TERRAPUB Journal of Oceanography

Journal of Oceanography, Vol. 60 (No. 2), pp. 293-301, 2004

Application of Sensitivity Analysis Using an Adjoint Model for Short-Range Forecasts of the Kuroshio Path South of Japan

Yoichi Ishikawa1*, Toshiyuki Awaji1, Nobumasa Komori2 and Takahiro Toyoda1

1Department of Geophysics, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
2Earth Simulator Center, Japan Marine Science and Technology Center, Yokohama 236-0001, Japan

(Received 15 August 2003; in revised form 9 December 2003; accepted 16 December 2003)

Abstract: A sensitivity experiment has been performed by assimilating altimetric data into a 1.5-layer primitive equation model as a first attempt to examine the impact of initialization on forecasts of the Kuroshio path variability south of Japan. By exploiting the advantage of an adjoint model, our approach clearly shows that a small meander off Shikoku Island has a large impact on the prediction of meander growth in the Kuroshio region. Further, the strengthening of the Kuroshio current and its recirculation clearly becomes an important factor in the development of the meander. These results demonstrate the effectiveness of our assimilation approach in identifying efficient initialization schemes on numerical forecasting of the Kuroshio south of Japan and should help in the construction of an effective observing system for improving the forecasting.

*Corresponding author E-mail: ishikawa@kugi.kyoto-u.ac.jp

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