ESA - Sentinel-4 updates

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https://twitter.com/ESA_EO/status/1980552589251846498

[jacqmans]

Sentinel-4 offers first glimpses of air pollutants
21/10/2025

The new Copernicus Sentinel-4 mission has delivered its first images, highlighting concentrations of atmospheric nitrogen dioxide, sulphur dioxide and ozone. Despite being preliminary, these images mark a major milestone in Europe’s ability to monitor air quality all the way from geostationary orbit, 36 000 kilometres above Earth.

Launched in July 2025, the Sentinel-4 ultraviolet–visible–near-infrared spectrometer is hosted on the first Meteosat Third Generation Sounder satellite. This dual-mission architecture allows for efficient use of the satellite, combining meteorological and atmospheric composition monitoring capabilities on a single platform.

The Sentinel-4 spectrometer is still undergoing commissioning for its operational life – so these first images, featured below, are merely an early glimpse of what’s to come.

Sentinel-4 measures solar light reflected by Earth’s surface and atmosphere, resolving spectral signatures or ‘fingerprints’ of trace gases and aerosols present in the atmosphere.

Unlike other satellite sensors that orbit Earth from pole to pole at a lower altitude, Sentinel-4 operates in geostationary orbit, continuously observing the same region – Europe and northern Africa – from a fixed position.

From this vantage point, Sentinel-4 can scan the same region every hour, providing near-realtime updates on key atmospheric constituents.

ESA’s Sentinel-4 Mission Scientist, Ben Veihelmann, said, “Sentinel-4 is the first European mission that will deliver hourly air-quality observations. By capturing fast changes in air pollution, Sentinel-4 is a game-changer for monitoring and forecasting air quality over Europe.”

Once operational, the instrument will routinely map concentrations of nitrogen dioxide, sulphur dioxide, ozone, formaldehyde, glyoxal and aerosols. These data will be fed into the Copernicus Atmosphere Monitoring Service.

In the meantime, the mission has already provided a few teasers, all of which are based on its very first measurements acquired on 8 October.


https://www.esa.int/Applications/Observing_the_Earth/Copernicus/Sentinel-4/Sentinel-4_offers_first_glimpses_of_air_pollutants#msdynmkt_trackingcontext=85c94aec-7a37-4568-a0dd-1b77b8920100