The Vertical Turbulent Exchange Features in the Black Sea Active Layer

Abstract

Physical processes of heat and mass vertical transfer in natural stratified basins depend mostly on the intensity of quasi-inertial internal waves breaking, which, in turn, is determined by the intensity of the wave source and local stratification in the basin. There are many research works including estimations of the dependence of the vertical turbulent diffusion coefficient K on the buoyancy frequency N (stratification). In this paper, on the base of a semiempirical model using the analysis of the pulsation data obtained at probing in the lower stratified part of the Black Sea active layer, the dependence of the coefficient of vertical turbulent diffusion K on the buoyancy frequency N is estimated. The measurements were carried out in the deep area of the basin. The measurement data were collected using a high-resolution probe-turbulimeter “Sigma-1”. A similar dependence for this layer was built based on a 1.5D model of the vertical exchange in the Black Sea deep region. Previously, the same results were obtained in the upper “strongly” stratified and the lower “weakly” stratified layers in the main pycnocline of the investigated basin. The joint analysis of three pairs of power dependencies $K \cong AN^{\alpha }$ m²s⁻¹ from different stratified layers showed that the exponents α in each pair were very close to each other, while the estimated (semi-empirical) coefficients A in each pair turned out to be much higher than the pattern coefficients.