Surface Albedo 2012-2024 (raster 1km), Ground-Based Observations for Validation project sites - version 1.1.0, Dec 2025

Surface albedo refers to the instantaneous ratio of surface-reflected radiation flux to incident radiation flux over the shortwave spectral domain (dimensionless). It is defined for broad spectral regions or for spectral bands of finite width. As the scattering of light by land surfaces depends on the direction of incoming radiation and the direction of observation, various albedo definitions have been introduced: ▪ white-sky (bi-hemispherical reflectance under isotropic illumination, BHRiso); ▪ black-sky (directional hemispherical reflectance, DHR under direct illumination); ▪ blue-sky (bi-hemispherical reflectance approximating ambient illumination and instantaneous atmospheric conditions, BHR). White-sky and black-sky albedo are provided for the benefit of Copernicus global land products validation through GBOV data portal. Ground albedometer footprints representing 1 km2 and 3 x 3 macropixels with an angular resolution of 1/112 degree are currently available in the database. The GBOV service (Ground-Based Observations for Validation) is a project funded by the European Commission. Its objective is to provide analysis-ready validation data to support the evaluation of Earth Observation products. The core aim of GBOV is to generate upscaled products derived from ground-based measurements. This dataset consists of Land Products (LPs) generated using shortwave in-situ measurements collected from stations located in North America, Europe, Australia, Africa and Asia. These ground data are combined with Sentinel-2 Level 2 surface reflectance products to build this upscaled Surface Albedo LP.