The Soil Moisture and Ocean Salinity (Smos) satellite was put into orbit Nov. 2.  The satellite is part of an armada of European spacecraft being sent into orbit over the next few years to study the planet. SMOS carries an interferometric radiometer called Miras. Some eight metres across, it has the look of helicopter rotor blades. Miras will measure changes in the wetness of the land and in the salinity of seawater by observing variations in the natural microwave emission coming up off the surface of the planet.

Space observations of surface salinity of the ocean are a new addition to Ocean Observing Systems.  Surface salinity maps will be important to improve global circulation models, identify the origins of eddies and rings, and will help improve El Nino observations and forecasts.  Changes in surface salinity may also be used to determine rainfall and evaporation in the open ocean.

For more see the BBC Article