The original calibration / validation plan for this sensor, corresponding to the operational phases (including the commissioning phase) of the sensors included in this satellite’s payload, is summarised in the Envisat Calibration / Validation Plan.
More information is available at the ATSR Sensors website.

The pre and post-launch calibration activities of this self-calibrating sensor (i.e. use of an onboard calibration system) were  led by the Rutherford Appleton Laboratory (UK). Their calibration assessment results, using Level 1 products from the Third Reprocessing, were the following:

• TIR channel radiometric uncertainty: < 0.1 K
• VIS-SWIR channel radiometric uncertainty: < 3%

Please note that the above are type B estimates of the uncertainty due to systematic effects and not the random noise estimates.

The earlier validation activities were led by the University of Leicester (UK). The results of their validation of AATSR Sea Surface Temperature (SST) and Land Surface Temperature (LST) retrievals, using Level 2 products from the Third Reprocessing, were the following:

• SST uncertainty: < 0.15K (k =1)
• LST bias: 0.0-2.0K (night) and 0.2-3.8K (day)

These validation activities are detailed in the LST Validation Report and SST Validation Report.
Note any future Level 2 product validation  activities  will be carried out by the ESA CCI project teams using their SST and LST products.

Previously, evidence of a small temperature-dependent discrepancy in AATSR 12 micron Brightness Temperature measurements was discovered. This was investigated by an Anomaly Review Board (ARB), who identified the most likely causes and made specific recommendations to take these anomalies into account.

• Download the user recommendations document
• Download the full ARB Final Report and its Addendum

These recommendations were included in the Fourth Reprocessing dataset. Users do not have to make any adjustments to this dataset.