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

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Abstract

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 24.5σ θ 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 24.5σ θ is the deepest layer of the Kuroshio pycnocline outcropping to the sea surface on the shallow shelf in early spring. Outcropping isopycnals above 24.5σ θ 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.

Original languageEnglish
Pages (from-to)853-863
Number of pages11
JournalJournal of Oceanography
Volume60
Issue number5
DOIs
Publication statusPublished - Jan 1 2004

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All Science Journal Classification (ASJC) codes

  • Oceanography

Cite this

Isobe, A., Fujiwara, E., Chang, P. H., Sugimatsu, K., Shimizu, M., Matsuno, T., & Manda, A. (2004). Intrusion of less saline shelf water into the Kuroshio subsurface layer in the East China Sea. Journal of Oceanography, 60(5), 853-863. https://doi.org/10.1007/s10872-005-5778-1