Effect of Spatial Resolution on Soil Properties Retrieval from Imaging Spectroscopy: An Assessment of the Hyperspectral Chime Mission Potential

The sensitivity of the estimation accuracy of topsoil properties to spatial resolution was explored in the context of the assessment of the forthcoming ESA Copernicus hyperspectral mission CHIME. A methodology was developed to allow a fair comparison across spatial resolution scales of the retrieval accuracy, considering the spatial support size and calibration/validation set size. Under these conditions, the prediction accuracy was found not degraded when decreasing the spatial resolution from 3.6 m (AVIRIS NG) to 20 m (Sentinel 2) or 30 m (CHIME). The best results were obtained for clay estimation, whereas for sand, silt, and soil organic carbon (SOC) the retrieval accuracy was slightly worse, although comparable or even better to what previously reported in the literature. When the spatial correlation between the estimated clay map and the spatialized (block kriging) ground truth map was examined, using the co-dispersion coefficient, the best results were obtained for the 30 m spatial resolution.