Towards high resolution evaporation data integrating satellite observations and hybrid modelling over Europe and Africa

Terrestrial evaporation (E) is a critical climate variable that links the water, carbon, and energy cycles. It plays a vital role in regulating precipitation, temperature, and extreme events such as droughts, floods, and heatwaves. In hydrology, E represents a net loss of water resources, while in agriculture, it determines irrigation demands. Despite its significance, global E estimates remain uncertain due to the scarcity of ground-based measurements, the complexity of physiological and atmospheric interactions, and challenges in capturing E through satellite observations. Addressing these limitations, the fourth generation of the Global Land Evaporation Amsterdam Model (GLEAM4¹) enhances the representation of E and its components by improving the representation of key processes such as interception loss, atmospheric water demand, soil moisture dynamics, and plant groundwater access. Using a hybrid framework that combines machine learning for evaporative stress estimation with physical principles, GLEAM4 balances interpretability with adaptability and validation against hundreds of eddy-covariance sites demonstrates its robustness and improved performance.

Building on GLEAM4, efforts are underway to develop a high-resolution (1 km) E dataset tailored to the needs of agriculture, water management, and climate adaptation. GLEAM-HR downscales precipitation from MSWEPv2.8 and radiative forcing data by optimally merging LSA SAF and MODIS. The innovations introduced in GLEAM-HR address fine-scale E dynamics, particularly in agricultural regions, while enabling the characterization of droughts, heatwaves, and water resource distribution in vulnerable areas. Preliminary results from GLEAM-HR over the Meteosat disk (covering Europe and Africa) highlight its potential to tackle water-related challenges, support sustainable water management practices, and contribute to evidence-based decision-making. In the future, the data products will be available publicly through an interactive 3D data cube application.

¹Miralles, D.G., Bonte, O., Koppa, A., Baez-Villanueva, O.M., Tronquo, E., Zhong, F., Beck, H., Hulsman, P., Dorigo, W., Verhoest, N.E. and Haghdoost, S. GLEAM4: global land evaporation dataset at 0.1° resolution from 1980 to near present, 20 November 2024, PREPRINT (Version 1) available at Research Square (https://doi.org/10.21203/rs.3.rs-5488631/v1)