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What is La Niña?
La Niña is characterized by unusually cold ocean temperatures in the Equatorial Pacific, compared to El Niño, which is characterized by unusually warm ocean temperatures in the Equatorial Pacific.
La Niña - December 1997

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Important historical El Niño & La Niña events Impact on global climate
Seen in Pacific Ocean temperatures The origin of the name, La Niña
Seen in Pacific Ocean temperature deviations Selected references and publications
Current conditions
3D Animation of El Niño and
La Niña
from TAO Visualizations
Pacific ocean temperatures recorded last night See current conditions on NOAA's El Niño page
See also
More information on NOAA's La Niña website 3D animations of La Niña and El Niño

NOTE: Until 1997, the 1982-1983 El Niño, was the largest El Niño of the twentieth century. These two important El Niño events are used for illustrations in this web page.

Shown below is the Reynolds sea surface temperature in the equatorial Pacific from Indonesia on the left to central America on the right (20N - 20S, 100E - 60W).

La Nina conditions Colour bar
La Niña (cold) Conditions
(December 1998)
Normal conditions
Normal Conditions
December 1993
El Niño conditions
El Niño (warm) Conditions
December 1997

Normal Equatorial Pacific Ocean surface temperatures (December 1993) are shown in the middle panel, including cool water, called the 'cold tongue', in the Eastern Pacific (in blue, on the right of the plot) and warm water in the Western Pacific (in red, on the left). Strong La Niña conditions during December 1998 are shown in the top panel. The Eastern Pacific is cooler than usual, and the cool water extends farther westward than is usual (see the blue color extending further to the left). Strong El Niño conditions, in December 1997, are shown on the bottom panel, with warm water (red) extending all along the equator. El Niño and La Niña are opposite phases of the El Niño-Southern Oscillation (ENSO) cycle, with La Niña sometimes referred to as the cold phase of ENSO and El Niño as the warm phase of ENSO.

Historical La Niña and El Niño events
Different La Niña and El Niño events vary in strength

In the left hand panel, you see the sea surface temperature at the Equator in the Pacific Ocean (Indonesia is towards the left, South America is towards the right). Time is increasing downwards from 1986 at the top of the plot, to the present, at the bottom of the plot. The first thing to note is the blue "scallops" on the right of the plot, in the eastern Pacific. These indicate the cool water typically observed in the Eastern Pacific (called the "cold tongue"). Cold tongue temperatures vary seasonally, being warmest in the northern hemisphere springtime and coolest in the northern hemisphere fall. The red color on the left is the warm pool of water typically observed in the western Pacific Ocean. El Niño is an exaggeration of the usual seasonal cycle.

Click for full size image  
Mean and anomalies of sea surface temperature from 1986 to present, showing El Niño events 1986-1987, 1991-1992, 1993, 1994 and 1997 and La Niña events in 1985 and 1995.  

During the El Niño in 1986-1987, you can see the warm water (red) penetrating eastward in the Spring of 1987. There is another El Niño in 1991-1992, and you can see the warm water penetrating towards the east in the northern hemisphere spring of 1992. The 1997-1998 El Niño (at the bottom) is unusually strong.

El Niño and La Niña years are easier to see in the anomalies on the right hand panel. The anomalies show how much the sea surface temperature is different from the usual value for each month. Water temperatures significantly warmer than the norm are shown in red, and water temperatures cooler than the norm are shown in blue. In the right-hand plot of sea surface temperature anomalies, it is very easy to see El Niños, with water warmer than usual (red) in the eastern Pacific, such as 1986-1987, 1991-1992, 1993, 1994 and 1997-1998. It is unusual for El Niños to occur in such rapid succession, as was the case during 1990-1994.

Notice the very cool water (blue), in the Eastern Pacific, in 1988-1989, and the somewhat less cool water in 1995. These are La Niña events, which occur after some (but not all) El Niños. Typically, El Niño occurs more frequently than La Niña. A list of El Niño and La Niña years is provided by the National Center for Environmental Prediction (NCEP).

El Niño and La Niña events vary in strength. For example, the La Niña in 1988 was stronger than the La Niña in 1995, and the 1997-1998 El Niño is unusually strong.

La Niña impact on the global climate
In the U.S., winter temperatures are warmer than normal in the Southeast, and cooler than normal in the Northwest.

Global climate La Niña impacts tend to be opposite those of El Niño impacts. In the tropics, ocean temperature variations in La Niña tend to be opposite those of El Niño.

At higher latitudes, El Niño and La Niña are among a number of factors that influence climate. However, the impacts of El Niño and La Niña at these latitudes are most clearly seen in wintertime. In the continental US, during El Niño years, temperatures in the winter are warmer than normal in the North Central States, and cooler than normal in the Southeast and the Southwest. During a La Niña year, winter temperatures are warmer than normal in the Southeast and cooler than normal in the Northwest. See U.S. La Niña impacts from the National Weather Service. Also see this graphically in plots of temperature and rainfall anomalies in El Niño and La Niña years from Florida State University. An anomaly is the value observed during El Niño or La Niña subtracted from the value in a normal year.

La Niña and El Niño animations
Where are animations of La Niña and El Niño events?

This animation shows the changes in monthly sea surface temperature in the tropical Pacific Ocean. A Java animation is also available. Notice the weak La Niña peaking in December 1995, and the strong El Niño building in 1997. The animation is about 1 Megabyte in size. As you view this animation, you will see a weak La Niña peaking in December 1995. The bottom panel in the animation, labeled anomalies, shows how much the sea surface temperature for each month is different from the long term average for that month. The green color in the anomalies plot indicates that the temperature of the water is slightly cooler than is normal for that month. A strong El Niño is shown by the warm water spreading from the western Pacific to the eastern Pacific during 1997. The red color in the anomalies plot indicates that the temperature of the water is much warmer than is normal for that month.

The origin of the names, La Niña and El Niño
La Niña is sometimes referred to as El Viejo

El Niño was originally recognized by fisherman off the coast of South America as the appearance of unusually warm water in the Pacific ocean, occurring near the beginning of the year. El Niño means The Little Boy or Christ child in Spanish. This name was used for the tendency of the phenomenon to arrive around Christmas. La Niña means The Little Girl. La Niña is sometimes called El Viejo, anti-El Niño, or simply "a cold event" or "a cold episode". There has been a confusing range of uses for the terms El Niño, La Niña and ENSO by both the scientific community and the general public, which is clarified in this web page on definitions of the terms ENSO, Southern Oscillation Index, El Niño and La Niña. Also interesting is the Web page Where did the name El Niño come from?

More information on La Niña and El Niño

Selected references and publications


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