• Baquero-Bernal, A., , and M. Latif, 2005: Wind-driven oceanic Rossby waves in the tropical south Indian Ocean with and without an active ENSO. J. Phys. Oceanogr., 35 , 729746.

    • Search Google Scholar
    • Export Citation
  • Cessi, P., , and S. Louazel, 2001: Decadal oceanic response to stochastic wind forcing. J. Phys. Oceanogr., 31 , 30203029.

  • Cessi, P., , and F. Primeau, 2001: Dissipative selection of low-frequency modes in a reduced-gravity basin. J. Phys. Oceanogr., 31 , 127137.

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

  • Deser, C., , M. A. Alexander, , and M. A. Timlin, 1999: Evidence for a wind-driven intensification of the Kuroshio Current Extension from the 1970s to the 1980s. J. Climate, 12 , 16971706.

    • 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.

    • Search Google Scholar
    • Export Citation
  • Février, S., , J. Sirven, , and C. Herbaut, 2007: Interaction of a coastal Kelvin wave with the mean state in the Gulf Stream separation area. J. Phys. Oceanogr., 37 , 14291444.

    • 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 stress forcing. J. Phys. Oceanogr., 27 , 15331546.

    • Search Google Scholar
    • Export Citation
  • Huang, R. X., , M. A. Cane, , N. Naik, , and P. Goodmand, 2000: Global adjustment of the thermocline in response to deep water formation. Geophys. Res. Lett., 27 , 759762.

    • Search Google Scholar
    • Export Citation
  • Johnson, H. L., , and D. P. Marshall, 2002: A theory for the surface Atlantic response to thermohaline variability. J. Phys. Oceanogr., 32 , 11211132.

    • 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.

    • Search Google Scholar
    • Export Citation
  • Kushnir, Y., 1994: Interdecadal variations in North Atlantic sea surface temperature and associated atmospheric conditions. J. Climate, 7 , 141157.

    • Search Google Scholar
    • Export Citation
  • LaCasce, J. H., 2000: Baroclinic Rossby waves in a square basin. J. Phys. Oceanogr., 30 , 31613178.

  • LaCasce, J. H., , and J. Pedlosky, 2002: Baroclinic Rossby waves in irregular basins. J. Phys. Oceanogr., 32 , 28282847.

  • LaCasce, J. H., , and J. Pedlosky, 2004: The instability of Rossby basin modes and the oceanic eddy field. J. Phys. Oceanogr., 34 , 20272041.

    • Search Google Scholar
    • Export Citation
  • Mac Veigh, J. P., , B. Barnier, , and C. Le Provost, 1987: Spectral and empirical orthogonal functions analysis of four years of European Center for Medium Range Weather Forecast wind stress curl over the North Atlantic Ocean. J. Geophys. Res., 92 , 1314113152.

    • Search Google Scholar
    • Export Citation
  • Milliff, R. F., , and J. C. McWilliams, 1994: The evolution of boundary pressure in ocean basins. J. Phys. Oceanogr., 24 , 13171338.

  • Primeau, F., 2002: Long Rossby wave basin-crossing time and the resonance of low-frequency basin modes. J. Phys. Oceanogr., 32 , 26522665.

    • Search Google Scholar
    • Export Citation
  • Sirven, J., , C. Frankignoul, , G. de Coëtlogon, , and V. Taillandier, 2002: Spectrum of wind-driven baroclinic fluctuations of the ocean in the midlatitudes. J. Phys. Oceanogr., 32 , 24052417.

    • Search Google Scholar
    • Export Citation
  • Wajsowicz, R. C., , and A. E. Gill, 1986: Adjustment of the ocean under buoyancy forces. Part I: The role of Kelvin waves. J. Phys. Oceanogr., 16 , 20972114.

    • Search Google Scholar
    • Export Citation
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Origin of the Annual to Decadal Peaks of Variability in the Response of Simple Ocean Models to Stochastic Forcing

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  • 1 LOCEAN/IPSL, Université Pierre et Marie Curie, Paris, France
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Abstract

The response of the ocean to stochastic forcings is studied in a closed basin, using a simple one-dimensional analytical model. The focus is on the mechanisms that determine the time scales of the response and their possible links with free basin modes. The response may be described as a forced solution plus propagating solutions whose spatial pattern does not depend on the forcing. The propagating solutions are of two types. The first ones propagate eastward and are strongly damped so that their influence remains limited to the western boundary layer. The others are damped long Rossby waves that propagate westward and whose amplitude depends on the spatial extension and the frequency of the forcing. The amplitude increases if the frequency of the forcing is close to the frequency of the basin modes, but the spatial pattern differs from that of the latter; higher frequencies are favored if the zonal extension of the forcing is reduced. The response of a 1.5-layer reduced-gravity ocean model forced by stochastic Ekman pumping confirms the results of the analytical model.

Corresponding author address: Dr. Jérôme Sirven, LOCEAN/IPSL, Université Pierre et Marie Curie, Tour 45, étage 4, CC100, 4 Place Jussieu, 75252 Paris CEDEX 05, France. Email: js@lodyc.jussieu.fr

Abstract

The response of the ocean to stochastic forcings is studied in a closed basin, using a simple one-dimensional analytical model. The focus is on the mechanisms that determine the time scales of the response and their possible links with free basin modes. The response may be described as a forced solution plus propagating solutions whose spatial pattern does not depend on the forcing. The propagating solutions are of two types. The first ones propagate eastward and are strongly damped so that their influence remains limited to the western boundary layer. The others are damped long Rossby waves that propagate westward and whose amplitude depends on the spatial extension and the frequency of the forcing. The amplitude increases if the frequency of the forcing is close to the frequency of the basin modes, but the spatial pattern differs from that of the latter; higher frequencies are favored if the zonal extension of the forcing is reduced. The response of a 1.5-layer reduced-gravity ocean model forced by stochastic Ekman pumping confirms the results of the analytical model.

Corresponding author address: Dr. Jérôme Sirven, LOCEAN/IPSL, Université Pierre et Marie Curie, Tour 45, étage 4, CC100, 4 Place Jussieu, 75252 Paris CEDEX 05, France. Email: js@lodyc.jussieu.fr

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