Purpose. The purpose of the study is to develop the physical concepts of dynamic interaction of two media on small and submesoscales, as well as to create an objective model for describing the turbulent regime of the sea near-surface layer.

Methods and Results. Significant scales of turbulence energy supply are established, and a non-stationary numerical model of turbulent exchange in the near-surface layer of the sea is proposed based on the large arrays of experimental data on marine turbulence intensity under different hydrometeorological conditions. Four basic generation mechanisms are considered as the sources of turbulence, namely drift current velocity shear, surface waves and their breakings, and submesoscale eddy structures. The influence of the latter is assessed through the structural function calculated using the synchronous measurements of current velocity in two points. The numerical solutions for velocity profiles, turbulence energy, and dissipation rate are compared to the experimental data, at that the necessary model constants are selected. Verification of the calculations has shown their good agreement with the measurements in a fairly wide range of wind speeds including the weak winds for which the other models yield the significantly lower results as compared to the experimental data.

Conclusions. A non-stationary model is proposed for calculating the turbulence characteristics in the upper mixed layer of the sea. The application of structural function in the turbulent energy balance equation improves the agreement between model calculations and experimental data. The developed model quite reliably describes the turbulent structure of the layer under study and permits to calculate the intensity of vertical turbulent exchange in different hydrometeorological conditions.