Eddy Formation Near the Izu-Ogasawara Ridge and its Link with Seasonal Adjustment of the Subtropical Gyre in the Pacific

  • Ihara, Chie (Dapartment of Earth and Planetary Science, Graduate School of Science, The University of Tokyo) ;
  • Kagimoto, Takashi (IGCR, Frontier Research System for Global Change) ;
  • Masumoto, Yukio (Dapartment of Earth and Planetary Science, Graduate School of Science, The University of Tokyo) ;
  • Yamagata, Toshio (Dapartment of Earth and Planetary Science, Graduate School of Science, The University of Tokyo)
  • Published : 2002.09.01

Abstract

Using OGCM results, we have shown that the ring-like cold baroclinic eddies associated with cyclonic circulation are shed from late summer to early fall near the Izu-Ogasawara Ridge from the Kuroshio Extension owing to baroclinic instability. On the other hand, warm baroclinic eddies are generated by the intensified western boundary current associated with the warm anomaly accumulated near the Ridge in winter, which corresponds to the basin-wide barotropic intensification of the wind-driven gyre in winter. We are successful in reproducing the behavior of those meso-scale eddies using a simple two-layer primitive equation model driven by seasonal winds associated with the positive curl. Those eddies carry barotropic seasonal signals originated in the Pacific Basin quite slowly west of the ridge; this process introduces a phase lag in the timing of the seasonal maximum transport in the Philippine Basin west of the ridge. It Is demonstrated that the existence of bottom topography, baroclinicity, and nonlinearity due to advection are three necessary elements for the generation of these eddies south of Japan.

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References

  1. Geophys. Astrophys. Fluid Dynamics v.92 Successive formation of planetary lenses in an intermediate layer Aki, H.;Yamagata, T. https://doi.org/10.1080/03091920008203709
  2. Deep-Sea Res. v.26A Non-linear propagation of long Ressby waves Anderson, D.L.T.;Killworth, P.D.
  3. J. of Oceanogr. v.56 Mososcale eddies observed by TOLEX-ADCP and TOPEX/POSEIDON altimeter in the Kuroshio recirculation region south of Japan Ebuchi, N.;Hanawa, K. https://doi.org/10.1023/A:1011110507628
  4. J. Phys. Oceanogr. Numerical simulation of the transient response of the kuroshio leading to the meander formation south of Japan Endoh, T.;Hibiya, T.
  5. International geophysics series v.30 Atmophere-Ocean Dynamics Gill, A.E.
  6. J. Geophys. Res. v.96 A diagnosis of interpentadal circulation changes in the North Atlantic Greatbatch, R.J.;Fanning, A.F.;Goulding, A.D.;Levitus, S. https://doi.org/10.1029/91JC02423
  7. Doctral Dissertation Numerical study on transport Variations of Kuroshio Kagimoto, T.
  8. J. Phys. Oceanogr. v.25 Variation of current path, velocity, tranport of the Kuroshio in relation with the large meander Kawabe, M. https://doi.org/10.1175/1520-0485(1995)025<3103:VOCPVA>2.0.CO;2
  9. Ocean modeling v.75 Topographic instabilities in level model OGCMs Killworth, P.D.
  10. NOAA Atlas NESDIS 4 v.4 World Ocean Atlas Vol. 4: Temperature Levitus, S.;Boyer, T.P.
  11. NOAA Atlas NESDIS 3 v.5 World Ocean Atlas Vol. 5: Salinity Levitus, S.;Burgett, R.;Boyer, T.P.
  12. J. Geophys. Res. v.104 An analysis of tropical instability waves in a numerical model of the Pacific Ocean 2. Generation and energetics of the waves Masina, S.;Philander, S.G.H;Bush, A.B.G. https://doi.org/10.1029/1999JC900226
  13. manuscript in preparation Eddy resolving Kuroshio simulation: Kuroshio path variation Miyazawa, Y.;Guo, X.;Hukuda, H.;Yamagata, T.
  14. GFDL Ocean Tech. Rep. 3.1 MOM2 documentation, user's guide and reference manual Pacanowski, R.C.
  15. J. Phys. Oceanogr. v.11 Parameterization of vertical mixing in numerical models of tropical oceans Pacanowski, R. C.;Philander, S. G. H. https://doi.org/10.1175/1520-0485(1981)011<1443:POVMIN>2.0.CO;2
  16. J. Phys. Oceanogr. v.18 A general circulation model for upper ocean simulation Rosati, A.;Miyakoda, K. https://doi.org/10.1175/1520-0485(1988)018<1601:AGCMFU>2.0.CO;2
  17. J. Marine Res. v.54 Seasonal transport variations of the wind-driven ocean circulation in a two-layer planetary geostrophic model with a continental slope Sakamoto, T.;Yamagata, T. https://doi.org/10.1357/0022240963213402
  18. Izv.Acad.Sci.USSR Atom.Oceanic.Phys. v.7 Joint effect of baroclinicity and bottom relief as an important factor in the dynamics of sea currents Sakisyan, A.S.;Ivanov, V.F.
  19. Mon. Wea. Rev. v.91 General circulation experiments with the primitive equations. I. The basic experiment Smagorinsky, J. https://doi.org/10.1175/1520-0493(1963)091<0099:GCEWTP>2.3.CO;2
  20. J. Climate v.9 Reconstruction of historical sea surface temperature using empirical orthogonal function Smith, T.M.;Reynolds, R.W.;Livezey, R.E.;Stokes, D.C. https://doi.org/10.1175/1520-0442(1996)009<1403:ROHSST>2.0.CO;2
  21. J. Phys. Oceanogr. On the eddy-Kuroshio interaction: initialization and evolution of meso-scale eddy Weseda, T.;Mitsudera, H.;Taguchi, B.;Yoshikawa, Y.
  22. J. Geophys. Res. v.105 Instabilities in the Agulhas retroflection current system: a comparative model study Wells, N.C.;Vchenko, V.O.;Best, S.E. https://doi.org/10.1029/1999JC900283