Emissivity signatures in the thermal IR band for remote sensing:calibration procedure and method of measurement.

Problems encountered in thermal infrared spectral emissivity signatures for remote sensing are addressed. Instrument calibration procedure is described, with particular attention to stray light effects. A method, which derives from the box method, for the absolute determination of spectral signatures of bare soils and mineral samples is proposed and illustrated with several materials (sand, loess, SiC powders). Excellent agreement is found between emissivity values obtained in this way, and values deduced from reflectivity measurements at 10.6 microm, as far as the angular behavior of the bidirectional reflectivity is taken into account. Comparison with spectral reflectivity measurements shows good spectral correlation.