What makes the satellite‐based EVI–GPP relationship unclear in a deciduous broad‐leaved forest?

Abstract

AbstractRecent studies have suggested that gross primary production (GPP) of terrestrial vegetation can be estimated directly with the satellite‐based Enhanced Vegetation Index (EVI). However, the reported EVI–GPP relationships showed wide variability, with the regression functions showing widely scattered data. In the present study, we examined the possible reasons for this variability in the EVI–GPP relationship using daily EVI values from satellite and field measurements and daily flux‐based GPP in a cool‐temperate deciduous broad‐leaved forest in Japan. The variability appears to be caused by noise due to cloud contamination in the satellite data as well as the different seasonality of EVI and GPP, especially during the leaf‐expansion period. Our findings indicate that improvement of cloud screening and consideration of the leaf‐expansion period are critical when applying the EVI–GPP relationship.