This paper describes a physically reliable model of the ocean surface layer. A Richardson-number-dependent stability function obtained from atmospheric boundary-layer data is applied to the oceanic layer. A nonstationary system of equations for motion and thermodynamics was solved numerically. The wind-driven current and water temperature profiles, with diurnal period, were obtained for various meteorological conditions. The results show fairly good agreement with existing observational data. The present model predicts a much faster penetration of the mixed-layer current to depths greater than that of the thermocline because of a larger eddy diffusivity for momentum than for heat under stable conditions. An oceanic mixed layer is formed at night and deepens; its daily mean value is approximately proportional to the wind speed. The surface drift current is found to be about equal to the wind friction velocity. The present ratio of the surface drift current to the friction velocity is somewhat larg... Abstract This paper describes a physically reliable model of the ocean surface layer. A Richardson-number-dependent stability function obtained from atmospheric boundary-layer data is applied to the oceanic layer. A nonstationary system of equations for motion and thermodynamics was solved numerically. The wind-driven current and water temperature profiles, with diurnal period, were obtained for various meteorological conditions. The results show fairly good agreement with existing observational data. The present model predicts a much faster penetration of the mixed-layer current to depths greater than that of the thermocline because of a larger eddy diffusivity for momentum than for heat under stable conditions. An oceanic mixed layer is formed at night and deepens; its daily mean value is approximately proportional to the wind speed. The surface drift current is found to be about equal to the wind friction velocity. The present ratio of the surface drift current to the friction velocity is somewhat larg...