EVENTOS IOUSP - Seminário
Série: Seminários de Oceanografia Física
Tema: Is vertical coupling between NBC rings a player in the export of South Atlantic Water?
19/09 às 14h30
Anfiteatro do Instituto
Instituto Oceanográfico - USP
Pça do Oceanográfico, 191 SP SP cep 05508120
Palestrante: Dr. Dante Campagnoli Napolitano
Laboratoire d'Océanographie Physique et Spatiale,
Université de Bretagne Occidentale
Recent multi-platform observations of the typical NBC rings, extending from the surface down to 400 m, reported surface and subsurface cores kept apart by strong stratification. As independent structures, the subsurface eddies often appeared below—even if not aligned with—the surface rings. Motivated by these observations, we investigate the occurrence and consequences of vertical coupling between surface and subsurface NBC rings by applying a simplified
theoretical model to a realistic numerical simulation. We find that long-lived coupled eddies, which are able to travel longer distances, appear due to coupling. The coupling effects are particularly important for the lower layer, which may carry South Atlantic Water for 1500\,km up to the Caribbean sea. During coupling, lower-layer eddies could be driven by their surface counterparts to move offshore and bypass a topographic choke point, leaving the NBC retroflection
region. As yet speculative, this notion explains the link between the coupling effect and the observed increase in both lifetime and distance traveled for these eddies.