The three-dimensional structure and seasonal variation of the North Pacific meridional overturning circulation

  • Hongwei Liu
  • Qilong Zhang
  • Yongliang Duan
  • Yijun Hou
Article

Abstract

The three-dimensional structure and the seasonal variation of the North Pacific meridional overturning circulation (NPMOC) are analyzed based on the Simple Ocean Data Assimilation data and Argo profiling float data. The NPMOC displays a multi-cell structure with four cells in the North Pacific altogether. The TC and the STC are a strong clockwise meridional cell in the low latitude ocean and a weaker clockwise meridional cell between 7°N and 18°N, respectively, while the DTC and the subpolar cell are a weaker anticlockwise meridional cell between 3°N and 15°N and a weakest anticlockwise meridional cell between 35°N and 50°N, respectively.

The DTC, the TC and the STC are all of very strong seasonal variations. As to the DTC, the southward transport is strongest in fall and weakest in spring. For the TC, the northward transport is strongest in winter and weakest in spring, while the southward transport is strongest in fall and weakest in spring, which is associated with the strong southward flow of the DTC in fall. As the STC, the northward transport is strongest in winter and weakest in summer, while the southward transport is strongest in summer and weakest in spring. This seasonal difference may be associated with the DTC. The zonal wind stress and the east-west slope of sea level play important roles in the seasonal variations of the TC, the STC and the DTC.

Key words

North Pacific meridional overturning circulation three-dimensional structure seasonal variation 

References

  1. Bryden H L, Brady E C. 1985. Diagnostic model of the three-dimensional circulation in the upper equatorial Pacific Ocean. J Phys Oceanogr, 15: 1255–1273CrossRefGoogle Scholar
  2. Bryden H L, Brady E C. 1989. Eddy momentum and heat fluxes and their effects on the circulation of the equatorial Pacific Ocean. J Mar Res, 47: 55–79CrossRefGoogle Scholar
  3. Gu D, Philander S G H. 1997. Interdecadal climate fluctuations that depend on exchanges between the tropics and extratropics. Science, 275: 805–807CrossRefGoogle Scholar
  4. Hansen D V, Paul C A. 1984. Genesis and effects of long waves in the equatorial Pacific, J Geophys Res, 89(C6): 10431–10440CrossRefGoogle Scholar
  5. Liu Z, Philander S G H, Pacanowski R C. 1994. A GCM study of tropical-subtropical upper-ocean water exchange. J Phys. Oceanogr, 24: 2606–2623CrossRefGoogle Scholar
  6. Lu P, McCreary J P. 1995. Influence of the ITCZ on the flow of thermocline water from the subtropical to the equatorial Pacific ocean. J Phys Oceanogr, 25: 3076–3088CrossRefGoogle Scholar
  7. Lu P, McCreary J P, Klinger B A. 1998: Meridional circulation cells and the source waters of the Pacific equatorial undercurrent. J Phys Oceanogr, 28: 62–84CrossRefGoogle Scholar
  8. McCreary J, Yu Z. 1992. Equatorial dynamics in the 2.5 layer model. Progr. Oceanogr., PergamonGoogle Scholar
  9. McCreary J P, Lu P. 1994. Interaction between the subtropical and equatorial ocean circulations: The subtropical cell. J Phys Oceanogr, 24: 466–497Google Scholar
  10. Nonaka M, Xie S, McCreary J P. 2002. Decadal variations in the Subtropical Cells and equatorial Pacific SST. Geophys Res Lett, 29(7): 1116, doi:10.1029/2001GL013-717CrossRefGoogle Scholar
  11. Pedlosky J. 1987. An inertial theory of the Equatorial Undercurrent. J Phys Oceanogr, 17: 1978–1985CrossRefGoogle Scholar
  12. Perez R C, Cronin M C, Kessler W S. 2010. Tropical cell and a secondary circulation near the northern front of the Equatorial Pacific cold tongue. J Phys Oceanogr, 40: 2091–2106CrossRefGoogle Scholar
  13. Sun F, Kim V S, Huang B, et al. 2004. Water exchange between the subpolar and subtropical North Pacific in an OGCM. Science in China, 47(1): 37–48Google Scholar
  14. Wang D, Wang J, Wu L, et al. 2003. Regime shifts in the North Pacific Simulated by a COADS-driven Isopycnal Modal. Advances in Atmospheric sciences, 20(5): 743–754CrossRefGoogle Scholar
  15. Wang D, Wang J, Wu L, et al. 2003. Relative importance of wind and buoyancy forcing for interdecadal regime shifts in the Pacific Ocean. Science in China, 46(5): 417–427CrossRefGoogle Scholar
  16. Wang Q, Huang R. 2005. Decadal variability of pycnocline flows from the subtropical to the Equatorial Pacific. J Phys Oceanogr, 35: 1861–1875CrossRefGoogle Scholar
  17. Wu L, Lee D E, Liu Z. 2005. The 1976/77 North Pacific climate regime shift: The role of subtropical ocean adjustment and coupled ocean -atmosphere feedbacks. J Climate, 18: 5125–5140CrossRefGoogle Scholar
  18. Wu L, Liu Z. 2003. Decadal variability in the North Pacific: the eastern North Pacific mode. J Climate, 16: 3111–3131CrossRefGoogle Scholar
  19. Wu L, Liu Z, Gallimore R, et al. 2003. Pacific decadal variability: the tropical Pacific mode and the North Pacific mode. J Climate, 16(8):1101–1120CrossRefGoogle Scholar
  20. Wyrtki, K. 1981. An estimate of equatorial upwelling in the Pacific. J Phys Oceanogr, 11: 1205–1214CrossRefGoogle Scholar
  21. Wyrtki K, Kilonsky B. 1984. Mean water mass and current structure during the Hawaii-to-Tahiti shuttle experiment. J Phys Oceanogr, 14: 242–254CrossRefGoogle Scholar
  22. Xie S, Kunitani T, Kubokawa A, et al. 2000. Interdecadal thermocline variability in the North Pacific for 1958 -97: A GCM simulation. J Phys Oceanogr, 30:2798–2813CrossRefGoogle Scholar
  23. Zhang, Q, Yang H, Zhong Y, et al. 2005. An idealized study of the impact of extratropical climate change on El Nino -Southern Oscillation. Climate Dynamics, 25: 869–880CrossRefGoogle Scholar
  24. Zhou T, Yu R, Liu X, et al. 2005. A numerical model of the North Pacific tropical-subtropical shallow cell under the global warming trend. Advances in Natural Science(in Chinese), 15(3): 367–371Google Scholar
  25. Zhou Y, Li B, Zhang Y, et al. 2002. World oceanic thermocline characteristics in winter and summer. Marine Science Bulletin(in Chinese), 21(1): 16–22Google Scholar

Copyright information

© The Chinese Society of Oceanography and Springer-Verlag Berlin Heidelberg 2011

Authors and Affiliations

  • Hongwei Liu
    • 1
    • 2
    • 3
  • Qilong Zhang
    • 1
    • 2
  • Yongliang Duan
    • 1
    • 2
    • 3
  • Yijun Hou
    • 1
    • 2
  1. 1.Institute of OceanologyChinese Academy of SciencesQingdaoChina
  2. 2.Key Laboratory of Ocean Circulation and Waves (KLOCAW)Chinese Academy of SciencesQingdaoChina
  3. 3.The Graduate School of the Chinese Academy of SciencesBeijingChina

Personalised recommendations