The next scientific seminar organised by the Masters in Marine Sciences, will take place in the OCEANOMED amphitheatre on Monday 17 November 2025 from 14:00 to 16:00. All MIO staff are welcome to attend this seminar.
Theme : Seawater salinity: concepts, measurements and challenges
Speaker : Nicolas Kolodziejczyk - Assistant Physicist (CNAP) UBO - IUEM and LOPS, Brest, France
Abstract Ocean salinity is an essential ocean and climate variable (EOV/ECV). Along with temperature (and pressure), salinity defines the density of seawater through the equation of state of seawater. It therefore plays a fundamental role in ocean dynamics, thermodynamics and biogeochemistry. Salinity is also one of the key environmental parameters affecting the health of marine ecosystems. Finally, ocean salinity is a tracer of the water cycle and its evolution under the effect of global warming, since its distribution depends primarily on evaporation and precipitation, continental run-off and the ice formation and melting cycle.
Despite its importance for oceanography and climate science, the concept and measurement of seawater salinity, as a quantity of dissolved material, has continually been a challenge for geochemists and oceanographers. Since 2010, with the adoption of the Thermodynamic Equation of Seawater (TEOS-10) as the oceanographic standard, Absolute Salinity has become the pivotal variable for deriving the thermodynamic and dynamic parameters of seawater. However, oceanographers do not yet know how to measure Absolute Salinity directly and operationally.
In this presentation we will try to put the different concepts of salinity into perspective, as well as the challenges posed by its in situ measurement and remote sensing. Finally, we will illustrate some key oceanic processes driven by salinity in the global ocean, from the finest to the largest scales.
Photo credit: IUEM