Global Retrieval of the Maximum Carboxylation Rate (Vcmax) of Plant Leaves by Solar-induced Chlorophyll Fluorescence from TROPOMI

Abstract

The maximum carboxylation rate (Vcmax) is a significant parameter in photosynthesis simulation. However, global Vcmax25 (Vcmax normalized to 25°C) datasets are limited in its spatial and temporal coverages. In this thesis, a global Vcmax25 dataset is retrieved with a daily temporal and a 0.1° × 0.1° spatial resolution from March 7th, 2018 to October 31st, 2018. The Vcmax25 dataset is derived in following two steps: 1) Retrieval of TROPOMI sun-induced fluorescence (SIF) dataset to study the relationship between SIF and gross primary productivity (GPP) at the canopy level; 2) Retrieval of Vcmax25 using a data assimilation system from GPP estimates of sunlit leaves in the canopy, which are estimated from the TROPOMI SIF dataset and a process-based ecosystem model (BEPS), respectively. The derived Vcmax25 dataset shows agreements with existing Vcmax25 datasets, literature Vcmax25 values, and local phenology information globally, indicating that the new Vcmax25 dataset is reliable.