The Advanced Along Track Scanning Radiometer (AATSR) and its predecessors ATSR-1 and ATSR-2: An introduction to the special issue

The Advanced Along Track Scanning Radiometer (AATSR) and its predecessors, ATSR-1 and ATSR-2, have always had the basic objective of determining surface temperature accurately enough to allow quantitative investigations of climatic behaviour. This is achieved by performing exacting measurements of emitted radiation from the Earth’s surface and atmosphere. In order to achieve the desired quality for sea surface temperature, it is necessary to have the use of three thermal channels (at least at night) with precise and stable radiometric calibration, high clarity and sensitivity of the thermal infra-red image data, dual-view geometry for an improved atmospheric correction, as well as additional visible and near infrared channels. This special issue, comprising 18 papers and this Preface, demonstrates the thermal calibration of the ATSR instruments, the high performance of sea surface temperature data from these sensors, and the way in which the ATSR observations have also been used to derive quantitative information about land surface properties (specifically, temperature and reflectance), aerosols and clouds, fires and gas flares. These papers celebrate the success of the ATSR instruments and the associated ground-based measurements which combined are providing exciting time series of climate observations.