Sentinel-3C returns its first views of Earth

5 min read · reported by ESA

Just two weeks after it was launched, the Copernicus Sentinel-3C satellite returned its first images and measurements from two of its key instruments – a major milestone that confirms the satellite is working well and on the road to monitoring the health of Earth’s oceans, land, cryosphere and atmosphere.

This first set of images includes stunning views of Italy, the Arctic and the Caribbean from the satellite’s ocean and land colour instrument, as well as measurements of the height of the Greenland ice sheet and sea surface from its synthetic aperture radar altimeter.

Sentinel-3C is the third satellite in the Sentinel-3 series and will continue the mission’s long-term task of delivering environmental data that are essential for a wide range of applications.

As the workhorse mission for Copernicus, the Sentinel-3 satellites carry the same suite of instruments to measure systematically Earth’s oceans, land, cryosphere and atmosphere.

Over oceans, Sentinel-3 measures the temperature, colour and height of the sea surface as well as the thickness of sea ice to support, for example, the monitoring of marine pollution and marine heatwaves.

Over land, this innovative mission monitors drought and wildfires, maps the way land is used, checks vegetation health, and measures the height of rivers, lakes, and polar ice sheets as shown in the animation of Greenland below.

Sentinel-3's observations are also particularly valuable for providing near-realtime parameters for weather forecasting and for monitoring long-term changes associated with climate change.

The European Space Agency is still in the process of commissioning Sentinel-3C for service, an important and intricate task that will take another five months, but after only two weeks in orbit, the satellite’s initial images already showcase that it is on the road to excellence.

The first image, captured by the ocean and land colour instrument on 30 September, is a striking natural-colour view that reveals Italy in beautiful detail, stretching from southern Germany in the north to Sicily and the southern Mediterranean.

Just above the centre of the image, the broad, flat expanse of the Po Valley – Italy’s agricultural heartland – stands out in shades of brown and green. Just to the north, the snow-capped Alps form a dramatic contrast with the lowlands, their bright peaks clearly visible against the surrounding landscape. Across the rest of Italy, variations in green and brown reflect differences in vegetation, agriculture and other types of land cover.

To the east, the deep blue waters of the Adriatic Sea separate Italy from the Balkan Peninsula, which is partially visible in the image. Noticeable variations in sea colour can be seen along Italy’s eastern coastline, where lighter blue waters hug the shore. These brighter tones are likely caused by sediment carried into the sea by rivers and transported along the coast.

On Italy’s western side, the dark waters of the Tyrrhenian Sea surround the islands of Sardinia and Sicily, which are clearly visible, while Corsica is largely obscured by cloud. Together, the contrasting colours of the land, snow-covered mountains and surrounding seas provide a vivid view of Italy’s diverse landscape from space.

The second image, also captured by the ocean and land colour instrument on 30 September, features part of the Canadian Arctic Archipelago, to the west of Greenland. Snow- and ice-covered islands dominate the scene, with rugged coastlines, deep fjords and exposed rock creating intricate patterns. At this time of the year sea ice is at a minimum but some fractured floes are visible on the dark open water.

The Arctic is warming much faster than the global average, causing rapid melting of ice on land and ice in the sea, which leads to further warming through feedback loops. Sentinel-3’s different instruments measure ice in different ways – all contributing to a better understanding of the vulnerable polar regions.

The third image captured on 29 September, also by the ocean and land colour instrument, is a spectacular view of part of the Caribbean, with Cuba to the south and the Bahamas towards the top of the image. Shallow waters around the islands appear in a beautiful turquoise set against the darker deeper waters of the open sea.

Low-lying islands and coastal regions around the world are at risk of sea-level rise. Sentinel-3’s synthetic aperture radar altimeter measures changes in the height of the sea surface to help monitor rising seas and contribute to action on climate change and mitigation strategies.

The map above shows measurements of sea-surface height across the Atlantic Ocean and Mediterranean Sea from Sentinel-3C’s synthetic aperture radar altimeter, compared to the Copernicus Marine Service multimission sea-level anomaly. These new data demonstrate that the altimeter is performing well and comparable to current measurements. Once commissioned, the altimeter will contribute to monitoring changes in sea-surface height around the world, complementing long-term records from missions such as Copernicus Sentinel-6 and Jason.

High-precision satellite altimetry has enabled scientists to establish the rate of global sea-level rise, which has averaged 3.64 mm per year since 1999 , with the rate of rise accelerating.

The altimeter will also measure changes in the height of lakes, rivers, sea ice and land ice, also complementing the upcoming Copernicus CRISTAL mission.

The animation above shows measurements of the height of the Greenland Ice Sheet acquired by Sentinel-3C between 30 September and 4 October. The measurements also demonstrate that the altimeter is performing well, with all of the measurement tracks closely matching the reference digital elevation model.

Monitoring changes in the height of the Greenland and Antarctic ice sheets is essential for understanding the impacts of climate change and, importantly, for improving predictions of future sea-level rise. Ice loss from the sheets is a major contributor to sea-level rise , and satellite altimetry provides a valuable way of tracking changes in their surface elevation over time.

All in all, these first acquisitions from Sentinel-3C’s ocean and land colour instrument and from its synthetic aperture radar altimeter provide early confirmation of the satellite’s performance and mark an important step towards full operational service following the completion of the commissioning phase.

Coming soon: the first observations from Sentinel-3C’s sea and land surface temperature radiometer – stay tuned.

About Sentinel-3 Sentinel-3 is part of Copernicus – the Earth observation component of the EU’s Space programme. For the Sentinel-3 satellites, ESA is responsible for the development and implementation of the satellites as well as the operations up to the completion of commissioning. After the commissioning phase, the Sentinel-3 mission is jointly managed by ESA and Eumetsat, where Eumetsat is responsible for routine satellite operations and the delivery of marine and atmospheric data, while ESA delivers land, cryosphere, inland water and offline atmospheric products. Together, the two agencies provide mission data for the Copernicus services and users worldwide.

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Published by the European Space Agency. View the original →