Topographically Generated Submesoscale Shear Instabilities Associated with Brazil Current Meanders
Abstract
The western boundary current system off southeastern Brazil is composed of the poleward-flowing Brazil Current (BC) in the upper 300 m and the equatorward flowing Intermediate Western Boundary Current (IWBC) underneath it, forming a first-baroclinic mode structure in the mean. Between 22° and 23°S, the BC-IWBC jet develops recurrent cyclonic meanders that grow quasi-stationarily via baroclinic instability, though their triggering mechanisms are not yet well understood. Our study, thus, aims to propose a mechanism that could initiate the formation of these mesoscale eddies by adding the submesoscale component to the hydrodynamic scenario. To address this, we perform a regional 1/50° (∼2 km) resolution numerical simulation using CROCO (Coastal and Regional Ocean Community model). Our results indicate that incoming anticyclones reach the slope upstream of separation regions and generate barotropic instability that can trigger the meanders’ formation. Subsequently, this process generates submesoscale cyclones that contribute, along with baroclinic instability, to the meanders’ growth, resulting in a submesoscale-to-mesoscale inverse cascade. Last, as the mesoscale cyclones grow, they interact with the slope, generating inertially and symmetrically unstable anticyclonic submesoscale vortices and filaments.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Jul 01, 2023
- Source ID
- 10.1175/jpo-d-22-0122.1
Entities
People
- Amit Tandon
- Caique D. Luko
- Cauê Z. Lazaneo
- Filipe Pereira
- Ilson Carlos Almeida da Silveira
Organizations
- Coordenação de Aperfeicoamento de Pessoal de Nível Superior
- Division of Ocean Sciences
- National Council for Scientific and Technological Development
- Office of Naval Research
- São Paulo Research Foundation
- University of Massachusetts Dartmouth
- University of São Paulo