el niño/southern oscillation
DESCRIPTION
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. - PowerPoint PPT PresentationTRANSCRIPT
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
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
The Southern Oscillation
The Southern Oscillation
• Pressure ’s regulate strength of the trades
• El Niño periods = weak trades
Southern Oscillation Index
• SOI = Tahiti - Darwin air pressure ’s
• Low SOI = El Niño conditions
Southern Oscillation Index
Southern Oscillation
Walker Circulation
• East-to-west pressure gradients drive
trades
Walker Circulation
• Vertical cell driven by warmest
waters
Western Pacific Warm Pool
Coupled Walker/Ocean Circulation
TOGA-TAO Array
• Equatorial array of buoys (also Atlantic &
Indian)
• U.S., Japan, India, French, etc.
partnership
• http://www.pmel.noaa.gov/tao/
Moorings
• Measure met &
ocean properties
• Thermocline focus
• Real-time data
transmission
• Used in weather &
climate forecasts
TAO Moorings
TAO Moorings
Southern Oscillation
El Niño Conditions
El NiñoEvents
• Relaxation of
trades causes
warm pool to
slosh across
Pacific basin
El Niño Conditions
La Nina
• Opposite phase of the ENSO
cycle
• Intensified trades & Walker
circulation
• Thermocline undergoes
maximum upwelling
Altimetry & ENSO States
• Most “action” is in the tropical
Pacific
• Effects are seen in other
places
– East subtropics
– Western NECC region
Equatorial Kelvin Waves
• Satellite altimetry from
TOPEX/Poseidon
• Scenes are 10 days apart
Equatorial Kelvin & Rossby Waves
Off-EquatorialRossby Waves
EquatorialKelvin Waves
Planetary Waves & El Niños
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
Effects of an El Niño
• Places that were wet are now dry and vice
versa
Effects of an El Niño
Teleconnections
• Discovered in 1928
by Sir Gilbert Walker
• Links ’s in global
climate indices
• Proposes a zonal
circulation cell over
the equatorial Pacific
El Niño & Hurricane Damage
El Niño & Diseases
El Niño
• Hadley cells intensify as source of heat is
now in central equatorial Pacific
• Jet stream intensifies & takes south path
El Niño in the United States
El Niño in the United States
El Niño in California
El Niño in California
El Niño in California
97/98 El Niño
• At its peak, the 97/98 El Niño was
biggest of all time
97/98 El Niño
97/98 El
Niño
97/98 El Niño
• TOPEX/Poseidon sea level anomaly - December 1, 1997
97/98 El Niño
OLR = outgoing longwave energy (high OLR = no clouds)
97/98 El Niño
97/98 El Niño
Present Conditions
Present Conditions
EL NIÑO/SOUTHERN OSCILLATION (ENSO) DIAGNOSTIC DISCUSSION
5 January 2012
Synopsis: La Niña is expected to continue into the Northern spring 2012.
Present Conditions
Nino Regions
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/McPhaden_elnino_review.pdf