The mixed layer, where ocean properties are uniform, is key to ocean dynamics and ocean-atmosphere interactions. We propose an alternative definition of the mixed layer as the layer in which water parcels can move with little or no work. This approach provides realistic estimates of mixed-layer depth across space and time under diverse ocean conditions. It has potential implications for improving our understanding of various ocean-atmosphere phenomena, including dynamic and thermodynamic ones.

We propose an approach to quantify energy barriers to the vertical movement (upward-downward) of water parcels in diverse aquatic bodies, which are associated with the vertical variation in density (stratification). The approach analyzes these barriers in detail and provides an objective measure of stratification intensity in any vertical section of the water column. This approach can enhance our understanding of the effects of stratification on diverse ocean-atmosphere interaction processes.

In this study, we present a methodology to locate the minimum and maximum depths of the strongest thermocline, its thickness, and its strength by adjusting the sigmoid function to the temperature profiles in the global ocean. The results of the methodology are compared with the results of other methods found in the literature, and an assessment of the ocean regions where the adjustment is valid is provided. The method proposed here has shown to be robust and easy to apply.