El Niño/Southern Oscillation Major climatic perturbation on the planet Coupled atmosphere ocean process Key is the western tropical Pacific – Ascending.
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Presentation on theme: "El Niño/Southern Oscillation Major climatic perturbation on the planet Coupled atmosphere ocean process Key is the western tropical Pacific – Ascending."— Presentation transcript:
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
La Nina Opposite phase of the ENSO cycle Intensified trades & Walker circulation Thermocline undergoes maximum upwelling
EL NIÑO/SOUTHERN OSCILLATION (ENSO) DIAGNOSTIC DISCUSSION issued by CLIMATE PREDICTION CENTER/NCEP May 11, 2006 Synopsis: ENSO-neutral conditions are expected to prevail during the next 3-6 months. The current patterns of anomalous ocean temperatures are consistent in indicating a return to ENSO-neutral conditions in the tropical Pacific. During April SSTs were close to average at most locations between Indonesia and 90ºW (Fig. 1), which is reflected in the near zero departures observed in all of the Niño regions, except for Niño 1+2 (Fig. 2). During the month, negative SST departures developed in the extreme eastern equatorial Pacific, which is a reversal from conditions observed during February-March.Fig. 1Fig. 2
Altimetry & ENSO States Most “action” is in the tropical Pacific Effects are seen in other places – East subtropics – Western NECC region
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
An El Niño History late 1800s Fishermen name El Niño to the periodic warm waters that appear off the coasts of Peru and Ecuador around Christmas. 1928 Gilbert Walker describes the Southern Oscillation. 1957 A large El Niño is observed which affects not just the coasts of Peru and Ecuador but the entire Pacific Ocean. 1969 Jacob Bjerknes links the Southern Oscillation with El Niño events.
An El Niño History 1975 Wyrtki uses island sea level to show how eastward flow causes SST’s to rise in east Pacific. 1976 An idealized computer model demonstrates that winds over the far western Pacific can change SST off Peru. 1982 A severe El Niño develops unexpectedly, but is recorded in detail with newly developed ocean buoys. 1985 Several nations launch the Tropical Ocean- Global Atmosphere (TOGA) program.
An El Niño History 1986 First coupled model of ocean & atmosphere predicts El Niño event. 1988 Researchers explain how the "memory" of the ocean--the lag between a change in the winds and the response of the ocean--influences terminations of El Niño and the onset of La Niña. 1996-1997 The array of instruments monitoring the Pacific, plus coupled ocean-atmosphere models, enable scientists to warn the public of an impending El Niño event.
Effects of an El Niño Places that were wet are now dry and vice versa