Anthocyanin Reflectance Index (ARI) detects anthocyanin pigments in vegetation, which are indicators of plant stress, senescence, or adaptation to environmental conditions. High ARI values suggest elevated anthocyanin levels linked to stress responses (e.g., drought, temperature extremes, or disease), while low values indicate healthy, unstressed plants. It is useful for early stress detection, crop management, and monitoring plant physiology.

Firefly = (1/B022)-(1/B071)
Sentinel = (1/B03)-(1/B05)