Antonio Geraldo Ferreira (Universidade Federal do Ceará, Brazil); Fabrice Hernandez (Institut de Recherche pour le Développement, France); Eduardo Savio Martins (Fundação Cearense de Meteorologia e Recursos Hídricos, Brazil)

Oceanic islands are regions of high primary productivity and biodiversity. These characteristics also apply to the Fernando de Noronha Archipelago and the Rocas Atoll, even though the area is located in the western portion of the Tropical Atlantic, where waters are highly oligotrophic. Studies on ocean dynamics in the region suggest the occurrence of subsurface eddies near the islands, associated with upwelling processes and primary productivity. However, the presence of surface eddies is still not well characterized due to the insufficient spatial resolution of available data. In this context, advancements in altimetric data collection with the launch of the SWOT mission have provided information with higher spatial resolution, enabling the identification of submesoscale eddies. This study uses data from SWOT 21-day repeat orbit to assess surface eddies near these islands, aiming to characterize submesoscale ocean dynamics in the region. SWOT altimetric KaRin data were used to estimate geostrophic currents in the western Tropical Atlantic. This information was compared to currents from the DUACS L4 products, estimated using all existing satellite altimetry missions. Chlorophyll and SST data were also used to identify relationships with local primary productivity. Preliminary results indicate that SWOT data are able to characterize flow in the western Tropical Atlantic in greater detail compared to DUACS data. Additionally, semi-permanent eddies were identified around Fernando de Noronha and Rocas Atoll. The association of this information with chlorophyll and SST is ongoing; however, it is already possible to observe relationships between the eddy cores and anomalies in these variables.