Copernicus Sentinel satellites: delivering accurate data

Copernicus Sentinel satellites: delivering accurate data
With the Sentinel-1 mission designed as a two-satellite constellation, Sentinel-1B will join its identical twin, Sentinel-1A, which was launched in 2014. © ESA-ATG medialab - Sentinel 1B

Two recent expeditions 26,000km across the Atlantic Ocean have returned critical information to make sure the Copernicus Sentinel satellites are delivering accurate data about the state of the world’s oceans.

Information provided by the Copernicus Sentinel satellites is used in several ways. Ocean forecasting is important for maritime safety, off-shore operations, and biological productivity helping industries such as the fishing industry.

However, monitoring the data provided by the satellites is crucial, meaning that scientists will have to take measurements themselves that can be compared with those taken from space.

European Space Agency (ESA) ocean scientist Craig Donlon said: “We rely on these measurements, which are fully traceable, independent and collected according to strict protocols.

“They are an essential part of making sure that the satellite data can be used with confidence for practical applications and scientific research.”

The Copernicus Sentinel-1, Sentinel-2 and Sentinel-3 satellites return different types of data about the oceans. For example:

  • Sentinel-1: This satellite can be used to look at waves and oil spills;
  • Sentinel-2 and Sentinel-3: both provide information about plankton, whichare important for the balance of CO2 in the atmosphere; and
  • Sentinel-3: this satellite is also used to map the sea surface temperature, which is needed for forecasting.

Measuring the ocean

The team collected reference measurements of chlorophyll, sea temperature and more, taking measurements at the same time as the Copernicus Sentinel satellites passed overhead.

Gavin Tilstone from the Plymouth Marine Laboratory, UK, said: “We voyaged through many different ocean regimes so that these measurements were as varied as possible, from productive coastal regions to desert-like gyres in the centre of the ocean that are rarely accessed by research ships.

“It was also important to compare measurements taken by different shipborne instruments, which is all part of making sure they are of the highest quality and rigorously calibrated before they are used to check the satellite data.”

Initial results suggest that measurements of chlorophyll by Sentinel-3A can be improved slightly, which is now being addressed.

Donlon concluded: “This is exactly why these campaigns are vital. They build confidence in our missions and data products and highlight issues that can be easily addressed by our expert teams. Regular-repeat campaigns are a core part of our satellite missions because they provide the evidence of mission quality for our users.”

Source: ESA

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