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Sea Surface Salinity CCI project



Salinity plays a fundamental role in the density-driven global ocean circulation, the water cycle, and climate. Synoptic monitoring of Sea Surface Salinity (SSS) by satellite remote sensing provides an essential tool for better monitoring, understanding and constraining the marine component of the water cycle and the thermohaline circulation, which in turn determine ocean carbon and heat storage across all ocean basins. In addition, SSS variations can modify the vertical stratification in density and strongly influence the air-sea exchange of gases and masses through the development of the so-called barrier layers. Last, SSS is a tracer of freshwater fluxes originating from river discharges, ice melting, air-sea exchange (Evaporation minus Precipitation (E-P)). SMOS (2010 to date), Aquarius (2011 to 2015) and SMAP (2015 - date) satellite missions monitor Sea Surface Salinity at global scale with a unique synoptic coverage at a 50-100km spatial resolution with a revisit time of 3 to 8 days. They reveal mesoscale features related to ocean circulation and river plumes, eddies propagation not observable by any other means. 

This Sea Surface Salinity project (SSS_cci) aims to produce the longest SSS Climate Data Record resulting from the combination of all the existing satellite missions capable to retrieve this variable from space.


The Climate Change Initiative (CCI) is an ESA project aiming to produce the longest SSS Climate Data Record resulting from the combination of all the existing satellite missions capable to retrieve this variable from space. This include not only all L-band satellites but there might be the possibility to use C and X band radiometers to extend the SSS dataset record back to 2002.

Particular efforts will be put at characterizing the magnitudes of the systematic and random uncertainties in the SSS products and their spatio-temporal dependencies.

CCI SSS is a science driven programme that will clearly contribute to Climate Science studies aiming to contribute to the next Annual Review for the Climate Change (2020).

About the project

Under the Climate Change Initiative the European Space Agency seeks to make step forward to understand the state of our warming planet including the physical changes undertaken in the ocean. Satellite observations unarguably aided the Climate Science community by providing a presented quality of observation with different applications. These applications include the use the Essential Climate Variables (ECV) like Sea Surface Temperature (SST), which is habitually being used to study different aspects of the thermal ocean component variability with the on-going climate change.

Salinity is a key ocean variable that together with temperature determines the density of the water, which drives the Global Ocean circulation. Regardless the importance of this variable, salinity observations are rare and not homogeneously distributed (neither in time nor in space). Hence 2019-2021 CCI project included the Sea Surface Salinity (SSS) to explore the potential of using SSS as another ECV. This means that SSS data products will be specifically adapted to climate applications (i.e. include information on accuracy and uncertainty in the data) with the aim to contribute the current Earth Observation (EO) works and to better understand.

Latest news 

Ocean Salinity Science Conference [6/11/2018]

Special heads up to "Ocean Salinity Science Conference", which will take place at Sorbonne University, Paris, from6 to 9 November 2018.

Please note the deadline for the abstract submission, which is 6 July 2018.

Let us know if you submit your abstract at this address: rcatany[at], so we can know how your work relates to the CCI SSS. 

For more information: 


CCI SSS Plenary Planning meeting.

The CCI SSS team presented a detailed plan of work to undertake within the following three years starting from the Kick Off meeting. This was a two day meeting, which took place 9-10 April 2018 in Paris.

View agenda here 

View presentations here 


About the project

Figure 1: Annual average Sea Surface Salinity map (salinity units using practical salinity scale, PSS) from SMOS data averaged for 2010 processed at Cersat Salinity Center (

In the fifth Annual Report the science community recognised that there are evidences showing that our oceans are changing their current physical state due to an on going climate change. In terms of salinity it seems that ocean model simulations exposed that since 1950 high salinity ocean regions like the North Atlantic are tending to become more saline and the fresh ones like the North East Pacific are becoming fresher. These salinity trends are difficult to be seen using actual in situ observations only due to its limitation in space and time. Like this Earth Observation from satellite will complement the current understanding of our oceans by providing SSS observations with an unprecedented temporal and spatial resolution. 

The European Space Agency funded CCI SSS phase 1, is a three year project (2019-2021), which aims to build the longest SSS dataset record to meet and to study the potential of using SSS a future ECV to better the understand the evolution of our climate. Furthermore CCI SSS will explore the need to improve the performance of current state of art SSS algorithm retrievals. 

Since the SSS satellite missions begun with the launch of SMOS back in November 2009, there have been different SSS dataset products have been available by different data providers. Hence CCI SSS aims to cast all these datasets using different algorithm retrievals methodologies with the intention to depict the most optimal salinity datasets based on how these perform in different oceanic conditions. This is an analysis of the SSS products and will take place each year of the project. (i.e. regardless of the satellite or data centre source) to be included in this data quality exercise (see Algorithm development documentation). Therefore the resulting CCI SSS product will keep the uppermost scientific quality in terms of precision and accuracy and it will be openly sourced together with throughout documentation. The CCI SSS quality assurance will follow the specifications set by GCOS requirements for the SSS ECV.

Resources, data and documents

Documentation to appear shortly

The project team

The Consortium is based on a close collaboration between the following partners: 

  • ARGANS (United Kingdom) – Prime
  • Laboratoire d'Océanographie et du Climat (LOCEAN) (France)
  • LOPS (France)
  • ACRI-ST (France)
  • AdwäisEO (Luxemburg)
  • Ocean Data Lab (ODL) (France)
  • Instituto de Ciencias del Mar de Barcelona (ICM-CSIC) (Spain)
  • National Oceanography Centre (NOC) (United Kingdom)
  • Universitat Hamburg (UoH)  (Germany)

Additional support from external partners

  • RSS (USA)


Contact us / support

Use the following emails to contact the Sea Surface Salinity_cci team:

  • Scientific leader: Jacqueline Boutin and Nicolas Reul
  • Project manager: Rafael J Catany 
  • ESA technical officer: Craig Donlon and Paolo Cipollini