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Studies have suggested that the South Atlantic Ocean plays an important role in modulating climate at global and regional scales and thus could serve as a potential predictor of extreme rainfall and temperature events globally. To understand how propagating modes of variability influence the circulation of the subtropical gyre and the southward flowing Brazil Current (BC) at interannual frequencies, a Complex Empirical Orthogonal Function (CEOF) analysis was performed on the satellite‐derived sea surface height (SSH). The first three CEOF modes explain about 23%, 16%, and 11% of the total interannual variability and show clear westward propagation with phase speeds comparable to that of theoretical baroclinic mode 1 Rossby waves. Results suggest that there is a change in the way energy is distributed among the modes before and after 2005. Before 2005, the SSH variability in the western boundary in the South Atlantic and the volume transport of the BC are more closely linked to the first and the second modes, while the third mode dominates after 2005. This change in energy distribution around 2005 is associated with the recent El Niño‐Southern Oscillation (ENSO) regime shift in the Pacific Ocean via atmospheric teleconnections. We found that the first CEOF mode is strongly correlated with eastern Pacific (i.e., canonical) ENSO events and the Pacific Decadal Oscillation, whereas the third CEOF is correlated to central Pacific (i.e., Modoki) ENSO. These results are useful to understand the overall dynamics of the South Atlantic and to potentially improve predictability of Meridional Overturning Circulation and monsoon pattern changes around the world. Plain Language Summary: The South Atlantic Ocean plays a major role in modulating climate at global and regional scales and therefore can serve as an important predictor of extreme weather events globally. Here we focus on understanding the large‐scale propagating modes of sea surface height (SSH) in the South Atlantic Ocean and explore their importance to the interannual variability of the Brazil Current. The propagating modes are estimated by performing a Complex Empirical Orthogonal Function (CEOF) analysis of the satellite‐derived SSH at interannual frequencies. The CEOF modes exhibit Rossby wave‐like propagation, and they greatly influence the SSH near the western boundary. Results show that the equatorial Pacific Ocean modulates the interannual variability of the CEOF modes via atmospheric teleconnections and thereby influences the southward flowing Brazil current. The results of this study are useful to understand the overall dynamics of the South Atlantic and to potentially improve predictability of Meridional Overturning Circulation and monsoon pattern changes globally. Key Points: Complex Empirical Orthogonal modes are estimated from sea surface heights in the South Atlantic Ocean at interannual frequenciesThese modes show Rossby wave‐like propagation which influences the sea surface height in the western boundaryThe modes are connected to the recent changes in the equatorial Pacific Ocean via atmospheric teleconnections [ABSTRACT FROM AUTHOR]

The Brazil Current transports from observations and the Hybrid Coordinate Model (HYCOM) model are analyzed to improve our understanding of the current's structure and variability. A time series of the observed transport is derived from a three-dimensional field of the velocity in the South Atlantic covering the years 1993 to 2015 (hereinafter called Argo&SSH). The mean transports of the Brazil Current increases from 3.8±2.2 Sv (1 Sv is 106 m3 s-1) at 25° S to 13.9±2.6 Sv at 32° S, which corresponds to a mean slope of 1.4±0.4 Sv per degree. Transport estimates derived from HYCOM fields are somewhat higher (5.2±2.7 and 18.7±7.1 Sv at 25 and 32° S, respectively) than those from Argo&SSH, but these differences are small when compared with the standard deviations. Overall, the observed latitude dependence of the transport of the Brazil Current is in agreement with the wind-driven circulation in the super gyre of the subtropical South Atlantic. A mean annual cycle with highest (lowest) transports in austral summer (winter) is found to exist at selected latitudes (24, 35, and 38° S). The significance of this signal shrinks with increasing latitude (both in Argo&SSH and HYCOM), mainly due to mesoscale and interannual variability. Both Argo&SSH, as well as HYCOM, reveal interannual variability at 24 and 35° S that results in relatively large power at periods of 2 years or more in wavelet spectra. It is found that the interannual variability at 24° S is correlated with the South Atlantic Subtropical Dipole Mode (SASD), the Southern Annular Mode (SAM), and the Niño 3.4 index. Similarly, correlations between SAM and the Brazil Current transport are also found at 35° S. Further investigation of the variability reveals that the first and second mode of a coupled empirical orthogonal function of the meridional transport and the sea level pressure explain 36 and 15% of the covariance, respectively. Overall, the results indicate that SAM, SASD, and El Niño-Southern Oscillation have an influence on the transport of the Brazil Current. [ABSTRACT FROM AUTHOR]