Abstract
Conditions south of Cape Shiono-misaki for the nearshore and offshore non-large-meander (NLM) paths of the Kuroshio Current are studied using a two-layer reduced gravity model. A steady and non-diffusive state is assumed, and the conservation laws of Bernoulli's function and potential vorticity along the current axis are used. Spatial changes of velocity and depth of the current are imposed as boundary conditions south of Cape Shiono-misaki. These conditions are based on the facts that are ohserved south of the cape: abrupt acceleration of the Kuroshio and the spatial change of sea levels. The current paths east of the cape are computed.
This model reproduces well the actual nearshore NLM paths. It also produces offshore NLM paths west of and over the Izu Ridge, but not east of the Izu Ridge. Diffusion of vorticity may be important for the eastern part of the offshore NLM path.
An increase of velocity south of the cape is necessary for producing realistic NLM paths. The velocity increase accompanies a decrease of current depth owing to Bernoulli's conservation, and the depth decrease in turn diminishes the absolute vorticity owing to the potential vorticity conservation. The velocity increase, on the other hand, strengthens the negative velocity shear and diminishes the relative vorticity. If the decreases of the relative and absolute vorticities compensate each other, the path goes excessively southward owing to the negative curvature south of the cape. Dominance of the relative vorticity change over the absolute vorticity change prevents, the path from shifting southward and causes the realistic NLM paths.
The NLM paths need different amplitudes of the changes south of the cape depending on the velocity and transport of the current, but in any case, the nearshore NLM path needs larger changes than the offshore NLM path. This property and the amplitude of the changes are consistent with observations.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Ishii, H., Y. Michida and H. Nishida (1986): Estimation of Kuroshio volume transport from ADCP data. Report of the Kuroshio Exploitation and Utilization Research (KER), No. 9, 167–180.
Kawabe, M. (1980): Sea level variations along the south coast of Japan and the large meander in the Kuroshio. J. Oceanogr. Soc. Japan,36, 97–104.
Kawabe, M. (1985): Sea level variations at the Izu Islands and typical stable paths of the Kuroshio. J. Oceanogr. Soc. Japan,41, 307–326.
Kawabe, M. (1986): Transition processes between the three typical paths of the Kuroshio. J. Oceanogr. Soc. Japan,42, 174–191.
Kawabe, M. (1989): Sea level changes south of Japan associated with the non-large-meander path of the Kuroshio. J. Oceanogr. Soc. Japan,45, 181–189.
Konaga, S. (1971): On the relation between Kuroshio strong current and water temperature of 200 m depth III. Umi to Sora,46, 77–85 (in Japanese with English abstract and legends).
Konaga, S., K. Shuto, H. Kusano and K. Hori (1967): On the relation between Kuroshio strong currents and the water temperature of 200 m depth (II). Umi to Sora, 43, 48–53 (in Japanese with English abstract and legends).
Masuzawa, J. (1961): Recent research on the Kuroshio current. Geogr. studies presented to Prof. Tsujimura in honor of his 70th birthday, 354–364 (in Japanese with English abstract).
Minami, H. (1977): Sudden increase of the Kuroshio surface current off Shionomisaki and the role of the southward flow off Kumano-nada. Umi to Sora,53, 15–22 (in Japanese with English abstract and legends).
Nitani, H. (1975): Variation of the Kuroshio south of Japan. J. Oceanogr. Soc. Japan,31, 154–173.
Shuto, K. (1979): The flow conditions of the Kuroshio in the vicinity of Cape Shionomisaki. Oceanogr. Mag.,30, 1–14.
Taft, B. (1972): Characteristics of the flow of the Kuroshio south of Japan. p. 165–216.In: Kuroshio—Its physical aspects, ed. by H. Stommel and K. Yoshida, Univ. Tokyo Press, Tokyo.
Tsumura, K. (1963): Investigation of the mean sea level and its variation along the coast of Japan (Part I)—Regional distribution of sea level variation. J. Geodetic Soc. Japan,9, 49–90 (in Japanese with English abstract and legends).
Yasuda, I., J.-H. Yoon and N. Suginohara (1985): Dynamics of the Kuroshio large meander—Barotropic model. J. Oceanogr. Soc. Japan,41, 259–273.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Kawabe, M. A steady model of typical non-large-meander paths of the Kuroshio Current. Journal of the Oceanographical Society of Japan 46, 55–67 (1990). https://doi.org/10.1007/BF02124815
Received:
Revised:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF02124815