Abstract. Two different types of low-cost, wide-band, infrared radiometers together with a high performance, internally calibrated radiometer - designed specifically for ATSR validation (SISTeR) - are evaluated for use in validating ATSR sea surface temperature (SST) measurements. The instruments were evaluated as part of the Mutsu Bay Experiment in Japan during July/August 1996. Careful consideration of various physical and environmental factors is necessary for accurate calibrations. These factors include: variations in the oceans emissivity; atmospheric emission; sun-glint; and solar heating of the instruments. These are discussed in this paper along with the need for regular and frequent calibration of the instruments. Preliminary analysis of results suggests that low-cost radiometers can be used effectively, in a limited range of conditions, for the validation of satellite SST's.

Keywords: ESA European Space Agency - Agence spatiale europeenne, observation de la terre, earth observation, satellite remote sensing, teledetection, geophysique, altimetrie, radar, chimique atmospherique, geophysics, altimetry, radar, atmospheric chemistry