Measurement And Application Of Ocean Mixing For Northern Bohai Strait

It has been many years reaching on Ocean turbulent mixing both in our country and abroad, at present, a lot of fruitful achievements have been made. Ocean mixing is affected by a number of factors, such as tide, wind, submarine topography and so on, therefore, mixing in different area shows different characteristics. The study on mixing on abroad is very extensive, measurement reaches have been developed from ocean mixing to lakes and rivers mixing. Reseaching on mixing in domestic mainly focused on South China Sea, and has got good results, for example discovery of salt fingering and double diffusion phenomenon. There are also some reseaches on Huanghai and East Sea, but mixing measurement on Bohai Strait and adjacent sea areas is few or none.In this paper, we use free-falling Turbulence Ocean Microstructure Acquisition Profiler (TurboMAP-9) to carry on twice field observations on13stations of northern Bohai Strait, the time is October28,2011and February22,2012, respectively. We obtained this area’s vertical distribution of temperature, salinity, turbulent energy dissipation rate, turbulent mixing rate, heat dissipation rate and thermal diffusivity coefficient in autumn and winter.In autumn, turbulent energy dissipation rate and heat dissipation rate distribute in the range of10-9～10-6. Relevant turbulent mixing rate and thermal diffusivity coefficient distribute in the range of10-5～10-1m2/s, average values are3.59×10-2m2/s and8.19×10-2m2/s, respectively.Average values of turbulent energy dissipation rate and dissipation rate in winter are1.75×10-6W/kg and4.06×10-8℃/s, respectively. Turbulent mixing rate distribute in the range of10-4～100m2/s, some stations’water depth exceed100m2/s; thermal diffusivity coefficient distribute in the range of10-7～10-2m2/s. For deep water stations, kρ and kθ differ by about1-2order of magnitude, whereas the both values differ by about3～4order of magnitude at stations near coast. The whole average values of turbulent mixing rate and thermal diffusivity coefficient is2.83×10-1/s and3.28×10-3m2/s.At last, we used mathematical model to imitate a hypothetic power plant’s thermal discharge in our observation region, we added turbulent mixing rate and thermal diffusivity coefficient that we got from our measurement into the simulation process. We divided turbulent mixing rate and thermal diffusivity coefficient into6operating conditions in the light of different order of magnitude. We computed the vertical exotherm field in condition of above each operating condition and vertical velocity field under circumstance of different turbulent mixing rates, studied the water’s vertical exotherm and velocity distribution.