Regional Patterns of Sea Level Change Related to Interannual Variability and Multidecadal Trends in the Atlantic Meridional Overturning Circulation

K. Lorbacher IFM-GEOMAR, Leibniz-Institut für Meereswissenschaften, Kiel, Germany

Search for other papers by K. Lorbacher in
Current site
Google Scholar
PubMed
Close
,
J. Dengg IFM-GEOMAR, Leibniz-Institut für Meereswissenschaften, Kiel, Germany

Search for other papers by J. Dengg in
Current site
Google Scholar
PubMed
Close
,
C. W. Böning IFM-GEOMAR, Leibniz-Institut für Meereswissenschaften, Kiel, Germany

Search for other papers by C. W. Böning in
Current site
Google Scholar
PubMed
Close
, and
A. Biastoch IFM-GEOMAR, Leibniz-Institut für Meereswissenschaften, Kiel, Germany

Search for other papers by A. Biastoch in
Current site
Google Scholar
PubMed
Close
Restricted access

Abstract

Some studies of ocean climate model experiments suggest that regional changes in dynamic sea level could provide a valuable indicator of trends in the strength of the Atlantic meridional overturning circulation (MOC). This paper describes the use of a sequence of global ocean–ice model experiments to show that the diagnosed patterns of sea surface height (SSH) anomalies associated with changes in the MOC in the North Atlantic (NA) depend critically on the time scales of interest. Model hindcast simulations for 1958–2004 reproduce the observed pattern of SSH variability with extrema occurring along the Gulf Stream (GS) and in the subpolar gyre (SPG), but they also show that the pattern is primarily related to the wind-driven variability of MOC and gyre circulation on interannual time scales; it is reflected also in the leading EOF of SSH variability over the NA Ocean, as described in previous studies. The pattern, however, is not useful as a “fingerprint” of longer-term changes in the MOC: as shown with a companion experiment, a multidecadal, gradual decline in the MOC [of 5 Sv (1 Sv ≡ 106 m3 s−1) over 5 decades] induces a much broader, basin-scale SSH rise over the mid-to-high-latitude NA, with amplitudes of 20 cm. The detectability of such a trend is low along the GS since low-frequency SSH changes are effectively masked here by strong variability on shorter time scales. More favorable signal-to-noise ratios are found in the SPG and the eastern NA, where a MOC trend of 0.1 Sv yr−1 would leave a significant imprint in SSH already after about 20 years.

Corresponding author address: C. W. Böning, IFM-GEOMAR, Leibniz-Institut für Meereswissenschaften, Düsternbrooker Weg 20, 24105 Kiel, Germany. Email: cboening@ifm-geomar.de

Abstract

Some studies of ocean climate model experiments suggest that regional changes in dynamic sea level could provide a valuable indicator of trends in the strength of the Atlantic meridional overturning circulation (MOC). This paper describes the use of a sequence of global ocean–ice model experiments to show that the diagnosed patterns of sea surface height (SSH) anomalies associated with changes in the MOC in the North Atlantic (NA) depend critically on the time scales of interest. Model hindcast simulations for 1958–2004 reproduce the observed pattern of SSH variability with extrema occurring along the Gulf Stream (GS) and in the subpolar gyre (SPG), but they also show that the pattern is primarily related to the wind-driven variability of MOC and gyre circulation on interannual time scales; it is reflected also in the leading EOF of SSH variability over the NA Ocean, as described in previous studies. The pattern, however, is not useful as a “fingerprint” of longer-term changes in the MOC: as shown with a companion experiment, a multidecadal, gradual decline in the MOC [of 5 Sv (1 Sv ≡ 106 m3 s−1) over 5 decades] induces a much broader, basin-scale SSH rise over the mid-to-high-latitude NA, with amplitudes of 20 cm. The detectability of such a trend is low along the GS since low-frequency SSH changes are effectively masked here by strong variability on shorter time scales. More favorable signal-to-noise ratios are found in the SPG and the eastern NA, where a MOC trend of 0.1 Sv yr−1 would leave a significant imprint in SSH already after about 20 years.

Corresponding author address: C. W. Böning, IFM-GEOMAR, Leibniz-Institut für Meereswissenschaften, Düsternbrooker Weg 20, 24105 Kiel, Germany. Email: cboening@ifm-geomar.de

Save
  • Baehr, J., K. Keller, and J. Marotzke, 2007: Detecting potential changes in the meridional overturning circulation at 26°N in the Atlantic. Climate Change, 91 , 1127. doi:10.1007/s10584-006-9153-z.

    • Search Google Scholar
    • Export Citation
  • Barnier, B., and Coauthors, 2006: Impact of partial steps and momentum advection schemes in a global ocean circulation model at eddy-permitting resolution. Ocean Dyn., 56 , 543567. doi:10.1007/s10236-006-0082-1.

    • Search Google Scholar
    • Export Citation
  • Barnier, B., and Coauthors, 2007: Eddy-permitting ocean circulation hindcasts of past decades. CLIVAR Exchanges, No. 42, International CLIVAR Project Office, Southampton, United Kingdom, 8–10.

    • Search Google Scholar
    • Export Citation
  • Biastoch, A., C. Völker, and C. W. Böning, 2007: Uptake and spreading of anthropogenic trace gases in an eddy-permitting model of the Atlantic Ocean. J. Geophys. Res., 112 , C09017. doi:10.1029/2006JC003966.

    • Search Google Scholar
    • Export Citation
  • Biastoch, A., C. W. Böning, J. Getzlaff, J-M. Molines, and G. Madec, 2008: Causes of interannual–decadal variability in the meridional overturning circulation of the midlatitude North Atlantic Ocean. J. Climate, 21 , 65996615.

    • Search Google Scholar
    • Export Citation
  • Bindoff, N. L., and Coauthors, 2007: Observations: Oceanic climate change and sea level. Climate Change 2007: The Physical Science Basis, S. Solomon et al., Eds., Cambridge University Press, 385–432.

    • Search Google Scholar
    • Export Citation
  • Böning, C. W., M. Scheinert, J. Dengg, A. Biastoch, and A. Funk, 2006: Decadal variability of subpolar gyre transport and its reverberation in the North Atlantic overturning. Geophys. Res. Lett., 33 , L21S01. doi:10.1029/2006GL026906.

    • Search Google Scholar
    • Export Citation
  • Bryan, K., 1996: The steric component of sea level rise associated with enhanced greenhouse warming: A model study. Climate Dyn., 12 , 545555.

    • Search Google Scholar
    • Export Citation
  • Bryden, H. L., and S. Imawaki, 2001: Ocean heat transport. Ocean Circulation and Climate: Observing and Modelling the Global Ocean, G. Siedler et al., Eds., Academic Press, 455–474.

    • Search Google Scholar
    • Export Citation
  • Bryden, H. L., H. R. Longworth, and S. A. Cunningham, 2005: Slowing of the Atlantic meridional overturning circulation at 25°N. Nature, 438 , 655657. doi:10.1038/nature04385.

    • Search Google Scholar
    • Export Citation
  • Cromwell, D., A. G. P. Shaw, P. Challenor, R. E. Houseago-Stokes, and R. Tokmakian, 2007: Towards measuring the meridional overturning circulation from space. Ocean Sci., 3 , 223228.

    • Search Google Scholar
    • Export Citation
  • Cunningham, S. A., and Coauthors, 2007: Temporal Variability of the Atlantic Meridional Overturning Circulation at 26.5°N. Science, 317 , 935938. doi:10.1126/science.1141304.

    • Search Google Scholar
    • Export Citation
  • Curry, R. G., and M. S. McCartney, 2001: Ocean gyre circulation changes associated with the North Atlantic Oscillation. J. Phys. Oceanogr., 31 , 33743400.

    • Search Google Scholar
    • Export Citation
  • Dommenget, D., 2007: Evaluating EOF modes against a stochastic null hypothesis. Climate Dyn., 28 , 517531. doi:10.1007/s00382-006-0195-8.

    • 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.

    • Search Google Scholar
    • Export Citation
  • Esselborn, S., and C. Eden, 2001: Sea surface height changes in the North Atlantic Ocean related to the North Atlantic Oscillation. Geophys. Res. Lett., 28 , 34733476.

    • Search Google Scholar
    • Export Citation
  • Fu, L., and R. Smith, 1996: Global ocean circulation from satellite altimetry and high-resolution computer simulation. Bull. Amer. Meteor. Soc., 77 , 26252636.

    • Search Google Scholar
    • Export Citation
  • Gent, P. R., and J. C. McWilliams, 1990: Isopycnal mixing in ocean circulation models. J. Phys. Oceanogr., 20 , 150155.

  • Greatbatch, R., 1994: A note on the representation of steric sea level in models that conserve volume rather than mass. J. Geophys. Res., 99 , (C6). 1276712771.

    • Search Google Scholar
    • Export Citation
  • Gregory, J. M., and Coauthors, 2005: A model intercomparison of changes in the Atlantic thermohaline circulation in response to increasing atmospheric CO2 concentration. Geophys. Res. Lett., 32 , L12703. doi:10.1029/2005GL023209.

    • Search Google Scholar
    • Export Citation
  • Griffies, S., and Coauthors, 2009: Coordinated Ocean-ice Reference Experiments (COREs). Ocean Modell., 26 , 146. doi:10.1016/j.ocemod.2008.08.007.

    • Search Google Scholar
    • Export Citation
  • Häkkinen, S., 2000: Decadal air–sea interaction in the North Atlantic based on observations and modeling results. J. Climate, 13 , 11951219.

    • Search Google Scholar
    • Export Citation
  • Häkkinen, S., 2001: Variability in the sea surface height: A qualitative measure for the meridional overturning in the North Atlantic. J. Geophys. Res., 106 , (C7). 1383713848.

    • Search Google Scholar
    • Export Citation
  • Häkkinen, S., and P. B. Rhines, 2004: Decline of Subpolar North Atlantic Circulation During the 1990s. Science, 304 , 555559. doi:10.1126/science.1094917.

    • 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.

    • Search Google Scholar
    • Export Citation
  • Hu, A., G. A. Meehl, W. Han, and J. Yin, 2009: Transient response of the MOC and climate to potential melting of the Greenland Ice Sheet in the 21st century. Geophys. Res. Lett., 36 , L10707. doi:10.1029/2009GL037998.

    • Search Google Scholar
    • Export Citation
  • Jungclaus, J. H., H. Haak, M. Esch, E. Roeckner, and J. Marotzke, 2006: Will Greenland melting halt the thermohaline circulation? Geophys. Res. Lett., 33 , L17708. doi:10.1029/2006GL026815.

    • Search Google Scholar
    • Export Citation
  • Kalnay, E., and Coauthors, 1996: The NCEP/NCAR 40-Year Reanalysis Project. Bull. Amer. Meteor. Soc., 77 , 437471.

  • Kanzow, T., and Coauthors, 2007: Observed Flow Compensation Associated with the MOC at 26.5°N in the Atlantic. Science, 317 , 938941. doi:10.1126/science.1141293.

    • Search Google Scholar
    • Export Citation
  • Landerer, F. W., J. H. Jungclaus, and J. Marotzke, 2007: Regional dynamic and steric sea level change in response to the IPCC-A1B scenario. J. Phys. Oceanogr., 37 , 296312.

    • 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, 112 pp.

    • Search Google Scholar
    • Export Citation
  • Levermann, A., A. Griesel, M. Hoffmann, M. Montoya, and S. Rahmstorf, 2005: Dynamic sea level changes following changes in the thermohaline circulation. Climate Dyn., 24 , 347354. doi:10.1007/s00382-004-0505-y.

    • Search Google Scholar
    • Export Citation
  • Madec, G., 2006: NEMO: The OPA ocean engine. IPSL Note du Pole de Modelisation, 110 pp.

  • Marotzke, J., S. A. Cunningham, and H. L. Bryden, cited. 2009: Monitoring the Atlantic meridional overturning circulation at 26.5°N. [Available online at http://www.noc.soton.ac.uk/rapidmoc/home.html].

    • Search Google Scholar
    • Export Citation
  • Meehl, G. A., and Coauthors, 2007: Global climate projections. Climate Change 2007: The Physical Science Basis, S. Solomon et al., Eds., Cambridge University Press, 747–845.

    • Search Google Scholar
    • Export Citation
  • Polito, P. S., and O. T. Sato, 2008: Global interannual trends and amplitude modulations of the sea surface height anomaly from the TOPEX/Jason-1 altimeters. J. Climate, 21 , 28242834.

    • Search Google Scholar
    • Export Citation
  • Rhines, P., S. Häkkinen, and S. A. Josey, 2008: Is oceanic heat transport significant in the climate system? Arctic-Subarctic Ocean Fluxes: Defining the Role of the Northern Seas in Climate, R. R. Dickson, J. Meincke, and P. Rhines, Eds., Springer, 87–109.

    • Search Google Scholar
    • Export Citation
  • Sarmiento, J. L., and C. LeQuéré, 1996: Oceanic carbon dioxide uptake in a model of century-scale global warming. Science, 27 , 13461350.

    • Search Google Scholar
    • Export Citation
  • Vellinga, M., and R. A. Wood, 2002: Global climate impacts of a collapse of the Atlantic thermohaline circulation. Climatic Change, 54 , 251267.

    • Search Google Scholar
    • Export Citation
  • von Storch, H., and F. W. Zwiers, 1999: Statistical Analysis in Climate Research. Cambridge University Press, 484 pp.

  • Wunsch, C., 2008: Mass and volume transport variability in an eddy-filled ocean. Nat. Geosci., 1 , 165168. doi:10.1038/ngeo126.

  • Wunsch, C., R. M. Ponte, and P. Heimbach, 2007: Decadal trends in sea level patterns: 1993–2004. J. Climate, 27 , 58895911.

  • Yin, J., M. E. Schlesinger, and R. J. Stouffer, 2009: Model projections of rapid sea-level rise on the northeast coast of the United States. Nat. Geosci., 2 , 262266. doi:10.1038/NGEO462.

    • Search Google Scholar
    • Export Citation
  • Zhang, R., 2008: Coherent surface-subsurface fingerprint of the Atlantic meridional overturning circulation. Geophys. Res. Lett., 35 , L20705. doi:10.1029/2008GL035463.

    • Search Google Scholar
    • Export Citation
All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 285 80 1
PDF Downloads 233 51 1