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Learn More About El Niño/La Niña & PDO

El Niño

The data from TOPEX/Poseidon, and in the future Jason-1, helps us study and understand the complex interactions between the oceans and the atmosphere which affect global weather and climate events. One well-known example of this interaction is an El Niño event.

El Niño was named by people who fish off the western coast of central America to refer to the warm current that invades their coastal waters around Christmastime. El Niño events disrupt fisheries and bring severe weather events worldwide.

In a normal year, the trade winds blow westward and push warm surface water near Australia and New Guinea. When warm water builds up in the western Pacific Ocean, nutrient-rich cold water comes up off the west coast of South America and fosters the growth of the fish population. Normal Conditions
El Nino Condition During an El Niño event, the trade winds weaken and warm, nutrient-poor water occupies the entire tropical Pacific Ocean. Heavy rains that are tied to the warm water move into the central Pacific Ocean and cause drought in Indonesia and Australia. This also alters the path of the atmospheric jet stream over North and South America.

The effects of El Niño disrupt normal winter conditions throughout the Pacific Ocean, and can persist into May or June. Reliable predictions of an El Niño occurrence will lead to better preparation for its widespread impact.

El Nino/La Nina image

La Niña

Warm El Niños and cold La Niñas follow each other against the backdrop of the ocean seasons. During a La Niña, the trade winds are stronger and cold, nutrient-rich water occupies much of the tropical Pacific Ocean. Most of the precipication occurs in the western tropical Pacific Ocean, so rain is abundant over Indonesia.

Pacific Decadal Oscillation (PDO)

The Pacific Decadal Oscillation (PDO) is a long-term ocean fluctuation of the Pacific Ocean. The PDO waxes and wanes approximately every 20 to 30 years.


Additional Information on El Niño/La Niña and PDO


Image series


El Niño/La Niña Watch - Latest images!

Sea Surface Height Movies

El Niño/La Niña explained (basics and links)


El Niño - Southern Oscillation (ENSO) - AVISO

National Geographic: "El Niño/La Niña - Nature's Vicious Cycle"

El Niño basics for kids and adults

Links to El Niño/La Niña Information

Eye on the Ocean

NOAA's Climate & Regional Weather Forecasts


El Niño/La Niña Education


"The Rise and Fall of the '97 - '98 El Niño" Poster "The Rise and Fall of the '97 - '98 El Niño" Poster

Demonstrate El Niño in your classroom

El Niño Skit for primary grades

El Niño pudding - delicious and educational!

On-line El Niño and altimetry slides - a undergraduate and educator primer


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