Copernicus Sentinel-4 is an ultraviolet, visible and near-infrared spectrometer carried on the Meteosat Third Generation Sounder (MTG-S) satellites. The mission also makes use of data from MTG’s infrared sounder instrument, and also from the flexible combined imager and lightning imager, both of which are carried on the Meteosat Third Generation Imager (MTG-I) satellites. From geostationary orbit, Sentinel-4 delivers data every hour. Complementing Sentinel-5, it provides information on a wide range of trace gases and pollutants, such as nitrogen dioxide, sulphur dioxide and aerosols to forecast and monitor air quality over Europe. It also provides information on ozone and solar radiation for UV forecasting, and contributes to climate monitoring.