Complimentarity of Different Approaches for Assessing Vertical Turbulent Exchange Intensity in Natural Stratified Basins

The comparison of previously proposed theoretical and semi-empirical approaches for assessing dependence of vertical turbulent exchange on stratification in the natural basins is carried out. The following models are compared: the semi-empirical model based on vertical probing data for revealing dependence of the required parameters on the stratification; the theoretical "spectral" model indicating qualitative differences in the exchange parameters in the "strongly" and "weakly" stratified layers of the main pycnocline in natural basins; the 1.5D model of the Black Sea vertical exchange developed within the framework of the inverse problem. The models, being analyzed in the course of calculating dependence of the energy dissipation rates and the diffusion coefficient K upon the buoyancy frequency N, show that they do not contradict each other and, if necessary, can complement each other. In addition, it is found that the greatest physical completeness among the considered models contains the "spectral" model that takes into account a variety of possible distributions in the upper "strongly" stratified layer. However, there are certain difficulties with assessment of the relevant coefficients in, dependencies. The latter problem can be solved within the framework of this approach via proper measurements in the investigated area using the semi-empirical approach relationships. A correspondence between the pair of "spectral" model and semi-empirical model and the 1.5D model for the Black Sea, which will be used in the future, should be also noted.