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Published byLouisa Bennett Modified over 9 years ago
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El Niño/Southern Oscillation Major climatic perturbation on the planet Coupled atmosphere ocean process Key is the western tropical Pacific – Ascending branch of the Walker circulation – Potential energy for Kelvin wave pulse www.pmel.noaa.gov/tao/elnino/nino-home.html
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The Southern Oscillation Discovered in 1928 by Sir Gilbert Walker Links ’ s in global climate indices Proposes a zonal circulation cell over the equatorial Pacific
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The Southern Oscillation
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Pressure ’ s regulate strength of the trades El Niño periods = weak trades
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Southern Oscillation Index SOI = Tahiti - Darwin air pressure ’ s Low SOI = El Niño conditions
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Southern Oscillation Index
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Southern Oscillation
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Walker Circulation East-to-west pressure gradients drive trades
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Walker Circulation Vertical cell driven by warmest waters
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Western Pacific Warm Pool
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Coupled Walker/Ocean Circulation
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TOGA-TAO Array Equatorial array of buoys (also Atlantic & Indian) U.S., Japan, India, French, etc. partnership http://www.pmel.noaa.gov/tao/
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Moorings Measure met & ocean properties Thermocline focus Real-time data transmission Used in weather & climate forecasts
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TAO Moorings
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Southern Oscillation
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El Niño Conditions
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El Niño Events Relaxation of trades causes warm pool to slosh across Pacific basin
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El Niño Conditions
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La Nina Opposite phase of the ENSO cycle Intensified trades & Walker circulation Thermocline undergoes maximum upwelling
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Altimetry & ENSO States Most “ action ” is in the tropical Pacific Effects are seen in other places – East subtropics – Western NECC region
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Equatorial Kelvin Waves Satellite altimetry from TOPEX/Poseidon Scenes are 10 days apart
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Equatorial Kelvin & Rossby Waves
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Off-Equatorial Rossby Waves Equatorial Kelvin Waves
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Planetary Waves & El Niños
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Effects of an El Niño Region of ascending air has moved to center of equatorial Pacific Climate system shifts over 10,000 km to east Affects the entire planet
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Effects of an El Niño Places that were wet are now dry and vice versa
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Effects of an El Niño
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Teleconnections Discovered in 1928 by Sir Gilbert Walker Links ’ s in global climate indices Proposes a zonal circulation cell over the equatorial Pacific
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El Niño & Hurricane Damage
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El Niño & Diseases
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El Niño Hadley cells intensify as source of heat is now in central equatorial Pacific Jet stream intensifies & takes south path
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El Niño in the United States
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El Niño in California
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97/98 El Niño At its peak, the 97/98 El Niño was biggest of all time
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97/98 El Niño
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TOPEX/Poseidon sea level anomaly - December 1, 1997
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97/98 El Niño
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OLR = outgoing longwave energy (high OLR = no clouds) 97/98 El Niño
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Present Conditions
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EL NIÑO/SOUTHERN OSCILLATION (ENSO) DIAGNOSTIC DISCUSSION 5 January 2012 Synopsis: La Niña is expected to continue into the Northern spring 2012.
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Present Conditions
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Nino Regions
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More readings NOAA ENSO Page www.pmel.noaa.gov/tao/elnino/nino-home.html Review of 97/98 El Nino www.icess.ucsb.edu/~davey/Geog158/Readings/Mc Phaden_elnino_review.pdf
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