Calibrations for AVHRR channels 1 and 2: review and path towards consensus

The over three-decade-long data record from the Advanced Very High Resolution Radiometer (AVHRR) is ideal for studies of the Earth's changing climate. However, the lack of on-board calibration requires that the solar channels be recalibrated after launch. Numerous calibration studies have been conducted, but significant differences remain among the calibrations. This study is one effort to outline a path towards consensus calibration of the AVHRR solar channels. The characteristics of the polar orbiting satellites bearing the AVHRRs, the AVHRR instruments and data are described as they are related to calibration. A review of past and current calibration studies is also presented and examples of their lack of consensus shown. A list of consensus items is then provided that, if followed by the AVHRR calibration community, should bring the various calibration methods to within the small percent difference required for long-term climate detection.