Airborne based spectroscopy to measure sun-induced chlorophyll fluorescence

Abstract

Sun-induced chlorophyll fluorescence (Fs) is a remote sensing (RS) observable to be linked to plant photosynthesis. Variations of measured canopy Fs are, however, related to several effects in addition to a physiological response of plants. The impact of atmospheric scattering and absorption processes were identified as most critical if Fs retrievals are based on atmospheric O2-absorption bands. In this contribution, we aim to demonstrate the feasibility of airborne based Fs retrievals using the O2-A absorption band. We applied two airborne spectroscopy experiments including a non-imaging repeat-track approach with changing flight altitudes and a multitemporal imaging approach using the new HyPlant spectrometer. Our results demonstrate that atmospheric effects can be compensated and accurate airborne based Fs measurements can be obtained using atmospheric absorption features. Our results are particularly important in view of ESA's potential Earth Explorer “Fluorescence Explorer” (FLEX) mission that intents to provide high resolution global maps of Fs using atmospheric oxygen absorption features.