Sentinel-6 A Spot

Copernicus Sentinel-6


Continuing high precision ocean altimetry measurements

Sentinel-6 A Spot
Sentinel-6 A Spot

The Copernicus Sentinel-6 Michael Freilich satellite was launched in November 2020 and provides global sea surface height observations for climate monitoring and ocean and seasonal forecasts. It continues a time series of mean sea level rise measurements dating back to 1992.

Last Updated

11 January 2024

Published on

19 May 2020

The satellite carries a Poseidon-4 radar altimeter and a microwave radiometer.

Variations in sea level in our changing climate (mm per year) can only be monitored on a global scale by ocean altimetry. These measurements are also essential to understand how the ocean stores and redistributes heat, water and carbon in the climate system.

In addition, the altimetry instrument provides measurements of wind speed at the ocean surface and significant wave height.

Other instruments on board the satellite collect high resolution vertical profiles of temperature, using the GNSS Radio Occultation sounding technique, to assess temperature changes in the troposphere and stratosphere and to support Numerical Weather Prediction.

Measuring global sea level

The Copernicus Sentinel-6 mission will extend the unique record of mean sea level rise that began in 1992 with the TOPEX/Poseidon mission (1992-2006) and continued with the Jason (2001-2013), Jason-2 (2008) and Jason-3 (2016) satellites.

After its launch, Copernicus Sentinel-6A took over the role as reference altimetry mission, which means its measurements are the standard against which other satellite altimetry data are cross-calibrated, to ensure accuracy.

There are two Sentinel-6 satellites in total - Sentinel-6B will launch in 2025 - and between them, they will provide the most accurate source of observations of sea surface height, mean sea level and ocean circulation, until at least 2030.

The mission is co-funded by the European Commission, the European Space Agency, EUMETSAT and the USA, through NASA and the National Oceanic and Atmospheric Administration (NOAA). EUMETSAT operates the satellite and delivers data to users.

The Copernicus Sentinel-6 satellites carry the following instruments:

Poseidon-4 radar altimeter

The Poseidon-4 radar altimeter provides highly accurate ocean altimetry measurements including sea surface height, significant wave height and wind speed over the ocean.

Advanced Microwave Radiometer (AMR-C)

The Advanced Microwave Radiometer (AMR-C) supports the measurement of range to the ocean surface by the radar altimeter by providing an estimate of the delay due to water vapour in the atmosphere.

Additional instruments

Three other instruments support the operations of the satellites: a Precise Orbit Determination (POD) suite comprising Global Navigation Satellite System (GNSS) receivers, a Laser Retroreflector Array (LRA) and a Doppler Orbitography Radio-positioning Integrated by Satellite (DORIS) system.