Reply to Magnani et al.: Linking large-scale chlorophyll fluorescence observations with cropland gross primary production

Abstract

The derivation of the first global maps of sun-induced chlorophyll fluorescence (SIF) from Greenhouse Gases Observing Satellite (GOSAT) data in 2011 (1, 2), and later from Global Ozone Monitoring Experiment-2 (GOME-2) (3), was perceived as a milestone in the fields of vegetation remote sensing and carbon modeling. As stated by Magnani et al. (4), space-borne SIF measurements are intrinsically related to photosynthetic activity and therefore have the potential to trigger a new era in the monitoring of vegetation functioning. In fact, the first results from the analysis of the GOSAT and GOME-2 global SIF datasets are confirming the expected link between SIF and the gross primary productivity (GPP) of terrestrial ecosystems (e.g., ref. 2). In particular, our specific study on the potential of SIF observations to monitor crop photosynthesis (5) empirically demonstrates a strong linear relationship between SIF and GPP for croplands and grasslands at 0.5° and monthly scales