Chapter 5 part 3: El Niño-Southern Oscillation• Warming of waters in the eastern equatorial Pacific

– Equatorial region off South America coast• El Niño – “the boy” reference to the Christ Child• Associated with numerous changes in weather patterns

worldwide• Typically occurs on time scales of 3 to 7 years for about 18

months

1Figure 5-37

Circulation patterns—Walker circulation

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Figure 5-38

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Figure 5-39: Bulge of warm water slowly moving across the equatorial Pacific Ocean.

• Patterns associated with El Niño

• ENSO—Southern oscillation

• La Niña—opposite of El Niño

• Causes of El Niño– Atmosphere changes first or

ocean changes first?– Weather effects

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Figure 5-40

Forecasting El Nino

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Figure 5-B: Buoy array.

Figure 5-C: Normal Conditions in tropical Pacific Ocean.

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Figure 5-D: El Nino Conditions in tropical Pacific Ocean.

Figure 5-E: La Nina Conditions in

tropical Pacific Ocean.

Summary:

•El Niño is a warming of eastern equatorial Pacific water and subsequent switching of the high and low air pressure patterns

•El Niño is associated with varied weather patterns in different locations globally 7

Cruise ship: Ocean Seeker (Ka’im-im-o-ana)