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 1 Figure 5-37

Circulation patternsWalker circulation 2 Figure 5-38

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

Patterns associated with El Niño ENSOSouthern oscillation La Niñaopposite of El Niño Causes of El Niño –Atmosphere changes first or ocean changes first? –Weather effects 4 Figure 5-40

Forecasting El Nino 5 Figure 5-B: Buoy array. Figure 5-C: Normal Conditions in tropical Pacific Ocean.

6 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 (Kaim-im-o-ana)