Our ability to measure photosynthesis (Gross Primary Production, GPP), one of the most important biological processes on Earth, at scales beyond a leaf is extremely limited. This leads to key uncertainties in predicting response and feedback of photosynthesis to climate change and, thus, carbon flux monitoring. Global remote sensing of Solar Induced Chlorophyll Fluorescence (SIF) represents a major breakthrough toward alleviating this deficiency, but the existing SIF record has several major long-term inconsistencies related to sensor differences, retrieval methodology, and lack of validation opportunities.
The goal of this project is to develop an Earth System Data Record (ESDR) quantifying global vegetation fluorescence (SIF) and photosynthesis (GPP) over a long-term data record of 25 years. The SIF ESDR is being developed using multiple missions and sensors to validate and cross-calibrate retrieval algorithms. The project leverages (1) next generation ground, airborne, and spaceborne sensors to anchor the production of a consistent, back-calibrated time series spanning the period 1996-2020, and (2) advanced model-data fusion techniques to merge calibrated SIF datasets with ancillary vegetation and environmental datasets to deliver a single, global spatially continuous record. The GPP ESDR is being developed using tower GPP data at biome-diverse eddy covariance locations to upscale spatially continuous SIF.