Pathways of the Overturning Circulation in the South Atlantic

Abstract:

The Atlantic Meridional Overturning Circulation (AMOC) plays an important role in regulating the Earth’s climate. At the core of our understanding of the AMOC, lies the study of its pathway. This work aims to revisit the overturning pathways of the South Atlantic and tropical Atlantic through the use of observational datasets. Specifically, we employ drogued surface drifters from the Global Drifter Program and Argo float trajectories. In combination with Markov chain theory and tools from dynamical systems analysis we are able to capture probable pathways of the AMOC at the surface and subsurface. More specifically, these pathways are computed as ensembles of paths transitioning directly between a specified source and target with high probability. Our focus lies on identifying pathways between the Drake Passage and Agulhas Current to the North Brazil Current, as well as pathways from the North Brazil Current to the Florida Current. Preliminary results suggest that pathways from the Drake Passage and Agulhas Current are equally probable and that both pathways feature some recirculation within the subtropical gyre. Pathways connecting the North Brazil Current to the Florida Current include the traditional pathway through the Caribbean Sea and Gulf of Mexico and a more direct route east of the Caribbean.