Abstract
With full-depth LADCP velocity data collected in a wide area southeast of Kyushu, Japan, large velocity currents, occasionally exceeding 15 cm s−1, were observed in a thick, 500–1,500 m, near-homogeneous density layer below approximately 3,000 m depth around the steep topographies. The currents were found not to flow along the topographic contours, and to be strongly ageostrophic. The directions of the bottom-layer currents are rather related with phase of the semi-diurnal tides, suggesting deeply intruded internal tides generated at the steep topographies.
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Acknowledgments
This study was conducted as a part of the cooperative research between Japan Agency for Marine-Earth Science and Technology (JAMSTEC) and Nagasaki Marine Observatory, Japan Meteorological Agency. Most of the study was done when K. Ichikawa belonged to JAMSTEC. The authors would like to thank the captain, crew and scientists on board the R/V Chofu-maru (Cruise number: CH0509) and Drs. H. Kamiya, S. Kawae, and A. Nishina for their support. Discussion about internal tides with Drs. T. Matsuno, T. Endoh, and E. Tsutsumi have been insightful. Thanks are extended to Drs. M. Visbeck, G. Krahmann, T. Saito, and K. Komaki for their advices on LADCP data processing, and the editors (Profs. T. Hibiya and Y. Yoshikawa) and anonymous reviewers for their helpful comments.
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Nagano, A., Ichikawa, K., Ichikawa, H. et al. Large ageostrophic currents in the abyssal layer southeast of Kyushu, Japan, by direct measurement of LADCP. J Oceanogr 69, 259–268 (2013). https://doi.org/10.1007/s10872-013-0170-z
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DOI: https://doi.org/10.1007/s10872-013-0170-z