FLEX - Fluorescence Explorer: A Remote Sensing Approach to Quantify Spatio-Temporal Variations of Photosynthetic Efficiency from Space

Photosynthetic efficiency is greatly affected by internal and external factors and until now no remote sensing approach is available to globally quantify photosynthetic efficiency from air- or space-borne platforms. Quantification of sun-induced steady state fluorescence that can be detected in the atmospheric absorption bands is currently the most promising approach towards a global monitoring platform. This approach was recently highlighted due to the selection of the FLEX proposal as one of the future candidate missions for an 'Earth Explorer'. Currently several modeling, laboratory and field studies are undertaken to (i) better understand the technical feasibility to monitor the comparably weak fluorescence signals from space; (ii) to proof the correlation of steady state fluorescence with photosynthetic carbon uptake; and (iii) to test the approach for a better modeling of regional carbon fluxes. This paper gives an overview over the status of this ESA project that may be the first and most ambitious remote sensing approach ever undertaken to globally map photosynthesis.