Vertical structure of turbulent mixing in the Bussol’ Strait and its impact on water masses in the Okhotsk Sea and the North Pacific

Estimation method of turbulent energy dissipation rate using density inversion (Thorpe scale) was improved and confirmed to be valid for > 10^-9 W/kg in the relatively strong turbulence zone in the Kuril Strait by comparing simultaneous microstructure measurements. Distribution of the turbulent kinetic energy dissipation rate across the Bussol' Strait was re-evaluated by applying this method to tide-resolving density observations. The improved estimates without excessive rejection of density inversions provide mean dissipation rate (1.45 ´ 10^-7 W/kg), vertical diffusivity (153 cm²/s) and depth-integrated dissipation rate (187 mW/m²). One-day mean vertical profiles in the potential density co-ordinate allows us to estimate diapycnal velocity at 3 ´ 10^-5 m/s downwards through the 26.85 isopycnal surface, and was almost zero through 26.7, suggesting the thinning of Okhotsk Sea Mode Water or of the core of North Pacific Intermediate Water as the water flows through the Bussol’ Strait from the Sea of Okhotsk to the North Pacific.