Calibration of visible and near-infrared channels of the NOAA-12 AVHRR using time series of observations over deserts

Abstract

Time series of desert sites are used to derive a post-launch calibration of the visible (ch1—0.63 µm) and near-infrared (ch2—0.86 µm) channels on the NOAA-12 AVHRR. This work extends the techniques that have been applied to NOAA satellites in afternoon orbits to a satellite in a morning orbit. An analysis of the bidirectional reflectance distribution function effects apparent in the data was used to limit the time period used to analyse the calibration slope of ch1 and ch2. Three desert sites were used to compute the relative degradation rates of the calibration slope of ch1 and ch2. Measurements from NOAA-9 over the Libyan Desert and from aircraft flights over White Sands, New Mexico were used to produce an absolute calibration. The resulting absolute calibrations for ch1 and ch2 agree with previous results to within 2%. The degradation results indicated that the calibration slope decreases by 3.14% per year for ch1 and 3.19% per year for ch2.