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Physical Process

El Nino-Southern Oscillation

el NEEN-yoh (El Nino)
Also Known As ENSO
Atmospheric and Climatic Processes

El Nino-Southern Oscillation, ENSO, is the irregular two-to-seven-year swing between a warm El Nino phase and a cool La Nina phase in the tropical Pacific Ocean and the atmosphere above it. El Nino weakens the trade winds and warms the eastern Pacific, La Nina strengthens them and cools it, and each phase redraws rainfall and drought patterns for a large share of the planet for about a year at a time. This description is adapted from Wikipedia contributors under CC BY-SA 4.0; changes were made. https://creativecommons.org/licenses/by-sa/4.0/

Facts
Process Type
Oceanic 1
Timescale
An irregular cycle recurring every two to seven years, each phase lasting about a year. 1
First Proposed Year
1969 2
Scientific Consensus Year
1983 1
Jacob Bjerknes proposed the coupled ocean-atmosphere mechanism linking El Nino and the Southern Oscillation in 1969 (see first-proposed-year); the year recorded here is when the major 1982 to 83 El Nino event is documented as having drawn the wider scientific community into sustained ENSO research, a distinct milestone from Bjerknes's own original proposal.
Connections

Associated With

Drought Formation, Physical Processes
Source Drought Formation (Wikipedia)
Indian Ocean Dipole, Physical Processes
Source Indian Ocean Dipole (Wikipedia)
La Nina, Physical Processes
Madden-Julian Oscillation, Physical Processes
Pacific Decadal Oscillation, Physical Processes
Source Pacific Decadal Oscillation (Wikipedia)
Southern Annular Mode, Physical Processes

Demonstrated By

Australia, Continents
Source El Nino-Southern Oscillation (Wikipedia)
South America, Continents
Source El Nino-Southern Oscillation (Wikipedia)
The Pacific Ocean, Bodies of Water

ENSO arises from variations in winds and sea surface temperatures over the tropical Pacific.

Source El Nino-Southern Oscillation (Wikipedia)
In the Other Atlases
Sources
1. El Nino-Southern Oscillation (Wikipedia)
Wikimedia Foundation
  • Definition section
    Future trends in ENSO due to climate change are uncertain, although climate change exacerbates the effects of droughts and floods.
  • History, During human history section
    The major 1982-83 El Niño led to an upsurge of interest from the scientific community.
  • Demonstrated By: South America, Definition and terminology section
    Peruvian sailors named the warm south-flowing current El Nino, referring to the Christ Child, because it was most noticeable around Christmas.
  • Demonstrated By: Australia, Australia section
    During El Nino events, the shift in rainfall away from the Western Pacific may mean that rainfall across Australia is reduced.
  • Part Of: Ocean Circulation and Currents, Fundamentals section
    If the trade winds (blowing from east to west) are weaker than average, then both the upwelling in the East Pacific and the flow of warmer ocean surface waters towards the West Pacific lessen.
View the Source
2. Jacob Bjerknes (Wikipedia)
Wikimedia FoundationProfessional career section
Quote, Professional career section
In 1969, Jacob Bjerknes helped toward an understanding of the El Nino-Southern Oscillation, by suggesting that the increased sea-surface temperatures were due to a reduction in the trade winds.
View the Source
Indian Ocean Dipole (Wikipedia)
Wikimedia FoundationAssociated With: Indian Ocean DipoleView the Source
Pacific Decadal Oscillation (Wikipedia)
Wikimedia FoundationAssociated With: Pacific Decadal OscillationView the Source
Drought Formation (Wikipedia)
Wikimedia FoundationAssociated With: Drought FormationView the Source
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