Global Retrieval of 24-hourly Solar-Induced Chlorophyll Fluorescence and Evapotranspiration from OCO-2, OCO-3 and ECOSTRESS over 1982–2022

Abstract. Solar-induced chlorophyll fluorescence (SIF) and evapotranspiration (ET) have been widely recognized as proxies for carbon gain and water loss at the ecosystem level. However, most SIF and ET products on the global scale are generally at coarse temporal resolutions of at least one day, which limits their ability to characterize diurnal carbon and water cycles. In this study, we extended the spatiotemporal scale of satellite SIF (from OCO-2 and OCO-3) and ET (from ECOSTRESS) data using machine learning methods, resulting in a global hourly SIF and ET dataset (HOUR_SIF_OCO and HOUR_ET_ECO) spanning from 1982 to 2022, with a spatial resolution of 0.1°. Our product also provides photosystem-level SIF derived from direct estimation and simulation of Soil Canopy Observation, Photochemistry and Energy fluxes (SCOPE) model, aiming to offer a more accurate description of photosynthesis. Our satellite-derived products show good correlations with in-situ flux tower measurements from the FLUXNET2015 community (hourly-scale median R² for SIF: 0.72, and ET: 0.53; daily-scale median R² for SIF: 0.73, and ET: 0.63). Globally, our product shows good consistency with popular SIF and ET gridded products: the mean proportions of pixels with monthly R² exceeding 0.7 are 69.5 % and 68.1 % when compared with four popular products, respectively. The causal-based attribution analysis revealed significant spatial heterogeneity in the lagged effects of different environmental factors on SIF, ET, and water use efficiency based on SIF and ET on the global scale. Overall, our dataset will provide new insights for monitoring the diurnal variations of carbon and water cycles and deepen our understanding of their changes over the past 40 years. The global hourly SIF and ET dataset (1982–2022) at 0.1° spatial resolution produced in this study is available at https://doi.org/10.57760/sciencedb.ecodb.00177 (Deng et al., 2025b).