This layer maps the Floating Algae Index (FAI) averaged over the selected time window, highlighting floating algae, cyanobacterial scums and aquatic vegetation on water surfaces. It is computed from Sentinel-2 Surface Reflectance (COPERNICUS/S2_SR_HARMONIZED, ESA/Copernicus) at about 20 m resolution using the narrow near-infrared band B8A. Higher (greener to red) values indicate denser floating algal material; near-zero and blue values indicate clear water.
The Floating Algae Index (FAI) detects floating algae, surface scums and aquatic vegetation, which reflect strongly in the near-infrared while open water absorbs it. For each Sentinel-2 acquisition in the selected window the index is computed and the per-pixel mean is returned as the period composite.
| Code | Provider | Resolution | Year |
|---|---|---|---|
| WRD_S2XXX_99 | ESA/Copernicus (Sentinel-2 SR Harmonized) | ~20 m | 2017-present |
From the COPERNICUS/S2_SR_HARMONIZED collection, cloud and shadow pixels are masked with the SCL scene classification and FAI is computed as B8A - [B4 + (B11 - B4) x lambda], with lambda = (865 - 665) / (1610 - 665) = 0.211, using narrow NIR (B8A, 865 nm), red (B4, 665 nm) and SWIR1 (B11, 1610 nm). The cloud-free acquisitions in the period are averaged pixel by pixel and rendered on a blue-to-red scale over the FAI range.