Solar radiation based calibration of a short-wave ir radiometer and a comparison of exoatmospheric solar spectral irradiance data sets

We have performed an absolute calibration comparison between the Sun and a NIST-calibrated spectral irradiance standard lamp. The comparison at seven bands ranging from 1.2 to 2.3 μm was made using a highly stable Short Wave IR Transfer Radiometer. The experiment consisted of laboratory and outdoor measurements of an irradiated diffusely reflecting panel. Outdoors, simultaneous atmospheric transmittance measurements were also obtained in order to correct for atmospheric effects. The results were used to compare three absolute exo-atmospheric solar spectral irradiance data sets currently used in various remote sensing applications to a NIST traceable radiometric calibration. The comparison with the limited set of recently produced SORCE-SIM data showed almost no differences at 1.2 and 1.6 μm; however, the comparison with three other data sets showed larger differences.