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.