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2. Objectives learn how El Niño and La Niña work
emphasize that the ocean & atmosphere are strongly coupled
understand that one component of the Earth’s system can have drastic effects on the rest of the Earth

3. El Niño: The Enigma
Unusual oceanic and atmospheric phenomenon - an anomaly
We don’t know everything about it
We can’t really predict it yet

4. El Niño: The Term First discovered in 1795
Recognized by local fisherman along Ecuador and Peru
Warm, surface countercurrent
North-->South
Discovered around Christmas-time
“The Christ Child”

5. El Niño Characteristics
Normally develops in W. tropical Pacific
Often results in natural disasters
Occurs every 2 to 10 years
Most recent and severe events in 1953, ‘57-’58, ‘65, ‘72-’73, ‘76-’77, ‘82-’83, ‘91-’92, ‘97-’98, ‘02-’04, ‘06-’07, ’09’10

6. Slides from 1982-’83 El Niño

9. -09-’10 INDEX = Air temperature Sea surface temp Surface winds
Cloudiness of sky
Sea level pressure
-09-’10

13. Pressure!!

16. Suppressed
Sea Surface
Elevated
Sea Surface

17. “Southern Oscillation” (SO)
Tradewinds weaken or fail
Tropical winds reverse and go east instead of west
Atmospheric pressure cells reverse
Wet areas become dry (drought)
Dry areas get flooded
“oscillates” like a giant sea-saw, taking 3-5 months

18. Non El Niño
El Niño

19. Coupled Ocean-Atmosphere
Circulation
Non El Niño
El Niño

20. Ocean’s Response to the SO
Warm water moves to the east
Elevates sea surface temperatures (SSTs) in SE Pacific
Shuts down upwelling, can induce downwelling
Reduces available nutrients
Kills fish and sea birds - especially bad off Peru

21. Non El Niño
El Niño

22. Animations

23. Ocean AND Atmosphere
El Niño is both an oceanic and an atmospheric phenomenon
Often called ENSO
Scientists knew of SO from wind and precip. data
Scientists knew of El Niño from SST data
Didn’t make connection until 1969

24. Jacob Bjerknes
Jacob Bjerknes, a Norwegian meteorologist made breakthrough in 1969
Combined wind, rain, AND SST data
Ocean & atm. part of “big climate engine”
Effects of ENSO not just local to Peru but could affect whole Pacific, whole world

25. Interdisciplinarity Rules!
Bjerknes was a meterologist who was willing to take a good, hard look at oceanographic data
Oceanography a versatile science

26. How Do We Track El Niño Today?
in situ (on site) measurements
Satellite sea surface temperature
Computer models

28. Autonomous Temperature Line Acquisition System

29. Tropical Ocn Global Atm
Tropical Atm-Ocn

30. La Niña NOT tied to the Southern Oscillation Tradewinds get stronger
SSTs are lowered in SE Pacific
Normal conditions are exaggerated
Dry areas get drier (drought)
Wet areas get wetter (floods)
Occurs in between El Niños

31. INDEX =
Air temperature
Sea surface temp
Surface winds
Cloudiness of sky
Sea level pressure

32. El Niño AND La Niña Both an ocean/atmosphere phenomenon
Both affect wind, rain, and SST
Both occur in cycles

33. More Animations

34. El Niño VERSUS La Niña “Southern Oscillation” Tradewinds fail
Reverse flow of air
Elevated SST
Upwelling decreased
Fish die
Dry areas flood
Wet areas dry up
No oscillation
Tradewinds increase
No reverse flow
Decreased SST
Upwelling increased
Fish thrive
Dry areas get drier
Wet areas flood

35. Lesson to be Learned Earth phenomena are very much interrelated
Ocean <----> Atmosphere
Bjerknes’ concept of “teleconnections”
We must understand in order to predict
Invest in soybean futures after an El Niño!
No fish meal for cattle, farmers will use soy

36. We’re dealing with the interplay between two very different fluids - atmosphere and ocean - in the boundless dimensions of time and space Abnormality in one causes abnormality in the other.... Events such as El Niños have no definite starting point and no end. It’s a matter of where you break into the scene, and where you leave it. Perhaps the only thing more complex is human behavior itself.
-- Dr. Jerome Namias, Scripps Institution of Oceanography