A landscape of mesoscale eddy vertical structure: the influence of bathymetric slope and roughness on kinetic energy

Abstract Surface and upper ocean measurements of mesoscale eddies have revealed the central role they play in ocean transport, but their interior and deep ocean characteristics remain under-sampled and under-explored. In this study, mooring arrays sampling with high vertical resolution and a high-resolution global atmosphere-ocean coupled simulation are used to characterize full-depth mesoscale eddy vertical structure. The vertical structure of eddy kinetic energy, e.g., partitioning of barotropic to baroclinic eddy kinetic energy or vertical modal structure, is shown to depend partly on bathymetric slope and roughness. This influence is contextualized alongside additional factors, such as latitude and vertical density stratification, to present a global landscape of vertical structure. Results generally reveal eddy vertical structure to decay with increasing depth, consistent with theoretical expectations relating to the roles of surface intensified stratification and buoyancy anomalies. However, at high latitudes and where the seafloor is markedly flat and smooth (approximately 20% of the ocean’s area), mesoscale eddy vertical structures are significantly more barotropic by an approximate factor of 2 to 5. From a climate modeling perspective, these results can inform the construction, implementation, and improvement of energetics parameterizations that account for the the under-representation of mesoscale eddies and their effects. They also offer expectation as to a landscape of eddy vertical structure to be used in inferring vertical structure from surface measurements.