Oceans and Coastal Studies (currents + El Niño & La Niña) Flashcards
What are ocean currents?
Large scale, persistent & dominantly horizontal flow of water in the upper ocean
Ocean currents are driven by prevailing winds and play a crucial role in regulating global temperatures.
What drives ocean currents?
Prevailing winds
Energy is transferred from wind to water as air blows over the water surface.
How do warm and cold currents move?
Warm currents flow polewards from the equator; cold currents flow towards the equator from the poles
They are important regulators of global temperatures.
What is the Coriolis effect?
Objects that are travelling will be deflected due to Earth’s rotation
This affects wind and ocean currents.
What is thermocline?
Pattern/trend of change in temperature as depth changes
It can be represented by a line graph.
What happens to temperature as ocean depth increases?
The greater the depth, the lower the temperature
Deep ocean water is colder, denser, and moves due to higher relative pressure.
What is the global ocean conveyor belt?
Shows thermohaline circulation
It involves several stages of water movement, starting from cold, salty, dense water sinking in the northern polar region.
What is the Gulf Stream?
A warm surface current that moves warmer ocean waters from the Gulf areas of North America towards the east coast of the US and Canada
It becomes the North Atlantic drift.
What is upwelling?
When cooler waters become warmer and rise
It brings vital nutrients to the surface, particularly around Antarctica.
What is downwelling?
When warmer water is cooled and sinks
This helps renew oxygen-rich surface water.
What does the Walker circulation involve?
Trade winds blowing westward from South America over the Pacific Ocean
It results in cool and dry climates in Peru and wetter conditions in Asia.
What are the impacts of the El Niño phase?
Drier conditions in the west Pacific; warmer and wetter conditions in the east Pacific
It leads to droughts in Australia and floods in South America.
What characterizes the La Niña phase?
The usual Walker circulation returns stronger
It brings extremely strong winds and rains, leading to tropical storms in Asia.
Fill in the blank: The cold current weakens during ________ years.
El Niño
This leads to less upwelling of nutrients and depletion of fish stocks.
True or False: El Niño causes more rainfall in the west Pacific.
False
It typically leads to drier conditions in that region.
What is the temperature effect of the Walker circulation on the west Pacific?
3-8 degrees Celsius warmer than the East Pacific
This creates a low-pressure zone that draws in warm, moist air.
What happens to fishing during El Niño?
Fish migrate, causing fishing stock to be depleted
This is due to weakened upwelling of nutrients.
