Physical Properties of Seawater and Basic Circulation Flashcards
(47 cards)
Why are the oceans a key element in the climate system?
They transport heat and freshwater and exchange these with the atmosphere.
What is WOCE?
The World Ocean Circulation Experiement was a part of World Climate Research Programme which used resources from about 30 countries to make satelitte obervations of the global ocean between 1990 and 1998 to observe physical processes.
What are the main oceanic components in terms of salinity?
Na^+, Mg^2+, Cl-, SO4^2-
What does salinity variation depend on?
The balance between evaporation and precipitation and upon mixing between surface and the deep oceans/
What does excess evaporation and excess precipitation coincide with in terms of salinity?
Higher precipitation adds more freshwater and lowers salinity; higher evaporation increases the salinity
What are Isohalines??
They are lines joining points of equal salinity
What is the general N-S trend of oceanic salinity
Surface maximum at 20N and 20S where E>P and decreases towards equator and poles
What is the Halocline?
Area of strong below surface gradient in salinity
Where is the most vertical salinity variation?
Surface waters
What does sea surface temperature depend upon?
Incoming radiation depends on the latitude and the season
What are Isotherms?
Lines joining points of equal temperature
What is the thermocline?
The rapid change in temperature with depth
What is the general N-S trend of sea surface temperature?
Highest at equator, (warmest equator area in Pacific and Indian Oceans N of Australia. Temperature decreases with latitude increase toward poles.
What is the temperature difference in Low, Mid and High latitude profiles?
Low lats have the largest surface temperature gradient, High lats have smallest and mid lats are more intermediate.
Explain potential temperature of water.
The CTD measures the ‘in situ’ temperature of water because sea water is compressable any vertical movement of the water will cool or warm the water as it expands or contracts. The ‘potential temperature’ is essentially therefore the temperature a parcel of water would be if it were brought tot he surface.
What is Density of seawater a function of?
Temperature, salinity and pressure.
What is potential density?
The density of water should it be brought to a reference level such as the surface
What is the pycnocline?
A great change/ gradient in density.
Which is more dense, cold or warm water and salty or fresh water?
Colder water is denser, as is saltier water. Dense water will sink.
How can water masses be defined?
Water masses can be defined by T and S and hence by density. They maintain characteristics over great distances and time.
Name the 10 main oceanic water masses.
AABW (Antarctic Bottom water); CPW (Circumpolar water); NADW, (North Atlantic Deep Water); PDW (Pacific Deep Water); AAIW (Antarctic Intermediate Water), AIW: (Arctic Intermediate Water); MedW (Mediterranean Water); RedSW (Red Sea Water); Central Water; Surface Water
What are T-S diagrams
Diagrams that show non-linear relationship between temperature and salinity and can be used to assess density and stability.
What is meant by a stable water column?
Some common parameters analyzed in the water column are pH, turbidity, temperature, salinity, total dissolved solids, and other chemicals. A ‘stable’ water column is one where these ‘layers’ do not mix.
What do T-S diagrams show?
Show layering of water masses, a full line to show the situation prior to mixing and a dahsed line to show the water column after mixing.
