On Hyperspectral Remote Sensing of Leaf Biophysical Constituents: Decoupling Vegetation Structure and Leaf Optics Using CHRIS–PROBA Data Over Crops in Barrax

摘要

Scattering from a leaf responds differently at differentwavelengths to changes in leaf properties such as pigmentconcentrations, chemical constituents, internal structure,and leaf-surface properties. Radiation scattered by leaves and exitingthe vegetation canopy toward the sensor is affected by canopystructure. The concept of canopy spectral invariants is usedto decompose multiangular hyperspectral Compact High ResolutionImaging Spectroradiometer–PROBA surface reflectancesover agricultural crops during peak growth season into structuraland optical components. The former, called the directionalarea scattering factor, is determined by the canopy geometricalproperties and varies with crop type. The latter is a function ofthe leaf scattering properties and more directly related to theleaf interior. For dense crops, the decomposition technique doesnot require the use of canopy radiation models, prior knowledge,or ancillary information regarding the leaf scattering propertiesand thus provides a powerful means to remove canopy structuralinfluences in hyperspectral remote sensing of leaf biochemical constituents.Our results also suggest that leaf-surface characteristicscan increase canopy scattering spectra. This may decrease theability to remotely sense leaf biochemistry.