Research progress of ocean bottom mixing layer

This study comprehensively reviews the research progress on the ocean bottom mixing layer, emphasizing its structural features, influencing mechanisms, thickness determination and parameterization methods, and global distribution patterns, while also exploring future research directions. The ocean bottom mixing layer, a water layer near the ocean floor influenced by strong turbulent mixing, has relatively uniform temperature, salinity, and density. As a crucial interface for marine physical, chemical, and biological processes, it plays a key role in global ocean energy exchange, material transport, and biogeochemical cycles. We thoroughly analyze the structural characteristics of the ocean bottom mixing layer. Various influencing mechanisms such as bottom shear flow, internal wave breaking, topography, tides, and geothermal flux are explored. Methods for determining the thickness of the bottom mixing layer are introduced, and parameterization of the bottom mixing layer thickness in relation to the seawater depth, buoyancy frequency, and turbulent diffusion coefficients is discussed. Finally, the distribution characteristics of the global ocean bottom mixing layer thickness are summarized, and future research methods and directions of the ocean bottom mixing layer are prospected.