Diapycnal Exchange in the Main Pycnocline of the Black Sea

The article discusses the application of 03 parameterization for calculating the vertical turbulent diffusion coefficient from vertical profiles of water density and current velocity. The work is based on the processing of data obtained during the 95th cruise of the R/V Professor Vodyanitsky with a depth resolution of about 10 meters in the central sector of the northern Black Sea from June 16 to July 4, 2017. Measurements of salinity and water temperature profiles were carried out using the SBE911plus probe, and current velocity – using the LADCP lowered acoustic Doppler current profiler. Transfer functions of the process of parameter measurement, calculation of vertical derivatives at finite increments and data processing were taken into account when integrating the canonical spectrum of internal waves. The results of calculating the vertical turbulent diffusion coefficient in the main pycnocline on the isopycnal surface with a conditional density of 15 kg/m, which was characterized by a maximum buoyancy frequency, are considered in detail. Intensification of diapycnal mixing was observed in the area of the Rim Current. The value of the vertical turbulent diffusion coefficient at the maximum was 1.3 · 10 m/s, in the center and on the periphery of the sea – 0.4 · 10 m/s and 0.65 · 10 m/s, respectively. Estimates of heat, salt and oxygen fluxes were also the highest in the area of the Rim Current. Fluxes in the center and on the periphery of the sea are 1.5–3 times less than their values at the maximum.