| Institution: | (1) Department of Earth System Science and Technology, Kyushu University, Kasuga-Koen, 816-8580 Kasuga, Japan;(2) Environmental Consultant for Ocean and Human, Kitaueno, Taito-ku, 110-0014 Tokyo, Japan;(3) Kuroshio Research Laboratory, National Research Institute of Fisheries Science, Sanbashi-dori, 780-8010 Kochi, Japan;(4) Research Institute for Applied Mechanics, Kyushu University, Kasuga-Koen, 816-8580 Kasuga, Japan;(5) Faculty of Fisheries, Nagasaki University, Bunkyo-cho, 852-8521 Nagasaki, Japan |
| 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 24.5σθ 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. |
