Why measure salinity?

Sea Surface Salinity is a key parameter to estimate the influence of oceans on climate. Along with temperature, salinity is a key factor that determines the density of ocean water and thus determines the convection and re-emergence of water masses.

The thermohaline circulation crosses all the oceans in surface and at depth, driven by temperature and salinity.

A global “conveyor belt” is a simple model of the large-scale thermohaline circulation. Deep-water forms in the North Atlantic, sinks, moves south, circulates around Antarctica, and finally enters the Indian, Pacific, and Atlantic basins. Currents bring cold water masses from North to South and vice versa.

This thermohaline circulation greatly influences the formation of sea ice at the world’s poles, and carries ocean food sources and sea life around the planet, as well as affects rainfall patterns, wind patterns, hurricanes and monsoons.




Amazon - June

How is it measured ?

By satellite
Microwave radiometer (starting in 2009 with the launch of SMOS)

In situ techniques
Profiling floats
Moored buoys

Numerical models
Until the launch of SMOS (2009), it was very difficult and expensive to measure Sea Surface Salinity, so the spatial distribution and the time variability of SSS are still very poorly known over most of the ocean surface.
Models are therefore crucial to estimate this parameter. With an ocean mixed-layer model (between 50 and 1000 m depth), Sea Surface Salinity can be estimated by modeling external (winds, evaporation/precipitation, river runoffs…) and internal (horizontal transport, vertical mixing,…) influences.


Source: MyOcean