The Advanced Along Track Scanning Radiometer: validation and early data

The European Space Agency´s (ESA) environmental research satellite, Envisat, was launched on 1^st March 2002. Carrying a suit of sensors, it offers opportunities for a broad range of scientific research activities and applications. One of the instruments on board Envisat is the Advanced Along Track Scanning Radiometer, AATSR. Funded primarily by the UK Department for Environment, Food and Rural Affairs (DEFRA) in support of their programme of climate monitoring and prediction, AATSR is designed to provide precise, accurate measurements of global sea surface temperature (better than 0.3K ± 1sigma), required for climate research and global climate change detection. It continues the work of ATSR and ATSR-2, and will lead to a 15+ year data record. This paper introduces the AATSR validation programme, designed to assess instrument performance and accuracy. Activities include algorithm verification, and the comparison of SST measurements from AATSR with those collected from buoys, precision radiometers, and modelled SST analysis fields. Data will be collected by scientists worldwide, over a range of geographic locations, sites and seasons. Validation results will be explicitly fed back into the AATSR operations programme, thus contributing to the successful commissioning of the instrument in the six-month period after launch.