The 2019 Brazilian oil spill: Insights on the physics behind the drift

Abstract

This study uses global numerical model results of ocean and atmospheric circulation, as well as local wind, wave and current meter data, to investigate the structure of the ocean and coastal circulation potentially associated with the transport of oil that affected thousands of kilometers of the Brazilian coast in 2019. Our analysis suggests the oil was brought close to the continental shelf sometime in August 2019 by the southern branch of South Equatorial Current, and was initially advected towards the north by the North Brazilian Current and shelf currents pushed by SE winds. The onset of negative along-shore winds close to the coast in September–October 2019 turned the coastal along-shore drift south, a situation that persisted throughout the spring and summer seasons. Along the east coast, where observational data was available, landward cross-shelf flows below 17 m of depth, associated with coastal upwelling conditions, advected the oil from the slope onto the outer and mid-shelf. On the inner-shelf the oil was finally pushed towards the beaches by the wave action close to the bottom. Reports of oil arriving on the east coast followed changes in coastal wind and current patterns very closely. It is suggested that before reaching the shelf, the oil drifted at depths larger than 17 m, perhaps reaching several tens of meters.