4. The MC-IT oscillates with a period about 40 days in some parameter range. This oscillation is due to eddy detachment from the Mindanao eddy. Analysis using constant potential vorticity trajectories shows that this oscillation tends to happen with 70cm/s ＜ vc ＜ 160cm/s where vc is the velocity of the MC at the southeastern coast of the Mindanao island. The oscillation is insensitive to the strength of the current in the southern hemisphere (not shown here).
Acknowledgments
Initial phase of this study was conducted when the first author was a visiting post-Doc of Wyrtki Center, the Univ, of Hawaii. We especially would like to thank Prof. Lukas for his valuable suggestions. Part of this was supported by Grant-in-Aids for Scientific Research. No., from the Ministry of Education, Science and Culture, Japan. Numerical calculations were done on the SP2 at the Maui High Performance Computer Center.
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