What is the equation of state for seawater?
The equation of state (EOS) for seawater is a diagnostic equation for the density in terms of temperature, salinity, and pressure. The international equation of state for seawater, IES80 (UNESCO 1981), gives the most widely accepted representation of this relation.
How does salinity affect thermodynamics?
When NaCl is added to H2O, the critical region migrates to higher temperature and pressure. However, the absolute magnitudes of thermodynamic properties that are defined as temperature and/or pressure derivatives (α, β, and cf) all decrease with increasing salinity.
How does salinity change with temperature?
The density of seawater (salinity greater than 24.7) increases as temperature decreases at all temperatures above the freezing point. The density of seawater is increased by increasing pressure. Between 4°C and the freezing point, the density of pure water decreases as temperature decreases.
What is the relationship between the temperature and salinity of water?
Increases in temperatures of surrounding entities like ice and an increase in precipitation adds fresh water into the sea, which lower salinity. Seawater with lower salinity is lighter in density and won’t sink as much as denser water.
How do you calculate salinity?
Calculate salinity, using the formula: salinity (ppt) = 0.0018066 5 Cl– (mg/L). 1. This test can be conducted on site or in the lab.
How do you find the density of seawater from temperature and salinity?
It can be approximated as: ΔDensity = α*ΔT+β*ΔS α and β are coefficients of thermal expansion and saline contraction. α is roughly 0.2 kg m-3 °C-1 β is roughly 1 kg m-3 psu-1 These values are where the 15°C and 3 psu come from. In the ocean, α and β also depend on salinity, temperature, and pressure.
How does salinity affect density of seawater?
The density of seawater depends on temperature and salinity. Higher temperatures decrease the density of seawater, while higher salinity increases the density of seawater. Seawater will become stratified with less dense water on the surface and more dense water below it.
What is the relationship between ocean salinity and density?
Salinity and density share a positive relationship. As density increases, the amount of salts in the water—also known as salinity, increases. Various events can contribute to change in the density of seawater. Salinity can decrease from the melting of polar ice or increase from the freezing of polar ice.
What changes the salinity of ocean water?
Evaporation of ocean water and formation of sea ice both increase the salinity of the ocean. However these “salinity raising” factors are continually counterbalanced by processes that decrease salinity such as the continuous input of fresh water from rivers, precipitation of rain and snow, and melting of ice.
What are the factor affecting the salinity of the sea water?
Salinity of seawater is affected by evaporation, precipitation, ice formation, and ice melting. Evaporation increases the salinity of seawater because when seawater evaporates, the salts are left behind, thus increasing their concentration.
What Happens When ocean salinity increases?
As the salinity of water increases, the freezing point decreases (29), meaning that an ocean of higher salinity has less potential to form sea ice and therefore remains ice free at much lower temperatures.