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What is El Niño and what are its effects on the planet?

El Niño, or more completely, the El Niño/Southern Oscillation (ENSO) refers to the phenomenon where the normal ocean/atmosphere circulation patterns in the South Pacific Ocean are disrupted, resulting in higher than normal sea surface temperatures in the eastern South Pacific Ocean. Because this disruption, when it appears every few years, is usually strongest around Christmas time, South American fishermen (who are adversely affected by it) called it El Niño (Spanish for the Christ child). Scientists are not yet certain of the causes underlying the phenomenon, but it is clear that there is a good connection with anomalous weather patterns around the world.

El Niño is where the normal criculation patterns of the atmosphere and ocean in the Southern Pacific break down and may even reverse.  La Niña on the other hand, is a abnormal strengthening of that normal circulation.  A more in depth overview of ENSO is available at the NOAA El Nino Theme Page.

For more information about El Niño and its effects, we suggest visiting the following web sites:

  • If you are looking for data on El Niño related variables, try the GCMD's Free Text Search. In the Data set text search box on the GCMD home page, type in El Nino and click your enter key.
Sea Surface height measurements from TOPEX/POSEIDON

Still have questions about El Niño? Ask the GCMD science staff at GCMD User Support.

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