LAI and Chlorophyll Retrieval Exploiting the Sentinel-2 Red-edge Bands - Results from the VALSE2 Project
Fernandes, Richard¹; Baret, Frederic²; Berthelot, Béatrice³; Camacho, Fernando⁴; Weiss, Marie⁵; Duca, Riccardo^6
1CCRS, CANADA; ²INRA France, FRANCE; ³Magellium, FRANCE; ⁴EOLAB, SPAIN; ⁵INRA, FRANCE; ⁶ESA, NETHERLANDS

The Sentinel-2 Multi Spectral Imager is unique among medium resolution multispectral imagers in that it has four bands within the red-edge spectral region. A number of empirical studies have documented strong relationships between features derived from red-edge reflectance and both LAI and canopy chlorophyll concentration (CCC). Under the framework of the VALSE2 validation experiment, physically based algorithms for retrieving LAI and CCC from red-edge reflectance are defined, implemented and tested. These include heritage algorithms such as the Meris Terrestrial Chlorophyll Index and empirical LAI-red-edge relationships as well as new algorithms developed for consideration as Level 2 MSI products.

Validation results using simulated MSI imagery within the VALSE2 project are presented as well as intercomparisons with heritage algorithms and the primary MSI LAI and CCC algorithm that relies on inversion of all spectral bands. Recommendations are provided for further development of such algorithms in the view of implementation within MSI processing chains or as plug-in tools. The potential of extension and synergy with Sentinel-3 will also be discussed.

Leaf chlorophyll concentration retrieved using CCRS red-edge algorithm with simulated MSI imagery over Ottawa VALSE2 site.

LAI retrieved using CCRS red-edge algorithm with simulated MSI imagery over Ottawa VALSE2 site.