Wind-Driven Variability of the Subtropical North Pacific Ocean

Donata Giglio Scripps Institution of Oceanography, University of California, San Diego, La Jolla, California

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Dean Roemmich Scripps Institution of Oceanography, University of California, San Diego, La Jolla, California

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Sarah T. Gille Scripps Institution of Oceanography, University of California, San Diego, La Jolla, California

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Abstract

The Argo array provides a unique dataset to explore variability of the subsurface ocean interior. This study considers the subtropical North Pacific Ocean during the period from 2004 to 2011, when Argo coverage has been relatively complete in time and space. Two distinct patterns of Argo dynamic height transport function () are observed: in 2004/05, the gyre is stronger, and in 2008/09 it is weaker. The orientation of the subtropical gyre also shifts over time: the predominantly zonal major axis shifts to a more northwest–southeast orientation in 2004/05 and to a more southwest–northeast orientation in 2008/09.

The limited temporal range of the Argo observations does not allow analysis of the correlation of ocean transport and wind forcing in the basin for the multiyear time scale (6–8-yr period) typical of the dominant gyre patterns. The meridional geostrophic transport anomaly between 180° and 150°E is computed both from Argo data (0–2000 db) and from the Sverdrup relation (using reanalysis winds): similarities are observed in a latitude–time plane, consistent with local forcing playing an important role. A forcing contribution from the eastern subtropics will also reach the region of interest, but on a longer time scale, and it is not analyzed in this study.

Compared with the 8-yr Argo record, the longer 19-yr time series of satellite altimetry shows a similar but somewhat modified pattern of variability. A longer Argo record will be needed to observe the decadal-scale fluctuations, to separate interannual and decadal signals, and to ensure statistical confidence in relating the wind forcing and the oceanic response.

Corresponding author address: Donata Giglio, Scripps Institution of Oceanography, University of California, San Diego, 8622 Kennel Way, La Jolla, CA 92037. E-mail: dgiglio@ucsd.edu

Abstract

The Argo array provides a unique dataset to explore variability of the subsurface ocean interior. This study considers the subtropical North Pacific Ocean during the period from 2004 to 2011, when Argo coverage has been relatively complete in time and space. Two distinct patterns of Argo dynamic height transport function () are observed: in 2004/05, the gyre is stronger, and in 2008/09 it is weaker. The orientation of the subtropical gyre also shifts over time: the predominantly zonal major axis shifts to a more northwest–southeast orientation in 2004/05 and to a more southwest–northeast orientation in 2008/09.

The limited temporal range of the Argo observations does not allow analysis of the correlation of ocean transport and wind forcing in the basin for the multiyear time scale (6–8-yr period) typical of the dominant gyre patterns. The meridional geostrophic transport anomaly between 180° and 150°E is computed both from Argo data (0–2000 db) and from the Sverdrup relation (using reanalysis winds): similarities are observed in a latitude–time plane, consistent with local forcing playing an important role. A forcing contribution from the eastern subtropics will also reach the region of interest, but on a longer time scale, and it is not analyzed in this study.

Compared with the 8-yr Argo record, the longer 19-yr time series of satellite altimetry shows a similar but somewhat modified pattern of variability. A longer Argo record will be needed to observe the decadal-scale fluctuations, to separate interannual and decadal signals, and to ensure statistical confidence in relating the wind forcing and the oceanic response.

Corresponding author address: Donata Giglio, Scripps Institution of Oceanography, University of California, San Diego, 8622 Kennel Way, La Jolla, CA 92037. E-mail: dgiglio@ucsd.edu
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  • Akitomo, K., T. Awaji, and N. Imasato, 1991: Kuroshio path variation south of Japan 1. Barotropic inflow-outflow model. J. Geophys. Res., 96, 25492560.

    • Search Google Scholar
    • Export Citation
  • Akitomo, K., S. Masuda, and T. Awaji, 1997: Kuroshio path variation south of Japan: Stability of the paths in a multiple equilibrium regime. J. Oceanogr., 53, 129142.

    • Search Google Scholar
    • Export Citation
  • Andres, M., Y.-O. Kwon, and J. Yang, 2011: Observations of the Kuroshio’s barotropic and baroclinic responses to basin-wide wind forcing. J. Geophys. Res., 116, C04011, doi:10.1029/2010JC006863.

    • Search Google Scholar
    • Export Citation
  • Barsugli, J., and D. Battisti, 1998: The basic effects of atmosphere–ocean thermal coupling on midlatitude variability. J. Atmos. Sci., 55, 477493.

    • Search Google Scholar
    • Export Citation
  • Brunke, M. A., Z. Wang, X. Zeng, M. Bosilovich, and C.-L. Shie, 2011: An assessment of the uncertainties in ocean surface turbulent fluxes in 11 reanalysis, satellite-derived, and combined global datasets. J. Climate, 24, 54695493.

    • Search Google Scholar
    • Export Citation
  • Chao, S. Y., 1984: Bimodality of the Kuroshio. J. Phys. Oceanogr., 14, 92103.

  • Cummins, P. F., and H. J. Freeland, 2007: Variability of the North Pacific Current and its bifurcation. Prog. Oceanogr., 75, 253265, doi:10.1016/j.pocean.2007.08.006.

    • Search Google Scholar
    • Export Citation
  • Dee, D. P., and Coauthors, 2011: The ERA-Interim reanalysis: Configuration and performance of the data assimilation system. Quart. J. Roy. Meteor. Soc., 137, 553597, doi:10.1002/qj.828.

    • Search Google Scholar
    • Export Citation
  • Deser, C., M. Alexander, and M. 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
  • Dommenget, D., and M. Latif, 2002: A cautionary note on the interpretation of EOFs. J. Climate, 15, 216225.

  • Douglass, E., D. Roemmich, and D. Stammer, 2006: Interannual variability in northeast Pacific circulation. J. Geophys. Res., 111, C04001, doi:10.1029/2005JC003015.

    • Search Google Scholar
    • Export Citation
  • Douglass, E., D. Roemmich, and D. Stammer, 2010: Interannual variability in North Pacific heat and freshwater budgets. Deep-Sea Res. II, 57, 11271140, doi:10.1016/j.dsr2.2010.01.001.

    • Search Google Scholar
    • Export Citation
  • Ducet, N., P. Le Traon, and G. Reverdin, 2000: Global high-resolution mapping of ocean circulation from TOPEX/Poseidon and ERS-1 and -2. J. Geophys. Res., 105, 19 47719 498.

    • Search Google Scholar
    • Export Citation
  • Freeland, H., 2006: What proportion of the North Pacific current finds its way into the Gulf of Alaska? Atmos.–Ocean, 44, 3741.

  • Kelly, K. A., R. J. Small, R. M. Samelson, B. Qiu, T. M. Joyce, Y.-O. Kwon, and M. F. Cronin, 2010: Western boundary currents and frontal air–sea interaction: Gulf Stream and Kuroshio Extension. J. Climate, 23, 56445667.

    • Search Google Scholar
    • Export Citation
  • Kwon, Y.-O., M. A. Alexander, N. A. Bond, C. Frankignoul, H. Nakamura, B. Qiu, and L. A. Thompson, 2010: Role of the Gulf Stream and Kuroshio–Oyashio Systems in large-scale atmosphere-ocean interaction: A review. J. Climate, 23, 32493281.

    • Search Google Scholar
    • Export Citation
  • Luyten, J. R., J. Pedlosky, and H. Stommel, 1983: The ventilated thermocline. J. Phys. Oceanogr., 13, 292309.

  • Lysne, J. A., and C. Deser, 2002: Wind-driven thermocline variability in the Pacific: A model–data comparison. J. Climate, 15, 829845.

    • Search Google Scholar
    • Export Citation
  • Miller, A. J., D. R. Cayan, and W. B. White, 1998: A westward-intensified decadal change in the North Pacific thermocline and gyre-scale circulation. J. Climate, 11, 31123127.

    • Search Google Scholar
    • Export Citation
  • North, G., 1984: Empirical orthogonal functions and normal modes. J. Atmos. Sci., 41, 879887.

  • Qiu, B., 2000: Interannual variability of the Kuroshio extension system and its impact on the wintertime SST field. J. Phys. Oceanogr., 30, 14861502.

    • Search Google Scholar
    • Export Citation
  • Qiu, B., 2002a: Large-scale variability in the midlatitude subtropical and subpolar North Pacific Ocean: Observations and causes. J. Phys. Oceanogr., 32, 353375.

    • Search Google Scholar
    • Export Citation
  • Qiu, B., 2002b: The Kuroshio Extension system: Its large-scale variability and role in the midlatitude ocean-atmosphere interaction. J. Oceanogr., 58, 5775.

    • Search Google Scholar
    • Export Citation
  • Qiu, B., 2003: Kuroshio Extension variability and forcing of the Pacific decadal oscillations: Responses and potential feedback. J. Phys. Oceanogr., 33, 24652482.

    • Search Google Scholar
    • Export Citation
  • Qiu, B., and T. Joyce, 1992: Interannual variability in the mid-and low-latitude western North Pacific. J. Phys. Oceanogr., 22, 10621079.

    • Search Google Scholar
    • Export Citation
  • Qiu, B., and W. Miao, 2000: Kuroshio path variations south of Japan: Bimodality as a self-sustained internal oscillation. J. Phys. Oceanogr., 30, 21242137.

    • Search Google Scholar
    • Export Citation
  • Qiu, B., and S. Chen, 2005: Variability of the Kuroshio Extension jet, recirculation gyre, and mesoscale eddies on decadal time scales. J. Phys. Oceanogr., 35, 20902103.

    • Search Google Scholar
    • Export Citation
  • Qiu, B., and S. Chen, 2010a: Eddy-mean flow interaction in the decadally modulating Kuroshio Extension system. Deep-Sea Res. II, 57, 10981110, doi:10.1016/j.dsr2.2008.11.036.

    • Search Google Scholar
    • Export Citation
  • Qiu, B., and S. Chen, 2010b: Interannual-to-decadal variability in the bifurcation of the North Equatorial Current off the Philippines. J. Phys. Oceanogr., 40, 25252538.

    • Search Google Scholar
    • Export Citation
  • Rhines, P. B., and W. R. Young, 1982: Homogenization of potential vorticity in planetary gyres. J. Fluid Mech., 122, 347367, doi:10.1017/S0022112082002250.

    • Search Google Scholar
    • Export Citation
  • 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, 81100, doi:10.1016/j.pocean.2009.03.004.

    • Search Google Scholar
    • Export Citation
  • Roemmich, D., and Coauthors, 2009: The Argo Program: Observing the global ocean with profiling floats. Oceanography, 22, 3443.

  • Sekine, Y., 1990: A numerical experiment on the path dynamics of the Kuroshio with reference to the formation of the large meander path south of Japan. Deep-Sea Res., 37, 359380.

    • Search Google Scholar
    • Export Citation
  • Tanimoto, Y., T. Kanenari, H. Tokinaga, and S. Xie, 2011: Sea level pressure minimum along the Kuroshio and its extension. J. Climate, 24, 44194434.

    • Search Google Scholar
    • Export Citation
  • Yamagata, T., and S. I. Umatani, 1989: Geometry-forced coherent structures as a model of the Kuroshio large meander. J. Phys. Oceanogr., 19, 130139.

    • Search Google Scholar
    • Export Citation
  • Yoon, J. H., and I. Yasuda, 1987: Dynamics of the Kuroshio large meander: Two-layer model. J. Phys. Oceanogr., 17, 6681.

  • Zhang, Y., L. Zhang, and Q. Lu, 2011: Dynamic mechanism of interannual sea surface height variability in the North Pacific subtropical gyre. Adv. Atmos. Sci., 28, 158168, doi:10.1007/s00376-010-0038-8.

    • Search Google Scholar
    • Export Citation
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