Abstract
Snow and glacier meltwater are vital for sustaining drinking water, agriculture, hydropower, and industry in mountain regions, yet their monitoring remains limited—particularly in the extra-tropical Andes, where millions depend on meltwater resources. Climate change further amplifies the need for reliable quantification to support hydrological forecasting and water management. The Horizon Europe project SNOWCOP addresses this challenge by delivering a novel, high-resolution (50 m, daily) reanalysis of snow water equivalent (SWE) and ice melt rates spanning more than 20 years. SNOWCOP integrates multi-source remote sensing, downscaled re-analysis atmospheric data, and physically based modelling within a modular workflow. Copernicus and third-party satellite observations (Sentinel-1, Sentinel-2, MODIS, Landsat, VIIRS) are exploited. Snow cover area is reconstructed by fusing high-resolution optical imagery with daily lower-resolution snow cover fraction, while meteorological inputs are downscaled from ERA5-Land. SWE is estimated with retrospective reconstruction methods that explore three different levels of complexity: energy balance, temperature index, and enhanced temperature index models. Calibration and evaluation rely on independent in situ measurements and field campaigns, including terrestrial lidar scanning and snow density surveys, respectively. An intercomparison with previous SWE estimates is also performed. All processing is conducted in the Copernicus Data Space Ecosystem (CDSE) and cloud platforms such as openEO, enabling scalable handling of large datasets and ensuring transparency, reproducibility, and open access to codes, observations, and outputs. The resulting products provide daily, high-resolution maps of SWE and ice melt, directly supporting hydrological modelling, drought and flood risk assessment, and water resource planning. This study demonstrates how the innovative approach developed in SNOWCOP, which combines Earth observation and cutting-edge European data infrastructure, improves the estimation of meltwater from ice and snow. ACKNOWLEDGEMENT: This project has received funding from the European Union’s Horizon Research and Innovation Actions programme under Grant Agreement 10180133 and from the Swiss State Secretariat for Education, Research and Innovation (SERI).