POSTER SESSION 2
10:30–12:30, Tuesday, September 15
Poster Session | 1 | 2 | 3 | 4 | Schedule at a Glance
ABSTRACT 1408 | POSTER 14
BASIN-WIDE MONITORING OF SARGASSUM RAFTS USING THE GEOSTATIONARY SATELLITE METEOSAT-THIRD GENERATION
Massive sargassum beaching events in the tropical Atlantic Ocean have become a critical concern for coastal environments, public health, tourism, and local economies. Since 2011, the emergence of the Great Atlantic Sargassum Belt (GASB), spanning from the West African coast to the Caribbean islands, has increased the intensity of the strandings across the region. Ocean color imagery is a valuable tool for monitoring Sargassum rafts at sea, providing essential support for mitigation operations and protection of coastal ecosystems. However, the Inter-Tropical Convergence Zone (ITCZ) generates persistent, widespread cloud cover over the tropical Atlantic, limiting systematic ocean surface monitoring from polar-orbiting satellites. The Flexible Combined Imagery (FCI) onboard the Meteosat Third Generation (MTG) geostationary satellite addresses this limitation by acquiring full-disk imagery of the tropical Atlantic every 10 minutes, enabling ocean surface observations even during brief clear-sky windows within transient cloud systems. Despite this temporal advantage, FCI has a low signal-to-noise ratio and reduced radiometric resolution compared to dedicated ocean-color sensors. Here, we demonstrate the capability of FCI to detect sargassum rafts through a processing chain from atmospheric correction, image binning, multi-temporal image composite, and the application of the Alternative Floating Algae Index (AFAI). This approach maximizes ocean coverage under ITCZ dynamics and improves the spectral contrast between the clear ocean surface and sargassum rafts. We present basin-wide sargassum detection in 2025 and evaluate FCI performance against Sentinel-3 Ocean and Land Colour Instrument (OLCI) detection.
Lucas Barbedo, CNRS, [email protected]
Thibault Guinaldo, Météo-France / CNRS, [email protected], https://orcid.org/0000-0001-9792-8398
Marianne Debue, Météo-France, CNRS, Univ. Toulouse, CNRM, Lannion, France, [email protected]
François Steinmetz, Hygéos, Lille, France, Lille, France, [email protected]
Poster Session | 1 | 2 | 3 | 4 | Schedule at a Glance
