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Objectives u learn how El Niño and La Niña work u emphasize that the ocean & atmosphere are strongly coupled u understand that one component of the Earth’s.

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Presentation on theme: "Objectives u learn how El Niño and La Niña work u emphasize that the ocean & atmosphere are strongly coupled u understand that one component of the Earth’s."— Presentation transcript:

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

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

5 El Niño Characteristics u Normally develops in W. tropical Pacific u Often results in natural disasters u Occurs every 2 to 10 years u 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

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

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13 Pressure!!

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16 Suppressed Sea Surface Elevated Sea Surface

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

18 Non El Niño El Niño

19 Non El NiñoEl Niño Coupled Ocean-Atmosphere Circulation

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

21 El Niño Non El Niño

22 Animations

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

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

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

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

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28 Autonomous Temperature Line Acquisition System

29 Tropical Atm-Ocn Tropical Ocn Global Atm

30 La Niña u NOT tied to the Southern Oscillation u Tradewinds get stronger u SSTs are lowered in SE Pacific u Normal conditions are exaggerated –Dry areas get drier (drought) –Wet areas get wetter (floods) u 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 u Both an ocean/atmosphere phenomenon u Both affect wind, rain, and SST u Both occur in cycles

33 More Animations

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

35 Lesson to be Learned u Earth phenomena are very much interrelated Ocean Atmosphere u Bjerknes’ concept of “teleconnections” u We must understand in order to predict u 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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