Salinity is an essential quantity to calculate many of physical
properties of oceans, but It is also a quantity hardly definable
considering the complexity of the middle in its bio-geo-chemical
composition and the imperfections of the existing measurement
techniques. The TEOS-10 gives several definitions to the notion of
absolute salinity, usable in function of the properties to study, but
they are based on the concept of a constant elemental composition of
seawater, so that, if its major inorganic components are well known,
its real composition vary in time and space and its determination is
still a challenge.
Most of salinity calculations are based on conductivity
measurements. This communication reviews other techniques which are
used or could be used to assess the absolute salinity of seawater, and
question about the mesurand of these techniques and the possibility to
redefine the concept of salinity from physical properties