Sentinel-3’s scanning radiometer

The Sentinel-3 satellites carry a package of different instruments including the Sea and Land Surface Temperature Radiometer (SLSTR). This instrument measures global sea- and land-surface temperatures every day to an accuracy of better than 0.3 K. Continuing the legacy of Envisat’s Advanced Along Track Scanning Radiometer, it maintains a dual-view along-track-scanning approach and delivers measurements at a spatial resolution of 500 m for visible/near-infrared and short-wavelength infrared channels and at 1 km for the thermal infrared channels. Furthermore, SLSTR includes two dedicated thermal infrared channels that are optimised for active fire detection and fire radiative power measurement – important for Copernicus Emergency Response and Climate Services.

The animation shows how SLSTR’s two rotating mirrors scan a curved swath on the ground, one at nadir and one inclined obliquely pointing to the rear of the satellite. The oblique view has a narrower swath of 740 km compared to 1400 km of the nadir swath. As each scanner rotates, it samples signals in nine separate bands covering the visible and infrared part of the electromagnetic spectrum, indicated by the colours rising towards the satellite. As the satellite orbits, the dual-view technique is used to improve atmospheric correction and generate more accurate data products compared to a nadir view alone.