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 re
Trang 2learn 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
Trang 3El Niño: The Enigma
Unusual oceanic and atmospheric phenomenon - an anomaly
–We don’t know everything about it
–We can’t really predict it yet
Trang 4El Niño: The Term
–Discovered around Christmas-time
–“The Christ Child”
Trang 6Slides from 1982-’83 El Niño
Trang 15Suppressed Sea Surface Elevated
Sea Surface
Trang 16Tradewinds 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
“Southern Oscillation” (SO)
Trang 17Non El Niño
El Niño
Trang 18Non El Niño El Niño
Coupled Ocean-Atmosphere
Circulation
Trang 19Ocean’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
Trang 20Animations
Trang 21Ocean AND Atmosphere
El Niño is both an oceanic and an
atmospheric phenomenon
–Often called ENSO
Trang 22Jacob 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
Trang 23Interdisciplinarity Rules!
Bjerknes was a meterologist who
was willing to take a good, hard look
at oceanographic data
Oceanography a versatile science
Trang 24How Do We Track El Niño Today?
in situ (on site) measurements
Satellite sea surface temperature
Computer models
Trang 26Autonomous Temperature Line Acquisition System
Trang 27Tropical Atm-Ocn Tropical Ocn Global Atm
Trang 28La NiñaNOT 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
Trang 30El Niño AND La Niña
Both an ocean/atmosphere
phenomenon
Both affect wind, rain, and SST Both occur in cycles
Trang 31More Animations
Trang 32El Niño VERSUS La Niña
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
Trang 33Lesson 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
Trang 34We’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