Prelaunch and in-flight radiometric calibration of the Atmospheric Infrared Sounder (AIRS)

With 2378 infrared spectral channels ranging in wavelength from 3.7-15.4 μm, the Atmospheric Infrared Sounder (AIRS) represents a quantum leap in spaceborne sounding instruments. Each channel of the AIRS instrument has a well-defined spectral bandshape and must be radiometrically calibrated to standards developed by the National Institute of Standards and Technology. This paper defines the algorithms, methods, and test results of the prelaunch radiometric calibration of the AIRS infrared channels and the in-flight calibration approach. Derivation of the radiometric transfer equations is presented with prelaunch measurements of the radiometric accuracy achieved on measurements of independent datasets.