New sea-level monitoring satellite goes live

Copernicus Sentinel-6 radar altimeter
ARCHIVE CONTENT 21 JUN. 2021 publication date 12473 Views

Following liftoff last November and more than six months spent carefully calibrating the most advanced mission dedicated to measuring sea-level rise, Copernicus Sentinel-6 Michael Freilich is now operational – meaning that its data are available to climate researchers, ocean-weather forecasts and other data users.

Craig Donlon, ESA’s Sentinel-6 mission scientist, said, “Building on a long line of European heritage dual-frequency altimeter missions, Sentinel-6’s Poseidon-4 altimeter was designed to bring new high-resolution Ku- band synthetic aperture radar measurements into the altimetry reference time series.

“To manage the transition from Jason-3’s lower resolution measurements to Sentinel-6’s high-resolution products with confidence, Poseidon-4 acquires both conventional low-resolution measurements simultaneously with high-resolution synthetic aperture radar measurements. The high-resolution products will be available later this year. We are really pleased to see that the data from Sentinel-6 show great performance based on validation by independent measurements on the ground.”

The Permanent Facility for Altimetry Calibration on the island of Crete in Greece is home to a transponder (CND1) that is key to this validation, ensuring that Sentinel-6’s low-resolution data are the same as that of Jason-3. The transponder receives the Sentinel-6 radar signal, which is amplified and transmitted back to the satellite providing a well-characterised external calibration source.

Dr Donlon explained, “Measurements from the CDN1 transponder show that the absolute difference between measurements from Sentinel-6 and Jason-3 is less than 2 mm, which is remarkable for two independent satellites operating at an altitude of 1330 km.

“Establishing the differences between Sentinel-6 and Jason-3 is important if stability in the sea-level rise time series from satellite altimetry is to be maintained with low uncertainties.”


Improvement of Sentinel-6 significant wave height with respect to Jason-3
Improvement of Sentinel-6 significant wave height with respect to Jason-3

Craig Donlon, ESA’s Sentinel-6 mission scientist, said, “Building on a long line of European heritage dual-frequency altimeter missions, Sentinel-6’s Poseidon-4 altimeter was designed to bring new high-resolution Ku- band synthetic aperture radar measurements into the altimetry reference time series.

“To manage the transition from Jason-3’s lower resolution measurements to Sentinel-6’s high-resolution products with confidence, Poseidon-4 acquires both conventional low-resolution measurements simultaneously with high-resolution synthetic aperture radar measurements. The high-resolution products will be available later this year. We are really pleased to see that the data from Sentinel-6 show great performance based on validation by independent measurements on the ground.”

The Permanent Facility for Altimetry Calibration on the island of Crete in Greece is home to a transponder (CND1) that is key to this validation, ensuring that Sentinel-6’s low-resolution data are the same as that of Jason-3. The transponder receives the Sentinel-6 radar signal, which is amplified and transmitted back to the satellite providing a well-characterised external calibration source.

Dr Donlon explained, “Measurements from the CDN1 transponder show that the absolute difference between measurements from Sentinel-6 and Jason-3 is less than 2 mm, which is remarkable for two independent satellites operating at an altitude of 1330 km.

“Establishing the differences between Sentinel-6 and Jason-3 is important if stability in the sea-level rise time series from satellite altimetry is to be maintained with low uncertainties.”


Improvement of Sentinel-6 range noise with respect to Jason-3
Improvement of Sentinel-6 range noise with respect to Jason-3

Craig Donlon, ESA’s Sentinel-6 mission scientist, said, “Building on a long line of European heritage dual-frequency altimeter missions, Sentinel-6’s Poseidon-4 altimeter was designed to bring new high-resolution Ku- band synthetic aperture radar measurements into the altimetry reference time series.

“To manage the transition from Jason-3’s lower resolution measurements to Sentinel-6’s high-resolution products with confidence, Poseidon-4 acquires both conventional low-resolution measurements simultaneously with high-resolution synthetic aperture radar measurements. The high-resolution products will be available later this year. We are really pleased to see that the data from Sentinel-6 show great performance based on validation by independent measurements on the ground.”

The Permanent Facility for Altimetry Calibration on the island of Crete in Greece is home to a transponder (CND1) that is key to this validation, ensuring that Sentinel-6’s low-resolution data are the same as that of Jason-3. The transponder receives the Sentinel-6 radar signal, which is amplified and transmitted back to the satellite providing a well-characterised external calibration source.

Dr Donlon explained, “Measurements from the CDN1 transponder show that the absolute difference between measurements from Sentinel-6 and Jason-3 is less than 2 mm, which is remarkable for two independent satellites operating at an altitude of 1330 km.

“Establishing the differences between Sentinel-6 and Jason-3 is important if stability in the sea-level rise time series from satellite altimetry is to be maintained with low uncertainties.”


Sentinel-6 and Jason-3 tandem

Craig Donlon, ESA’s Sentinel-6 mission scientist, said, “Building on a long line of European heritage dual-frequency altimeter missions, Sentinel-6’s Poseidon-4 altimeter was designed to bring new high-resolution Ku- band synthetic aperture radar measurements into the altimetry reference time series.

“To manage the transition from Jason-3’s lower resolution measurements to Sentinel-6’s high-resolution products with confidence, Poseidon-4 acquires both conventional low-resolution measurements simultaneously with high-resolution synthetic aperture radar measurements. The high-resolution products will be available later this year. We are really pleased to see that the data from Sentinel-6 show great performance based on validation by independent measurements on the ground.”

The Permanent Facility for Altimetry Calibration on the island of Crete in Greece is home to a transponder (CND1) that is key to this validation, ensuring that Sentinel-6’s low-resolution data are the same as that of Jason-3. The transponder receives the Sentinel-6 radar signal, which is amplified and transmitted back to the satellite providing a well-characterised external calibration source.

Dr Donlon explained, “Measurements from the CDN1 transponder show that the absolute difference between measurements from Sentinel-6 and Jason-3 is less than 2 mm, which is remarkable for two independent satellites operating at an altitude of 1330 km.

“Establishing the differences between Sentinel-6 and Jason-3 is important if stability in the sea-level rise time series from satellite altimetry is to be maintained with low uncertainties.”


Craig Donlon, ESA’s Sentinel-6 mission scientist, said, “Building on a long line of European heritage dual-frequency altimeter missions, Sentinel-6’s Poseidon-4 altimeter was designed to bring new high-resolution Ku- band synthetic aperture radar measurements into the altimetry reference time series.

“To manage the transition from Jason-3’s lower resolution measurements to Sentinel-6’s high-resolution products with confidence, Poseidon-4 acquires both conventional low-resolution measurements simultaneously with high-resolution synthetic aperture radar measurements. The high-resolution products will be available later this year. We are really pleased to see that the data from Sentinel-6 show great performance based on validation by independent measurements on the ground.”

The Permanent Facility for Altimetry Calibration on the island of Crete in Greece is home to a transponder (CND1) that is key to this validation, ensuring that Sentinel-6’s low-resolution data are the same as that of Jason-3. The transponder receives the Sentinel-6 radar signal, which is amplified and transmitted back to the satellite providing a well-characterised external calibration source.

Dr Donlon explained, “Measurements from the CDN1 transponder show that the absolute difference between measurements from Sentinel-6 and Jason-3 is less than 2 mm, which is remarkable for two independent satellites operating at an altitude of 1330 km.

“Establishing the differences between Sentinel-6 and Jason-3 is important if stability in the sea-level rise time series from satellite altimetry is to be maintained with low uncertainties.”


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