Testing The Measurability Of Sun Induced Fluorescence Under Optimal And Non-Optimal Sky Conditions

The capability to measure the sun-induced chlorophyll fluorescence (SIF) by remote sensing groups has been recently reinforced with the selection of FLuorescence EXplorer (FLEX) as the next Earth Explorer mission by the European Space Agency (ESA). The aim of this work is to improve the knowledge about the sensitivity of Fraunhofer Line Depth (FLD) methods to different canopy structures and illumination conditions for fluorescence estimation. This work presents in situ spectral reflectance and SIF measurements with a dual system of two ASD FieldSpec3 spectroradiometers over two different vegetation types. The measurements are carried out under variable conditions of direct and diffuse irradiance predominance, taking spectral irradiance measurements continuously in time.