ObjectivesObjectives learn how El Niño and La learn how El Niño and La

Niña workNiña work emphasize that the ocean emphasize that the ocean

& atmosphere are & atmosphere are strongly strongly coupledcoupled

understand that understand that oneone component of the Earth’s component of the Earth’s system can have drastic system can have drastic effects on the effects on the rest ofrest of the the EarthEarth

El Niño: The EnigmaEl Niño: The Enigma

Unusual oceanic and atmospheric Unusual oceanic and atmospheric phenomenon - an anomalyphenomenon - an anomaly–We don’t know everything about itWe don’t know everything about it

–We can’t really predict it yetWe can’t really predict it yet

El Niño: The TermEl Niño: The Term

First discovered in 1795First discovered in 1795 Recognized by local fisherman along Recognized by local fisherman along

Ecuador and PeruEcuador and Peru–Warm, surface countercurrentWarm, surface countercurrent–North-->SouthNorth-->South–Discovered around Christmas-timeDiscovered around Christmas-time–““The Christ Child”The Christ Child”

El Niño CharacteristicsEl Niño Characteristics

Normally develops in W. tropical Normally develops in W. tropical PacificPacific

Often results in natural disastersOften results in natural disasters Occurs every 2 to 10 yearsOccurs every 2 to 10 years Most recent and severe events in Most recent and severe events in

1953, ‘57-’58, ‘65, ‘72-’73, ‘76-’77, 1953, ‘57-’58, ‘65, ‘72-’73, ‘76-’77, ‘82-’83‘82-’83, ‘91-’92, , ‘91-’92, ‘97-’98‘97-’98, ‘02-’04, , ‘02-’04, ‘06-’07, ’09’10 ‘06-’07, ’09’10

Slides from 1982-’83 El NiñoSlides from 1982-’83 El Niño

-09-’10

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

SuppressedSea Surface

ElevatedSea Surface

Tradewinds weaken or failTradewinds weaken or fail Tropical winds reverse and go east Tropical winds reverse and go east

instead of west instead of west Atmospheric pressure cells reverseAtmospheric pressure cells reverse

–Wet areas become dry (drought)Wet areas become dry (drought)

–Dry areas get floodedDry areas get flooded ““oscillates” like a giant oscillates” like a giant seasea-saw, -saw,

taking 3-5 monthstaking 3-5 months

““Southern Oscillation” (SO)Southern Oscillation” (SO)

Non El Niño

El Niño

Non El Niño El Niño

Coupled Ocean-AtmosphereCirculation

Ocean’s Response to the SOOcean’s Response to the SO Warm water moves to the eastWarm water moves to the east Elevates sea surface temperatures Elevates sea surface temperatures

(SSTs) in SE Pacific(SSTs) in SE Pacific Shuts down upwelling, can induce Shuts down upwelling, can induce

downwellingdownwelling Reduces available nutrientsReduces available nutrients Kills fish and sea birds - especially Kills fish and sea birds - especially

bad off Perubad off Peru

AnimationsAnimations

Ocean AND AtmosphereOcean AND Atmosphere El Niño is both an oceanic and an El Niño is both an oceanic and an

atmospheric phenomenonatmospheric phenomenon–Often called ENSOOften called ENSO

Scientists knew of Scientists knew of SO from from wind and wind and precip.precip. data data

Scientists knew of Scientists knew of El NiñoEl Niño from from SSTSST data data Didn’t make connection until 1969Didn’t make connection until 1969

Jacob BjerknesJacob Bjerknes Jacob Bjerknes, a Norwegian Jacob Bjerknes, a Norwegian

meteorologist made meteorologist made breakthrough inbreakthrough in 19691969

Combined wind, rain, AND SST dataCombined wind, rain, AND SST data Ocean & atm. part of “big climate Ocean & atm. part of “big climate

engine”engine” Effects of ENSO not just local to Peru Effects of ENSO not just local to Peru

but could affect whole Pacific, whole but could affect whole Pacific, whole worldworld

Interdisciplinarity Rules!Interdisciplinarity Rules!

Bjerknes was a meterologist who Bjerknes was a meterologist who was willing to take a good, hard look was willing to take a good, hard look at oceanographic dataat oceanographic data

Oceanography a versatile scienceOceanography a versatile science

How Do We Track El Niño Today?How Do We Track El Niño Today?

in situin situ (on site) measurements (on site) measurements Satellite sea surface temperatureSatellite sea surface temperature Computer modelsComputer models

Autonomous Temperature Line Acquisition System

Tropical Atm-Ocn

Tropical Ocn Global Atm

La NiñaLa Niña NOT tied to the Southern OscillationNOT tied to the Southern Oscillation Tradewinds get Tradewinds get strongerstronger SSTs are lowered in SE PacificSSTs are lowered in SE Pacific Normal conditions are exaggeratedNormal conditions are exaggerated

– Dry areas get drier (drought)Dry areas get drier (drought)– Wet areas get wetter (floods)Wet areas get wetter (floods)

Occurs in between El NiñosOccurs in between El Niños

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

El Niño AND La NiñaEl Niño AND La Niña

Both an ocean/atmosphere Both an ocean/atmosphere phenomenonphenomenon

Both affect wind, rain, and SST Both affect wind, rain, and SST Both occur in cyclesBoth occur in cycles

More AnimationsMore Animations

El Niño VERSUS La NiñaEl Niño VERSUS La Niña ““Southern Oscillation”Southern Oscillation” Tradewinds failTradewinds fail Reverse flow of airReverse flow of air Elevated SSTElevated SST Upwelling decreasedUpwelling decreased Fish dieFish die Dry areas floodDry areas flood Wet areas dry upWet areas dry up

No oscillationNo oscillation Tradewinds increaseTradewinds increase No reverse flowNo reverse flow Decreased SSTDecreased SST Upwelling increasedUpwelling increased Fish thriveFish thrive Dry areas get drierDry areas get drier Wet areas floodWet areas flood

Lesson to be LearnedLesson to be Learned

Earth phenomena are very much Earth phenomena are very much interrelatedinterrelatedOcean <----> AtmosphereOcean <----> Atmosphere

Bjerknes’ concept of “teleconnections”Bjerknes’ concept of “teleconnections” We must understand in order to predictWe must understand in order to predict Invest in soybean futures after an El Niño!Invest in soybean futures after an El Niño!

– No fish meal for cattle, farmers will use soyNo fish meal for cattle, farmers will use soy

We’re dealing with the interplay between two We’re dealing with the interplay between two very different very different fluidsfluids - atmosphere and ocean - in - atmosphere and ocean - in the boundless dimensions of time and space. ... the boundless dimensions of time and space. ...

Abnormality in one causes abnormality in the Abnormality in one causes abnormality in the other....other.... Events such as El Niños have no definite Events such as El Niños have no definite starting point and no end. It’s a matter of where starting point and no end. It’s a matter of where

you break into the scene, and where you leave it. you break into the scene, and where you leave it. Perhaps the only thing more complex is human Perhaps the only thing more complex is human

behavior itself.behavior itself.

-- Dr. Jerome Namias, Scripps Institution of Oceanography