The Thermosalinograph or TSG is an
measuring instrument
Instrumentation is a collective term for measuring instruments, used for indicating, measuring, and recording physical quantities. It is also a field of study about the art and science about making measurement instruments, involving the related ...
mounted near the water intake of
ships
A ship is a large vessel that travels the world's oceans and other navigable waterways, carrying cargo or passengers, or in support of specialized missions, such as defense, research and fishing. Ships are generally distinguished from boats, ...
to continuously measure
sea surface temperature
Sea surface temperature (or ocean surface temperature) is the ocean temperature, temperature of ocean water close to the surface. The exact meaning of ''surface'' varies in the literature and in practice. It is usually between and below the sea ...
and
conductivity while the ship is in motion.
Various
programs have been developed to assist in the collection and analysis of data from a TSG. The data can be used to calculate
salinity
Salinity () is the saltiness or amount of salt (chemistry), salt dissolved in a body of water, called saline water (see also soil salinity). It is usually measured in g/L or g/kg (grams of salt per liter/kilogram of water; the latter is dimensio ...
,
density
Density (volumetric mass density or specific mass) is the ratio of a substance's mass to its volume. The symbol most often used for density is ''ρ'' (the lower case Greek letter rho), although the Latin letter ''D'' (or ''d'') can also be u ...
,
sound velocity
The speed of sound is the distance travelled per unit of time by a sound wave as it propagates through an elastic medium. More simply, the speed of sound is how fast vibrations travel. At , the speed of sound in air is about , or in or one m ...
within the water, and other parameters. There are various types of thermosalinographs available on the market today.
Background
Programs collecting TSG data
NOAA fleet
Ship of Opportunity Program (SOOP)
Global Ocean Observing System (GOOS)
GOSUD Global Ocean Surface Underway Data (http://www.gosud.org)
Measurement devices
The thermosalinograph uses a conductivity cell to measure
conductivity, which can then be translated into a value of
salinity
Salinity () is the saltiness or amount of salt (chemistry), salt dissolved in a body of water, called saline water (see also soil salinity). It is usually measured in g/L or g/kg (grams of salt per liter/kilogram of water; the latter is dimensio ...
. Also a
thermistor
A thermistor is a semiconductor type of resistor in which the resistance is strongly dependent on temperature. The word ''thermistor'' is a portmanteau of ''thermal'' and ''resistor''. The varying resistance with temperature allows these devices ...
cell measures the
temperature
Temperature is a physical quantity that quantitatively expresses the attribute of hotness or coldness. Temperature is measurement, measured with a thermometer. It reflects the average kinetic energy of the vibrating and colliding atoms making ...
of the surface water, which when combined with the conductivity can be used calculate the
density
Density (volumetric mass density or specific mass) is the ratio of a substance's mass to its volume. The symbol most often used for density is ''ρ'' (the lower case Greek letter rho), although the Latin letter ''D'' (or ''d'') can also be u ...
of the water and the
sound velocity
The speed of sound is the distance travelled per unit of time by a sound wave as it propagates through an elastic medium. More simply, the speed of sound is how fast vibrations travel. At , the speed of sound in air is about , or in or one m ...
within it.
Types
Sources of error
Water is measured in the engine room, which can cause biases from heat in the room.
[Saur, J. F. T., 1963: A study of the quality of sea water temperatures reported in logs of ships weather observations. J. Appl. Meteorol., 2, 417–425]
References
Water transport
Measuring instruments
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