El Niño

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Satellites and moored instruments in the Pacific provide the measurements we need to keep track of El Niño.


Three types of satellites are used to watch El Niño:

scientific data of el nino

Right: A map of the deviation of surface temperature from normal conditions. It shows warm water on the equator in the east, which is typical of El Niño. Image courtesy Center for Space Research, University of Texas.

Left: A map of the deviation of surface height from normal conditions. It shows sea level higher than 28 cm above normal in the eastern tropical Pacific. The high areas are indicated by arrows. High sea level corresponds to warm water. Image courtesy Center for Space Research, University of Texas.

Moored Instruments

The National Oceanic and Atmospheric Administration's Pacific Marine Environmental Laboratory in Seattle, with the help of oceanographers in other countries, operates around 70 moorings in the tropical Pacific. A mooring is a steel or plastic rope that goes from a float on the surface to an anchor on the sea floor. The moorings holds instruments that measure surface winds, air temperature, relative humidity, sea surface temperature, and underwater temperatures. Data from the mooring are sent to Seattle by special satellite links.

scientific data of el nino
Here is what the mooring looks like.
ATLAS means Autonomous Temperature Line Acquisition System.
(Image courtesy NOAA)

Here are the conditions in the Pacific measured by the ATLAS moorings in December 1997. The maps show temperatures in the east 6°C warmer than normal. Winds in the west are weaker than normal. Arrows pointing toward the east indicate winds weaker than normal trade-winds, which have arrows that point west.

scientific data of el nino

Top: Sea surface temperature in Celsius in color, red is hotter. The arrows give wind speed and direction.

Bottom: Deviations from normal conditions. Temperature deviations are in color. Wind deviations are arrows.The image is from the Tropical Atmosphere and Ocean TAO project at the Pacific Marine Environmental Laboratory of the National Oceanic and Atmospheric Administration.

For the most recent data on TAO array sea surface data and wind speeds visit


neon dividing line

Questions that come to mind are:

1. What is El Niño?

2. How has it come to be called El Niño (the [male] child)?

3. What causes El Niño?

4. What's the big deal? What does El Niño mean to me?

5. What do scientists know about El Niño and how do they know what they know?

6. Where and when does El Niño occur and how often?

To find out the answers to these and other questions you may have, check out our "Helpful Links"!

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