Why measure seawater temperature and salinity?

　Since the vertical movement and mixing of seawater is governed by density differences, the movement of water has been studied from the density differences of water by measuring salinity and water temperature.

　Water masses in a given area and at a given depth have a certain characteristic (unique) range of salinity and temperature. To understand the movement and mixing of water masses, it is fundamental to investigate water temperature and salinity.

　Currently, the electrical conductivity of seawater is measured and converted to salinity. The density is obtained from the salinity and water temperature. An oceanographic observation device equipped with sensors for electrical conductivity (C), temperature (T), and depth (D) is called a CTD sensor. The basic oceanographic observation is to investigate the structure of water masses by lowering the CTD sensor below the sea surface on an observation vessel.

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Reasons for measuring salinity and temperature of seawater (summary)

１）Calculate density and investigate water flow
２）Investigate water mass-specific salinity and temperature ranges

Methods：CTD sensor
C : Conductivity
T : Temperature
D : Depth
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