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

 

Read more on
Some recent El Niņo and La Niņa events Impact on global climate
See La Niņa and El Niņo animations The origin of the name, La Niņa
Where to find more information Selected references and publications
Current conditions
El Niņo and La Niņa in the entire Pacific ocean Pacific ocean temperatures recorded last night Current conditions from NOAA's La Niņa page
See also
Everything you wanted to know about El Niņo 3D animations of La Niņa and El Niņo

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 Niņa (cold) Conditions
(December 1998)
Normal conditions
Normal Conditions
December 1993
El Niņo conditions
El Niņo (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 Niņa 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 Niņo conditions, in December 1997, are shown on the bottom panel, with warm water (red) extending all along the equator. El Niņo and La Niņa are opposite phases of the El Niņo-Southern Oscillation (ENSO) cycle, with La Niņa sometimes referred to as the cold phase of ENSO and El Niņo as the warm phase of ENSO.

Recent La Niņa and El Niņo events
Different La Niņa and El Niņo 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 Niņo 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 Niņo events 1986-1987, 1991-1992, 1993, 1994 and 1997 and La Niņa events in 1985 and 1995.

During the El Niņo in 1986-1987, you can see the warm water (red) penetrating eastward in the Spring of 1987. There is another El Niņo 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 Niņo (at the bottom) is unusually strong.
El Niņo and La Niņa 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 Niņos, with water warmer than usual (red) in the eastern Pacific, during in 1986-1987, 1991-1992, 1993, 1994 and 1997-1998. It is unusual for El Niņos 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 Niņa events, which occur after some (but not all) El Niņos. Typically, El Niņo occurs more frequently than La Niņa. A list of El Niņo and La Niņa years is provided by the National Center for Environmental Prediction (NCEP).

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

La Niņa 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 Niņa impacts tend to be opposite those of El Niņo impacts. In the tropics, ocean temperature variations in La Niņa tend to be opposite those of El Niņo.

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

La Niņa and El Niņo animations
Where are animations of La Niņa and El Niņo events?

If you have an MPEG animation viewer, and sufficient memory, you can view an animation which shows the changes in monthly sea surface temperature in the tropical Pacific Ocean. A Java animation is also available. Notice the weak La Niņa peaking in December 1995, and the strong El Niņo building in 1997. The animation is about 1 Megabyte in size. As you view this animation, you will see a weak La Niņa 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 Niņo 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 Niņa and El Niņo
La Niņa is sometimes referred to as El Viejo

El Niņo 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 Niņo means The Little Boy or Christ child in Spanish. This name was used for the tendency of the phenomenon to arrive around Christmas. La Niņa means The Little Girl. La Niņa is sometimes called El Viejo, anti-El Niņo, or simply "a cold event" or "a cold episode". There has been a confusing range of uses for the terms El Niņo, La Niņa 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 Niņo and La Niņa. Also interesting is the Web page Where did the name El Niņo come from?

More information on La Niņa and El Niņo

Selected references and publications


Credits and Acknowledgements | TAO Diagrams

http://www.pmel.noaa.gov/tao/elnino/la-nina-story.html