Ocean Turbulent Mixing in Northern Bohai Strait, China

Abstract

The measurements of ocean microstructure through which ocean internal mixing mechanism is revealed are taken more often recently. Free-falling turbulence microstructure profiler TurboMAP-9 is used to take a field observation on the area of northern Bohai Strait. 13 stations distributed in Bohai Sea, Yellow Sea and the “division line” between them are measured. Turbulent mixing characteristics of northern Bohai Strait for different seasons are described by analyzing the observation data of ocean turbulence microstructure profile. The results show that the northern Bohai Strait is a strong mixing area during non-stratification period. Turbulent energy dissipation rate ε of winter is bigger than that of autumn and it is strongest near the bottom layers which is in the order of 10−5W/kg. Heat dissipation rate χθ is in the same order of 10−6–10−5°C2/s in autumn as ε and 2–3 orders smaller than ε in winter. Thermal diffusivity coefficient kθ is a little bigger than turbulent mixing rate kρ in autumn and 1–2 orders smaller than kρ in winter. Both the kρ and kθ along the “division line” of Bohai Sea and Yellow Sea are bigger than that of the Bohai Sea and Yellow Sea. Base on the measured data and the analysis, heat dissipation rate and thermal dispersion coefficient can change 2–3 orders in non-stratification seasons which should be paid much attention to, especially for ocean model parameterization and pollutant discharge modeling.