Journal of Oceanography

, Volume 60, Issue 5, pp 853–863 | Cite as

Intrusion of less saline shelf water into the Kuroshio subsurface layer in the East China Sea

  • Atsuhiko Isobe
  • Eiji Fujiwara
  • Pil-Hun Chang
  • Koichi Sugimatsu
  • Manabu Shimizu
  • Takeshi Matsuno
  • Atsuyoshi Manda


The possible origin and cause of the less saline shelf water detected in the Kuroshio subsurface layer around the shelf edge of the East China Sea are investigated using observational results obtained in May 1998–2001 in conjunction with a dataset archived by Japan Oceanographic Data Center and a numerical model. The observations show that subsurface intrusions of less saline water are always detected in May in layers above 24.5σθ isopycnal surface, and that salinity inversions (i.e., areas in which the less saline water lies beneath the saline water) are detected around the trough of the Kuroshio frontal eddy (or wave). Analyses of the archived dataset reveal that the isopycnal surface of 24.5σθ is the deepest layer of the Kuroshio pycnocline outcropping to the sea surface on the shallow shelf in early spring. Outcropping isopycnals above 24.5σθ encounter a less saline water plume originating from the Changjiang, especially in the western East China Sea. Thereafter, the less saline water moves along isopycnal layers and reaches the Kuroshio front around the shelf edge. Numerical models demonstrate that, when the frontal wave captures the less saline water, the shelf water takes the form of a salinity inversion in the trough because isohalines in the frontal wave have a phase lag between the upper and lower layers in consequence of the baroclinic instability.


Salinity inversion Kuroshio frontal eddy East China Sea 


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  1. Boyer, T., Levitus, S. 1994Quality control and processing of historical oceanographic temperature, salinity, and oxygen dataNOAA Technical Report NESDIS 81U.S. NOAAWashington, D.C.Google Scholar
  2. Candela, J., Beardsley, R. C., Limeburner, R. 1992Separation of tidal currents in ship-mounted acoustic Doppler current profiler observationsJ. Geophys. Res.97769788Google Scholar
  3. Chang, P.-H., Isobe, A. 2003A numerical study on the Changjiang Diluted Water in the East and Yellow China SeasJ. Geophys. Res.1083299CrossRefGoogle Scholar
  4. Chen, A. C.-T., Wang, S.-L. 1999Carbon, alkalinity and nutrient budgets on the East China Sea continental shelfJ. Geophys. Res.1042067520686Google Scholar
  5. Chen, C., Beardsley, R. C., Limeburner, R., Kim, K. 1994Comparison of winter and summer hydrographic observations in the Yellow and East China Sea and adjacent Kuroshio during 1986Cont. Shelf Res.14909929CrossRefGoogle Scholar
  6. Fu, Z., Hu, J., Yu, G. 1991Seawater flux through Taiwan StraitChin. J. Oceanol. Limnol.9232239Google Scholar
  7. Fukamachi, Y., McCreary, J. P.,Jr., Jeffrey, A. P. 1995Instability of density fronts in layer and continuously stratified modelsJ. Geophys. Res.10025592577CrossRefGoogle Scholar
  8. Gao, Y., Arimoto, R., Duce, R. A., Lee, D. S., Zhou, M. 1992Input of atmospheric trace elements and mineral matter to the Yellow Sea during the spring of a low-dust yearJ. Geophys. Res.9737673777Google Scholar
  9. Gill, A. E. 1982Atmosphere-Ocean DynamicsAcademic PressSan Diego, CaliforniaGoogle Scholar
  10. Ichikawa, H. 1993Short period variations of the Kuroshio volume transport in the East China SeaUmi to Sora69135148(in Japanese)Google Scholar
  11. Ichikawa, H., Beardsley, R. C. 1993Temporal and spatial variability of volume transport of the Kuroshio in the East China SeaDeep-Sea Res.40583605Google Scholar
  12. Ichikawa, H., Chaen, M. 2000Seasonal variation of heat and freshwater transports by the Kuroshio in the East China SeaJ. Mar. Sys.24119129Google Scholar
  13. Isobe, A., M. Ando, T. Watanabe, T. Senjyu, S. Sugihara and A. Manda (2002): Freshwater and Temperature transports through the Tsushima-Korea Straits. J. Geophys. Res., 107(C7), 10.1029/2000JC000702.Google Scholar
  14. James, C., Wimbush, M., Ichikawa, H. 1999Kuroshio meanders in the East China SeaJ. Phys. Oceanogr.29259272CrossRefGoogle Scholar
  15. Kaneko, A., Koterayama, W., Honji, H., Mizuno, S., Kawatate, K., Gordon, R. L. 1990Cross-stream survey of the upper 400m of the Kuroshio by an ADCP on a towed fishDeep-Sea Res.37875889CrossRefGoogle Scholar
  16. Large, W. G., Pond, S. 1981Open ocean momentum flux measurements in moderate to strong windsJ. Phys. Oceanogr.11324336CrossRefGoogle Scholar
  17. Lee, T. N., Atkinson, L. P., Legeckis, R. 1981Observations of a Gulf Stream frontal eddy on the Georgia continental shelf, April 1977Deep-Sea Res.28347378CrossRefGoogle Scholar
  18. Manda, A., Isobe, A., Matsuno, T., Yanagi, T., Han, I.-S., Kamio, K., Nishida, H., Kuno, T., Morii, Y., Yamawaki, N., Yoshimura, H., Kanehara, H., Aoshima, T. 2000The results of the intensive ADCP observations of the Kuroshio front in the East China Sea and the detiding procedureEngineering Sciences Report, Kyushu Univ.21343348(in Japanese)Google Scholar
  19. Masuzawa, J. 1972Water characteristics of the North Pacific central regionStommel, H.Yoshida, K. eds. Kuroshio: Its Physical AspectsUniversity of Washington PressSeattle95128Google Scholar
  20. Matsuno, T. and S. Ohsaki (1990): Subduction of low salinity water into the intermediate layer of the Kuroshio in the East China Sea. Proc. CREAMS’99 Intl. Sympo., 64–67.Google Scholar
  21. Matsuno, T., Ohsaki, S., Kanari, S., Takaki, Y., Kuno, T. 2000Mixing processes and horizontal intrusion around the shelf break in the Easy China SeaYanagi, T. eds. Interactions between Estuaries, Coastal Seas and Shelf SeasTERRAPUBTokyo177195Google Scholar
  22. McCreary, J. P.,Jr., Fukamachi, Y., Kundu, P. K. 1991A numerical investigation on jets and eddies near an eastern ocean boundaryJ. Geophys. Res.9625152534Google Scholar
  23. Mellor, G. L. 1998User’s guide for a three-dimensional, primitive equation, numerical ocean modelProgram in Atmospheric and Oceanographic Sciences ReportPrinceton UniversityPrincetonGoogle Scholar
  24. Mellor, G. L., Yamada, T. 1982Development of a turbulence closure model for geographical fluid problemsRev. Geophys. Space Phys.20851875Google Scholar
  25. Qiu, B., Toda, T., Imasato, N. 1990On Kuroshio front fluctuations in the East China Sea using satellite and in situ observational dataJ. Geophys. Res.951819118204Google Scholar
  26. Sugimoto, T., Kimura, S., Miyaji, K. 1988Meander of the Kuroshio front and current variability in the East China SeaJ. Oceanogr. Soc. Japan44125135CrossRefGoogle Scholar
  27. Woodruff, S. D., Slutz, R. J., Jenne, R. L., Steurer, P. M. 1987A comprehensive ocean-atmosphere data setBull. Amer. Meteorol. Soc.6812391250Google Scholar
  28. Yanagi, T. 1994Material transport in the Yellow/East China SeasBull. Coastal Oceanogr.31239256(in Japanese)Google Scholar
  29. Yanagi, T., Shimizu, T., Lie, H.-J. 1998Detailed structure of the Kuroshio frontal eddy along the shelf edge of the East China SeaCont. Shelf Res.1810391056CrossRefGoogle Scholar
  30. Zhu, J., P. Ding, S. Hu and L. Yang (2001): Observation of the Changjiang Diluted Water, plume front and upwelling off the Changjiang mouth during August in 2001. Proc. the 11th PAMS/JECSS Workshop, CD-ROM.Google Scholar

Copyright information

© The Oceanographic Society of Japan 2004

Authors and Affiliations

  • Atsuhiko Isobe
    • 1
  • Eiji Fujiwara
    • 1
  • Pil-Hun Chang
    • 1
  • Koichi Sugimatsu
    • 2
  • Manabu Shimizu
    • 3
  • Takeshi Matsuno
    • 4
  • Atsuyoshi Manda
    • 5
  1. 1.Department of Earth System Science and TechnologyKyushu UniversityKasugaJapan
  2. 2.Environmental Consultant for Ocean and HumanTokyoJapan
  3. 3.Kuroshio Research LaboratoryNational Research Institute of Fisheries ScienceKochiJapan
  4. 4.Research Institute for Applied MechanicsKyushu UniversityKasugaJapan
  5. 5.Faculty of FisheriesNagasaki UniversityNagasakiJapan

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