On the suitability of North Brazil Current transport estimates for monitoring basin‐scale AMOC changes

Abstract

AbstractThe North Brazil Current (NBC) constitutes a bottleneck for the mean northward return flow of the Atlantic Meridional Overturning Circulation (AMOC) in the tropical South Atlantic. Previous studies suggested a link between interannual to multidecadal NBC and AMOC transport variability and proposed to use NBC observations as an index for the AMOC. Here we use a set of hindcast, sensitivity, and perturbation experiments performed within a hierarchy of ocean general circulation models to show that decadal to multidecadal buoyancy‐forced changes in the basin‐scale AMOC transport indeed manifest themselves in the NBC. The relation is, however, masked by a strong interannual to decadal wind‐driven gyre variability of the NBC. While questioning the NBC transport as a “direct” index for the AMOC, the results support its potential merit for an AMOC monitoring system, provided that the wind‐driven circulation variability is properly accounted for.