Citation:Pawlowicz,R.(2013)Key physics Variables in the Ocean: Temperature, Salinity, and Density.chathamtownfc.net education and learning Knowledge4(4):13
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What execute oceanographers measure in the ocean? What room temperature and also salinity and how space they defined?

The physical properties the seawater include both "thermodynamic properties" like density and freezing point, and "transport properties" favor the electric conductivity and also viscosity. Thickness in particular is an important property in s science because small spatial alters in density an outcome in spatial sports in press at a provided depth, which subsequently drive the s circulation.

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Physical properties deserve to be measure up directly. However, direct measurements have the right to be facility to bring out, particularly in the field, and in many situations it is more convenient to measure a few important "state variables" on i beg your pardon the chathamtownfc.net depend, and then look up the preferred property as a function of the measure state in a table, or calculation it utilizing a mathematics formula. The table or formula the is offered is usually obtained from cautious laboratory measurements. Together a table or formula, once formally defined in a published paper and endorsed by a clinical authority, is well-known as a standard.

Physical properties vary v the amount of heat and also the lot of dissolved matter had in the water, and the ambient pressure. Crucial state variables measured for parcels that water in the s are thus temperature, i m sorry is pertained to the heat content, salinity, i beg your pardon is related to the lot of dissolved matter, and also the press (Table 1). In enhancement to managing physical properties, the sports in room and time of temperature and also salinity are additionally important water fixed tracers that deserve to be used to map the ocean circulation. Density is commonly calculated using a mathematical duty of temperature, salinity, and also pressure, sometimes called an equation of state. For plenty of years the internationally accepted standard for seawater densities has actually been the 1980 worldwide Equation that State, known by the acronym EOS-80. However, a brand-new international standard for seawater density, and all other thermodynamic properties, has actually recently to be developed. This brand-new standard is dubbed the Thermodynamic Equation that Seawater (2010), or TEOS-10. In turn, standards like EOS-80 or TEOS-10 count on other international standards the precisely specify the state variables that temperature and also salinity. Standards thus play crucial role in s science.

Variable ocean Range s Mean forced Accuracy Temperature -2°C come 40°C 3.5°C ±0.002°C absolute Salinity 0 g/kg come 42 g/kg 34.9 g/kg ±0.002 g/kg push 0 dbar to 11000 dbar 1850 dbar In-situ thickness 1000 to 1060 kg/m3 1036 kg/m3 ±0.004 kg/m3Table 1. ocean state variables, their usual ranges and mean values in the ocean, and the accuracy to which they space measured (or estimated) in the deep ocean. Pressures in the ocean are generally measured in dbar (decibars), with values offset to read zero at the surface. Pressure values expressed in this way are numerically similar (within 2%) to depth in meters listed below the surface. That is, the pressure at a depth the 1000 meter is about 1000 dbars.


What is temperature? This is more challenging to specify than it first appears. A textbook an interpretation (the Zeroth regulation of Thermodynamics) says:

"There exist a scalar quantity referred to as temperature, i beg your pardon is a building of every thermodynamic equipment (in equilibrium states) such that temperature equality is a necessary and also sufficient condition for heat equilibrium."

As a corollary come this definition, objects in contact with one an additional will tend toward thermal equilibrium by an exchange of heat between them. Thus, if we recognize the temperature the one object (call that a thermometer), and also it is in thermal equilibrium with water roughly it, i beg your pardon will occur after sufficient time has actually passed, we also know the temperature that the water. Conversely, if water and also a thermometer in ~ it are at different temperatures, then there need to be a flow of power (heat) between the water and also the thermometer. This gives us both a way of talking about energy and also a way of measure temperature utilizing a known reference.

In turn, the temperature that the thermometer have the right to be related to its physics properties. These physical properties incorporate the volume-to-mass ratio of a solid, liquid, or gas, or the electric resistance of a steel or a semiconductor. Temperature can therefore be determined through direct measurements of these properties.

But how do we define a numerical range for temperature, together measured by ours thermometer? The simplest method is to specify two referral points, plus a an approach that deserve to be offered to interpolate in between them. In 1742, Anders Celsius defined a temperature scale in which the freezing suggest of water (at sea-level pressure) was taken together a lower reference allude with a worth of 0, through the difference between the freezing suggest and the boiling allude (also in ~ sea level pressure) taken as 100 units, measure up in regards to the readjust in volume of a fluid.

As time walk on, much more and much more precisely specified interpretations (or standards) because that temperature became necessary as clinical questions required intercomparing an ext and much more accurate observations of temperature. However, in bespeak to keep a historical continuity, these redefinitions were generally formulated in together a method as to allow easy comparison v older observations. We thus still use the °C as a unit that temperature, and also water still freezes at about 0°C and also boils at around 100°C, although temperature scales space no longer characterized in terms of the freezing and also boiling point out of water.

An essential step in the history of temperature emerged in the 1800s, as soon as the principle of temperature acquired a theoretical backing through the advancement of the scientific research of thermodynamics. William Thomson (who later came to be Lord Kelvin) argued a thermodynamic temperature scale in i m sorry the ratio of temperatures above an "absolute zero" would certainly be in proportion to the heat took in and rejected by a theoretical construct dubbed a Carnot cycle engine, operating in between these 2 temperatures.

A thermodynamic range is therefore implicitly referenced to a reduced limit of pure zero, i beg your pardon is identified to be 0K (kelvin). The freezing allude of water was preferred to be a 2nd reference. By numerically defining the temperature the the freezing point of water to be 273.15K, the thermodynamic temperature the the boiling suggest is discovered to be 373.15K, 100 systems higher, so the an expression of 1K and 1°C are identical.

However, identify thermodynamic temperature is an extremely difficult, and also for most applications more practical approaches are needed. This practical definitions of temperature usually rely on solving the values of particular reference points based upon careful measurements of their thermodynamic temperatures, and also then specifying a method of interpolating in between them. Points in ~ which different phases of details materials co-exist are beneficial reference points. However, rather than boiling and also freezing points (which depend on the approximately pressure), far better fixed points take place at the triple point out of different substances. A triple allude is the single unique mix of temperature and also pressure in ~ which solid, liquid, and also gas phases that a particular substance deserve to all coexist.

The present standard because that temperature is the international Temperature range (1990), or ITS-90. In ITS-90, temperature in the variety of oceanographic interest are set by:

1. the triple point of mercury, defined to be ≡ -38.8344°C exactly

2. the triple point of pure water with a specified isotopic composition, identified to it is in ≡ 0.01°C (or 273.16K) exactly

3. the melting suggest of gallium, identified to it is in ≡ 29.7646°C.

In addition, a an approach of calculating temperatures between these reference points is additionally described by ITS-90. Such temperatures are interpolated making use of a specified polynomial duty of the measured electrical resistance the a platinum wire. Temperatures external the oceanographic range are identified using various other fixed points and methods that interpolation.

Temperatures stated using the previous global standard temperature range (the International handy Temperature scale 1968 or IPTS-68) differ from ITS-90 by as much as 0.01°C over the selection of oceanographic interest. Return our typical day-to-day activities usually don"t require accuracies of much more than around 0.1°C at best, a difference of 0.01°C is somewhat larger than the accuracy to which deep ocean measurements are now made (Table 1). Mindful adherence to requirements is as such necessary to allow us compare dimensions made by different people roughly the world, and also to compare modern measurements to dimensions made in the past and in the future.

Although in-situ temperature t identified by ITS-90 is normally the amount we measure, that is no the most advantageous variable for describing warm content itself. Two effects can cause problems. First, the energy required to readjust the temperature that seawater by a solved amount (say, 1°C), dubbed the warm capacity, is itself a duty of temperature and also salinity. It takes around 5% less energy to warm average seawater through 1° C 보다 it go to warmth the very same mass the freshwater by 1°C. Second, the effects of pressure have the right to act to change the in-situ temperature that water without transforming the warmth content. Squeezing common seawater (or air) reasons the temperature come rise. A pressure of 100 settings (or about 1000 dbar) is sufficient to boost measured seawater temperatures by around 0.1°C. However, the temperature that near-freezing new water actually falls as press increases.

To account because that the push effects, a variable called potential temperature, denoted θ, is traditionally supplied in oceanography. The potential temperature of a water thoreau is the temperature that would certainly be measured if the water parcel were enclosed in a bag (to prevent the loss or gain of any type of salt) and also brought to the s surface adiabatically (i.e., without exchanging any kind of heat with its surroundings). The potential temperature is because of this insensitive to press by definition, but is reduced than the in-situ temperature by around 0.1°C because that every 1000 m the depth increase (Figure 1a).


a) Vertical profiles of in-situ temperature t, potential temperature θ, and also Conservative Temperature Θ. Inset shows an broadened view that deep s values. Potential and also Conservative temperature space within 0.0003°C in the deep ocean. Note that warmth content (proportional come Θ) in reality decreases with depth, but pressure effects reason a increase in the in-situ temperature t. B) Vertical profiles of practical Salinity SP (with no units), referral Salinity SR, and Absolute Salinity SA. C) Vertical profiles of in-situ thickness (σ), potential density referenced to the sea surface ar (σθ), and also potential thickness referenced come 4000 dbar (σ4). Many of the in-situ thickness increase with depth is due to pressure effects, i beg your pardon are removed in the calculation of potential densities, showing exactly how weakly stratified the s actually is.

However, potential temperature does not account for the varying warm capacity of seawater, and is as such not a conservative measure of heat content. A variable is conservative if its value in a mixture of two parcels of seawater is the mean of its values in the two initial parcels. Conservative variables are very useful in make budgets. Return the warmth content that a mixture of two seawaters is the average heat content of the two, both the in-situ and also potential temperature that a mixture have the right to differ native the average temperature that the two initial parcels.

A different form of temperature, characterized in TEOS-10, much more precisely scale with heat content and is for all practical purposes conservative, and also insensitive to pressure. That is dubbed Conservative Temperature, and denoted Θ. Conservative Temperature differs from potential temperature by as much as 1°C for warm fresh waters, but is generally well within ±0.05°C for most ocean waters (Figure 1a).

Although the differences in between these different species of temperature space small, they can be substantially larger than the precision to which temperature dimensions of the s are routinely reported (Table 1). The is because of this important to do clear i m sorry temperature is under consideration in any kind of discussion.


Salinity is a measure up of the ‘saltiness" that seawater, or more precisely the lot of dissolved matter within seawater. Operationally, liquified matter is the which remains after pass the seawater with a really fine filter to eliminate particulate matter. Historically, a glass fiber filter v a nominal pore size of 0.45 μm was used. Much more recently, filters through 0.2 μm pores have become standard, since filters with this pore dimension will record the the smallest bacteria.

However, the background of the salinity concept, and its various meanings (which have adjusted over time) is a long and facility story, dating earlier to the so late 19th century. The story is complex for 2 reasons. First, any useful meaning of salinity has approximations of part kind. These approximations room necessary since the liquified matter in seawater is a complicated mixture of essentially every recognized element and also it is difficult to measure up the complete composition that every water sample. Second, subtle technical details of this approximations, which have undergone transforms as more has to be learned around seawater, are really important in practice. These details room important due to the fact that the required measurement accuracy for salinity, essential to know the ocean basic circulation, is exceptionally high (about ±0.006%, watch Table 1), so the even tiny changes in number values have the right to have significant implications if erroneously interpreted.

Most valuable definitions of salinity are rooted in the well-known fact that the relative ratios of many of the essential constituents the seawater room approximately continuous in the ocean (the principle of continuous Proportions). Therefore, practical but approximate procedures of the total dissolved content can be found by scaling measurements of a single property.

Originally the property most conveniently measured was the chlorinity, or halide ion (mainly Cl-and Br-) concentration. Chlorinity was measured utilizing a straightforward chemistry titration, and then convert to a measure up of salinity making use of a basic linear function. Together salinities can frequently be established by an attached unit of ppt, or the prize ‰.

However, virtually all contemporary estimates that salinity count on measurements of the electrical conductivity (or, in ~ high precision, on measurements of the proportion of the conductivity the a sample of seawater to the conductivity the a special reference material dubbed IAPSO conventional Seawater). Due to the fact that the electrical conductivity of seawater is also highly temperature-dependent, and also mildly pressure-dependent, temperature and pressure must also be measure up in this approach. The conversion indigenous measured temperature, pressure, and conductivity come salinity is facility and nonlinear. Due to the fact that the beforehand 1980s, oceanographers have used a calculated value formally called the helpful Salinity (denoted SP) together a proxy for true salinity. Helpful Salinity is defined as a duty of temperature, pressure, and also conductivity by another standard, the valuable Salinity range 1978 (or PSS-78). As soon as oceanographers use the word salinity they frequently mean helpful Salinity, although it is much better to use the full name to protect against ambiguity.

It is necessary to emphasize that useful Salinities do not have actually units. This fact, confusing come non-specialists, is concerned technical worries that impede an absolute definition when PSS-78 was constructed. Periodically this absence of devices is awkwardly taken on by additionally the acronym PSU (Practical Salinity Units) come the number value, although doing therefore is official incorrect and strongly discouraged. Handy Salinities are numerically smaller sized by about 0.5% than the mass fraction of liquified matter when this mass fraction is expressed together grams that solute every kilogram that seawater. Helpful Salinities were, however, defined to it is in reasonably equivalent with numerical worths of chlorinity-based salinities, to preserve a historical continuity.

The unique reference material used come calibrate salinity instruments, IAPSO traditional Seawater, is produced by a solitary company (Ocean Scientific global Ltd., UK) and also is produced using seawater derived from a particular an ar of the phibìc Atlantic. Back the usage of conventional Seawater to determine practical Salinity has been routine for many years, the dependency of valuable Salinity dimensions on a physics artifact recognized to degrade with period leads to a variety of technical problems, specifically in terms of the permanent stability and also intercomparability of high-precision s measurements.

The brand-new seawater typical TEOS-10 defines a better measure that the salinity, referred to as Absolute Salinity (denoted SA). This new meaning incorporates several functions designed to address the technical challenges discussed above and provides the best easily accessible estimate the the mass portion of liquified matter. It is usually linked with an attached unit of g/kg.

First, the meaning of salinity is no longer based upon properties of IAPSO traditional Seawater. Instead, the ideal estimates that the concentrations of the necessary inorganic components of conventional Seawater are supplied in TEOS-10 come exactly define an artificial seawater with referral Composition (Table 2). Because that practical and historical reasons, the meaning of recommendation Composition ignores dissolved organic matter, and most gases, although it otherwise consists of the most important constituents in real low-nutrient seawater.

recommendation Composition mmol/kg mg/kg Na+ 468.9675 10781.45 Mg2+ 52.8170 1283.72 Ca2+ 10.2820 412.08 K+ 10.2077 399.10 Sr2+ 0.0907 7.94 Cl- 545.8695 19352.71 SO42- 28.2353 2712.35 Br- 0.8421 67.29 F- 0.0683 1.30 HCO3- 1.7178 104.81 CO32- 0.2389 14.34 B(OH)3 0.3143 19.43 B(OH)4- 0.1008 7.94 CO2 0.0097 0.43 OH- 0.0080 0.14 it was observed Variations checked out in genuine seawater O2 0 - 0.3 0 - 10 N2 0.4 14 Si(OH)4 0 - 0.17 0 - 16 NO3- 0 - 0.04 0 - 2 PO4- 0 - 0.003 0 - 0.2 ΔCa+ 0 - 0.1 0 - 4 ΔHCO3- 0 - 0.3 0 - 20 liquified Organic matter (DOM) – 0 - 2 Table 2. reference Composition the seawater v SP ≡ 35.000 and also SR ≡ 35.16504 g/kg. Concentrations in seawater of higher or reduced salinities can be found approximately by scaling all worths up or under by the same factor. Units of concentration are per kilogram of seawater. Genuine seawater contains additional constituents which space not had in the referral Composition yet whose concentrations (and your variation) may be larger than 1 mg/kg. Concentration of this constituents execute not boost or decrease through salinity however are largely controlled by biogeochemical processes.

Next, a numerical reference Salinity (denoted SR) is defined, representing the mass portion of solute in this reference Composition seawater. Reference Salinity has actually units the grams of solute per kilogram that seawater, and also is numerically determined by multiplying the concentrations of the different components of the recommendation Composition by your atomic weights, and then summing. Salinities identified in this way are said to lied on the referral Composition Salinity Scale. Keep in mind that suspicion in the atomic weights themselves contributes an uncertainty of around 1 mg/kg come this definition.

Standard Seawater is now treated as a physical artifact that approximates referral Composition Seawater. A specific sample of typical Seawater is then assigned a reference Salinity top top the referral Composition Salinity Scale. This recommendation Salinity is numerically different from the useful Salinity of the sample (Figure 1b), however it deserve to be obtained from the conductivity-based handy Salinity making use of a simple scaling. However, reference Salinity can also be approximated using various other approaches (e.g., by straight measurements the density and inversion that the TEOS-10 equation the state).

Although the an interpretation of the referral Composition provides a conventional for the an interpretation of the salinity of standard Seawater, once considering actual seawaters second problem arises. This is due to the fact that the loved one chemical ingredient of seawater is in reality slightly various in various geographic locations. The most crucial variations that occur in the real s arise from alters in the carbon system, and in the concentrations of Calcium (Ca2+) and the macronutrents nitrate (NO3-) and also silicic acid (Si(OH)4) (Table 2). This constituents are impacted by biogeochemical processes in the ocean. They are removed by the formation of organic material, and also returned through its dissolution.

When utilizing PSS-78 these changes in loved one composition room ignored. However, this way that waters that the same practical Salinity, from different parts the the ocean, might contain different mass fountain of liquified matter. The difference can be as large as 0.025 g/kg in the open ocean (Figure 1b). In seaside waters, wherein the visibility of flow salts is second factor, the distinction can it is in as large as 0.1 g/kg. Differences of this dimension are an ext than an bespeak of magnitude bigger than the precision to which salinity is reported (Table 1).

Under TEOS-10 these changes in the family member composition are explicitly accounted because that in the an interpretation of pure Salinity. The TEOS-10 pure Salinity have the right to be established by very first measuring the electric conductivity, temperature, and pressure of a water parcel, together before. Then referral Salinity is calculated as if the water had actually Reference Composition. Finally, a small correction aspect is added to account because that the compositional variations. This correction, additionally known together the salinity anomaly, is denoted ΔSA. It is about correlated through the concentration of macronutents in seawater, and is biggest in the deep north Pacific, where these concentrations are greatest.


The most important thermodynamic residential property of seawater for studies of oceanic circulation is its thickness (denoted ρ). Typical densities span a narrow selection (Table 1, figure 1c).

It is because of this conventional in discussions the the s to usage a obtained variable σ because that density, where

σ = ρ/(kg/m3) - 1000

so the the top "10", virtually always present in numerical values of density, is dropped. Because that example, a density of 1027.534 kg/m3 would generally be composed as a σ-value of 27.534 kg/m3.

Density counts on warmth content and also salinity. Due to the fact that seawater is not perfectly incompressible, it likewise varies slightly through pressure. The sports of σ with Conservative Temperature and also Absolute Salinity have the right to be illustrated using a T-S diagram, or much more properly a Θ-SA diagram (Figure 2). A water parcel v a specific Θ and also SA is plotted as a allude in such a diagram. By calculating the thickness at all possible points (keeping push fixed at a mentioned value), and contouring the calculation values, isopycnal lines deserve to be drawn on the diagram joining together various combinations the temperature and salinity that an outcome in the exact same density.


A diagram deserve to be offered to highlight relationships in between temperature, salinity, and also density for different water masses." />
Figure 2:This Θ -SA diagram have the right to be offered to highlight relationships in between temperature, salinity, and density for various water masses.
Lines of consistent σ space contoured in ~ the surface ar (red curves for ns = 0 dbar), and also at about 1100 m depth (blue curves, ns = 1100 dbar). Close to the surface water masses A and B, with various temperatures and Absolute Salinities, both have σ ≈ 27 kg/m3, v the density of water A slightly much less than the thickness of water B. However, at 1100 dbar whereby σ ≈ 32 kg/m3 water fixed A is more dense than water massive B.

As one would expect, more saline waters at a particular temperature are more dense. Raising the absolute Salinity by about 1 g/kg increases density by around 0.8 kg/m3. However, isopycnal lines joining water varieties of different temperature and also salinity however the same density are no straight. Instead, they room curved, v a right-facing concavity. The curvature of the isopycnals mirrors that the effects of temperature on density are very much greater in heat waters (i.e., near the surface in the tropics) than they room in cold waters discovered at depth and also in the polar regions.

However, over there is constantly a small temperature effect, and also so the isopycnal curves never come to be vertical because that seawaters v salinities common of the open up ocean. Although preferably densities take place at temperatures of approximately 4°C for fresh waters, for absolute Salinities higher than 23.8 g/kg, seawaters in ~ the freezing suggest are many dense. Freezing temperature also decreases through salinity, with typical seawater freezing at roughly -1.9°C in ~ atmospheric pressure.

The curvature of the isopycnals gives rise come a phenomenon known as cabbeling, or a contraction on mixing. Think about two water masses, A and also B, with different Conservative Temperature and also Absolute Salinity, which space plotted at various locations top top the Θ-SA diagram (Figure 2). Water mass A is fresher, but colder, than water fixed B. However, close to the surface as soon as pressure is 0 dbar, the thickness of every water fixed is less than or same to 1027 kg/m3, together the clues representing these water masses space on or left the the 27 kg/m3 isopycnal (red curves in figure 2). The Conservative Temperature and also Absolute Salinity that a mixture of two water masses will certainly lie along the straight line (the "mixing line") joining castle in this diagram. However, the curvature of the isopycnals means that the density of this mixture may be to the appropriate of the 27 kg/m3 isopycnal (i.e., its density may be greater than 1027 kg/m3). This boost in density is crucial in the southerly Ocean. There, various water masses on the surface can be lugged together by ocean currents. The parcels mix, and also after mix together, the denser blended water that results sinks below the surface.

If we draw this chart at higher pressures (e.g., blue curve in number 2), the general features remain the same, however quantitative facets can change. An obvious readjust is the the freeze temperature decreases through pressure. For this reason meltwater native the base of thick Antarctic ice shelves, which is at the freezing point at depth when pressures are high, can become supercooled after climbing upwards in the water column. Such waters are daunting to measure up as instruments lowered into them rapidly end up being coated in ice cream crystals. Also, as push increases, the isopycnals perform not stay in the same location in the diagram. Instead, densities rise with pressure and the isopycnal curves relocate leftwards. Isopycnals calculated at a push of 1100 dbar present that densities because that a given Θ and also SA are around 5 kg/m3 higher than they are at the surface.

This boost in thickness with pressure is a trouble when trying to decision which of two water parcels in the ocean, initially at various depths, would be lighter than the various other if lock were brought together. This is because the pressure impacts often result in the largest obvious differences (Figure 1c). Instead of to compare the in-situ densities, it is much more useful to to compare the densities as if both parcels are lugged adiabatically to the same recommendation pressure. As soon as this reference press is taken to be at the surface, the resulting measure up of thickness is referred to as potential density, denoted σθ.

However, in enhancement to normally moving leftwards as push increases, the isopycnals on this diagram additionally rotate slightly. The isopycnals calculated in ~ 1100 dbar room tilted rightward family member to those calculated at 0 dbar. The density of warmer waters does not increase quite as much as the density of chillier waters because that the same adjust in pressure. Thus, two water parcels with various temperatures and also salinities yet the same density at the surface ar (i.e., with the same potential density) will in fact have slightly different densities at one more depth also if their warm content and also salinity remain the same. This is called the thermobaric effect. In deep convection areas, i m sorry are locations in the Labrador and also Greenland seas, and in part locations approximately Antarctica where surface water is cooled and also eventually sinks to depths of numerous thousand meters, the thermobaric effect can be crucial in accelerating downward convection, result in huge vertical displacements in the position of water parcels.

On the various other hand, the rotation the isopycnals can also lead to mistakes in the translate of potential density. Take into consideration water parcels A and B in number 2 again. Close to the surface, thoreau B is slightly an ext dense 보다 parcel A. However, in ~ 1100 dbar, thoreau A is slightly much more dense 보다 parcel B. If we room trying to decide which of the 2 water masses is heavier at depths near 1100 dbar, then comparing potential densities will offer an untrue answer. This difficulty is vital factor in correctly understanding water characteristics near the bottom that the south Atlantic. There, waters with larger potential density are it was observed to lie above waters with smaller sized potential density, i m sorry at first glance argues a large instability. However, the shallower water mass is heavier than the depths water mass only if both are brought to the surface. If both are carried to the s bottom, the shallower water fixed is lighter 보다 the depth water mass and one can conclude that the water pillar is stably stratified.

when comparing various water masses it is because of this best to minimize the effects of this isopycnal rotation. Thus, as soon as comparing different water masses near, say, 4000 m (especially in the south Atlantic), frequently densities are pressure-corrected to exactly 4000 dbar fairly than to the surface. The result potential thickness referenced to 4000 dbar is denoted together σ4 (Figure 1c). Deciding which measure of thickness to usage in oceanographic analyses can be challenging, and also is quiet an area of recurring research.

The key reference toTEOS-10, and also the details of just how conservation of power (i.e. The first Law ofThermodynamics) is taken on in the ocean, is the manual:

IOC, SCOR and also IAPSO, The worldwide thermodynamic equation ofseawater - 2010: Calculations and use the thermodynamic properties.Intergovernmental Oceanographic Commission, Manuals and Guides No. 56, UNESCO (English), 196 pp. (2010). Http://www.teos-10.org in addition to softwareand various other information.

Complete details ofITS-90 space in

Preston-Thomas, H.,
The worldwide Temperature range of 1990, Metrologia 27, 3-10, (1990).

Additional informationabout ITS-90 is offered at http://www.its-90.com.

PSS-78 and also EOS-80 aredescribed in 2 special reports (that are mainly a compendium that journalarticles):

UNESCO, Backgroundpapers and also supporting data top top the handy Salinity scale 1978, UNESCOTechnical files in naval Science 37,144 pp. (1981).UNESCO, Backgroundpapers and supporting data ~ above the global Equation that State that Seawater1980, UNESCO Technical records in naval Science 38, 192 pp. (1981).

Many that the intricatedetails associated in PSS-78 are likewise found in the articles contained in:

Special issue on the useful SalinityScale 1978, IEEE J. Oceanic design 5, 1-62 (1980).

More details ~ above theactual composition of sea and river waters, and their impacts on variousmethods of determining density and/or salinity have the right to be discovered in:

Millero, F.J., ChemicalOceanography, Boca Raton Fl: CRC Press, (2005).

Basic informationabout thermodynamic temperatures and the Carnot cycle can be uncovered in anyintroductory physics text, e.g.

Halliday D., and R. Resnick, Fundamentals that Physics, Wiley, (various editions and also years).

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Less technical articlesdescribing the civilization and background behind few of the scientific concerns relatedto seawater salinity and also density have the right to be discovered at:

Pawlowicz, R. Et al.. An historical perspective top top thedevelopment the the Thermodynamic Equation the Seawater - 2010, s Sci. 8, 161-174, (2012).Millero, F. J., history of the Equation of Stateof Seawater, Oceanography 23(3), 18-33, (2010).