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“El Niño -
Southern Oscillation”Outline:Outline: What is El Nino?What is El Nino? How does it work?How does it work? What affect does El Niño What affect does El Niño
have on California?have on California?
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What is El Niño?
• El Niño is:
• El Niño occurs:
• The name, “El Niño” (means ‘boy child’ in
Spanish) as it often occurs around Christmas
time.
a warming of the equatorial eastern Pacific Ocean
about about once every 2 to 7 years
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Normal Conditions
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El Niño Conditions
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‘Normal’ conditions (sea surface temps)
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El Niño (sea surface temps)
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How does El Niño work?
El Niño is a coupled ocean-atmosphere process• It involves:
1. _____________ of the trade winds
2. __________of the eastern equatorial Pacific
3. _______ movement of the heavy rain region
4. _________ pressure in the west and reduced pressure in the east
WeakeningWeakening
WarmingWarmingEastwardEastwardIncreasedIncreased
Normal conditions:
warm water and rain in the west Pacific
El Niño conditions: warm water and rain in the central Pacific
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ENSO (El Niño-Southern Oscillation)
• The Southern Oscillation:– is the part of El Niño
– The Southern Oscillation Index is the pressure difference between Tahiti and Darwin,
– During El Niño, the pressure is _______ in the west and _______ in the east
– During El Nino, the Southern Oscillation Index is (positive/negative).
higherhigher
lower
atmospheric
Pressure(Tahiti) – Pressure(Darwin)
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Southern Oscillation Index
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How does El Niño affect the other parts of the globe
• http://www.usatoday.com/weather/tg/wninogrf/wninogrf.htm
• May change ‘normal’ storm tracks
• i.e. – Warmer and drier in pacific northwest– Wetter in California– Wetter over Southern States
• Some areas flood, other areas have drought
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m
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El Niño
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El Niño…
• …is an important modifier of local climates
• …may change global wind patterns
• …can cause floods or drought
• …is NOT a storm!!!
• …is pretty fascinating!!!
