“…SIF variations at the leaf level and at short time scales may reflect changes in LUE (Agati et al, 1995; Corp et al, 2003; Long & Bernacchi, 2003; van der Tol et al, 2009); however, it is less clear whether the signal seen by coarse satellite observations over longer term period (several days) reflects mainly changes in LUE. Indeed, it appears that most of the variability of the SIF signal at the ecosystem might be explained by APAR Ch , that is, the product of fPAR Ch and PAR, thus reflecting changes in canopy structure and light absorption (Badgley et al, 2017; Li et al, 2017), at least for the farâred signal (Du et al, 2017).…”