Consistency assessment of Atmospheric Infrared Sounder and Infrared Atmospheric Sounding Interferometer radiances: Double differences versus simultaneous nadir overpasses

Quantifying the radiometric difference and creating a calibration link between Atmospheric Infrared Sounder (AIRS) on Aqua and Infrared Atmospheric Sounding Interferometer (IASI) on MetOp are crucial for creating fundamental climate data records and intercalibrating other narrowband or broadband satellite instruments. This study employs two different methods to assess the AIRS and IASI radiance consistency within the four Geostationary Operational Environmental Satellite (GOES) imager infrared channels (with central wavelengths at 6.7, 10.7, 12.0, and 13.3 mu m) through a period of 2 years and 9 months. The first method employs the differences of AIRS and IASI relative to the GOES observations sampled in the tropics to indirectly track the AIRS and IASI radiance differences. The second approach directly compares AIRS and IASI in the polar regions through the simultaneous nadir overpass observations. Both methods reveal that AIRS and IASI radiances are in good agreement with each other both in the tropics and in the polar regions within GOES imager channels used in this study, while AIRS is found to be slightly warmer than IASI by less than 0.1 K.