• Allison, L. C., 2009: Spin-up and adjustment of the Antarctic Circumpolar Current and global pycnocline. Ph.D. thesis, University of Reading, 207 pp.

  • Andrews, D. G., and M. E. McIntyre, 1978: Generalized Eliassen-Palm and Charney-Drazin theorems for waves on axisymmetric mean flows in compressible atmospheres. J. Atmos. Sci., 35, 175185, https://doi.org/10.1175/1520-0469(1978)035<0175:GEPACD>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Broecker, W. S., 1991: The great ocean conveyor. Oceanography, 4, 7989, https://doi.org/10.5670/oceanog.1991.07.

  • Broecker, W. S., T. H. Peng, J. Jouzel, and G. Russell, 1990: The magnitude of global fresh-water transports of importance to ocean circulation. Climate Dyn., 4, 7379, https://doi.org/10.1007/BF00208902.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Bryan, F. O., C. W. Böning, W. R. Holland, F. O. Bryan, and W. R. Holland, 1995: On the midlatitude circulation in a high-resolution model of the North Atlantic. J. Phys. Oceanogr., 25, 289305, https://doi.org/10.1175/1520-0485(1995)025<0289:OTMCIA>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Cessi, P., and C. S. Jones, 2017: Warm-route versus cold-route interbasin exchange in the meridional overturning circulation. J. Phys. Oceanogr., 47, 19811997, https://doi.org/10.1175/JPO-D-16-0249.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Craig, P., D. Ferreira, and J. Methven, 2016: The contrast between Atlantic and Pacific surface water fluxes. Tellus, 69A, 1330454, https://doi.org/10.1080/16000870.2017.1330454.

    • Search Google Scholar
    • Export Citation
  • Danabasoglu, G., and J. C. McWilliams, 1995: Sensitivity of the global ocean circulation to parameterizations of mesoscale tracer transports. J. Climate, 8, 29672987, https://doi.org/10.1175/1520-0442(1995)008<2967:SOTGOC>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Eden, C., and J. Willebrand, 2001: Mechanism of interannual to decadal variability of the North Atlantic circulation. J. Climate, 14, 22662280, https://doi.org/10.1175/1520-0442(2001)014<2266:MOITDV>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Ferrari, R., S. M. Griffies, A. J. G. Nurser, and G. K. Vallis, 2010: A boundary-value problem for the parameterized mesoscale eddy transport. Ocean Modell., 32, 143156, https://doi.org/10.1016/j.ocemod.2010.01.004.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Ferreira, D., J. Marshall, and J.-M. Campin, 2010: Localization of deep water formation: Role of atmospheric moisture transport and geometrical constraints on ocean circulation. J. Climate, 23, 14561476, https://doi.org/10.1175/2009JCLI3197.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Geay, J. E., M. A. Cane, and N. Naik, 2003: Warren revisited: Atmospheric freshwater fluxes and “Why is no deep water formed in the North Pacific.” J. Geophys. Res., 108, 3178, https://doi.org/10.1029/2001JC001058.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Gent, P. R., and J. C. McWilliams, 1990: Isopycnal mixing in ocean circulation models. J. Phys. Oceanogr., 20, 150155, https://doi.org/10.1175/1520-0485(1990)020<0150:IMIOCM>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Gent, P. R., and Coauthors, 2011: The Community Climate System Model version 4. J. Climate, 24, 49734991, https://doi.org/10.1175/2011JCLI4083.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Gnanadesikan, A., 1999: A simple predictive model for the structure of the oceanic pycnocline. Science, 283, 20772079, https://doi.org/10.1126/science.283.5410.2077.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Gordon, A. L., J. R. E. Lutjeharms, and M. L. Gründlingh, 1987: Stratification and circulation at the Agulhas retroflection. Deep-Sea Res., 34A, 565599, https://doi.org/10.1016/0198-0149(87)90006-9.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Häkkinen, S., and P. B. Rhines, 2004: Decline of subpolar North Atlantic circulation during the 1990s. Science, 304, 555559, https://doi.org/10.1126/science.1094917.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Hátún, H., A. B. Sandø, H. Drange, B. Hansen, and H. Valdimarsson, 2005: Influence of the Atlantic Subpolar Gyre on the thermohaline circulation. Science, 309, 18411844, https://doi.org/10.1126/science.1114777.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Hewitt, C., R. Stouffer, A. Broccoli, J. Mitchell, and P. J. Valdes, 2003: The effect of ocean dynamics in a coupled GCM simulation of the Last Glacial Maximum. Climate Dyn., 20, 203218, https://doi.org/10.1007/s00382-002-0272-6.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Hughes, T. M. C., and A. J. Weaver, 1994: Multiple equilibria of an asymmetric two-basin ocean model. J. Phys. Oceanogr., 24, 619637, https://doi.org/10.1175/1520-0485(1994)024<0619:MEOAAT>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Huisman, S. E., H. A. Dijkstra, A. S. von der Heydt, W. P. M. de Ruijter, A. S. von der Heydt, and W. P. M. de Ruijter, 2012: Does net E–P set a preference for North Atlantic sinking? J. Phys. Oceanogr., 42, 17811792, https://doi.org/10.1175/JPO-D-11-0200.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Jones, C. S., and P. Cessi, 2016: Interbasin transport of the meridional overturning circulation. J. Phys. Oceanogr., 46, 11571169, https://doi.org/10.1175/JPO-D-15-0197.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Kamphuis, V., S. E. Huisman, and H. A. Dijkstra, 2011: The global ocean circulation on a retrograde rotating Earth. Climate Past, 7, 487499, https://doi.org/10.5194/cp-7-487-2011.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Lévy, M., P. Klein, A.-M. Tréguier, D. Iovino, G. Madec, S. Masson, and K. Takahashi, 2010: Modifications of gyre circulation by sub-mesoscale physics. Ocean Modell., 34, 115, https://doi.org/10.1016/j.ocemod.2010.04.001.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • McCartney, M. S., and C. Mauritzen, 2001: On the origin of the warm inflow to the Nordic Seas. Prog. Oceanogr., 51, 125214, https://doi.org/10.1016/S0079-6611(01)00084-2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Nilsson, J., P. L. Langen, D. Ferreira, and J. Marshall, 2013: Ocean basin geometry and the salinification of the Atlantic Ocean. J. Climate, 26, 61636184, https://doi.org/10.1175/JCLI-D-12-00358.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Redi, M. H., 1982: Oceanic isopycnal mixing by coordinate rotation. J. Phys. Oceanogr., 12, 11541158, https://doi.org/10.1175/1520-0485(1982)012<1154:OIMBCR>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Reid, J. L., 1961: On the temperature, salinity, and density differences between the Atlantic and Pacific Oceans in the upper kilometre. Deep-Sea Res., 7, 265275, https://doi.org/10.1016/0146-6313(61)90044-2.

    • Search Google Scholar
    • Export Citation
  • Reid, J. L., 1979: On the contribution of the Mediterranean Sea outflow to the Norwegian-Greenland Sea. Deep-Sea Res., 26A, 11991223, https://doi.org/10.1016/0198-0149(79)90064-5.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Schmitt, R. W., P. S. Bogden, C. E. Dorman, R. W. Schmitt, P. S. Bogden, and C. E. Dorman, 1989: Evaporation minus precipitation and density fluxes for the North Atlantic. J. Phys. Oceanogr., 19, 12081221, https://doi.org/10.1175/1520-0485(1989)019<1208:EMPADF>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Schmittner, A., T. A. Silva, K. Fraedrich, E. Kirk, and F. Lunkeit, 2011: Effects of mountains and ice sheets on global ocean circulation. J. Climate, 24, 28142828, https://doi.org/10.1175/2010JCLI3982.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Seager, R., N. Naik, and G. A. Vecchi, 2010: Thermodynamic and dynamic mechanisms for large-scale changes in the hydrological cycle in response to global warming. J. Climate, 23, 46514668, https://doi.org/10.1175/2010JCLI3655.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Seager, R., H. Liu, N. Henderson, I. Simpson, C. Kelley, T. Shaw, Y. Kushnir, and M. Ting, 2014: Causes of increasing aridification of the Mediterranean region in response to rising greenhouse gases. J. Climate, 27, 46554676, https://doi.org/10.1175/JCLI-D-13-00446.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Stocker, T. F., D. G. Wright, and W. S. Broecker, 1992: The influence of high-latitude surface forcing on the global thermohaline circulation. Paleoceanography, 7, 529541, https://doi.org/10.1029/92PA01695.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Stommel, H., 1957: A survey of ocean current theory. Deep-Sea Res., 4, 149184, https://doi.org/10.1016/0146-6313(56)90048-X.

  • Stommel, H., 1961: Thermohaline convection with two stable regimes of flow. Tellus, 13, 224230, https://doi.org/10.3402/tellusa.v13i2.9491.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Talley, L. D., 2008: Freshwater transport estimates and the global overturning circulation: Shallow, deep and throughflow components. Prog. Oceanogr., 78, 257303, https://doi.org/10.1016/j.pocean.2008.05.001.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Talley, L. D., 2013: Closure of the global overturning circulation through the Indian, Pacific, and Southern Oceans: Schematics and transports. Oceanography, 26, 8097, https://doi.org/10.5670/oceanog.2013.07.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Wang, X., P. H. Stone, and J. Marotzke, 1995: Poleward heat transport in a barotropic ocean model. J. Phys. Oceanogr., 25, 256265, https://doi.org/10.1175/1520-0485(1995)025<0256:PHTIAB>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Warren, B. A., 1981: Deep circulation of the World Ocean. Evolution of Physical Oceanography, B. A. Warren and C. Wunsch, Eds., MIT Press, 6–41.

  • Warren, B. A., 1983: Why is no deep water formed in the North Pacific? J. Mar. Res., 41, 327347, https://doi.org/10.1357/002224083788520207.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Weaver, A. J., C. M. Bitz, A. F. Fanning, and M. M. Holland, 1999: Thermohaline circulation: High-latitude phenomena and the difference between the Pacific and Atlantic. Annu. Rev. Earth Planet. Sci., 27, 231285, https://doi.org/10.1146/annurev.earth.27.1.231.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Wills, R. C., and T. Schneider, 2015: Stationary eddies and the zonal asymmetry of net precipitation and ocean freshwater forcing. J. Climate, 28, 51155133, https://doi.org/10.1175/JCLI-D-14-00573.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Young, W. R., 2012: An exact thickness-weighted average formulation of the Boussinesq equations. J. Phys. Oceanogr., 42, 692707, https://doi.org/10.1175/JPO-D-11-0102.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Zhang, R., and G. K. Vallis, 2007: The role of bottom vortex stretching on the path of the North Atlantic western boundary current and on the northern recirculation gyre. J. Phys. Oceanogr., 37, 20532080, https://doi.org/10.1175/JPO3102.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
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Size Matters: Another Reason Why the Atlantic Is Saltier than the Pacific

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  • 1 Scripps Institution of Oceanography, University of California, San Diego, La Jolla, California
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Abstract

The surface salinity in the North Atlantic controls the position of the sinking branch of the meridional overturning circulation (MOC); the North Atlantic has higher salinity, so deep-water formation occurs there rather than in the North Pacific. Here, it is shown that in a 3D primitive equation model of two basins of different widths connected by a reentrant channel, there is a preference for sinking in the narrow basin even under zonally uniform surface forcing. This preference is linked to the details of the velocity and salinity fields in the “sinking” basin. The southward western boundary current associated with the wind-driven subpolar gyre has higher velocity in the wide basin than in the narrow basin. It overwhelms the northward western boundary current associated with the MOC for wide-basin sinking, so freshwater is brought from the far north of the domain southward and forms a pool on the western boundary in the wide basin. The fresh pool suppresses local convection and spreads eastward, leading to low salinities in the north of the wide basin for wide-basin sinking. This pool of freshwater is much less prominent in the narrow basin for narrow-basin sinking, where the northward MOC western boundary current overcomes the southward western boundary current associated with the wind-driven subpolar gyre, bringing salty water from lower latitudes northward and enabling deep-water mass formation.

© 2017 American Meteorological Society. For information regarding reuse of this content and general copyright information, consult the AMS Copyright Policy (www.ametsoc.org/PUBSReuseLicenses).

Corresponding author: C. S. Jones, csjones@ucsd.edu

Abstract

The surface salinity in the North Atlantic controls the position of the sinking branch of the meridional overturning circulation (MOC); the North Atlantic has higher salinity, so deep-water formation occurs there rather than in the North Pacific. Here, it is shown that in a 3D primitive equation model of two basins of different widths connected by a reentrant channel, there is a preference for sinking in the narrow basin even under zonally uniform surface forcing. This preference is linked to the details of the velocity and salinity fields in the “sinking” basin. The southward western boundary current associated with the wind-driven subpolar gyre has higher velocity in the wide basin than in the narrow basin. It overwhelms the northward western boundary current associated with the MOC for wide-basin sinking, so freshwater is brought from the far north of the domain southward and forms a pool on the western boundary in the wide basin. The fresh pool suppresses local convection and spreads eastward, leading to low salinities in the north of the wide basin for wide-basin sinking. This pool of freshwater is much less prominent in the narrow basin for narrow-basin sinking, where the northward MOC western boundary current overcomes the southward western boundary current associated with the wind-driven subpolar gyre, bringing salty water from lower latitudes northward and enabling deep-water mass formation.

© 2017 American Meteorological Society. For information regarding reuse of this content and general copyright information, consult the AMS Copyright Policy (www.ametsoc.org/PUBSReuseLicenses).

Corresponding author: C. S. Jones, csjones@ucsd.edu
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