Editorial Type:
Article
Article Type:
Research Article

Simulating the Role of Surface Forcing on Observed Multidecadal Upper-Ocean Salinity Changes

Véronique Lago * Centre for Australian Weather and Climate Research, CSIRO Oceans and Atmosphere, Hobart, Tasmania, Australia
Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, Tasmania, Australia

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Susan E. Wijffels * Centre for Australian Weather and Climate Research, CSIRO Oceans and Atmosphere, Hobart, Tasmania, Australia

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Paul J. Durack * Centre for Australian Weather and Climate Research, CSIRO Oceans and Atmosphere, Hobart, Tasmania, Australia
Program for Climate Model Diagnosis and Intercomparison, Lawrence Livermore National Laboratory, Livermore, California

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John A. Church * Centre for Australian Weather and Climate Research, CSIRO Oceans and Atmosphere, Hobart, Tasmania, Australia

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Nathaniel L. Bindoff * Centre for Australian Weather and Climate Research, CSIRO Oceans and Atmosphere, Hobart, Tasmania, Australia
Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, Tasmania, Australia
Antarctic Climate and Ecosystems Cooperative Research Centre, Hobart, Tasmania, Australia

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Simon J. Marsland Centre for Australian Weather and Climate Research, CSIRO Oceans and Atmosphere Flagship, Aspendale, Victoria, Australia

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Print Publication:
01 Aug 2016
DOI:
https://doi.org/10.1175/JCLI-D-15-0519.1
Page(s):
5575–5588
Restricted access

Abstract

The ocean’s surface salinity field has changed over the observed record, driven by an intensification of the water cycle in response to global warming. However, the origin and causes of the coincident subsurface salinity changes are not fully understood. The relationship between imposed surface salinity and temperature changes and their corresponding subsurface changes is investigated using idealized ocean model experiments. The ocean’s surface has warmed by about 0.5°C (50 yr)−1 while the surface salinity pattern has amplified by about 8% per 50 years. The idealized experiments are constructed for a 50-yr period, allowing a qualitative comparison to the observed salinity and temperature changes previously reported. The comparison suggests that changes in both modeled surface salinity and temperature are required to replicate the three-dimensional pattern of observed salinity change. The results also show that the effects of surface changes in temperature and salinity act linearly on the changes in subsurface salinity. Surface salinity pattern amplification appears to be the leading driver of subsurface salinity change on depth surfaces; however, surface warming is also required to replicate the observed patterns of change on density surfaces. This is the result of isopycnal migration modified by the ocean surface warming, which produces significant salinity changes on density surfaces.

Corresponding author address: Véronique Lago, CSIRO Marine and Atmospheric Research, GPO Box 1538, Hobart, TAS 7001, Australia. E-mail: veronique.lago@csiro.au

Abstract

The ocean’s surface salinity field has changed over the observed record, driven by an intensification of the water cycle in response to global warming. However, the origin and causes of the coincident subsurface salinity changes are not fully understood. The relationship between imposed surface salinity and temperature changes and their corresponding subsurface changes is investigated using idealized ocean model experiments. The ocean’s surface has warmed by about 0.5°C (50 yr)−1 while the surface salinity pattern has amplified by about 8% per 50 years. The idealized experiments are constructed for a 50-yr period, allowing a qualitative comparison to the observed salinity and temperature changes previously reported. The comparison suggests that changes in both modeled surface salinity and temperature are required to replicate the three-dimensional pattern of observed salinity change. The results also show that the effects of surface changes in temperature and salinity act linearly on the changes in subsurface salinity. Surface salinity pattern amplification appears to be the leading driver of subsurface salinity change on depth surfaces; however, surface warming is also required to replicate the observed patterns of change on density surfaces. This is the result of isopycnal migration modified by the ocean surface warming, which produces significant salinity changes on density surfaces.

Corresponding author address: Véronique Lago, CSIRO Marine and Atmospheric Research, GPO Box 1538, Hobart, TAS 7001, Australia. E-mail: veronique.lago@csiro.au
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  • Arakawa, A., and V. R. Lamb, 1977: Computational design and the basic dynamical processes of the UCLA general circulation model. Methods Comput. Phys., 17, 173–265.

    • Search Google Scholar
    • Export Citation

  • Bi, D., and Coauthors, 2013: ACCESS-OM: The ocean and sea ice core of the ACCESS coupled model. Aust. Meteor. Oceanogr. J., 63, 213–232.

    • Search Google Scholar
    • Export Citation

  • Bindoff, N. L., and T. J. McDougall, 1994: Diagnosing climate change and ocean ventilation using hydrographic data. J. Phys. Oceanogr., 24, 1137–1152, doi:10.1175/1520-0485(1994)024<1137:DCCAOV>2.0.CO;2.

    • Search Google Scholar
    • Export Citation

  • Boyer, T. P., S. Levitus, J. I. Antonov, R. A. Locarnini, and H. E. Garcia, 2005: Linear trends in salinity for the World Ocean, 1955–1998. Geophys. Res. Lett., 32, L01604, doi:10.1029/2004GL021791.

    • Search Google Scholar
    • Export Citation

  • Cravatte, S., T. Delcroix, D. Zhang, M. McPhaden, and J. Leloup, 2009: Observed freshening and warming of the western Pacific warm pool. Climate Dyn., 33, 565–589, doi:10.1007/s00382-009-0526-7.

    • Search Google Scholar
    • Export Citation

  • Curry, R., B. Dickson, and I. Yashayaev, 2003: A change in the freshwater balance of the Atlantic Ocean over the past four decades. Nature, 426, 826–829, doi:10.1038/nature02206.

    • Search Google Scholar
    • Export Citation

  • Dickson, B., I. Yashayaev, J. Meincke, B. Turrell, S. Dye, and J. Holfort, 2002: Rapid freshening of the deep North Atlantic Ocean over the past four decades. Nature, 416, 832–837, doi:10.1038/416832a.

    • Search Google Scholar
    • Export Citation

  • Drijfhout, S., D. Marshall, and H. Dijkstra, 2013: Conceptual models of the wind-driven and thermohaline circulation. Ocean Circulation and Climate: A 21st Century Perspective, G. Siedler et al., Eds., International Geophysics Series, Vol. 103, Academic Press, 257–282.

  • Durack, P. J., and S. E. Wijffels, 2010: Fifty-year trends in global ocean salinities and their relationship to broadscale warming. J. Climate, 23, 4342–4362, doi:10.1175/2010JCLI3377.1.

    • Search Google Scholar
    • Export Citation

  • Durack, P. J., S. E. Wijffels, and R. J. Matear, 2012: Ocean salinities reveal strong global water cycle intensification during 1950 to 2000. Science, 336, 455–458, doi:10.1126/science.1212222.

    • Search Google Scholar
    • Export Citation

  • Durack, P. J., S. E. Wijffels, and T. P. Boyer, 2013: Long-term salinity changes and implications for the global water cycle. Ocean Circulation and Climate: A 21st Century Perspective, G. Siedler et al., Eds., International Geophysics Series, Vol. 103, Academic Press, 727–757.

  • Freeland, H., K. Denman, C. S. Wong, F. Whitney, and R. Jacques, 1997: Evidence of change in the winter mixed layer in the northeast Pacific Ocean. Deep-Sea Res. I, 44, 2117–2129, doi:10.1016/S0967-0637(97)00083-6.

    • Search Google Scholar
    • Export Citation

  • Gordon, A. L., and C. F. Giulivi, 2008: Sea surface salinity trends over fifty years within the subtropical North Atlantic. Oceanography, 21, 20–29, doi:10.5670/oceanog.2008.64.

    • Search Google Scholar
    • Export Citation

  • Griffies, S. M., 2009: Elements of MOM4p1. GFDL Ocean Group Tech. Rep. 6, 444 pp.

  • Griffies, S. M., and Coauthors, 2009: Coordinated Ocean-Ice Reference Experiments (COREs). Ocean Modell., 26, 1–46, doi:10.1016/j.ocemod.2008.08.007.

    • Search Google Scholar
    • Export Citation

  • Hartmann, D. L., and Coauthors, 2013: Observations: Atmosphere and surface. Climate Change 2013: The Physical Science Basis, T. F. Stocker et al., Eds., Cambridge University Press, 159–254, doi:10.1017/CBO9781107415324.008.

  • Hegerl, G. C., and Coauthors, 2014: Challenges in quantifying changes in the global water cycle. Bull. Amer. Meteor. Soc., 96, 1097–1115, doi:10.1175/BAMS-D-13-00212.1.

    • Search Google Scholar
    • Export Citation

  • Held, I. M., and B. J. Soden, 2006: Robust responses of the hydrological cycle to global warming. J. Climate, 19, 5686–5699, doi:10.1175/JCLI3990.1.

    • Search Google Scholar
    • Export Citation

  • Helm, K. P., N. L. Bindoff, and J. A. Church, 2010: Changes in the global hydrological-cycle inferred from ocean salinity. Geophys. Res. Lett., 37, L18701, doi:10.1029/2010GL044222.

    • Search Google Scholar
    • Export Citation

  • Hosoda, S., T. Suga, N. Shikama, and K. Mizuno, 2009: Global surface layer salinity change detected by Argo and its implication for hydrological cycle intensification. J. Oceanogr., 65, 579–596, doi:10.1007/s10872-009-0049-1.

    • Search Google Scholar
    • Export Citation

  • Hunke, E. C., and W. H. Lipscomb, 2010: CICE: The Los Alamos Sea Ice Model documentation and software user’s manual. Los Alamos National Laboratory Tech. Rep. LA-CC-06-012, 76 pp. [Available online at http://csdms.colorado.edu/w/images/CICE_documentation_and_software_user's_manual.pdf.]

  • Johnson, G. C., and J. M. Lyman, 2007: Global oceans: Sea surface salinity [in “State of the Climate in 2006”]. Bull. Amer. Meteor. Soc., 88 (6), S34–S35, doi:10.1175/BAMS-88-6-StateoftheClimate.

    • Search Google Scholar
    • Export Citation

  • Kouketsu, S., M. Fukasawa, D. Sasano, Y. Kumamoto, T. Kawano, H. Uchida, and T. Doi, 2010: Changes in water properties around North Pacific Intermediate Water between the 1980s, 1990s and 2000s. Deep-Sea Res. II, 57, 1177–1187, doi:10.1016/j.dsr2.2009.12.007.

    • Search Google Scholar
    • Export Citation

  • Large, W. G., and S. G. Yeager, 2004: Diurnal to decadal global forcing for ocean and sea ice models: The data sets and flux climatologies. NCAR Tech. Note NCAR/TN-460+STR, 105 pp.

  • Large, W. G., and S. G. Yeager, 2009: The global climatology of an interannually varying air–sea flux data set. Climate Dyn., 33, 341–364, doi:10.1007/s00382-008-0441-3.

    • Search Google Scholar
    • Export Citation

  • Levitus, S., J. Antonov, and T. Boyer, 2005: Warming of the world ocean, 1995–2003. Geophys. Res. Lett., 32, L02604, doi:10.1029/2004GL021592.

    • Search Google Scholar
    • Export Citation

  • Levitus, S., and Coauthors, 2012: World ocean heat content and thermosteric sea level change (0–2000 m), 1955–2010. Geophys. Res. Lett., 39, L10603, doi:10.1029/2012GL051106.

    • Search Google Scholar
    • Export Citation

  • Potter, R. A., and M. S. Lozier, 2004: On the warming and salinification of the Mediterranean outflow waters in the North Atlantic. Geophys. Res. Lett., 31, L01202, doi:10.1029/2003GL018161.

    • Search Google Scholar
    • Export Citation

  • Rhein, M. S. R., and Coauthors, 2013: Observations: Ocean. Climate Change 2013: The Physical Science Basis, T. F. Stocker et al., Eds., Cambridge University Press, 255–315, doi:10.1017/CBO9781107415324.010.

  • Roemmich, D., and J. Gilson, 2009: The 2004–2008 mean and annual cycle of temperature, salinity, and steric height in the global ocean from the Argo program. Prog. Oceanogr., 82, 81–100, doi:10.1016/j.pocean.2009.03.004.

    • Search Google Scholar
    • Export Citation

  • Schanze, J. J., R. W. Schmitt, and L. L. Yu, 2010: The global oceanic freshwater cycle: A state-of-the-art quantification. J. Mar. Res., 68, 569–595, doi:10.1357/002224010794657164.

    • Search Google Scholar
    • Export Citation

  • Skliris, N., R. Marsh, S. A. Josey, S. A. Good, C. Liu, and R. P. Allan, 2014: Salinity changes in the World Ocean since 1950 in relation to changing surface freshwater fluxes. Climate Dyn., 43, 709–736, doi:10.1007/s00382-014-2131-7.

    • Search Google Scholar
    • Export Citation

  • Sloyan, B. M., and I. V. Kamenkovitch, 2007: Simulation of subantarctic mode and Antarctic Intermediate Waters in climate models. J. Climate, 20, 5061–5080, doi:10.1175/JCLI4295.1.

    • Search Google Scholar
    • Export Citation

  • Terray, L., L. Corre, S. Cravatte, T. Delcroix, G. Reverdin, and A. Ribes, 2012: Near-surface salinity as nature’s rain gauge to detect human influence on the tropical water cycle. J. Climate, 25, 958–977, doi:10.1175/JCLI-D-10-05025.1.

    • Search Google Scholar
    • Export Citation

  • Valcke, S., 2006: OASIS3 user guide: prism_2-5. PRISM Support Initiative CERFACS Rep. 3, 68 pp.

  • von Schuckmann, K., F. Gaillard, and P.-Y. Le Traon, 2009: Global hydrographic variability patterns during 2003–2008. J. Geophys. Res., 114, C09007, doi:10.1029/2008JC005237.

    • Search Google Scholar
    • Export Citation

  • Wong, A. P. S., N. L. Bindoff, and J. A. Church, 1999: Large-scale freshening of intermediate waters in the Pacific and Indian Oceans. Nature, 400, 440–443, doi:10.1038/22733.

    • Search Google Scholar
    • Export Citation

  • Wong, A. P. S., N. L. Bindoff, and J. A. Church, 2001: Freshwater and heat changes in the North and South Pacific Oceans between the 1960s and 1985–94. J. Climate, 14, 1613–1633, doi:10.1175/1520-0442(2001)014<1613:FAHCIT>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
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