The data from the TOPEX/Poseidon and Jason missions help us study and understand the complex interactions between the ocean and the atmosphere that affect global weather and climate events. El Niño is one well-known example of this interaction.

Learn more about this and other important climate phenomena in the links below.

Learn More About El Niño/La Niña & PDO

El Niño

Normal Conditions

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.

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.

La Niña

El Nino/La Nina image

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 precipitation 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

Sea Surface Height Movies

El Niño/La Niña explained (basics and links)

Links to El Niño/La Niña Information

Eye on the Ocean

NOAA's Climate & Regional Weather Forecasts

El Niño/La Niña Education

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

El Niño/La Niña & PDO Links

El Niño/La Niña Information on the Web

There are many excellent sites containing basic information on these phenomena, the effects of El Niño and La Niña on weather and climate, and forecasts.

Major sites containing background information

  • An El Niño and La Niña Theme Page - a comprehensive primer with access to relevant data, information on effects, and predictions. If you are just going to visit one site, this is probably the one!
  • The ENSO cycle - processes and displays of relevant data

Climate and regional weather forecasts

Spaceborne monitoring tools