Scaling plant fluorescence from the leaf to the satellite: Towards global mapping of terrestrial photosynthesis?
Recent advances in retrieval of chlorophyll fluorescence from space (solar induced chlorophyll fluorescence, SIF) promise improved mapping of plant photosynthesis globally. While these advances are encouraging, unresolved issues related to the spatial, spectral, and temporal dynamics of fluorescence complicate our ability to interpret satellite derived SIF measurements. Broadly speaking, we are trying to answer the question of how the relationships between SIF and photosynthesis converge/diverge at the leaf, canopy (tower and airborne), and ecosystem scales (satellite)? To address these issues, we link spectral fluorescence and photosynthesis under a range of environmental conditions at the leaf scale (with gas-exchange and pulse-modulated amplitude (PAM) fluorescence), and at the increasingly larger scales – from tower based scanning spectrometers (PhotoSpec) and an airborne imaging spectrometer (CFIS), developed at JPL. The necessity for such methodological advances, the instrumentation, and initial results highlighting the importance of understanding the spectral response of fluorescence to photosynthesis across scales will be discussed.