Journal of Oceanography

, Volume 62, Issue 4, pp 587–596 | Cite as

Velocity structures and transports of the Kuroshio and the Ryukyu current during fall of 2000 estimated by an inverse technique

Short Contribution


An inverse calculation using hydrographic section data collected from October to December 2000 yields velocity structure and transports of the Kuroshio in the Okinawa Trough region of the East China Sea (ECS) and south of central Japan, and of the Ryukyu Current (RC) southeast of the Ryukyu Islands. The results show the Kuroshio flowing from the ECS, through the Tokara Strait (TK), with a subsurface maximum velocity of 89 cm s−1 at 460 dbar. In a section (TI) southeast of Kyushu, a subsurface maximum velocity of 92 cm s−1 at 250 dbar is found. The results also show the RC flowing over the continental slope from the region southeast of Okinawa (OS) to the region east of Amami-Ohshima (AE) with a subsurface maximum velocity of 67 cm s−1 at 400 dbar, before joining the Kuroshio southeast of Kyushu (TI). The volume transport around the subsurface velocity maximum southeast of Kyushu (TI) balances well with the sum of those in TK and AE. The temperature-salinity relationships found around these velocity cores are very similar, indicating that the same water mass is involved. These results help demonstrate the joining of the RC with the Kuroshio southeast of Kyushu. The net volume transport of the Kuroshio south of central Japan is estimated to be 64∼79 Sv (1 Sv ≡ 106 m3s−1), of which 27 Sv are supplied by the Kuroshio from the ECS and 13 Sv are supplied by the RC from OS. The balance (about 24∼39 Sv) is presumably supplied by the Kuroshio recirculation south of Shikoku, Japan.


Kuroshio Ryukyu Current inverse technique subsurface velocity core volume transport 


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  1. Book, J., M. Wimbush, S. Imawaki, H. Ichikawa, H. Uchida and H. Kinoshita (2002): Kuroshio temporal and spatial variations south of Japan, determined from inverted-echosounder measurements. J. Geophys. Res., 107, 3121, doi:10.1029/2001JC000795.CrossRefGoogle Scholar
  2. Feng, M., H. Mitsudera and Y. Yoshikawa (2000): Structure and variability of the Kuroshio current in Tokara Strait. J. Phys. Oceanogr., 30, 2257–2276.CrossRefGoogle Scholar
  3. Ichikawa, H. and R. C. Beardsley (1993): Temporal and spatial variability of volume transport of the Kuroshio in the East China Sea. Deep-Sea Res., 40, 583–605.CrossRefGoogle Scholar
  4. Ichikawa, H., H. Nakamura, A. Nishina and M. Higashi (2004): Variability of northeastward current southeast of northern Ryukyu Islands. J. Oceanogr., 60, 351–363.CrossRefGoogle Scholar
  5. Ichikawa, K. (2001): Variation of the Kuroshio in the Tokara Strait induced by meso-scale eddies. J. Oceanogr., 57, 55–68.CrossRefGoogle Scholar
  6. Imawaki, S. H. Uchida, H. Ichikawa, M. Fukazawa, S. Umatani and the ASUKA Group (2001): Satellite altimeter monitoring the Kuroshio transport south of Japan. Geophys. Res. Lett., 28, 17–20.Google Scholar
  7. Kaneko, A., W. Koterayama, H. Honji, S. Mizuno, K. Kawatate and R. L. Gordon (1990): Cross-stream survey of up 400m of Kuroshio by an ADCP on a towed fish. Deep-Sea Res., 37, 875–889.CrossRefGoogle Scholar
  8. Kaneko, A., S. Mizuno, W. Koterayama and R. L. Gordon (1992): Cross-stream velocity structures and their variation of Kuroshio around Japan. Deep-Sea Res., 39, 1583–1594.CrossRefGoogle Scholar
  9. Kaneko, I., Y. Takatsuki and H. Kamiya (2001): Circulation of intermediate and deep waters in the Philippine Sea. J. Oceanogr., 57, 397–420.CrossRefGoogle Scholar
  10. Konda, M., H. Ichikawa, I.-S. Han, X.-H. Zhu and K. Ichikawa (2005): Variability of current structure due to the meso-scale eddies on the bottom slope southeast of Okinawa Island. J. Oceanogr., 61, 1089–1099.CrossRefGoogle Scholar
  11. Liu, Y. G. and Y. C. Yuan (1999): Variability of the Kuroshio in the East China Sea in 1992. Acta Oceanologica Sinica, 18, 179–184.Google Scholar
  12. Liu, Y. G. and Y. C. Yuan (2000): Variation of the currents east of Ryukyu Islands in 1998. La mer, 38, 1–15.Google Scholar
  13. Liu, Y. G., Y. C. Yuan, T. Shiga, H. Yamamoto, S. Tsubaki and M. Imai (2000): Circulation southeast of the Ryukyu Islands, Nagasaki. p. 23–37. In Proceedings of China and Japan Joint Symposium on Cooperative Study of Subtropical Circulation System, China Ocean Press, Beijing.Google Scholar
  14. Nakano, T., I. Kaneko and Y. Takatsuki (1994): The Kuroshio structure and transport estimated by the inverse method. J. Phys. Oceanogr., 24, 609–618.CrossRefGoogle Scholar
  15. Nakano, T., I. Kaneko, M. Endoh and M. Kamachi (2005): Interannual and decadal variabilities of NPIW salinity minimum core observed along JMA’s hydrographic repeat sections. J. Oceanogr., 61, 681–697.CrossRefGoogle Scholar
  16. Nitani, H. (1972): Beginning of the Kuroshio. p. 129–163. In Kuroshio: Its Physical Aspects, ed. by H. Stommel and K. Yoshida, Univ. Tokyo Press, Tokyo.Google Scholar
  17. Oka, E. and M. Kawabe (2003): Dynamic structure of the Kuroshio south of Kyushu in relation to the Kuroshio path variations. J. Oceanogr., 59, 595–608.CrossRefGoogle Scholar
  18. Qiu, B. (1999): Seasonal eddy field modulation of the North Pacific Subtropical Countercurrent: TOPEX/Poseidon observations and theory. J. Phys. Oceanogr., 29, 2471–2486.CrossRefGoogle Scholar
  19. Sekine, Y. and K. Kutsuwada (1994): Seasonal variation in volume transport of the Kuroshio south of Japan. J. Phys. Oceanogr., 24, 261–272.CrossRefGoogle Scholar
  20. Shiga, T., D. Ueno, Y. Takatsuki and Y. Liu (2000): Variations of oceanic conditions east of the Ryukyu Islands in 1997. p. 57–65. In Proceedings of Japan and China Joint Symposium on Cooperative Study of Subtropical Circulation System, China Ocean Press.Google Scholar
  21. Talley, L. D. (1993): Distribution and formation of North Pacific Intermediate Water. J. Phys. Oceanogr., 23, 517–537.CrossRefGoogle Scholar
  22. Van Scoy, K. A., D. B. Olson and R. A. Fine (1991): Ventilation of North Pacific Intermediate Waters: The role of the Alaskan Gyre. J. Geophys. Res., 96, 16801–16810.Google Scholar
  23. Wang, Y. and X. Sun (1990): A study on the features of Ryukyu Current. p. 237–245. In Proceedings of Investigation of Kuroshio, No. 2, China Ocean Press.Google Scholar
  24. Worthington, V. L. and H. Kawai (1972): Comparison between Deep Sections Across the Kuroshio and the Florida Current and Gulf Stream. p. 371–385. In Kuroshio, Its Physical Aspects, ed. by H. Stommel and K. Yoshida, Washington Univ. Press.Google Scholar
  25. Wunsch, C. (1978): The North Atlantic general circulation west of 50°W determined by inverse methods. Rev. Geophys. Space Phys., 16, 583–620.Google Scholar
  26. Yang, Y., C.-T. Liu, J.-H. Hu and M. Koga (1999): Taiwan Current (Kuroshio) and impinging eddies. J. Oceanogr., 55, 609–617.CrossRefGoogle Scholar
  27. You, S. H. and J. H. Yoon (2004): Modeling of the Ryukyu Current along the Pacific side of the Ryukyu Islands. Pacific Oceanogr., 2, 44–51.Google Scholar
  28. Yuan, Y. C., K. Takano, Z. Pan, J. Su, K. Kawatate, S. Imawaki, H. Yu, H. Chen, H. Ichikawa and S. Umatani (1994): The Kuroshio east in the East China Sea and the currents east of Ryukyu Islands during autumn 1991. La mer, 32, 235–244.Google Scholar
  29. Yuan, Y. C., J. Su, Z. Pan, H. Chen, H. Ichikawa, S. Imawaki, K. Kawatate, K. Takano and S. Umatani (1995): The west boundary current east of Ryukyu Islands. La mer, 33, 1–11.Google Scholar
  30. Yuan, Y. C., A. Kaneko, J. Su, X. Zhu, Y. Liu, N. Gohda and H. Chen (1998): The Kuroshio east of Taiwan and in the East China Sea and the currents east of Ryukyu Islands during early summer of 1996. J. Oceanogr., 54, 217–226.Google Scholar
  31. Zhu, X.-H., A. Kaneko, T. Saito and N. Gohda (2001): Kuroshio stream path variation and its associated velocity structures south of Shikoku, Japan. Geophys. Res. Lett., 28, 4615–4618.CrossRefGoogle Scholar
  32. Zhu, X.-H., I.-S. Han, J.-H. Park, H. Ichikawa, K. Murakami, A. Kaneko and A. Ostrovskii (2003): The northeastward current southeast of Okinawa Island observed during November 2000 to August 2001. Geophys. Res. Lett., 30, 1071, doi:10.1029/2002GL015867.CrossRefGoogle Scholar
  33. Zhu, X.-H., H. Ichikawa, K. Ichikawa and K. Takeuchi (2004): Variability of the volume transport southeast of Okinawa Island estimated from satellite altimeter data. J. Oceanogr., 60, 953–962.CrossRefGoogle Scholar
  34. Zhu, X.-H., J.-H. Park and I. Kaneko (2005): The northeastward current southeast of Ryukyu Islands in early winter of 2000 estimated by an inverse technique. Geophys. Res. Lett., 32, L05608, doi: 10.1029/2004GL022135.Google Scholar

Copyright information

© The Oceanographic Society of Japan/TERRAPUB/Springer 2006

Authors and Affiliations

  1. 1.Institute of Observational Research for Global Change/JAMSTECNatsushima-cho, YokosukaJapan
  2. 2.State Key Laboratory of Satellite Ocean Environment Dynamics, Second Institute of OceanographyState Oceanic AdministrationHangzhouChina
  3. 3.Graduate School of OceanographyUniversity of Rhode IslandNarragansettUSA
  4. 4.Nagasaki Marine ObservatoryJapan Meteorological AgencyNagasakiJapan

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