The southern branch of the South Equatorial Current (SSEC) is the northern limit of the South Atlantic Subtropical Gyre. When this current reaches Brazil around 14°S it bifurcates into a southward flow as the Brazil Current (BC) and the surface portion of the northward flowing North Brazil Undercurrent (NBUC). The SSEC system is a key component of the western boundary supply, influencing the NBUC/BC variability and, therefore, global climate through the Meridional Overturning Circulation. In this study, using altimetry satellite data and reanalyzes outputs (1993–2018), we revisit the SSEC mean state and show this current arriving at the South Atlantic western boundary as a multi‐banded flow with surface signatures resulting from different subsurface cores. These bands have velocities between 0.02 and 0.07 m s⁻¹ and, as shown by ADCP data from the PIRATA project, their signature in synoptic scenarios is obscured by eddies and waves with velocities between 0.1 and 0.3 m s⁻¹. In addition, the SSEC annual cycle analysis shows that the seasonality of the bands is out of phase with each other, presenting westward transport anomalies between 0.4 and 2.6 Sv. Finally, our results show that the seasonality of this multi‐banded flow both defines where the BC is born, and modulates the seasonality of semi‐permanent mesoscale eddies off Brazil.

This paper presents the graphical results of the Lagrangian-model and the weathering processes associated with oil spills in the tropical South Atlantic, taking into account the meteorological and oceanographic conditions of the study region. The scenarios were created in the Brazilian-NE waters adjacent, with simulation times of 670 h, and densities of 35, 25, and 15API with volume of 1590 m³ were considered. The main results showed that the meteo-oceanographic characteristics of the study region influence the trajectories and weathering processes in the oil spill. The trajectories varied for each launch point and reached the continent severely in January and October. The associated weathering processes showed higher rates in September and lower rates in April, indicative of the influence of phenomena such as Intertropical Tropical Convergence Zone and warm pool in the South Atlantic region. Sea surface temperature and wind speed are key factors that correlate positively with these months.

Following the highly impactful 2013–2016 Marine Heatwave (MHW), another MHW occurred in the Northeast Pacific during summer 2019. While the physical drivers of this event are well described, its biogeochemical impacts remain poorly understood. We use Ocetrac, a Python package that tracks spatiotemporal extreme events, to identify physical and biogeochemical anomalies associated with the 2019 MHW within two observation‐based products, GOBAI‐O ₂ and MOBO‐DIC, and model output from the Community Earth System Model Forced Ocean Sea Ice Reconstruction (FOSI). Our findings reveal that warm temperature anomalies associated with the MHW negatively correlate with dissolved inorganic carbon (DIC) and dissolved oxygen (DO). Model reconstruction suggests that DIC anomalies were driven by air‐sea flux and biological processes, while anomalies in DO are linked to air‐sea flux and circulation. These results underscore the utility of new observational products and models for assessing the biogeochemical consequences of MHWs.

The western tropical North Atlantic (WTNA) is a very complex region, with the influence of intense western boundary currents in connection with equatorial zonal currents, important atmospheric forcings ( e.g Intertropical Convergence Zone), mesoscale activities ( e.g NBC rings), and the world’s largest river discharge as the Amazon River runoff. The volume discharge is equivalent to more than one-third of the Atlantic river freshwater input, with a plume that spreads over the region reaching the northwestward Caribbean Sea and eastward longitudes of 30°W, and influencing from physical to biological structures. Therefore, in order to enable and encourage more understanding of the region, here we present a dataset based on an idealized scenario of no river runoff of the Amazon River and Para´ River in the WTNA. The numerical simulations were conducted with a regional oceanic modeling system (ROMS) model and three pairs of files were generated with the model outputs: (i) ROMS-files, with the parameters of the ROMS-outputs raw data in a NetCDF format and monthly and weekly frequencies; (ii) MATLAB-files, which contain oceanographic parameters also in monthly and weekly frequencies; and (iii) NetCDF-files, with oceanographic parameters again in monthly and weekly frequencies. For each file, we present the coordinates and variable names, descriptions, and correspondent units. The dataset is available in the Science Data Bank repository (doi: https://doi.org/10.57760/sciencedb.02145).

The North Atlantic Ocean has a crucial role in the regional and global climate, with significant socio-economic impacts related to droughts, hurricanes and changes in the weather pattern. The Atlantic Meridional Overturning Circulation (AMOC) is the main component of ocean heat transport to the North Atlantic as part of the Earth’s major circulation system. The AMOC is considered a tipping element of the planet’s climate, and abrupt and strong changes in this global-scale circulation could lead to shifts in European and North American climates and warming in the Southern Ocean and Antarctica. Hence, it is critical to better comprehend the drivers influencing the AMOC state and its variability. The direct connection between the AMOC and the deep-water formation is being challenged by recent studies, suggesting this relationship cannot explain alone the broad spectrum of AMOC variations. Moreover, the Gulf Stream is responsible for a substantial part of meridional heat transport and is considered part of the AMOC system in the North Atlantic. Recent studies show the latitudinal displacement of the current could affect the AMOC variability. Furthermore, the advection at intermediate level (800-1200m) of the Mediterranean outflow is suggested to be a possible key contributor to the strength and variability of the AMOC, although large uncertainty remains concerning the pathway of these waters into the North Atlantic and its contribution in the precondition phase of the deep-water formation in the Labrador and Greenland Island Norwegian sea. Understanding the influence of each of these drivers is vital. The scarcity of direct observational records in space and time poses an important challenge to disentangle the AMOC drivers and their variability in the North Atlantic, especially since the North Atlantic Ocean presents unusual variability at decadal and multi-decadal scales. Previous studies have used either short observation records, low-resolution numerical models or indirect (proxy) observations to investigate the AMOC. Long-term and three-dimensional datasets are needed to understand the ocean’s changes at large space and time scales. Therefore, the aim of our work is to investigate the multi-drivers of the AMOC variability using a large ensemble (32 members) of global historical ocean reanalyses covering the period from 1961 to 2022. We focus on the deep-water formation, Gulf Stream shift and Mediterranean Outflow Water (MOW) as multi-drivers of the AMOC in the North Atlantic. It is the first time that a large ensemble of 60-year observation-based ocean dataset is used to investigate multiple drivers responsible for changes in the AMOC and the North Atlantic’s decadal climate. We calculated indexes for each driver and used multivariate regression methods (e.g. LASSO) to explore the role of multi-drivers. Preliminary results show that at the interannual time scale, the variability of the Gulf Stream is well correlated with the AMOC variability and at a longer time scale, the deep-water formation and Mediterranean outflow have a close correlation with the AMOC transport. Further investigation is ongoing to quantify the relative contribution from these drivers to the AMOC variability at different time scales.