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We present the results of a 3-D computational model of an idealized seamount in rotating, stratified flow. The emergent vortex structures in the lee of the seamount indicate that the vertical coherence of vortices is strongly dependent on the Coriolis parameter and the background buoyancy frequency. A novel finding from this work is that above a critical Burger number the vortex shedding frequency varies vertically with the local seamount diameter and adjusts such that the Strouhal number based on the local seamount diameter is consistent with high Reynolds number flow past a circular cylinder. This study extends previous literature into a regime exhibiting stronger stratification and rotation, where the transition into vertically decoupled eddies occurs. Physically, this transition is associated with the loss of geostrophy in the eddies. The mechanisms governing the transition to vertically decoupled vortices may play an important role in the energetics of a seamount interacting with a barotropic flow.

Plain Language Summary We use an open-source ocean modeling code to explore the effects of the Earth's rotation and stratification on an oceanic flow past a mountain. Previous literature has reported that the entire mountain sheds eddies as a unit. However, we report that for strongly stratified flow with a relatively weak effect of rotation, the eddies do not shed as a unit but individually at different vertical levels. This effect is consistent with the flow behaving as many independent 2-D layers. It is possible to predict the transition from eddies shedding as a single unit to many independent levels using the relative strengths of the rotation and stratification. This prediction is well supported by physical arguments.