12:15–12:30 | ABSTRACT 1313
Integrating satellite observations and ocean hydrodynamic modelling to resolve Sargassum transport toward the Amazon coast
Massive Sargassum influxes have increased across the tropical Atlantic. Along the Amazon coast, predicting arrivals remains difficult due to strong river discharge, macrotidal dynamics, complex circulation, high optical complexity, and persistent cloud cover, which hampers nearshore satellite detection. We combine satellite-derived Sargassum distribution fields from the University of South Florida Sargassum Watch System (SaWS) and the Copernicus Marine floating algae product with hydrodynamic modelling to investigate transport pathways from basin to coast. These fields are used to initialize Lagrangian simulations forced by Copernicus Marine currents, including GLORYS/NEMO reanalysis fields. Sargassum arrivals are validated using PlanetDove, Sentinel-2, and Sentinel-3 imagery. A case study of the massive March–April 2025 event on the Brazilian Amazon coast indicates that Sargassum originated in the Great Atlantic Sargassum Belt and was transported westward over approximately three months. Simulated trajectories suggest entrainment into the North Brazil Current, which advects biomass toward the Amazon margin. Results indicate an air–sea–river interaction window for coastal landing between March and April, when peak Amazon discharge coincides with prevailing northeast winds, favoring cross-shelf transport. The interaction between the current and river plume creates a turbulent frontal system that may enhance coastal retention under macrotidal conditions, increasing the likelihood of nearshore accumulation during flood tide. Satellite observations indicate rising Sargassum abundance in the tropical Atlantic, suggesting that entrainment into the North Brazil Current may become more frequent. Integrating satellite data with numerical modelling is essential for resolving transport pathways, improving arrival prediction, and supporting adaptation strategies along the Amazon coast.
Nelson Gouveia, University of Victoria, [email protected], https://orcid.org/0000-0002-3868-1919
Julio Lara Hernandez, University of Victoria, [email protected]
Santiago Ramirez Said, University of Victoria, [email protected]
Eduardo Tavares Paes, Federal Rural University of Amazon, [email protected]
Eduardo Vitarelli de Queiroz, Federal University of Pará, [email protected]
Maycira Costa, University of Victoria, [email protected]
