Water has an emissivity () very close to 1. Therefore, it is possible to obtain relatively accurate water-surface temperature measurements. It is important to remember, however, that it is only a surface measurement. If there is a significant change in temperature just a few meters below the surface, it may not be detected by the thermal infrared detectors.
Two of the most important thermal infrared remote sensing instrument used to measure sea-surface temperature are found on the NOAA Advanced Very High Resolution Radiometer and NOAA Geostationary Operational Environmental Satellite (GOES). Data from these sensor is in public domain and are used heavily to obtain sea-surface temperature (SST) measurements over large oceanic surface.