February 1st lecture Flashcards
What is the mixed layer?
homogeneous layer at the ocean’s surfcae within which oceanic properties ( T and S ) change very little.
When is the Mixed layer deepest?
During the winter
When is the mixed layer the shallowest?
in the summer
What does the seasonal change of the mixed layer allow the surface water to do?
It allows for the surface layer of the ocean to be take up by the interior of the ocean (subduction)
What factors influence the mixed layer depth? ( 6 things )
- Wind driven mixing
- Stability of underlying water
- Surface buoyancy changes
- Surface heating or cooling
- provision of freshwater to the oceans surface
- Large scale ocean circulation
The competition of what two things leads to the Stratification process?
heating/river runoff and cooling/tidal and wind mixnig
What does Heating and river run off do to the mixed layer?
Acts to stratify fluid ( layer the surface )
What does cooling/Wind and tidal mixing do to the mixed layer?
acts to mix fluid vertically
What is the density of sea water dependent on?
Temperature, Salinity and pressure
How does pressure affect ocean density?
although water is basically incompressable due to how close their molecules are to one another ,there are still small changes in volume and density that occur due to pressure changes.
When is water compressed in the ocean?
In the deep ocean where pressures are 1000x that of the atmospheric pressure, water is compressed by 25
How does Temperature influence density?
Density decreases as temperature increases
How does Salinity influence density?
Increasing salinity increases density
What is density
The interplay of Temperature and salinity to determine the density of water
Where are temperature changes most important to the alteration of density?
in the tropics, where the slope of density line is greater for temperature than salinity
What has a larger effect on the whole ocean’s density? T or S?
Salinity has a much greater effect, as most of the ocean is cold, thus a temperature change in a local area will not effect the densities of waters around it.
Where is salinity change most important in the change in density?
In the higher latitudes, where the slope of density line greater for salinity than for temperature.
What is the Equation of state?
a complicated equation that describes how ocean density depends on temperature and salinity as well as pressure
In general how do we determine density?
Density is meaused through a calculation from observational measurement of temperature, salinity, and pressure.
What is the avarge surface density of the ocean?
1026 kg m-3
What is the Pycoline?
A depth range in the ocean where density changes rapidly in the vertical due to changes in Temperature, salinity and pressure
Where is the Pycoline usually?
Normally at a depth of 100 - 500m depth
What is a thermocline?
It is when there is a rapid change of density associated with temperature
What is a Halocline?
A rapid change in density associated with salinity
