| Izu-Ogasawara Ridge is well known to have a great impact on fluctuation of the Kuroshio flow-path south of Japan. Sea surface temperature (SST) was observed continuously from 1983 to 1997 by a ferryboat which made round trips every 5-7 days along the eastern side of the ridge between Tokyo (35.6N) and Chichijima Island (27.0N). Variation of SST deviated from seasonal change consisted of some distinguished modes with same period as typical modes of the Kuroshio fluctuation, and more important, the SST variation in the southern region from 31N was in advance of the variation in the northern region which was synchronized by the Kuroshio fluctuation. The meridional time-lag was clearly found also in variation of sea surface height (SSH) of TOPEX/POSEIDON, which could be partly attributed to meridional difference of interaction process between topography and mesoscale eddies propagated from the eastern region. Positive (Negative) anomaly of SSH in the southern region was closely related to northward (southward) shift of the Kuroshio flow-path, which indicated a possibility to estimate the two-years later position of the Kuroshio from a signal in the southern region. |
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