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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

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