A highly chlorophyll-sensitive and LAI-insensitive index based on the red-edge band: CSI

Leaf chlorophyll content (Chl _leaf ) is a crucial parameter in carbon cycle modeling and agricultural monitor. Taking advantage of remotely sensed red-edge vegetation index (VI) is an easy approach to estimate Chl _leaf at a large spatial scale. However, the spectral signals of Chl _leaf and other canopy/foliar/background factors (e.g. leaf area, leaf angle, soil moisture, etc.) are always coupled together, leading to the relatively low accuracy in direct Chl _leaf estimation. A new chlorophyll sensitive index (CSI) based on the red-edge band is proposed to estimate Chl _leaf , with minimal canopy structural influences. Validation results using in-situ measurements show CSI performed better to estimate Chl _leaf of winter wheat and soybean at canopy scale: RMSE=8.24μg/cm ₂ for CSI; RMSE=10.04 μg/cm ₂ for the best existing index, MTCI. CSI also has the potential ability to estimate Chl _leaf across diverse structural species types with high accuracy. Therefore, CSI provides an effective and convenient way to estimate Chl _leaf over large areas using satellite data.