Ecosystem Modelling of Biospheric Responses to Anomalous Climate Events with Sun-Induced Fluorescence

Heatwaves and droughts, intensified by climate change, pose a significant threat to European ecosystems, reducing gross primary productivity (GPP) and disrupting the global carbon cycle. The EMBRACE-SIF project seeks to improve the predictive accuracy of sun-induced fluorescence (SIF)-enabled terrestrial biosphere models (TBMs) under stress conditions. Currently, models like ORCHIDEE struggle to capture the photosynthetic response during extreme events due to limitations in modeling photosynthesis and characterizing non-photochemical quenching (NPQ). To overcome these challenges, the project will implement the Johnson and Berry (J&B) photosynthesis model, which provides a mechanistic framework for electron transport rates (ETR), and extend it to better represent NPQ under heat and drought stress. Using the unique Austro-SIF dataset and assimilating canopy-scale SIF and GPP data, EMBRACE-SIF will optimize key parameters in ORCHIDEE, enhancing its ability to simulate GPP during past European heatwaves (e.g., 2003, 2010, 2018, 2022) and at a global scale. The project's results will improve GPP predictions, contributing to climate resilience and supporting the European Green Deal's target of achieving carbon neutrality by 2050. Additionally, it will strengthen the fellow's expertise in remote sensing and biosphere modeling, positioning them for leadership in these critical fields.