Journal of Oceanography

, Volume 65, Issue 6, pp 737–756 | Cite as

Water mass variability in the western North Pacific detected in a 15-year eddy resolving ocean reanalysis

  • Yasumasa MiyazawaEmail author
  • Ruochao Zhang
  • Xinyu Guo
  • Hitoshi Tamura
  • Daisuke Ambe
  • Joon-Soo Lee
  • Akira Okuno
  • Hiroshi Yoshinari
  • Takashi Setou
  • Kosei Komatsu
Original Articles


This paper describes a reanalysis of the variability of water mass properties and currents in the western North Pacific using an ocean forecast system, Japan Coastal Ocean Predictability Experiment 2 (JCOPE2), to provide the basic description and information about the quality for data users. We have created the reanalysis data with high horizontal resolution of 1/12° to describe the oceanic variability associated with the Kuroshio-Kuroshio Extension, the Oyashio, and the mesoscale eddies from 1993 to 2007. The products made by an eddy-resolving ocean model combined with the three-dimensional variational data assimilation well reproduced the mean water mass property in the western North Pacific and the interannual variations of the Kuroshio-Kuroshio Extension and the Oyashio coastal branch. From the reanalysis data, we found that both the mean kinetic energy of the Kuroshio Extension axis at the first meandering crest and southward intrusion of the Oyashio coastal branch were closely related with the horizontal distribution of both the Oyashio Water and North Pacific Intermediate Water within the appropriate interannual time scale. The reanalysis data also indicated that the north-south migration of the Kuroshio Extension associated with its regime transitions affected the decadal modulation of the Subtropical Mode Water formation in the recirculation gyre of the Kuroshio Extension.


Data assimilation reanalysis eddy-resolving model western North Pacific North Pacific Intermediate Water (NPIW) mode water Kuroshio Oyashio Mixed Water Region 


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Copyright information

© Springer Science+Business Media B.V. 2009

Authors and Affiliations

  • Yasumasa Miyazawa
    • 1
    Email author
  • Ruochao Zhang
    • 1
  • Xinyu Guo
    • 1
    • 2
  • Hitoshi Tamura
    • 1
  • Daisuke Ambe
    • 3
  • Joon-Soo Lee
    • 3
  • Akira Okuno
    • 3
  • Hiroshi Yoshinari
    • 3
  • Takashi Setou
    • 3
  • Kosei Komatsu
    • 3
    • 4
  1. 1.Research Institute for Global ChangeJapan Agency for Marine-Earth Science and TechnologyYokohama, KanagawaJapan
  2. 2.Center for Marine Environmental StudiesEhime UniversityMatsuyama, EhimeJapan
  3. 3.Fisheries Research AgencyNational Research Institute of Fisheries ScienceYokohama, KanagawaJapan
  4. 4.Graduate School of Frontier SciencesThe University of TokyoKashiwa, ChibaJapan

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