The second Sentinel-3 satellite, Copernicus Sentinel-3B, has been launched and has joined its identical twin Sentinel-3A in orbit. This pairing of satellites increases coverage and data delivery for the European Union’s Copernicus environment program. It is also good news for research at NERSC.

The Dubbed Sentinel-3B will be the 7th satellite to join the constellation of Copernicus Earth-monitoring satellites since 2014. Its twin satellite, the Sentinel-3A was launched on 2016 February and the ESA (European Space Agency) confirmed that with its help, full-time data can be provided after 3 hours of its capture. They are now both operating with an expected lifetime of 12 years. The sentinel-3B is one of the most comprehensive of all the missions and is fitted with a wide range of science instruments

Highlights from launching the Sentinel-3B

Photo Credit: ESA, ATG Medialab: A view of the Sentinel-3B satellite.

This is the seventh launch of a Sentinel satellite in the last four years. With this launch, the first set of Sentinel missions for the Copernicus environmental monitoring network are in orbit, carrying a range of technologies to monitor Earth’s land, oceans and atmosphere. - At NERSC we use these satellite observations for research and development studies of the upper ocean and sea ice covered regions, with special focus in the Nordic Seas and Arctic Ocean. The satellite data are also highly important for the Copernicus Marine Environment Monitoring Service, says professor Johnny Johannessen at NERSC.

Research Director, Laurent Bertino, at NERSC tells that the Sentinel-3B observes several aspects of the ocean that are of relevance for the Copernicus Marine Services in the Arctic. - Sea level observations will be assimilated by the TOPAZ forecasting system as soon as the calibration phase is completed, using the Ensemble Kalman Filter method developed by NERSC. These observations improve the forecasts of currents in the upper ocean. Sea surface temperatures will also be assimilated in the same system and will improve the forecast of surface temperature and ocean vertical mixing. Ocean colour will be initially use to validate the TOPAZ forecasts of ocean primary production and will be assimilated as well later in 2020. This is expected to be useful for a broad range of studies in marine biology, says Bertino.  

In addition, Sentinel-3B will as well measure sea ice thickness and significant wave heights, the latter will be assimilated into MET Norway’s wave forecast model, also a contribution to the Copernicus Marine Services. 

- Data from Sentinel-3B also ensures continuity in ocean and sea measurements and ensures the ability to build long time series of key essential climate variables. Including surface temperature, water level, ice thickness and chlorophyll amount in the ocean. ESA has an important program called Climate Change Initiative where such long-time series are checked or improved. NERSC is involved in many projects funded by this program, says Johannessen.

In a press release from ESA the Director of Earth Observation Programs, Josef Aschbacher, said, “With Sentinel-3B, Europe has put the first constellation of Sentinel missions into orbit – this is no small job and has required strong support by all involved. It allows us to get a very detailed picture of our planet on a daily basis and provides crucial information for policy makers.

ESA also informed that during the three-day launch and the early orbit phase, controllers will check that all the satellite’s systems are working and begin calibrating the instruments to commission the satellite. The mission is expected to begin routine operations after five months.

FACTS:

The Sentinel satellite missions are the biggest and most expensive component of the Copernicus program and the satellites are designed by ESA and built by European industry. The two satellites are in a polar orbit with an inclination of about 82 degrees and operates 3 distinct instruments:  a radar altimeter; an imaging spectrometer; and an infrared radiometer.

The instruments provide global, repeat observations. Over the ocean this includes: sea surface slope and surface current, significant wave height, wind speed and sea level from radar altimetry at about 10 km resolution: sea surface temperature under cloud free conditions from the infrared radiometer at about 300 m resolution; chlorophyll a and phytoplankton from the imaging spectrometer under cloud free conditions at about 300 m resolution. Over the sea ice field the observations include: sea ice freeboard height and hence sea ice thickness from radar altimetry; sea ice surface temperature and sea ice drift from respectively infrared radiometer and imaging spectrometer under cloud free conditions.

Sentinel-3A/B flies in constellation with Sentinel-1 A/B. Sentinel-1A/B operate a synthetic aperture radar (SAR) with advanced observation capabilities in all weather conditions over the ocean (wind, waves, and surface current) and sea ice field (sea ice deformation, lead fraction and sea ice drift).