Composite maps of sargassum detection index AFAI (Alternative Floating Algae Index).

Types of dataset: dataset using VENµS VM5 Super-Spectral Camera (VSSC)

DOI: 10.24400/527896/a01-2025.011  -  more metadata

Contents: Alternative Floating Algae Index (AFAI) maps of coastal AFAI Sargassum detection derived from VENµS multispectral imagery.

Condition of access: these products are delivered for any purposes as stated in the licence agreement

Description: Alternative Floating Algae Index (AFAI) maps of coastal AFAI Sargassum detection derived from VENµS multispectral imagery across five Caribbean zones (northern–southern Yucatán, northern–southern Guadeloupe, Martinique) over 2022–2024.

The following variables are provided at a 4m ground resolution and every 2 days : 

• AFAI_raw : raw spectral index, computed from VENµS surface reflectance bands B7 B10 B12.
• AFAI_landfree_cloudfree : same field after masking land, cloud and negative reflectances.
• AFAI_deviation : AFAI deviation from local background and its denoised (gaussian filtered) version AFAI_deviation_denoised.
• AFAI_detection : pixels whose index value is greater than a μ + 3,5σ threshold, where μ and σ are respectively mean and standard deviation of AFAI_deviation_denoised field for every scene ; other is set to 0 if water, Nan if masked.
• AFAI_detection_bin : binary classification of presence (1) or absence (0) of sargassum
• RGB

Citation: Any use of this dataset must be verified in the AVISO+ license and must cite its DOI 10.24400/527896/a01-2025.011 as well as the following sentence: "This Coastal Sargassum Floating Algae Detection product was produced by Léna Pitek at LEGOS as part of the TOSCA SARGAT project, distributed by AVISO+ with the support of CNES."

Geographic coverage: -90/-60/10/25

Format: NetCDF-4 Classic with CF standards.

References:

• Dick, A., Raynaud, J.-L., Rolland, A., Pelou, S., Coustance, S., Dedieu, G., Hagolle, O., Burochin, J.-P., Binet, R., & Moreau, A. (2022). VENμS: Mission Characteristics, Final Evaluation of the First Phase and Data Production. Remote Sensing, 14(14), 3281. https://doi.org/10.3390/rs14143281
• Pitek L., Brilouet P.-E., Jouanno J., Graffin M., 2026. High-Spatial- and -Temporal-Resolution Sargassum AFAI Coastal Dataset for Guadeloupe, Martinique and Yucatán. Remote Sensing, https://doi.org/10.3390/rs18040624