Sunlit Leaf Photosynthesis Rate Correlates Best with Chlorophyll Fluorescence of Terrestrial Ecosystems

This thesis attempts to link carbon assimilation micro-processes to macro-scale chlorophyll fluorescence measurements. The Boreal Ecosystem Productivity Simulator (BEPS), a process-based model, is adopted to simulate the hourly global-scale gross primary productivity (GPP) in 2010. The total GPP is stratified into sunlit and shaded GPP using a two-leaf scaling approach. Concurrently, the usefulness of solar-induced chlorophyll fluorescence as a proxy of GPP is also assessed. Relatively precise global monitoring of fluorescence is made possible with a new retrieval method applied to GOME-2 observations. Linear correlation analysis is used to examine the monthly spatio-temporal patterns between GPP and fluorescence. The hypothesis that sunlit GPP is better correlated with fluorescence than total or shaded GPP has been successfully tested with GOME-2 data and BEPS results. Since shaded GPP is about 40% of the total GPP globally, this result points to a limitation of using fluorescence as a proxy of the total GPP.M.Sc