Interocean waters that are carried northward through South Atlantic surface boundary currents get meridionally split between two large-scale systems when meeting the South American coast at the western subtropical portion of the basin. This distribution of the zonal flow along the coast is investigated for past, present and future climates through an index for the latitude of the bifurcation of the South EquatorialCurrent (SBL) off the coast of Brazil. Results show that this robust index can be associated with changes either on the AMOC transport or strength of theSubtropical Gyre. Changes in the SBL are also associated with changes in in theSouth and Tropical Atlantic temperature distributions which allow us to examine how the associated modes of variability have changed together with its impact on the accompanying hydro climate. Results show that there is intensification of the subtropical gyre circulation and poleward migration of the system in the late 20thC. CMIP6 simulations show that the leading SST modes of the TropicalAtlantic show reduced variability which is associated with anomalous warming of the Northern Tropical Atlantic, northward shift of the ITCZ.

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