Revisited Estimation of Moderate Resolution Sargassum Fractional Coverage Using Decametric Satellite Data (S2-MSI)

Since 2011, massive stranding of the brown algae Sargassum has regularly affected coastal waters West Caribbean, Brazil and Africa, leading to significant environmental socio-economic impacts. The AFAI algal index (Alternative Floating Algae Index) is often used with remote sensing data in order estimate coverage, more precisely deviation, which consists difference between Sargassum-free background. In this study, deviation computed using NASA’s 1 km Terra/MODIS (Moderate-Resolution Imaging Spectroradiometer) ESA/Copernicus’s 20 m Sentinel-2/MSI (Multi Spectral Instrument) for same sites at time. Both MODIS MSI deviations are compared confirm relevance technique two very different spatial resolutions. A high coefficient determination was found, thus confirming a satisfactory downsampling from (MSI) (MODIS). Then, fractional coverage (noted FC). new linear relationship FC established dense aggregations observed by data. proportional factor proportionality close 0.08. Finally, it shown that dependent on spectral reflectance, submersion or physiological state.