Estimation of the Leaf Area Index of a Homogeneous Idealized Canopy. Potential and Limitations of a Remote Sensing Approach in the Solar Domain

Abstract

The Leaf Area Index (LAI) of a plant canopy is a key variable for parameterizing the exchanges of water, carbon and energy over terrestrial surfaces. This variable may be derived from remote sensing measurements to the extent that it constitutes one of the radiative state variables of the radiation transfer problem. However, the accuracy of the retrieval of these LAI values is limited for a number of reasons, including theoretical aspects intrinsically linked to the plant canopy radiation transfer problem. In this study, we investiga the sensitivity of the remote sensing signal with respect to the specification of the lower radiative boundary condition, for a variety of leaf angle distribution functions and illumination conditions. The results are discussed with respect to the red and near-infrared wavwlenghts regions.