Inter-satellite calibration linkages for the visible and near-infared channels of the Advanced Very High Resolution Radiometer on the NOAA-7, -9, and -11 spacecraft

摘要

The post-launch degradation of the visible (channel 1:#x2248;0#xB7; 58#x2013;0#xB7;68#x3BC;m) and near-infrared (channel 2: #x2248; O#xB7;72#x2013;1#xB7;1 #x3BC;m) channels of the Advanced Very High Resolution Radiometer (AVHRR) on the NOAA#x2013;7, #x2013;9, and #x2013;11 Polar-orbiting Operational Environmental Satellites (POES) was estimated using the south-eastern part of the Libyan desert as a radiometrically stable calibration target. The relative annual degradation rates, in per cent, for the two channels are, respectively: 3#xB7;6 and 4#xB7;3 (NOAA#x2013;7) 5#xB7;9 and 3#xB7;5 (NOAA#x2013;9); and 1#xB7;2 and 2#xB7;0 (NOAA#x2013;11). Using the relative degradation rates thus determined, in conjunction with absolute calibrations based on congruent path aircraft/satellite radiance measurements over White Sands, New Mexico (U.S.A.), the variation in time of the absolute gain or #x2018;slope#x2019; of the AVHRR on NOAA#x2013;9 was evaluated. Inter-satellite calibration linkages were established, using the AYHRR on NOAA#x2013;9 as a normalization standard. Formulae for the calculation of calibrated radiances and albedos (AYHRR usage), based on these interlinkages, are given for the three AYHRRs.