Journal of Oceanography

, Volume 69, Issue 1, pp 1–13 | Cite as

Mixing process on the northeast coast of Hokkaido in summer

  • Miho Ishizu
  • Yujiro Kitade
  • Yutaka Michida
Original Article


Direct measurements using a free-falling micro-profiler were conducted on the northeast coast of Hokkaido in the summer of 2007 to clarify the mixing process in the Soya Warm Current (SWC) region in terms of microstructure. The distribution of the Turner angle (Tu) showed that these regions have a high potential for double diffusive convection, but direct measurements of the turbulent dissipation rate (ε) and dissipation of temperature variance (\( \chi_{T} \)) did not necessarily correspond to each other in the SWC region, especially in the offshore front of SWC and farther offshore. The mixing efficiency indicated that, even though the Turner angle (Tu) indicated a high potential for double diffusive convection, turbulent mixing was the main contributor to the mixing process in this region, and double-diffusive convection only contributed partially and sparsely, especially in the boundary off SWC water. The bottom mixed layer (BML) is known to thicken off the SWC. The vertical diffusivity coefficient was enhanced near the bottom (10−4–10−3 m2 s−1) off the SWC, and these results support that turbulence near the bottom off the SWC contributed to the thickening of the BML.


Mixing process Turbulence Double diffusion Microstructure Coastal upwelling 



The authors thank the officers of the JCG 1st region, and the crew of P/V “Sorachi” for their support in the field program. We greatly appreciate Dr. T. Hibiya (Tokyo University) and an anonymous reviewer for reading our manuscript carefully and giving useful comments. We also thank Dr. J. Yoshida (Tokyo University of Marine Science and Technology), Dr. K. Shimada (Tokyo University of Marine Science and Technology), Dr. F. Li (JFE Advantech Co., Ltd; formerly JFE Alec Co., Ltd.), and Dr. M. Gregg (University of Washington) for their helpful comments and suggestions on our analysis.


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Copyright information

© The Oceanographic Society of Japan and Springer Japan 2012

Authors and Affiliations

  1. 1.University of Hawaii at ManoaInternational Pacific Research CenterHonoluluUSA
  2. 2.Department of Ocean ScienceTokyo University of Marine Science and TechnologyTokyoJapan
  3. 3.Department of Natural Environment, Coastal Ecosystem DivisionInternational Coastal Research CenterKashiwaJapan

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