Scientific challenge

Satellite land-product validation requires reference measurements representative of areas much larger than those directly sampled by individual ground instruments. Upscaling ground-based observations to satellite-pixel scales therefore introduces assumptions about vegetation structure, spatial heterogeneity and the representativeness of measurement locations.

Scientific challenge

The Copernicus Hyperspectral Imaging Mission for the Environment (CHIME) will acquire hyperspectral observations in the visible to shortwave infrared spectral range. Preparing and evaluating its instrument and processing chain requires realistic radiance scenes that reproduce the spectral and spatial variability of the Earth as viewed from space.

Scientific challenge

Accurate radiometric calibration and validation (Cal/Val) of Earth observation instruments requires a detailed understanding of how radiation interacts with the atmosphere and the Earth’s surface. Conventional one-dimensional (1D) radiative transfer models generally assume horizontally homogeneous conditions. In heterogeneous environments, however, radiation scattered from neighbouring surfaces can contribute to the signal measured over a target. This adjacency effect can influence both satellite and ground-based observations.

Scientific challenge

Bright desert Pseudo-Invariant Calibration Sites (PICS) play an important role in monitoring the radiometric stability and consistency of Earth observation instruments. Their relatively stable surface reflectance makes them suitable for long-term calibration and validation activities.