Ocean. Ocean Dyn., 56 , 525542. doi:10.1007/s10236-005-0054-x.

    • Search Google Scholar
    • Export Citation
  • Sallée, J., , R. Morrow, , and K. Speer, 2008a: Eddy diffusion and Subantarctic Mode Water formation. Geophys. Res. Lett., 35 , L05607. doi:10.1029/2007GL032827.

    • Search Google Scholar
    • Export Citation
  • Sallée, J., , K. Speer, , and R. Morrow, 2008b: Response of the Antarctic Circumpolar Current to atmospheric variability. J. Climate, 21 , 30203039.

    • Search Google Scholar
    • Export Citation
  • Sallée, J., , K. Speer, , R. Morrow, , and R. Lumpkin, 2008c: An estimate of Lagrangian eddy statistics and diffusion in the mixed layer of the Southern Ocean. J. Mar. Res., 66 , 441463.

    • Search Google Scholar
    • Export Citation
  • Sarmiento, J., 1983: A tritium box model of the North Atlantic thermocline. J. Phys. Oceanogr., 13 , 12691274.

  • Schlosser, P., , J. Bullister, , R. Fine, , W. Jenkins, , R. Key, , J. Lupton, , W. Roether, , and W. Smethie, 2001: Transformation and age of water masses. Ocean Circulation and Climate: Observing and Modelling the Global Ocean, G. Siedler et al., Eds., International Geophysics Series, Vol. 77, Academic Press, 427–450.

    • Search Google Scholar
    • Export Citation
  • Screen, J., , N. Gillett, , D. Stevens, , G. Marshall, , and H. Roscoe, 2009: The role of eddies in the Southern Ocean tempereature response to the Southern Annular Mode. J. Climate, 22 , 806818.

    • Search Google Scholar
    • Export Citation
  • Shuckburgh, E., , E. Jones, , J. Marshall, , and C. Hill, 2009: Understanding the regional variability of eddy diffusivity in the Pacific sector of the Southern Ocean. J. Phys. Oceanogr., 39 , 20112023.

    • Search Google Scholar
    • Export Citation
  • Sloyan, B., , and S. Rintoul, 2001: Circulation, renewal, and modification of Antarctic Mode Water and Intermediate Water. J. Phys. Oceanogr., 31 , 10051030.

    • Search Google Scholar
    • Export Citation
  • Smith, K. S., , and J. Marshall, 2009: Evidence for deep eddy mixing in the Southern Ocean. J. Phys. Oceanogr., 39 , 5069.

  • Sorensen, J., , J. Ribbe, , and G. Shaffer, 2001: On Antarctic Intermediate Water mass formation in general circulation models. J. Phys. Oceanogr., 31 , 7791.

    • Search Google Scholar
    • Export Citation
  • Speer, K., , and E. Tziperman, 1992: Rates of water mass formation in the North Atlantic Ocean. J. Phys. Oceanogr., 22 , 93104.

  • Speer, K., , S. R. Rintoul, , and B. M. Sloyan, 2000: The diabatic Deacon cell. J. Phys. Oceanogr., 30 , 32123222.

  • Suga, T., , and L. D. Talley, 1995: Antarctic Intermediate Water circulation in the tropical and subtropical South Atlantic. J. Geophys. Res., 100 , (C7). 1344113453.

    • Search Google Scholar
    • Export Citation
  • Sundermeyer, M. A., , and J. Price, 1998: Lateral mixing and the North Atlantic Tracer Release Experiment: Observations and numerical simulations of Lagrangian particles and a passive tracer. J. Geophys. Res., 103 , (C10). 2148121497.

    • Search Google Scholar
    • Export Citation
  • Thomas, L., , C. Lee, , and Y. Yoshikawa, 2010: The subpolar Front of the Japan/East Sea. Part II: Inverse method for determining the frontal vertical circulation. J. Phys. Oceanogr., 40 , 325.

    • Search Google Scholar
    • Export Citation
  • Toggweiler, J. R., , K. Dixon, , and K. Bryan, 1989: Simulations of radiocarbon in a coarse-resolution World Ocean Model. 2. Distributions of bomb-produced carbon 14. J. Geophys. Res., 94 , (C6). 82438264.

    • Search Google Scholar
    • Export Citation
  • Treguier, A., , I. Held, , and V. Larichev, 1997: Parameterization of quasigeostrophic eddies in primitive equation ocean model. J. Phys. Oceanogr., 27 , 567580.

    • Search Google Scholar
    • Export Citation
  • Treguier, A., , M. England, , S. Rintoul, , G. Madec, , J. Le Sommer, , and J. Molines, 2007: Upper-ocean meridional circulation in a numerical model of the Antarctic Circumpolar Current. Ocean Sci., 4 , 653698.

    • Search Google Scholar
    • Export Citation
  • Vivier, F., , D. Iudicone, , F. Busdraghi, , and Y-H. Park, 2010: Dynamics of sea surface temperature anomalies in the Southern Ocean diagnosed from a 2-D mixed layer model. Ocean Modell., 40 , 325.

    • Search Google Scholar
    • Export Citation
  • Welander, P., 1959: An advective model of the ocean thermocline. Tellus, 11 , 309318.

  • Woods, J. D., 1985: The physics of thermocline ventilation. Coupled Ocean–Atmosphere Models, J. C. J. Nihoul, Ed., Elsevier Oceanography Series, Vol. 40, Elsevier, 543–590.

    • Search Google Scholar
    • Export Citation
  • Zhurbas, V., , and I. Oh, 2004: Drifter-derived maps of lateral diffusivity in the Pacific and Atlantic Oceans in relation to surface circulation patterns. J. Geophys. Res., 109 , C05015. doi:10.1029/2003JC002241.

    • Search Google Scholar
    • Export Citation
All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 101 101 25
PDF Downloads 83 83 29

Southern Ocean Thermocline Ventilation

View More View Less
  • 1 CSIRO-CMAR/CAWCR, Hobart, Tasmania, Australia
  • 2 Department of Oceanography, The Florida State University, Tallahassee, Florida
  • 3 CSIRO-CMAR/CAWCR/ACE-CRC, Hobart, Tasmania, Australia
  • 4 CSIRO-CMAR/CAWCR, Hobart, Tasmania, Australia
© Get Permissions
Restricted access

Abstract

An approximate mass (volume) budget in the surface layer of the Southern Ocean is used to investigate the intensity and regional variability of the ventilation process, discussed here in terms of subduction and upwelling. Ventilation resulting from Ekman pumping is estimated from satellite winds, the geostrophic mean component is assessed from a climatology strengthened with Argo data, and the eddy-induced advection is included via the parameterization of Gent and McWilliams, together with eddy mixing estimates. All three components contribute significantly to ventilation. Finally, the seasonal cycle of the upper ocean is resolved using Argo data.

The circumpolar-averaged circulation shows an upwelling in the Antarctic Intermediate Water (AAIW) density classes, which is carried north into a zone of dense Subantarctic Mode Water (SAMW) subduction. Although no consistent net production is found in the light SAMW density classes, a large subduction of Subtropical Mode Water (STMW) is observed. The STMW area is fed by convergence of a southward and a northward residual meridional circulation. The eddy-induced contribution is important for the water mass transport in the vicinity of the Antartic Circumpolar Current. It balances the horizontal northward Ekman transport as well as the vertical Ekman pumping.

While the circumpolar-averaged upper cell structure is consistent with the average surface fluxes, it hides strong longitudinal regional variations and does not represent any local regime. Subduction shows strong regional variability with bathymetrically constrained hotspots of large subduction. These hotspots are consistent with the interior potential vorticity structure and circulation in the thermocline. Pools of SAMW and AAIW of different densities are found along the circumpolar belt in association with the regional pattern of subduction and interior circulation.

Corresponding author address: Jean-Baptiste Sallée, CSIRO-CMAR/CAWCR, Castray Esplanade, Hobart 7000, TAS, Australia. Email: jbsallee@gmail.com

Abstract

An approximate mass (volume) budget in the surface layer of the Southern Ocean is used to investigate the intensity and regional variability of the ventilation process, discussed here in terms of subduction and upwelling. Ventilation resulting from Ekman pumping is estimated from satellite winds, the geostrophic mean component is assessed from a climatology strengthened with Argo data, and the eddy-induced advection is included via the parameterization of Gent and McWilliams, together with eddy mixing estimates. All three components contribute significantly to ventilation. Finally, the seasonal cycle of the upper ocean is resolved using Argo data.

The circumpolar-averaged circulation shows an upwelling in the Antarctic Intermediate Water (AAIW) density classes, which is carried north into a zone of dense Subantarctic Mode Water (SAMW) subduction. Although no consistent net production is found in the light SAMW density classes, a large subduction of Subtropical Mode Water (STMW) is observed. The STMW area is fed by convergence of a southward and a northward residual meridional circulation. The eddy-induced contribution is important for the water mass transport in the vicinity of the Antartic Circumpolar Current. It balances the horizontal northward Ekman transport as well as the vertical Ekman pumping.

While the circumpolar-averaged upper cell structure is consistent with the average surface fluxes, it hides strong longitudinal regional variations and does not represent any local regime. Subduction shows strong regional variability with bathymetrically constrained hotspots of large subduction. These hotspots are consistent with the interior potential vorticity structure and circulation in the thermocline. Pools of SAMW and AAIW of different densities are found along the circumpolar belt in association with the regional pattern of subduction and interior circulation.

Corresponding author address: Jean-Baptiste Sallée, CSIRO-CMAR/CAWCR, Castray Esplanade, Hobart 7000, TAS, Australia. Email: jbsallee@gmail.com

Save