Simulating passive and active measurements of canopy fluorescence yield: a 3D approach
Résumé
Chlorophyll fluorescence emission is closely linked to changes in photosynthetic efficiency. Current techniques for remote sensing of fluorescence aim at quantifying the laser-and sun-induced fluorescence (resp. LIF and SIF) within radiation going out vegetation. The CALSIF project aims at building a new airborne instrument for simultaneous measurement of LIF and SIF. To help the design of a new airborne instrument for simultaneous measurement of LIF and SIF as well as the interpretation of future measurements, we have developed a new 3D fluorescence model. It calculates the multispectral radiance (total and due to fluorescence) observed by a radiometer located above a 3D canopy lit either naturally or with a laser. The model couples, using a two-pass method, a 3D radiative transfer model (nested radiosity), a leaf fluorescence model (FluorMODleaf), and a new virtual radiometer. Simulated radiance from SIF and LIF for various conditions of lighting and measurements are presented and discussed.