Length Scales of Eddy Generation and Nonlinear Evolution of the Seasonally Modulated South Pacific Subtropical Countercurrent

Bo Qiu Department of Oceanography, University of Hawaii at Manoa, Honolulu, Hawaii

Search for other papers by Bo Qiu in
Current site
Google Scholar
PubMed
Close
,
Robert B. Scott Institute for Geophysics, The University of Texas at Austin, Austin, Texas

Search for other papers by Robert B. Scott in
Current site
Google Scholar
PubMed
Close
, and
Shuiming Chen Department of Oceanography, University of Hawaii at Manoa, Honolulu, Hawaii

Search for other papers by Shuiming Chen in
Current site
Google Scholar
PubMed
Close
Restricted access

We are aware of a technical issue preventing figures and tables from showing in some newly published articles in the full-text HTML view.
While we are resolving the problem, please use the online PDF version of these articles to view figures and tables.

Abstract

The dynamical processes behind the seasonal modulation of the two-dimensional eddy kinetic energy (EKE) wavenumber spectrum in the Subtropical Countercurrent region of the South Pacific are investigated with 14 yr of satellite altimeter data and climatological hydrographic data. The authors find a seasonally modulated generation of EKE via baroclinic instability in modes with larger meridional length scales. Subsequent nonlinear eddy–eddy interactions redistribute the EKE to larger total horizontal length scales, and larger zonal scales in particular. This is confirmed by diagnosing the spectral transfer of EKE in the surface geostrophic flow, which is found to drive an anisotropic inverse cascade, being redirected in the sense consistent with the β effect, as predicted by geostrophic turbulence theory on the β plane. Because of the seasonal renewal of meridionally elongated anomalies by baroclinic instability and possibly because of the barotropization process, however, the net outcome for the formation of surface zonal flows is observed to be limited.

Corresponding author address: Dr. Bo Qiu, Department of Oceanography, University of Hawaii at Manoa, 1000 Pope Road, Honolulu, HI 96822. Email: bo@soest.hawaii.edu

Abstract

The dynamical processes behind the seasonal modulation of the two-dimensional eddy kinetic energy (EKE) wavenumber spectrum in the Subtropical Countercurrent region of the South Pacific are investigated with 14 yr of satellite altimeter data and climatological hydrographic data. The authors find a seasonally modulated generation of EKE via baroclinic instability in modes with larger meridional length scales. Subsequent nonlinear eddy–eddy interactions redistribute the EKE to larger total horizontal length scales, and larger zonal scales in particular. This is confirmed by diagnosing the spectral transfer of EKE in the surface geostrophic flow, which is found to drive an anisotropic inverse cascade, being redirected in the sense consistent with the β effect, as predicted by geostrophic turbulence theory on the β plane. Because of the seasonal renewal of meridionally elongated anomalies by baroclinic instability and possibly because of the barotropization process, however, the net outcome for the formation of surface zonal flows is observed to be limited.

Corresponding author address: Dr. Bo Qiu, Department of Oceanography, University of Hawaii at Manoa, 1000 Pope Road, Honolulu, HI 96822. Email: bo@soest.hawaii.edu

Save
  • Antonov, J. I., R. A. Locarnini, T. P. Boyer, A. V. Mishonov, and H. E. Garcia, 2006: Salinity. Vol. 2, World Ocean Atlas 2005, NOAA Atlas NESDIS 62, 182 pp.

    • Search Google Scholar
    • Export Citation
  • Arbic, B. K., and G. R. Flierl, 2004: Baroclinically unstable geostrophic turbulence in the limits of strong and weak bottom Ekman friction: Application to midocean eddies. J. Phys. Oceanogr., 34 , 22572273.

    • Search Google Scholar
    • Export Citation
  • Bowen, M. M., J. L. Wilkin, and W. J. Emery, 2005: Variability and forcing of the East Australian Current. J. Geophys. Res., 110 .C03019, doi:10.1029/2004JC002533.

    • Search Google Scholar
    • Export Citation
  • Charney, J., 1971: Geostrophic turbulence. J. Atmos. Sci., 28 , 10871095.

  • Chelton, D. B., M. G. Schlax, R. M. Samelson, and R. A. de Szoeke, 2007: Global observations of large oceanic eddies. Geophys. Res. Lett., 34 .L15606, doi:10.1029/2007GL030812.

    • Search Google Scholar
    • Export Citation
  • Danilov, S. D., and D. Gurarie, 2000: Quasi-two-dimensional turbulence. Phys. Uspekhi, 43 , 863900.

  • Ducet, N., P-Y. 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 , 1947719498.

    • Search Google Scholar
    • Export Citation
  • Frisch, U., 1995: Turbulence: The Legacy of A. N. Kolmogorov. Cambridge University Press, 296 pp.

  • Fu, L-L., and G. R. Flierl, 1980: Nonlinear energy and enstrophy transfers in a realistically stratified ocean. Dyn. Atmos. Oceans, 4 , 219246.

    • Search Google Scholar
    • Export Citation
  • Fu, L-L., and D. B. Chelton, 2001: Large-scale ocean circulation. Satellite Altimetry and Earth Sciences, L.-L. Fu and A. Cazenava, Eds., Academic Press, 133–169.

    • Search Google Scholar
    • Export Citation
  • Galperin, B., H. Nakano, H-P. Huang, and S. Sukoriansky, 2004: The ubiquitous zonal jets in the atmospheres of giant planets and earth’s oceans. Geophys. Res. Lett., 31 .L13303, doi:10.1029/2004GL019691.

    • Search Google Scholar
    • Export Citation
  • Galperin, B., S. Sukoriansky, N. Dikovskaya, P. L. Read, Y. H. Yamazaki, and R. Wordsworth, 2006: Anisotropic turbulence and zonal jets in rotating flows with a beta-effect. Nonlinear Processes Geophys., 13 , 8398.

    • Search Google Scholar
    • Export Citation
  • Halliwell Jr., G. R., G. Peng, and D. B. Olson, 1994: Stability of the Sargasso Sea subtropical frontal zone. J. Phys. Oceanogr., 24 , 11661183.

    • Search Google Scholar
    • Export Citation
  • Hua, B. L., and D. B. Haidvogel, 1986: Numerical simulations of the vertical structure of quasi-geostrophic turbulence. J. Atmos. Sci., 43 , 29232936.

    • Search Google Scholar
    • Export Citation
  • Huang, H-P., A. Kaplan, E. N. Curchister, and N. A. Maximenko, 2007: The degree of anisotropy for mid-ocean currents from satellite observations and an eddy-permitting model simulation. J. Geophys. Res., 112 .C09005, doi:10.1029/2007JC004105.

    • Search Google Scholar
    • Export Citation
  • Huang, R. X., and B. Qiu, 1998: The structure of the wind-driven circulation in the subtropical South Pacific. J. Phys. Oceanogr., 28 , 11731186.

    • Search Google Scholar
    • Export Citation
  • Kobashi, F., and H. Kawamura, 2002: Seasonal variation and instability nature of the North Pacific Subtropical Countercurrent and the Hawaiian Lee Countercurrent. J. Geophys. Res., 107 .3185, doi:10.1029/2001JC001225.

    • Search Google Scholar
    • Export Citation
  • Lapeyre, G., and P. Klein, 2006: Dynamics of the upper oceanic layers in terms of surface quasigeostrophy theory. J. Phys. Oceanogr., 36 , 165176.

    • Search Google Scholar
    • Export Citation
  • Larichev, V. D., and I. M. Held, 1995: Eddy amplitudes and fluxes in a homogeneous model of fully developed baroclinic instability. J. Phys. Oceanogr., 25 , 22852297.

    • Search Google Scholar
    • Export Citation
  • Le Traon, P-Y., and R. Morrow, 2001: Ocean currents and eddies. Satellite Altimetry and Earth Sciences, L.-L. Fu and A. Cazenava, Eds., Academic Press, 171–215.

    • Search Google Scholar
    • Export Citation
  • Le Traon, P-Y., F. Nadal, and N. Ducet, 1998: An improved mapping method of multi-satellite altimeter data. J. Atmos. Oceanic Technol., 25 , 522534.

    • Search Google Scholar
    • Export Citation
  • Locarnini, R. A., A. V. Mishonov, J. I. Antonov, T. P. Boyer, and H. E. Garcia, 2006: Temperature. Vol. 1, World Ocean Atlas 2005, NOAA Atlas NESDIS 61, 182 pp.

    • Search Google Scholar
    • Export Citation
  • Maximenko, N. A., B. Bang, and H. Sasaki, 2005: Observational evidence of alternating zonal jets in the World Ocean. Geophys. Res. Lett., 32 .L12607, doi:10.1029/2005GL022728.

    • Search Google Scholar
    • Export Citation
  • Morrow, R., and P-Y. Le Traon, 2006: Fifteen years of satellite altimetry and mesoscale eddy dynamics. Proc. 15 Years of Progress in Radar Altimetry Symp., Venice, Italy, ESA. [Available online at http://earth.esa.int/workshops/venice06/participants/889/paper_889_morrow-v2.pdf.].

  • Okuno, A., and A. Masuda, 2003: Effect of horizontal divergence on the geostrophic turbulence on a beta-plane: Suppression of the Rhines effect. Phys. Fluids, 15 , 5665.

    • Search Google Scholar
    • Export Citation
  • Panetta, R. L., 1993: Zonal jets in wide baroclinically unstable regions: Persistence and scale selection. J. Atmos. Sci., 50 , 20732106.

    • Search Google Scholar
    • Export Citation
  • Pedlosky, J., 1987: Geophysical Fluid Dynamics. Springer-Verlag, 710 pp.

  • Qiu, B., 1999: Seasonal eddy field modulation of the North Pacific Subtropical Countercurrent: TOPEX/Poseidon observations and theory. J. Phys. Oceanogr., 29 , 24712486.

    • Search Google Scholar
    • Export Citation
  • Qiu, B., and S. Chen, 2004: Seasonal modulation in the eddy field of the South Pacific Ocean. J. Phys. Oceanogr., 34 , 15151527.

  • Rhines, P. B., 1975: Waves and turbulence on a beta-plane. J. Fluid Mech., 69 , 417443.

  • Rhines, P. B., 1977: The dynamics of unsteady currents. The Sea, E. D. Goldberg et al., Eds., Vol. 6, Marine Modeling, John Wiley and Sons, 189–318.

    • Search Google Scholar
    • Export Citation
  • Robinson, A. R., 1983: Eddies in Marine Science. Springer-Verlag, 609 pp.

  • Roemmich, D., and B. Cornuelle, 1990: Observing the fluctuations of gyre-scale ocean circulation: A study of the subtropical South Pacific. J. Phys. Oceanogr., 20 , 19191934.

    • Search Google Scholar
    • Export Citation
  • Roemmich, D., and J. Gilson, 2001: Eddy transport of heat and thermocline waters in the North Pacific: A key to interannual/decadal climate variability? J. Phys. Oceanogr., 31 , 675687.

    • Search Google Scholar
    • Export Citation
  • Rotschi, H., 1973: Hydrography at 170°E in the South Pacific. Oceanography of the South Pacific 1972, New Zealand National Commission for UNESCO, 113–128.

    • Search Google Scholar
    • Export Citation
  • Salmon, R., 1980: Baroclinic instability and geostrophic turbulence. Geophys. Astrophys. Fluid Dyn., 15 , 167211.

  • Salmon, R., 1998: Lectures on Geophysical Fluid Dynamics. Oxford University Press, 378 pp.

  • Scott, R. B., and F. Wang, 2005: Direct evidence of an oceanic inverse kinetic energy cascade from satellite altimetry. J. Phys. Oceanogr., 35 , 16501666.

    • Search Google Scholar
    • Export Citation
  • Scott, R. B., and B. K. Arbic, 2007: Spectral energy fluxes in geostrophic turbulence: Implications for ocean energetics. J. Phys. Oceanogr., 37 , 673688.

    • Search Google Scholar
    • Export Citation
  • Smith, K. S., and G. K. Vallis, 2001: The scales and equilibration of midocean eddies: Freely evolving flow. J. Phys. Oceanogr., 31 , 554571.

    • Search Google Scholar
    • Export Citation
  • Smith, K. S., and G. K. Vallis, 2002: The scales and equilibration of midocean eddies: Forced dissipative flow. J. Phys. Oceanogr., 32 , 16991720.

    • Search Google Scholar
    • Export Citation
  • Vallis, G. K., 2006: Atmospheric and Oceanic Fluid Dynamics: Fundamentals and Large. -Scale Circulation. Cambridge University Press, 744 pp.

    • Search Google Scholar
    • Export Citation
  • Vallis, G. K., and M. E. Maltrud, 1993: Generation of mean flows and jets on a beta plane and over topography. J. Phys. Oceanogr., 23 , 13461362.

    • Search Google Scholar
    • Export Citation
  • Wunsch, C., 1997: The vertical partition of oceanic horizontal kinetic energy and the spectrum of global variability. J. Phys. Oceanogr., 27 , 17701794.

    • Search Google Scholar
    • Export Citation
All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 959 535 87
PDF Downloads 435 101 6