Kuroshio pathways in a climatologically forced model
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A high-resolution ocean model forced with an annually repeating atmosphere is used to examine variability of the Kuroshio, the western boundary current in the North Pacific Ocean. A large meander (LM) in the path of the Kuroshio south of Japan develops and disappears in a highly bimodal fashion on decadal timescales. The modeled meander is comparable in timing and spatial extent to an observed feature in the region. Various characteristics of the LM are examined, including relative vorticity, transport, and velocity shear. The many similarities between the model and observations indicate that the meander results from intrinsic oceanic variability, which is represented in this climatologically forced model. Each LM is preceded by a smaller “trigger” meander that originates at the south end of Kyushu, moves up the coast, and develops into the LM. However, there are also many meanders very similar in character to the trigger meander that do not develop into LMs. Formation of an LM only occurs when a deep anticyclone associated with the trigger meander forms near Koshu Seamount. Furthermore, the major axis of that deep anticyclone must be oriented away from the coast, rather than alongshore. In the specific case of interaction of a trigger meander with a deep anticyclone with major axis oriented away from the coastline, LM formation occurs.
KeywordsNorth Pacific Kuroshio Large meander Trigger meander Bimodal variability Interannual variability
E.M.D. acknowledges support of the Doherty Foundation and National Science Foundation OCE-0849808. S.R.J was sponsored by the National Science Foundation OCE-0849808. Participation of S.P. and F.B. was supported by the National Science Foundation by its sponsorship of the National Center for Atmospheric Research. The simulation was performed at the National Center for Computational Sciences at Oak Ridge National Laboratory with computer time awarded under the INCITE program, and at the National Center for Atmospheric Research Computational and Information Systems Laboratory.
- Endoh T, Hibiya T (2009) Interaction between the trigger meander of the Kuroshio and the abyssal anticyclone over Koshu Seamount as seen in the reanalysis data. Geophys Res Lett 36:L18604Google Scholar
- Kawabe M (1985) Sea level variations at the Izu Islands and typical stable paths of the Kuroshio. J Oceanogr 41:307–326Google Scholar
- Kawabe M (1987) Spectral properties of sea level and time scales of Kuroshio path variations. J Oceanogr 43:111–123Google Scholar
- Smith R, Gent P (2002) Reference manual for the parallel ocean program (POP). Los Alamos unclassified report LA-UR-02-2484Google Scholar
- Solomon H (1978) Occurrence of small “trigger” meanders in the Kuroshio off southern Kyushu. J Oceanogr 34:81–84Google Scholar
- Stommel H, Yoshida K (eds) (1972) Kuroshio: its physical aspects. University of Tokyo Press, TokyoGoogle Scholar
- White W, McCreary J (1976) Formation of Kuroshio meander and its relationship to large-scale ocean circulation. Deep-Sea Res 23(1):33–47Google Scholar