Sentinel-6 A Spot


Continuing high precision ocean altimetry measurements

Sentinel-6 A Spot
Sentinel-6 A Spot

The Copernicus Sentinel-6 radar altimeter mission will provide high-precision measurements of global sea-level.

Last Updated

26 May 2021

Published on

19 May 2020

The Copernicus Sentinel-6 mission implemented through two satellites (Sentinel-6 Michael Freilich and Sentinel-6B), aims to continue high precision ocean altimetry measurements in the 2020–2030 time-frame.

A secondary objective is to 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.

Key features

  • Measurements of ocean topography, being the equivalent of surface pressure in the atmosphere, are enabling numerical prediction of the three-dimensional ocean, which is a prerequisite to the development of operational oceanography in synergy with marine meteorology.
  • The development of operational oceanography is, in turn, necessary to improve forecasts of the weather conditions likely to prevail two to four weeks ahead (monthly forecasts), e.g. heat waves or sustained heavy downpours, and in the next seasons (seasonal forecasts) e.g. a cold winter or a hot summer, as a result of the sustained influence of the ocean on the atmosphere.
  • Variations of sea level (some mm per year) in our changing climate can only be monitored on global scale by High Precision Ocean Altimetry (HPOA) observations (composed of Jason-3 and Sentinel-6 data) observations, and ocean surface topography measurements are essential to understand how the ocean stores and redistributes heat, water and carbon in the climate system.
Jason-CS overview
Figure 1: System overview

Characteristics and instruments

The proposed payload is composed of the following instruments:

  • a radar altimeter, developed by ESA, based on the Sentinel-3 SARL instrument, but with a design adopted to allow the interleaved mode combining the SAR and the LRM modes;
  • AMR-C Microwave radiometer, provided by NASA;
  • GNSS Precise Orbit Determination (POD) Receiver, developed by ESA and derived from the GNSS Receiver on Sentinel-3;
  • the same DORIS Receiver as on Jason-3 and Sentinel-3;
  • the same Laser Reflector Array as on Jason-3, provided by NASA;
  • radio-occultation instrument based on a Tri-G receiver, provided by NASA.

Figure 2: Copernicus Sentinel-6 (Copyright ESA 2015, Airbus Defence and Space)

Services and applications

The main aim is the continuity of service with the Jason-3 mission, including meeting user requirements to provide a reference for cross-calibrating other altimetry missions, in particular from the Copernicus Sentinel-3 marine mission, also operated by EUMETSAT.

Main products, key variables and applications

  Products Main variables Main applications
Near Real Time (NRT) Operational Geophysical Data Record (OGDR) Significant Wave Height (SWH)
Surface Wind Speed (WIND)
Sea Surface Height (SSH)
Real time operational oceanography
Marine nowcasting
Operational wave forecasting
Slow Time Critical (STC) Interim Geophysical Data Record (IGDR) Same as above plus Absolute Dynamic Topography (ADT)
Ocean Geostrophic Velocities
More accurate Sea Surface Height (SSH)
Operational oceanography
Seasonal Forecasting
Non Time Critical (NTC) Geophysical Data Record (GDR) Same as above
Most accurate Sea Surface Height (SSH)
Sea level monitoring
Climate monitoring
Climate research


  • EUMETSAT is leading the system definition and is responsible for the ground segment development; operations preparation and operations of both satellites, and will co-fund the second satellite, together with the European Commission (EC).
  • ESA is responsible for the development of the first satellite; the prototype processors; delivery of the LEOP services, and the procurement of the second satellite on behalf of EUMETSAT and the EC.
  • The EC co-funds the second satellite with EUMETSAT and funds the operations of Jason-3 and both Sentinel-6 satellites, including the LEOP service for the second satellite.
  • NOAA provides US ground stations for data down links.
  • NASA provides the launch services for both Sentinel-6 satellites; US payload instruments and ground segment support, and will contribute to the operations and data processing.

Sentinel-6 documents