Journal of Oceanography

, Volume 68, Issue 1, pp 139–150 | Cite as

Interannual variations in low potential vorticity water and the subtropical countercurrent in an eddy-resolving OGCM

  • Masami NonakaEmail author
  • Shang-Ping Xie
  • Hideharu Sasaki
Special Section: Short Contribution New developments in mode-water research: Dynamic and climatic effects


Interannual-to-decadal variations in the subtropical countercurrent (STCC) and low potential vorticity (PV) water and their relations in the North Pacific Ocean are investigated on the basis of a 60-year-long hindcast integration of an eddy-resolving ocean general circulation model. Although vertically coherent variations are dominant for STCC interannual variability, a correlation analysis shows that an intensified STCC vertical shear accompanies lower PV than usual to the north on 25.5- to 26.1-σθ isopycnal surfaces, and intensified meridional density gradient in subsurface layers, consistent with Kubokawa’s theory (J Phys Oceanogr 29:1314–1333, 1999). The low-PV signals appear at least 2 years before peaks of STCC, propagating southwestward from the subduction region.


Subtropical countercurrent Low potential vorticity water North Pacific Interannual variability Eddy-resolving ocean general circulation model 



The OFES simulations were conducted on the Earth Simulator under the support of JAMSTEC. We thank the members of the OFES group, including Drs. H. Sakuma, Y. Masumoto, and T. Yamagata, for their efforts and support in the model development. Our thanks are extended to Drs. A. Kubokawa, F. Kobashi, and E. Oka for useful discussions. This study is partially supported by Grand-In-Aid for Scientific Research defrayed by the Ministry of Education, Culture, Sports, Science and Technology of Japan (22106006, 23340139). IPRC/SOEST publication #790/8196.


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Copyright information

© The Oceanographic Society of Japan and Springer 2011

Authors and Affiliations

  • Masami Nonaka
    • 1
    Email author
  • Shang-Ping Xie
    • 2
  • Hideharu Sasaki
    • 3
  1. 1.Research Institute for Global Change, Japan Agency for Marine-Earth Science and Technology (JAMSTEC)YokohamaJapan
  2. 2.International Pacific Research Center (IPRC) and Department of Meteorology, School of Ocean and Earth Science and Technology (SOEST)University of Hawaii at ManoaHonoluluUSA
  3. 3.Earth Simulator Center, JAMSTECYokohamaJapan

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