Pre-launch instrument calibration testing of the current series of GOES Imagers and Sounders has shown a systematic non-linearity in the radiometric response of the SWIR channels of approximately 0.2 percent. Possible mechanisms for the observed non-linearity include; inherent InSb detector non-linearity, non-constant temperature error on the blackbody calibration target, relative spectral response error, and electronics non-linearity. A calibration model common to the GOES and POES radiometers is presented. The sensitivity of the SWIR channels' non-linear response to errors in spectral response is derived. Systematic shift of spectral response center wavenumber of approximately 10 cm-1 are found to induce a 0.1 percent non-linearity in response. Pre-launch calibration coefficients from recent NOAA radiometers are analyzed. Operational calibration errors caused by incorrect quadratic coefficients are found to be as large as 0.15K for warm scenes.
Edward C. Wack, Edward C. Wack,
"SWIR nonlinear radiometric response due to errors in relative spectral response", Proc. SPIE 3117, Earth Observing Systems II, (18 September 1997); doi: 10.1117/12.278923; https://doi.org/10.1117/12.278923