Floating Algae Index (FAI) detects and monitors floating algae in water bodies by analyzing the reflectance of near-infrared light. It helps differentiate algae from other water surfaces and floating debris. FAI values range from -1 to +1, where higher values indicate the presence of floating algae, which could signify algal blooms or eutrophication, while lower values indicate clear water surfaces. It is useful for assessing water quality, tracking algal blooms, and managing aquatic ecosystems.

Sentinel = B08 - (B04 + (B11 - B04)*((200)/(935)))
Landsat 8-9 = nir08 - (red + (swir16 - red)*((200)/(935)))