Sentinel-6B Goes Operational, Extending the Sea-Level Record Behind ENSO Forecasts

The European meteorological satellite agency EUMETSAT announced that Copernicus Sentinel-6B entered operational service on 30 October 2026, with its high-precision altimetry data now available to users. The agency says the step secures the continuation into the 2030s of a satellite sea-level record that began more than 30 years ago, and that the mission's measurements feed seasonal forecasts, including predictions of El Niño and La Niña.

Sentinel-6B is operated by EUMETSAT on behalf of the European Commission. According to the agency, the satellite will soon become the world's reference mission for high-precision ocean altimetry — the benchmark used to calibrate other sea-level satellites.

From ocean height to seasonal forecasts

EUMETSAT describes the data as working across timescales from days to months. Within hours of collection, the agency says, the measurements enter the models of national weather services, where they support forecasts of rough seas during Atlantic winter storms and Mediterranean cyclones and help estimate how strong hurricanes will become. The accumulated sea-level record, EUMETSAT states, also informs seasonal prediction, including El Niño and La Niña outlooks. Sea-surface height is a standard altimetric measure of how heat is distributed through the upper ocean, which is why altimetry sits alongside temperature indices in ENSO monitoring (see How El Niño Is Measured).

The satellite also carries a radio occultation instrument that adds observations of atmospheric temperature and water vapour, according to EUMETSAT. The agency says Copernicus applies Sentinel-6B observations across its services, including climate services tracking long-term ocean change and ocean forecasts that map major currents — information ships use to adjust course depending on current position and wave direction. A high-resolution mode on both Sentinel-6 satellites provides detailed measurements near coastlines and over inland waters, which EUMETSAT links to maritime navigation, coastal protection and water-resource management.

The numbers in the record

EUMETSAT reports that global average sea level has risen by more than 11.5 cm since December 1992 and that the pace is accelerating: 2.8 cm during the first decade of the record, and as much as 4.0 cm over the most recent decade. The agency attributes the rise to a combination of melting glaciers and ice sheets and to ocean warming, which causes seawater to expand.

Sentinel-6B and its twin, Sentinel-6 Michael Freilich, launched in November 2020, will together provide sea-level data across up to 95% of the ice-free ocean, along with measurements of ocean currents, wave height, wind speed and water levels in rivers and lakes, EUMETSAT says.

"No other technology can follow changes in sea level across the whole globe as consistently as satellite altimetry, and its data are essential for both climate research and policy and weather and ocean forecasting," said Phil Evans, Director-General of EUMETSAT. He added that "around 900 million people live in low-lying coastal areas worldwide, and weather and ocean services across our Member States rely on Sentinel-6 data to protect people, infrastructure and ecosystems," and described the combination of Sentinel-6B with altimetry from Copernicus Sentinel-3 and wind and atmospheric data from Metop satellites as giving a fuller picture of the oceans.

Tandem flight and the handover

The Sentinel-6 series continues a record begun in 1992 by TOPEX/Poseidon and carried on by the Jason satellites, EUMETSAT says, within a long-standing European–United States collaboration. The agency operates the satellites around the clock and delivers their data within about three hours.

Since December 2025, EUMETSAT reports, the two twins have flown in tandem at an altitude of 1,336 km and 30 seconds apart, allowing scientists to calibrate Sentinel-6B against Sentinel-6 Michael Freilich. Sentinel-6B is expected to become the internationally agreed reference in the coming months, after which Sentinel-6 Michael Freilich will move to a new orbit, ending the tandem phase and widening overall ocean coverage.

The mission is run by EUMETSAT on behalf of the European Commission in partnership with the European Space Agency, NASA and NOAA, with support from the French space agency CNES. Further detail is in the EUMETSAT announcement.