Most of the numerical calculations were carried out on an NEC SX-3/44R computer at the Computing Center of Tohoku University. During the course of this study, we had useful discussions with members of Hokkaido University. Drs. Atushi Kubokawa and Shan-Ping Xie have provided invaluable comments. Discussions with Drs. Julian P. McCreary and Zhengyu Liu were also appreciated. Dr. Kim Van Scoy, Dr. Monica Stephenson, and Ms. Mary Kennedy helped us in improving our paper. Two reviewers have contributed to the quality of our paper. We expressed our thanks to all of them. In writing this paper, the first author was partially supported by the NSF sponsored Physical Oceanography Program in a grant to the Department of Atmospheric and Oceanic Sciences, University of Wisconsin—Madison.
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