Intercomparison of Imaging Spectrometers over the Salar De Uyuni (bolivia)

A-MODIS, AATSR, MERIS, POLDER-3 and SeaWiFS data are directly compared at top of the atmosphere level for nearly concomitant observation carried out under nearly identical or reciprocal geometries. Comparisons are carried out over the Salar de Uyuni in Bolivia. The results indicate that MERIS and A-MODIS are radiometrically in line. In comparison to these sensors, the SeaWiFS data exhibit a systematic underestimation of TOA reflectances of approximately 10 % in all bands. AATSR compares relatively well to MERIS and A-MODIS but shows a rapid decrease of sensitivity in 2005. The results of these intercomparisons also seem to indicate a degradation of the POLDER-3 sensitivity of several percent through its first year of operation.