Abstract
The seasonal variation of the Kuroshio transport south of Japan has been investigated using the results of an assimilation model. Annual and semiannual variations of the transport and dynamic depth anomaly are reconstructed by CEOF (complex orthogonal empirical function) analysis. In the basin west of the Izu-Ogasawara Ridge, the annual component of the variation propagates westward with the phase speed of the long Rossby wave associated with the first baroclinic mode. The variation also shows a similar tendency to that reproduced in a wind-driven, two-layer model with a ridge. This suggests that the annual variation revealed in the assimilation model is associated with the baroclinic first mode of motion excited above the Izu-Ogasawara Ridge. Furthermore, it is found that both the semiannual component and the annual component are important members determining the seasonal variation of the Kuroshio transport south of Japan. The semiannual component is revealed as a double gyre pattern in the basin west of the Izu-Ogasawara Ridge.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Barnett, T. P. (1983): Interaction of the monsoon and Pacific Trade Wind system at interannual time scales. part I: The equatorial zone. Mon. Wea. Rev., 111, 756–773.
Gill, A. E. and P. P. Niiler (1973): The theory of the seasonal variability in the ocean. Deep-Sea Res., 20, 141–177.
Greatbatch, R. J. and A. Goulding (1990): On the seasonal variation of transport through the Tokara Strait. J. Oceanogr. Soc. Japan, 46, 9–20.
Hasunuma, K. and K. Yoshida (1978): Splitting of the subtropical gyre in the western North Pacific. J. Oceanogr. Soc. Japan, 37, 160–172.
Ichikawa, H., H. Nakamura, A. Nishina and M. Higashi (2004): Variability of northeastward current southeast of northern Ryukyu Islands. J. Oceanogr., 60, this issue, 351–363.
Imawaki, S., H. Uchida, H. Ichikawa, M. Fukasawa, S. Umatani and ASUKA Group (2001): Satellite altimeter monitoring the Kuroshio transport south of Japan. Geophys. Res. Lett., 28, 17–20.
Isobe, A. and S. Imawaki (2002): Annual variation of the Kuroshio transport in a two-layer numerical model with a ridge. J. Phys. Oceanogr., 32, 994–1009.
Kamachi M., T. Kuragano, N. Yoshioka, J. Zhu and F. Uboldi (2001): Assimilation of satellite altimetry into a western North Pacific operational model. Adv. Atmos. Sci., 18, 767–786.
Kamachi, M., T. Kuragano, H. Ichikawa, H. Nakamura, A. Nishina, A. Isobe, D. Ambe, M. Arai, N. Gohda, S. Sugimoto, K. Yoshita, T. Sakurai and F. Uboldi (2004): Operational data assimilation system for the Kuroshio south of Japan: Reanalysis and validation. J. Oceanogr., 60, this issue, 303–312.
Kawabe, M. (1988): Variability of Kuroshio velocity assessed from the sea-level difference between Naze and Nishinoomote. J. Oceanogr. Soc. Japan, 44, 293–304.
Kubota, M., H. Yokota and T. Okamoto (1995): Mechanism of the seasonal transport variation through the Tokara Strait. J. Oceanogr., 51, 441–458.
Thompson, K. R., J. R. N. Lazier and B. Taylor (1986): Windforced changes in Labrador Current transport. J. Geophys. Res., 91, 14261–14268.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Isobe, A., Kamachi, M., Masumoto, Y. et al. Seasonality of the Kuroshio Transport Revealed in a Kuroshio Assimilation System. Journal of Oceanography 60, 321–328 (2004). https://doi.org/10.1023/B:JOCE.0000038338.05850.5e
Issue Date:
DOI: https://doi.org/10.1023/B:JOCE.0000038338.05850.5e