Inter-calibration of the Moderate-Resolution Imaging Spectroradiometer and the AlongTrack Scanning Radiometer-2

The performance of the on board calibrator for bands 1 ( , 0.66 µm), 2 ( , 0.86 µm) and 4 ( , 0.55 µm) of the Moderate-Resolution Imaging Spectroradiometer (MODIS Terra) has been evaluated by comparison of the top-of-atmosphere (TOA) albedos measured in the three bands over a six-day period with a three-year record of TOA albedos measured in the 0.56, 0.66 and 0.86 µm channels of the Along-Track Scanning Radiometer-2 (ATSR-2). The albedo measurements were made over two radiometrically stable sites located in the Libyan desert (22°0'N, 28°30'E), Sudan, and in the Sonoran desert (32°0'N, 114°6'W), Mexico. MODIS Terra albedos are within - 2.5 per cent of those measured in the corresponding channels of ATSR-2. Analysis of the measurements, and of model-derived albedos in the three channels (bands) of the two instruments, indicates that the MODIS Terra on board calibrator for bands 1, 2 and 4 is functioning as expected, and that either of the two instruments can be used to monitor the in-orbit performance of the other.