Drivers of ventilation in the CapeBasin using Apparent OxygenUtilization (AOU) as a tracer.

The Cape Basin is a highly dynamic region subjected to ocean ventilation and deepwater mass formation. Flowtopography interactions along the Agulhas Retroflection produce standing meanders with elevated Eddy Kinetic Energy and modified frontal structures. While numerical studies have shown that these features enhance deep water mass formation and tracer stirring, observational data on these processes have been limited due to their fine spatial and temporal scales. This study combines high-resolution Seaglider measurements of Apparent Oxygen Utilization (AOU) with backscatter data to map ventilation pathways. Results demonstrate the transport of low AOU values to depth via advection and stirring along isopycnals, as well as across-isopycnal transport near ocean fronts with strong buoyancy gradients and elevated diapycnal spiciness curvature. These findings provide critical observational evidence for the role of submesoscale processes in deep water mass formation and their broader implications for global climate dynamics and ocean circulation.