AATSR: Global-change and surface-temperature measurements from Envisat

The Advanced Along-Track Scanning Radiometer (AATSR) onboard ESAs Envisat s pacecraft is designed to meet the challenging task of monitoring and detect ing climate change. It builds on the success of its predecessor instruments on the ERS-1 and ERS-2 satellites, and will lead to a 15+ year record of p recise and accurate global Sea Surface Temperature (SST) measurements, ther eby making a valuable contribution to the long-term climate record. The exceptionally high radiometric accuracy and stability of AATSR data are achieved through a number of unique features. A comprehensive pre-launch c alibration programme, combined with continuous in-flight calibration, ensur es that the data are continually corrected for sensor drift and degradation . A further innovative feature providing substantial advantages over tradit ional nadir-viewing instruments is the use of a 'dual-view' technique offer ing improved atmospheric correction. The accuracies achieved with this conf iguration are further enhanced by using low-noise infrared detectors, coole d to their optimum operating temperature by a pair of Stirling-cycle cooler s. With its high-accuracy, high-quality imagery and channels in the visible, n ear-infrared and thermal wavelengths, AATSR data will support many applicat ions in addition to oceanographic and climate research, including a wide ra nge of land-surface, cryosphere and atmospheric studies.