Journal of Oceanography

, Volume 64, Issue 3, pp 373–384 | Cite as

Variations of Kuroshio geostrophic transport south of Japan estimated from long-term IES observations

  • Koji Kakinoki
  • Shiro Imawaki
  • Hiroshi Uchida
  • Hirohiko Nakamura
  • Kaoru Ichikawa
  • Shin-Ichiro Umatani
  • Ayako Nishina
  • Hiroshi Ichikawa
  • Mark Wimbush
Original Articles

Abstract

Two inverted echo sounders were maintained on coastal and offshore sides of the Kuroshio south of Japan from October 1993 to July 2004. Applying the gravest empirical mode method, we obtained a time series of geostrophic transport. Estimated transports generally agree well with geostrophic transports estimated from hydrography. Their agreement with the hydrographic transports is better than that of transports estimated from satellite altimetry data. The geostrophic transport is expressed as the surface transport per unit depth multiplied by the equivalent depth. The geostrophic transport varies mostly with the surface transport and fractionally with the equivalent depth. Seasonal variation of the geostrophic transport has a minimum in March and a maximum in September, with a range of about one fifth of the total transport.

Keywords

Inverted echo sounder geostrophic transport steric height seasonal variation satellite altimetry ASUKA Kuroshio 

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. Ambe, D., S. Imawaki, H. Uchida and K. Ichikawa (2004): Estimating the Kuroshio axis south of Japan using combination of satellite altimetry and drifting buoys. J. Oceanogr., 60, 375–382.CrossRefGoogle Scholar
  2. AVISO (2004): SSALTO/DUACS User Handbook. SALP-MUP-EA-21065-CLS.Google Scholar
  3. Book, J. W., M. Wimbush, S. Imawaki, H. Ichikawa, H. Uchida and H. Kinoshita (2002): Kuroshio temporal and spatial variations south of Japan determined from inverted echo sounder measurements. J. Geophys. Res., 107(C9), 3121, doi:10.1029/2001JC000795.CrossRefGoogle Scholar
  4. Chatterjee, S. and B. Price (1977): Regression Analysis by Example. John Wiley & Sons Inc., 228 pp.Google Scholar
  5. Fields, E., K. L. Tracey and D. R. Watts (1991): Inverted echo sounder data processing report. Tech. Rep. 91-3, Grad. Sch. of Oceanogr., Univ. of R.I., U.S.A.Google Scholar
  6. He, Y., D. R. Watts and K. L. Tracey (1998): Determining geostrophic velocity shear profiles with inverted echo sounders. J. Geophys. Res., 103(C3), 5607–5622.CrossRefGoogle Scholar
  7. Imawaki, S., H. Uchida, H. Ichikawa, M. Fukasawa, S. Umatani and the ASUKA group (2001a): Satellite altimeter monitoring the Kuroshio transport south of Japan. Geophys. Res. Lett., 28, 17–20.CrossRefGoogle Scholar
  8. Imawaki, S., S. Aoki, Y. Fukuda, K. Ichikawa, S. Ito, H. Kawamura, M. Kubota, T. Kuragano, K. Matsumoto, T. Nagai, A. Sengoku and H. Yoritaka (2001b): Mass, heat and salt transports in the western North Pacific. Aviso News Lett., 8, 62–64.Google Scholar
  9. Isobe, A. and S. Imawaki (2002): Annual variation of the Kuroshio transport in a two-layer numerical model with a ridge. J. Phys. Oceanogr., 32, 994–1009.CrossRefGoogle Scholar
  10. James, C. E. and M. Wimbush (1995): Inferring dynamic height variations from acoustic travel time in the Pacific Ocean. J. Oceanogr., 51, 553–569.CrossRefGoogle Scholar
  11. Kakinoki K., S. Imawaki, H. Uchida, H. Nakamura, S. Umatani, A. Nishina, H. Ichikawa and M. Wimbush (2006): Sea-surface dynamic height of the Kuroshio south of Japan estimated from inverted echo sounders and its error estimation. Rep. Res. Inst. for Applied Mechanics, Kyushu Univ., 130, 11–20 (in Japanese with English abstract).Google Scholar
  12. Kakinoki K., S. Imawaki, K. Ichikawa and S. Umatani (2007): Comparison of sea surface dynamic heights estimated from inverted echo sounder data and satellite altimeter data. Eng. Sci. Rep., Kyushu Univ., 29(1), 13–17.Google Scholar
  13. Meinen, C. S. (2001): Structure of the North Atlantic current in stream-coordinates and the circulation in the Newfoundland basin. Deep-Sea Res., 48, 1553–1580.CrossRefGoogle Scholar
  14. Meinen, C. S. and D. R. Watts (2000): Vertical structure and transport on a transect across the North Atlantic Current near 42°N: Time series and mean. J. Geophys. Res., 105(C9), 21,869–21,891.CrossRefGoogle Scholar
  15. Mitchell, D. A., M. Wimbush, D. R. Watts and W. J. Teague (2004): The residual GEM technique and its application to the southwestern Japan/East Sea. J. Atmos. Oceanic. Technol., 21, 1895–1909.CrossRefGoogle Scholar
  16. Park, J.-H., D. R. Watts, K. L. Tracey and D. A. Mitchell (2005): A multi-index GEM technique and its application to the southwestern Japan/East Sea. J. Atmos. Oceanic Technol., 22, 1282–1293.Google Scholar
  17. Rossby, T. (1969): On monitoring depth variations of the main thermocline acoustically. J. Geophys. Res., 74, 5542–5546.CrossRefGoogle Scholar
  18. Sun, C. and D. R. Watts (2001): A circumpolar gravest empirical mode for the Southern Ocean hydrography. J. Geophys. Res., 106(C2), 2833–2855.CrossRefGoogle Scholar
  19. Teague, W. J., Z. R. Hallock, G. A. Jacobs and J. L. Mitchell (1995): Kuroshio sea surface height fluctuations observed simultaneously with inverted echo sounders and TOPEX/POSEIDON. J. Geophys. Res., 100(C12), 24,987–24,994.CrossRefGoogle Scholar
  20. Watts, D. R., C. Sun and S. Rintoul (2001): A two-dimentional gravest empirical mode determined from hydrographic observations in the subantarctic front. J. Phys. Oceanogr., 31, 2186–2209.CrossRefGoogle Scholar
  21. Zhu, X.-H., I.-S. Han, J.-H. Park, H. Ichikawa, K. Murakami, A. Kaneko and A. Ostrovskii (2003): The northward current southeast of Okinawa Island observed during November 2000 to August 2001. Geophys. Res. Lett., 30(2), 1071, doi:10.1029/2002GL015867.CrossRefGoogle Scholar
  22. Zhu, X.-H., H. Ichikawa, K. Ichikawa and K. Takeuchi (2004): Volume transport variability southeast of Okinawa Island estimated from satellite altimeter data. J. Oceanogr., 60, 953–962.CrossRefGoogle Scholar

Copyright information

© The Oceanographic Society of Japan/TERRAPUB/Springer 2008

Authors and Affiliations

  • Koji Kakinoki
    • 1
  • Shiro Imawaki
    • 1
  • Hiroshi Uchida
    • 2
  • Hirohiko Nakamura
    • 3
  • Kaoru Ichikawa
    • 1
    • 2
  • Shin-Ichiro Umatani
    • 1
  • Ayako Nishina
    • 3
  • Hiroshi Ichikawa
    • 2
  • Mark Wimbush
    • 4
  1. 1.Research Institute for Applied MechanicsKyushu UniversityKasuga, FukuokaJapan
  2. 2.Japan Agency for Marine-Earth Science and TechnologyYokosuka, KanagawaJapan
  3. 3.Faculty of FisheriesKagoshima UniversityKagoshimaJapan
  4. 4.Graduate School of OceanographyUniversity of Rhode IslandNarragansettUSA

Personalised recommendations