The Advanced Along Track Scanning Radiometer (AATSR) is one of the Announcement of Opportunity (AO) instruments on board the European Space Agency (ESA)'s Envisat satellite.
This instrument is a multi-channel imaging radiometer with the principal objective of providing data concerning global Sea Surface Temperature (SST) to the high levels of accuracy and stability required for monitoring and carrying out research into the behaviour of the Earth’s climate.
AATSR can measure Earth's surface temperature to a precision of 0.3 K (0.5 °F), for climate research. Among the secondary objectives of AATSR is the observation of environmental parameters such as aerosols, clouds, fires, gas flares, water content, biomass, and vegetal health and growth. AATSR is the successor of ATSR-1 and ATSR-2, payloads of ERS-1 and ERS-2.