Abstract
Under strong surface wind forcing during winter, direct current observations in the northern Sea of Japan show the existence of strong near-inertial currents in the deep water that is characterized by the extremely homogeneous vertical structures of temperature and salinity. However, the mechanism generating internal waves in the deep water of the northern Sea of Japan has not been well understood. In this study, to clarify the dynamical link between the surface wind forcing and near-inertial currents in the deep water of the northern Sea of Japan, we drive a general circulation model taking into account realistic wind stress, ocean bottom and land topography. In the northern Sea of Japan, the numerical results show that vertically coherent horizontal currents with a speed of ~ 0.05 m s−1 are excited throughout the homogeneous deep water. A two-layer model successfully reproduces the pattern of the horizontal current velocities shown by the general circulation model, indicating that internal waves emanate westward from the northwestern coast of Japan through coastal adjustment to the strong wind forcing event and, while propagating into the ocean interior, they excite evanescent near-inertial response throughout the lower layer below the interface.
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Acknowledgements
The authors thank T. Matsuno and S. Kida of Kyushu University and T. Gamo of the University of Tokyo for helpful discussions and two anonymous reviewers for their invaluable comments and suggestions on the original manuscript. The present study was supported in part by the Japanese Ministry of Education, Culture, Sports, Science and Technology through a Grant-in-Aid for Scientific Research on Innovative Areas 4702 (15H05824) to T. Hibiya.
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Watanabe, M., Hibiya, T. A near-inertial current event in the homogeneous deep layer of the northern Sea of Japan during winter. J Oceanogr 74, 209–218 (2018). https://doi.org/10.1007/s10872-017-0451-z
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DOI: https://doi.org/10.1007/s10872-017-0451-z