Surface Ocean Circulation

What are two features of equatorial currents?

1. They are productive

2. Affect climate and weather on a global scale

Why are equatorial currents productive?

This is because of upwelling which is driven by Ekman transport moving water away from the equator

What is located along the equator?

North and south equatorial currents that both flow from east to west (North equatorial current is east to west in the north)(South equatorial current is east to west in the south)

What occurs between north and south equatorial currents?

Equatorial countercurrent that flows from west to east

Why does the equatorial countercurrent exist?

This is due to the position of the ITCZ north of the equator

What are east to west equatorial currents generated by?

Ekman transport from the trade winds

Describe in more detail how the North equatorial current is generated

Northeast Tradewinds are occurring North of the equator. Ekman transport is 90 degrees to the right of these NE Tradewinds

Describe in more detail how the South equatorial current is generated

Southeast Tradewinds are occurring South of the equator. Ekman transport is 90 degrees to the left of southeast Tradewinds

What do Southeast Tradewinds cross?

The equator to flow into the ITCZ (zone of low pressure caused by the warm, moist air)

Does direction of Ekman transport flip when it crosses the equator?

Yes it does

What drives the equatorial countercurrent?

90 degree to the right Ekman transport caused by SE Tradewinds is what drives the equatorial countercurrent

Why is ITCZ located north of the geographic equator?

This is because there is more landmass in the northern hemisphere and climatically that pulls it north of the equator.

Describe current steering that takes place for equatorial countercurrent

Countercurrent north of equator will turn south and countercurrent south of equator will turn north. This is all while the current is pinned to the equator and why it is a narrow, intense band.

What do trade winds normally cause in equatorial ocean?

Normally Tradewinds cause transport of warm water from the east to the west. This causes warm water to pile up over Australia and Indonesia

What happens during El Niño in equatorial ocean?

Tradewinds will relax (became weaker) so water isn’t pushed so hard over towards Australia and Indonesia. Warm water will flow back from West to east across the pacific.

Describe atmospheric pressure normally

Pressure is low in the west (Australia and Indonesia) (warm water and is wetter). Pressure is high in the east (colder water and dry)

Describe atmospheric pressure during El Niño

Low pressure will move to the east (becomes wetter) and high pressure in the west (becomes drier)

What happens during La Niña

Stronger trade winds which causes increased westward transport of warm water. There is intensified low pressure in the west (get flooding and too much rain) and high pressure in the east (drought in South America because of persistent high pressure)

What does ENSO stand for?

El Niño Southern Oscillation

What is El Niño?

Warming of the sea surface temperatures off the coast of South America

What is teleconnections? What is ENSO Teleconnections?

Is where the effects of this change in the distribution of pressure in sea surface temperatures is found around the globe. ENSO is found around the globe.

What is Southern Oscillation?

Oscillation in pressure that’s associated wit the change in atmospheric pressure

Does La Niña produce different effects to El Niño?

Yes