The North Brazil Current (NBC) is an intense western boundary current, which is the dominant feature of the surface circulation in the Western Tropical North Atlantic (WTNA). It flows predominantly northwestward along Brazilian northern coast and, around 6°N-8°N and 45°W, the current separates from the coast and retroflects to the east, feeding the North Equatorial Countercurrent (NECC; Garzoli et al., 2003; Johns

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<p>Benguela Niños are events of anomalous Sea Surface Temperature (SST) increase in the Southeastern Tropical Atlantic Ocean. In 1995, the strongest Benguela Niño observed in the satellite era took place. It had a drastic impact on the Angola-Benguela Area (ABA, 8ºS – 20ºS, 8ºE to the coast) ecosystem, including high mortality, poor recruitment, and southward shift of sardine populations, as well as reductions in the number of benthic organisms. Although low Sea Surface Salinity (SSS) values extending as far south as 18ºS have been observed during this event, the role of freshwater input for the SST increase in the 1995 Benguela Niño has not been analyzed yet. In this study, we use satellite data, CTD profiles, and reanalysis products to investigate the impact that freshwater anomalies from anomalously high Congo river discharge (CRD) and precipitation might have had on the evolution of the 1995 Benguela Niño. We find that in the onset phase of the event a freshwater plume from the north was spreading southward towards the Angola-Namibia coastal area, concomitant with signatures of positive Barrier Layer Thickness (BLT) and stratification (N2) anomalies. At the same time, a strong poleward Angola current anomaly was observed. Positive SST anomalies peaked in March when SSS values averaged over the ABA were almost 3 psu lower than normal. Our analysis suggests that the anomalous CRD combined with higher than usual precipitation in November/December 1994 generated a negative SSS plume north of ABA, which was advected into the Angola-Namibia coastal region by the poleward surface current anomaly, increasing ocean stability, and reducing the mixing. A Mixed Layer Heat Budget analysis suggests that both anomalous advection and absence of entrainment contributed to the surface warming while the net surface heat flux provided a damping effect. Thus, the high freshwater input that was advected southwards inhibited the entrainment of cool subsurface waters into the surface mixed layer in the ABA, which contributed to the SST increase in the exceptionally strong 1995 Benguela Niño event.</p>

Northeast Brazil (NEB) is a susceptible region to the occurrence of extreme rainfall events. Sea surface temperature (SST) is used as an indicator for predicting intense weather events in this region. The westernmost Tropical South Atlantic region, also called Southern Atlantic Warm Pool (SAWP), is characterized by a source of heat and humidity which creates atmospheric instability for the NEB. In June 2010 the eastern coast of NEB (ENEB)was influenced by heavy rainfall, causing flash floods and landslides. On the other hand, 2012 marked the beginning of a period of droughts that affected the whole NEB area. The SAWP temperature in turn recorded anomalous values ​​of + 1ºC (-0.5ºC) in 2010 (2012), respectively, although in June 2012 intense rainfall was recorded in ENEB, even with intense negative SST anomalies. With the Coupled-Ocean-Atmosphere-Wave and Sediment Transport (COAWST) model, simulations were made to characterize 2010 and 2012 atmospheric conditions, modifying the SST input data in both situations. The goal of this work is to assess the meteorological systems that occurred in 2010 and 2012 using observational, reanalysis, and simulated data, as well as to identify changes in atmospheric instability patterns, which are under influences of different SST conditions. We performed four cases, including: a) SST measured in 2010 with 2010 atmospheric conditions; b) SST measured in 2012 with weather conditions of 2010; c) SST measured in 2012 with 2012 weather conditions; d) measured in2010 with atmospheric conditions from 2012. The results showed that SAWP temperature significantly influenced the instability of meteorological systems. The impacts were more significant in the lower layer of the atmosphere, especially in the variables that lead to low-level instabilities. Also, it was observed that warmer atmospheric conditions favor the ocean environment to remain warmer, maintaining the unstable conditions over SAWP.