Remote sensing of solar-induced chlorophyll fluorescence (SIF) in vegetation: 50 years of progress

Remote sensing of solar-induced chlorophyll fluorescence (SIF) is a rapidly advancing front in terrestrial vegetation science, with emerging capability in space-based detection methods and diverse application prospects. Although remote sensing of SIF is a contemporary new specialty for terrestrial plants, it is founded upon a multi-decadal history of research, applications, and sensor developments in active and passive sensing of chlorophyll fluorescence. Current technical capabilities allow SIF to be measured across a range of biological, spatial, and temporal scales. As an optical signal, it may be discriminated remotely using highly resolved spectral sensors and state-of-the-art retrieval approaches to separate the emission from reflected and/or scattered ambient light. Because the red to far-red SIF emission is detectable non-invasively, it may be sampled repeatedly to acquire spatiotemporally explicit information about vegetation photosynthetic light responses and steady-state behaviour. Progress in this field is accelerating with novel sensor developments, retrieval methods, and modelling advances. This review distills historical and current developments spanning the last several decades. It highlights SIF heritage and complementarity within the broader field of fluorescence science, the maturation of physiological and radiative transfer modelling, SIF signal retrieval strategies, techniques for field and airborne sensing, advances in satellite-based detection systems, and applications of these novel capabilities in assessment of photosynthesis and stress effects. Progress, challenges, and future directions are considered for this unique avenue of remote sensing.JRC.D.5-Food Securit