The paper by Pacanowski and Philander (1981) explores the parameterization of vertical mixing processes in numerical models of tropical oceans, focusing on the equatorial region. They highlight that mixing is intense near the surface but weak below the thermocline, except in regions with large vertical temperature gradients and shear, such as the core of the Equatorial Undercurrent. The authors propose a parameterization of eddy mixing coefficients that depend on the Richardson number (Ri), which improves the realism of simulations compared to constant values. This parameterization is crucial for simulating the response of equatorial oceans to different wind stress patterns, particularly eastward and westward winds. The results agree well with measurements in the Indian Ocean for eastward winds but require consideration of nonzero heat flux into the ocean for westward winds, as this stabilizes the upper layers and reduces mixing intensity. The study also discusses the sensitivity of model results to the values of the mixing parameters and suggests that realistic surface boundary conditions are essential for accurate simulations. The authors conclude that their parameterization scheme provides better results than constant values for vertical mixing coefficients, provided specific values are assigned to the background mixing parameters.The paper by Pacanowski and Philander (1981) explores the parameterization of vertical mixing processes in numerical models of tropical oceans, focusing on the equatorial region. They highlight that mixing is intense near the surface but weak below the thermocline, except in regions with large vertical temperature gradients and shear, such as the core of the Equatorial Undercurrent. The authors propose a parameterization of eddy mixing coefficients that depend on the Richardson number (Ri), which improves the realism of simulations compared to constant values. This parameterization is crucial for simulating the response of equatorial oceans to different wind stress patterns, particularly eastward and westward winds. The results agree well with measurements in the Indian Ocean for eastward winds but require consideration of nonzero heat flux into the ocean for westward winds, as this stabilizes the upper layers and reduces mixing intensity. The study also discusses the sensitivity of model results to the values of the mixing parameters and suggests that realistic surface boundary conditions are essential for accurate simulations. The authors conclude that their parameterization scheme provides better results than constant values for vertical mixing coefficients, provided specific values are assigned to the background mixing parameters.