Reconstruction of southwestern Atlantic sea surface temperatures during the last Century: Cabo Frio continental shelf (Brazil)

• Disentangling alkenone-SST on Southeastern Brazilian shelf
• Significant cross-shelf heterogeneity was detected.
• Seasonal signals were observed in the inshore and central shelf areas.
• Intensification of upwelling mechanisms and warming of offshore waters.
• The observed oscillations of oceanographic mechanisms may be related to climate.

Modern sea surface temperatures (SSTs) were estimated from UK′37 values of ten core-top sediment samples collected under the Cabo Frio upwelling system and validated by comparison with satellite-derived SSTs. UK′37-SSTs were found to reflect annual SST means in the offshore area and seasonal means (winter/spring) in the inshore and central areas. The latter areas are mainly influenced by upwelling processes whereas the offshore area is under the influence of the thermal front of the Brazil Current (BC). SST variability during the last century was then reconstructed from three short sediment cores. The record showed a general cooling trend in the inshore and central areas, suggesting intensification of the upwelling process. The trends at the offshore area reflected oscillations of the BC thermal front, with piling up of warmer BC waters closer to the coast since ca. 1950.