Formation of Anticyclones above Topographic Depressions

Abstract Long-lived anticyclonic eddies (ACs) have been repeatedly observed over several North Atlantic basins characterized by bowl-like topographic depressions. Motivated these previous findings, the authors conduct numerical simulations of spindown initialized in idealized bowls. In experiments with one or two isopycnal layers, it is found that a bowl-trapped AC an emergent circulation pattern under wide range parameters. The trapped AC, often formed repeated mergers ACs bowl interior, anomalously low potential vorticity (PV). Several PV segregation mechanisms can contribute to formation are examined. one-layer experiments, dynamics largely determined nonlinearity parameter ? quantifies relative bowl’s gradient. for , but moderate values ( ) partial allows reside at finite distances from center bowl. For higher freely cross topography and not confined These regimes across suite model using homogenization parameter. Two-layer show be top bottom intensified, as domain-mean initial vertical energy distribution. findings contrast theories mesoscale turbulence predict prograde slope current, do AC.