| The Kuroshio path is detected from the sea-surface velocity field obtained by combining satellite altimeter and sea-surface drifter data. Satellite altimeter can measure the sea-surface height over the wide area uniformly with high accuracy. Assuming geostrophy, the altimeter data can provide the sea-surface velocity field. From altimeter data, however, only anomaly components (deviations from the mean) are usable because the present geoid model is not accurate enough. The missing mean sea-surface velocity field has been estimated for the North Pacific by Uchida and Imawaki (2003; Geophys. Res. Lett.). This field was derived by combing anomalies of sea-surface velocity obtained from TOPEX/POSEIDON and ERS-1/2 altimeter data and in-situ surface velocities estimated from trajectories of WOCE-TOGA surface drifting-buoys. This mean velocity field is combined with anomaly field obtained from altimeter data, in order to provide the high-resolution surface velocity field every 10 days. In this study, we try to detect the position of Kuroshio path from this surface velocity field, and obtain a time series of the position with a high-resolution in time and space. Assuming that the flow associated with the Kuroshio is continuous in space, the Kuroshio path is determined by tracking the maximum speed of the surface velocity. 295 cases out of 299 are successfully detected, every ten days, during eight years from 1993 to 2000. It is clearly shown that the Kuroshio goes over the Izu Ridge extremely frequently between Miyake and Mikura islands. These results and others suggest that the bottom topography has a strong influence on the Kuroshio path. The spatial pattern of the Kuroshio path detected here is similar to that shown in the Å2Quick Bulletin of Ocean Conditions¡|published by the Hydrographic and Oceanographic Department of the Japan Coast Guard generally, but the present path shows more detailed variations. Statistical distribution is similar to the histograms of the Kuroshio axis position shown by Ebuchi and Hanawa (2003; J. Oceanogr.). |
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