TERRAPUB Journal of Oceanography

Journal of Oceanography, Vol. 65 (No. 2), pp. 273-279, 2009

Observations of Wind-Driven Deepening of the Surface Mixing Layer in the Tsushima Strait

Takahiro Endoh1*, Takeshi Matsuno1, Yutaka Yoshikawa1, Yasuto Tatsuyama2 and Joji Ishizaka3

1Research Institute for Applied Mechanics, Kyushu University, Kasuga-kouen, Kasuga, Fukuoka 816-8580, Japan
2Machinery and Engineering Company, Kobe Steel, Ltd., Takasago, Hyogo 676-8670, Japan
3Faculty of Fisheries, Nagasaki University, Bunkyo, Nagasaki 852-8521, Japan

(Received 29 February 2008; in revised form 7 November 2008; accepted 25 November 2008)

Abstract: A detailed description of wind-driven deepening of the mixing layer in the Tsushima strait is given by combining current data from the acoustic Doppler current profiler (ADCP) attached to a satellite-tracked surface drifter, with microstructure data from the Turbulence Ocean Microstructure Acquisition Profiler (TurboMAP) deployed from a ship following the surface drifter. By collecting data in a Lagrangian manner we attempted to minimize the effect of horizontal advection. The dissipation rate of turbulent kinetic energy (TKE), ε, was measured directly using the TurboMAP, whereas the production rate of TKE, P, was estimated from horizontal velocities obtained using the ADCP based on the one-dimensional linear equation of motion. The TKE budget in the mixing layer is examined by applying the integrated TKE equation to the observed data. The sum of the temporal change of potential energy, shear production, dissipation, TKE flux, and the surface buoyancy flux terms changes dramatically with time, indicating the importance of the temporal change of TKE in the deepening process on a time scale shorter than one day, which is neglected in widely used bulk mixed-layer models.

*Corresponding author E-mail: endo@riam.kyushu-u.ac.jp

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