February 8th lecture Flashcards
Ekman transport can lead to weer being piled up or being removed from an area. What is this called?
When water piles up it is called Convergence
When water is removed it is called divergence
If the winds blew continuously would we see a continual pile up or removal of water? why?
no we would not see a continual pile up or removal of water?
Other motions tend to try and restore the sea surface towards a “flat”state.
What are the motions that try and restore the ocean back to a flat state?
They are Horizontal pressure gradients
How do pressure gradients work in the ocean?
Pressure gradient forces move water from high
pressure regions under an elevated sea surface to
low pressure regions
What is the difference between Ekman transport and pressure gradient transfer?
Unlike Ekman motion, pressure gradients transfer occurs at all depths where a pressure gradient may be found
Can Ekman transport and Pressure gradient transport flow in opposite directions?
Pressure flow in deeper layers may oppose the Ekman transport
What is a result of Pressure gradient movement in the ocean
It produces upwelling and downwelling
What must we consider if pressure gradient forces generate motion?
The Coriolis effect
How does the Coriolis effect alter the flow of Pressure gradients?
As the water parcel starts to move, it is deflected by the coriolis effect so that the direction of flow is no longer directly down the pressure gradient.
How are pressure gradients balanced by the Coriolis effect? What happens to the resulting current?
Flows are accelerated and deflected until the pressure gradient is balanced,
The resulting Geistrophic current is thus deflected 90 degrees to the right of the pressure gradient in the northern hemisphere
What is a Geostrophic current?
A current that is produced by the balance between the pressure gradient force and the Coriolis force with the direction of the flow 90 degrees to the right of the pressure gradient in the northern hemisphere.
What direction is the pressure gradient deflected in the southern Hemisphere die to the Coriolis effect?
The flow is 90° to the left of the pressure gradient in the southern
hemisphere
In real world applications do we ever see actual geostrophic currents?
No, other affects come into play such as friction.
What are ocean currents inintaed by?
Ekman transport
What are surface currents maintained as>?
Geostrophic currents
how deep do open ocean surface currents go?
they generally reach a few hundred meters deep although some can reach as far as 2km
What is a Sverdrup?
one typical ocean unity of volume transport
What is ekman transport based on? what does it lead to?
it is based on large scale atmospheric circulation.
Leads to bands of convergence and divergence
What do Ekman transport chains lead to?
large scale geostrophic currents that would flow around the earth.
What can alter the circulation of gyers?
The presence of land
Where in the world can currents flow all around the world?
in the south of the southern hemi-sphere
At most latitudes waht type of currents do we get due to the presence of land deflecting currents?
Zonal currents
What are gyers>
Closed circulation loops within the ocean
What are subtropical gyers?
gyes which flow clockwise or anti-cyclonic in the northern hemi-sphere
What are sub-polar gyers?
Gyers that flow counter clockwise or cyclonic in the northern hemisphere
