The new Copernicus Sentinel-4 mission has presented its first results, having recorded the concentrations of the main atmospheric pollutants - nitrogen dioxide, sulfur dioxide and ozone. Although the data obtained are preliminary, they mark a key stage in the development of European air quality monitoring capabilities – for the first time from geostationary orbit at an altitude of about 36 thousands of kilometers above the Earth.
Launched in July 2025 year, the Sentinel-4 ultraviolet-visible-infrared spectrometer is placed on board the first satellite of the Meteosat Third Generation Sounder series (MTG-S1). This mission architecture makes it possible to combine meteorological observations with atmospheric composition analysis on a single platform, ensuring more efficient use of satellite resources.
The device is currently at the stage of commissioning, therefore, the obtained images serve as a preliminary confirmation of its operability. Sentinel-4 analyzes sunlight, reflected from the Earth's surface and atmosphere, and detects spectral signatures of gases and aerosols.
Unlike satellites in low orbits, that fly over the planet several times a day, Sentinel-4 is located in geostationary orbit, constantly monitoring the same territory - Europe and North Africa. Thanks to this, it can update the data every hour, providing almost continuous monitoring of key atmospheric constituents.
The mission will be the first in Europe, capable of providing regular hourly measurements of air quality. This will allow monitoring dynamic changes in pollution levels and will significantly improve the ability to forecast and respond to their fluctuations. In normal mode, Sentinel-4 will measure nitrogen dioxide concentrations, sulfur dioxide, ozone, formaldehyde, glyoxal and aerosols. The collected data will be used in the Copernicus Atmospheric Monitoring Service (CAMS).
The first results of observations
The first picture shows nitrogen dioxide concentrations (NO₂) in the troposphere. The most pronounced zones of pollution are recorded along the coast of the Mediterranean Sea and in the valley of the Po River in Italy. No measurements were taken in areas with dense clouds, therefore, the map shows areas without data.
Nitrogen dioxide is produced during the burning of fuel in transport, power plants and heating systems. This gas is toxic and participates in the formation of secondary pollutants — ozone and fine dust, which negatively affect human health and the state of the environment.
The second image shows the distribution of sulfur dioxide (SO₂). It shows a pillar of pollution, which rises from Mount Etna in Italy and spreads southeast over the sea. Despite the relatively calm state of the volcano, during eruptions, such plumes are much larger.
In addition to natural sources, sulfur dioxide enters the atmosphere due to human activity, in particular from ships, that burn fuel with a high sulfur content, and from thermal power plants, which operate on brown coal. The gas is toxic and contributes to the formation of fine particles, dangerous to health.
The third image shows the vertical distribution of ozone (O₃). In the stratosphere, ozone performs a protective function, shielding the Earth from ultraviolet radiation, while in the lower atmosphere it is a harmful pollutant, which worsens air quality. Current ozone levels are within normal limits, and its distribution – with a maximum over the Balkans and Greece and a minimum over the Baltic region – coincides with data from other satellite missions, such as GOME-2 (MetOp) ta Tropomi (Sentinel-5P).
Last image, which covers Europe and part of North Africa, created on the basis of the first spectral measurements of reflected terrestrial radiation. It is displayed in false colors, which makes it possible to distinguish land, ocean and clouds, demonstrating the high quality of the received data.
Further prospects of the mission
The first results of Sentinel-4 confirm the successful operation of the system and the effectiveness of the joint work of the European Space Agency, European Commission, the EUMETSAT organization and industrial partners.
The mission is in the final stage of commissioning, and in the near future its data will become a key tool for improving the accuracy of air quality assessment and pollution forecasting. Expected, that Sentinel-4 will provide continuous, highly detailed observation of the state of the atmosphere, which will help strengthen environmental safety and health protection of the European population.
Source: https://phys.org