A Simple Model of the Response of the Atlantic to the North Atlantic Oscillation

Xiaoming Zhai Centre for Ocean and Atmospheric Sciences, School of Environmental Sciences, University of East Anglia, Norwich, United Kingdom

Search for other papers by Xiaoming Zhai in
Current site
Google Scholar
PubMed
Close
,
Helen L. Johnson Department of Earth Sciences, University of Oxford, Oxford, United Kingdom

Search for other papers by Helen L. Johnson in
Current site
Google Scholar
PubMed
Close
, and
David P. Marshall Department of Physics, University of Oxford, Oxford, United Kingdom

Search for other papers by David P. Marshall in
Current site
Google Scholar
PubMed
Close
Restricted access

Abstract

The response of an idealized Atlantic Ocean to wind and thermohaline forcing associated with the North Atlantic Oscillation (NAO) is investigated both analytically and numerically in the framework of a reduced-gravity model. The NAO-related wind forcing is found to drive a time-dependent “leaky” gyre circulation that integrates basinwide stochastic wind Ekman pumping and initiates low-frequency variability along the western boundary. This is subsequently communicated, together with the stochastic variability induced by thermohaline forcing at high latitudes, to the remainder of the Atlantic via boundary and Rossby waves. At low frequencies, the basinwide ocean heat content changes owing to NAO wind forcing and thermohaline forcing are found to oppose each other. The model further suggests that the recently reported opposing changes of the meridional overturning circulation in the Atlantic subtropical and subpolar gyres between 1950–70 and 1980–2000 may be a generic feature caused by interplay between the NAO wind and thermohaline forcing.

Corresponding author address: Xiaoming Zhai, School of Environmental Sciences, University of East Anglia, Norwich NR4 7TJ, United Kingdom. E-mail: xiaoming.zhai@uea.ac.uk

Abstract

The response of an idealized Atlantic Ocean to wind and thermohaline forcing associated with the North Atlantic Oscillation (NAO) is investigated both analytically and numerically in the framework of a reduced-gravity model. The NAO-related wind forcing is found to drive a time-dependent “leaky” gyre circulation that integrates basinwide stochastic wind Ekman pumping and initiates low-frequency variability along the western boundary. This is subsequently communicated, together with the stochastic variability induced by thermohaline forcing at high latitudes, to the remainder of the Atlantic via boundary and Rossby waves. At low frequencies, the basinwide ocean heat content changes owing to NAO wind forcing and thermohaline forcing are found to oppose each other. The model further suggests that the recently reported opposing changes of the meridional overturning circulation in the Atlantic subtropical and subpolar gyres between 1950–70 and 1980–2000 may be a generic feature caused by interplay between the NAO wind and thermohaline forcing.

Corresponding author address: Xiaoming Zhai, School of Environmental Sciences, University of East Anglia, Norwich NR4 7TJ, United Kingdom. E-mail: xiaoming.zhai@uea.ac.uk
Save
  • 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, doi:10.1175/2008JCLI2404.1.

    • Search Google Scholar
    • Export Citation
  • Bingham, R. J., C. W. Hughes, V. Roussenov, and R. G. Williams, 2007: Meridional coherence of the North Atlantic meridional overturning circulation. Geophys. Res. Lett., 34, L23606, doi:10.1029/2007GL031731.

    • 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
  • Cessi, P., and S. Louazel, 2001: Decadal oceanic response to stochastic wind forcing. J. Phys. Oceanogr., 31, 30203029, doi:10.1175/1520-0485(2001)031<3020:DORTSW>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Cessi, P., and P. Otheguy, 2003: Oceanic teleconnections: Remote response to decadal wind forcing. J. Phys. Oceanogr., 33, 16041617, doi:10.1175/2400.1.

    • Search Google Scholar
    • Export Citation
  • Curry, R. G., M. S. McCartney, and T. M. Joyce, 1998: Oceanic transport of subpolar climate signals to mid-depth subtropical waters. Nature, 391, 575577, doi:10.1038/35356.

    • Search Google Scholar
    • Export Citation
  • Deshayes, J., and C. Frankignoul, 2005: Spectral characteristics of the response of the meridional overturning circulation to deep-water formation. J. Phys. Oceanogr., 35, 18131825, doi:10.1175/JPO2793.1.

    • Search Google Scholar
    • Export Citation
  • Deshayes, J., and C. Frankignoul, 2008: Simulated variability of the circulation in the North Atlantic from 1953 to 2003. J. Climate, 21, 49194933, doi:10.1175/2008JCLI1882.1.

    • Search Google Scholar
    • Export Citation
  • Dickson, R. R., and J. Brown, 1994: The production of North Atlantic deep water: Sources, rates, and pathways. J. Geophys. Res., 99, 12 31912 341, doi:10.1029/94JC00530.

    • Search Google Scholar
    • Export Citation
  • Dickson, R. R., J. Lazier, J. Meincke, P. Rhines, and J. Swift, 1996: Long-term co-ordinated changes in the convective activity in the North Atlantic. Prog. Oceanogr., 38, 241295, doi:10.1016/S0079-6611(97)00002-5.

    • Search Google Scholar
    • Export Citation
  • Dong, B., and R. T. Sutton, 2005: Mechanism of interdecadal thermohaline circulation variability in a coupled ocean–atmosphere GCM. J. Climate, 18, 11171135, doi:10.1175/JCLI3328.1.

    • Search Google Scholar
    • Export Citation
  • Eden, C., and T. Jung, 2001: North Atlantic interdecadal variability: Oceanic response to the North Atlantic Oscillation (1865–1997). J. Climate, 14, 676691, doi:10.1175/1520-0442(2001)014<0676:NAIVOR>2.0.CO;2.

    • 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, doi:10.1175/1520-0442(2001)014<2266:MOITDV>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Eden, C., and R. J. Greatbatch, 2003: A damped oscillation in the North Atlantic climate system. J. Climate, 16, 40434060, doi:10.1175/1520-0442(2003)016<4043:ADDOIT>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Fine, R. A., and R. L. Molinari, 1988: A continuous deep western boundary current between Abaco (26.5°N) and Barbados (13°N). Deep-Sea Res., 35, 14411450, doi:10.1016/0198-0149(88)90096-9.

    • Search Google Scholar
    • Export Citation
  • Frankignoul, C., P. Müller, and E. Zorita, 1997: A simple model of the decadal response of the ocean to stochastic wind forcing. J. Phys. Oceanogr., 27, 15331546, doi:10.1175/1520-0485(1997)027<1533:ASMOTD>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Häkkinen, S., 1999: Variability of the simulated meridional heat transport in the North Atlanic for the period 1951-1993. J. Geophys. Res., 104, 10 99111 007, doi:10.1029/1999JC900034.

    • Search Google Scholar
    • Export Citation
  • Hurrell, J. W., 1995: Decadal trends in the North Atlantic Oscillation and relationships to regional temperatures and precipitation. Science, 269, 676679, doi:10.1126/science.269.5224.676.

    • Search Google Scholar
    • Export Citation
  • Johnson, H. L., and D. P. Marshall, 2002a: A theory for the surface Atlantic response to thermohaline variability. J. Phys. Oceanogr., 32, 11211132, doi:10.1175/1520-0485(2002)032<1121:ATFTSA>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Johnson, H. L., and D. P. Marshall, 2002b: Localization of abrupt change in the North Atlantic thermohaline circulation. Geophys. Res. Lett., 29 (6), doi:10.1029/2001GL014140.

    • Search Google Scholar
    • Export Citation
  • Johnson, H. L., and D. P. Marshall, 2004: Global teleconnections of meridional overturning circulation anomalies. J. Phys. Oceanogr., 34, 17021722, doi:10.1175/1520-0485(2004)034<1702:GTOMOC>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Josey, S. A., J. P. Grist, and R. Marsh, 2009: Estimates of meridional overturning circulation variability in the North Atlantic from surface density flux fields. J. Geophys. Res., 114, C09022, doi:10.1029/2008JC005230.

    • Search Google Scholar
    • Export Citation
  • Kalnay, E., and Coauthors, 1996: The NCEP/NCAR 40-Year Reanalysis Project. Bull. Amer. Meteor. Soc., 77, 437471, doi:10.1175/1520-0477(1996)077<0437:TNYRP>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Kanzow, T., H. L. Johnson, D. P. Marshall, S. A. Cunningham, J. J.-M. Hirschi, A. Mujahid, H. L. Bryden, and W. E. Johns, 2009: Observing basinwide integrated volume transports in an eddy-filled ocean. J. Phys. Oceanogr., 39, 30913110, doi:10.1175/2009JPO4185.1.

    • Search Google Scholar
    • Export Citation
  • Leadbetter, S. J., R. G. Williams, E. L. McDonagh, and B. A. King, 2007: A twenty year reversal in water mass trends in the subtropical North Atlantic. Geophys. Res. Lett., 34, L12608, doi:10.1029/2007GL029957.

  • Lozier, M. S., S. Leadbetter, R. G. Williams, V. Roussenov, M. S. C. Reed, and N. J. Moore, 2008: The spatial pattern and mechanisms of heat-content change in the North Atlantic. Science, 319, 800803, doi:10.1126/science.1146436.

    • Search Google Scholar
    • Export Citation
  • Lozier, M. S., V. Roussenov, M. S. C. Reed, and R. G. Williams, 2010: Opposing decadal changes for the North Atlantic meridional overturning circulation. Nat. Geosci., 3, 728734, doi:10.1038/ngeo947.

    • Search Google Scholar
    • Export Citation
  • Marsh, R., 2000: Recent variability of the North Atlantic thermohaline circulation inferred from surface heat and freshwater fluxes. J. Climate, 13, 32393260, doi:10.1175/1520-0442(2000)013<3239:RVOTNA>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Marshall, D. P., and H. L. Johnson, 2013: Propagation of meridional circulation anomalies along western and eastern boundaries. J. Phys. Oceanogr., 43, 26992717, doi:10.1175/JPO-D-13-0134.1.

    • Search Google Scholar
    • Export Citation
  • Marshall, J., and F. Schott, 1999: Open ocean deep convection: Observations, models and theory. Rev. Geophys., 37, 164, doi:10.1029/98RG02739.

    • Search Google Scholar
    • Export Citation
  • Marshall, J., H. Johnson, and J. Goodman, 2001: A study of the interaction of the North Atlantic Oscillation with ocean circulation. J. Climate, 14, 13991421, doi:10.1175/1520-0442(2001)014<1399:ASOTIO>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • McDougall, T. J., 2003: Potential enthalpy: A conservative oceanic variable for evaluating heat content and heat fluxes. J. Phys. Oceanogr., 33, 945963, doi:10.1175/1520-0485(2003)033<0945:PEACOV>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Primeau, F., 2002: Long Rossby wave basin-crossing time and the resonance of low-frequency basin modes. J. Phys. Oceanogr., 32, 26522665, doi:10.1175/1520-0485-32.9.2652.

    • Search Google Scholar
    • Export Citation
  • Robson, J., R. Sutton, K. Lohmann, D. Smith, and M. D. Palmer, 2012: Causes of the rapid warming of the North Atlantic Ocean in the mid-1990s. J. Climate, 25, 41164134, doi:10.1175/JCLI-D-11-00443.1.

    • Search Google Scholar
    • Export Citation
  • Sirven, J., C. Herbaut, J. Deshayes, and C. Frankignoul, 2007: Origin of the annual to decadal peaks of variability in the response of simple ocean models to stochastic forcing. J. Phys. Oceanogr., 37, 21462157, doi:10.1175/JPO3095.1.

    • Search Google Scholar
    • Export Citation
  • Sturges, W., and B. G. Hong, 1995: Wind forcing of the Atlantic thermocline along 32°N at low frequencies. J. Phys. Oceanogr., 25, 17061715, doi:10.1175/1520-0485(1995)025<1706:WFOTAT>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Talley, L. D., and M. S. McCartney, 1982: Distribution and circulation of Labrador Sea Water. J. Phys. Oceanogr., 12, 11891205, doi:10.1175/1520-0485(1982)012<1189:DACOLS>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Visbeck, M., E. P. Chassignet, R. G. Curry, T. L. Delworth, R. R. Dickson, and G. Krahmann, 2003: The ocean’s response to North Atlantic Oscillation variability. The North Atlantic Oscillation: Climatic Significance and Environmental Impact, Geophys. Monogr., Vol. 134, Amer. Geophys. Union, 113–146.

  • Wunsch, C., 1999: The interpretation of short climate records, with comments on the North Atlantic and Southern Oscillations. Bull. Amer. Meteor. Soc., 80, 245255, doi:10.1175/1520-0477(1999)080<0245:TIOSCR>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Wunsch, C., and P. Heimbach, 2013: Two decades of the Atlantic meridional overturning circulation: Anatomy, variations, extremes, prediction, and overcoming its limitations. J. Climate, 26, 71677186, doi:10.1175/JCLI-D-12-00478.1.

    • Search Google Scholar
    • Export Citation
  • Zhai, X., and L. Sheldon, 2012: On the North Atlantic ocean heat content change between 1955–70 and 1980–95. J. Climate, 25, 36193628, doi:10.1175/JCLI-D-11-00187.1.

    • Search Google Scholar
    • Export Citation
  • Zhai, X., H. L. Johnson, and D. P. Marshall, 2010: Significant sink of ocean-eddy energy near western boundaries. Nat. Geosci., 3, 608612, doi:10.1038/ngeo943.

    • Search Google Scholar
    • Export Citation
  • Zhai, X., H. L. Johnson, and D. P. Marshall, 2011: A model of Atlantic heat content and sea level change in response to thermohaline forcing. J. Climate, 24, 56195632, doi:10.1175/JCLI-D-10-05007.1.

    • Search Google Scholar
    • Export Citation
All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 261 90 15
PDF Downloads 180 80 11