2 minute read

El Niño and La Niña

Predicting El Niño And La Niña



The widespread weather impacts of the two extreme phases of the El Niño Southern Oscillation cycle make understanding and predicting ENSO events a high priority for atmospheric scientists and oceanographers. Researchers have developed computer models of the Southern Oscillation that mimic the behavior of the real atmosphere-ocean system, and predict future events. These computer simulations require the input of very large amounts of data about sea and wind conditions in the equatorial Pacific. A large and growing network of instruments, many of them owned and maintained by the National Atmospheric and Oceanographic Administration (NOAA, provides these data. Ocean buoys, permanently moored in a transect across the equatorial Pacific, constantly relay information on water temperature, wind, and air pressure to weather prediction stations around the world. The buoys are augmented by surface ships, island weather stations, and Earth observing satellites. Even with mounting data and improving computer models, El Niño, La Niña and the Southern Oscillation remain difficult to predict. However, the ENSO models, and analyses of past ENSO cycles, are now being used in several countries to help prepare for the next El Niño. Countries most affected by the variations in El Niño, such as Peru, Australia and India, presently use El Niño prediction to improve agricultural planning.



Resources

Books

Open University Course Team. Ocean Circulation. Oxford: Pergamon Press, 1993.

Williams, Jack. The Weather Book. New York: Vintage Books, 1992.

Periodicals

Kerr, R.A. "A Successful Forecast of an El Niño Winter." Science (January 24, 1992): 402.

McPhaden, M.J. "TOGA-TAO and the 1991–93 El Niño-Southern Oscillation Event." Oceanography 6 (1993): 36–44.

Other

National Oceanographic and Atmospheric Administration. "El Niño theme page" [cited November 6, 2002]. <http://www.pmel.noaa.gov/tao/elnino/nino-home.html>.


James Marti

Laurie Duncan

KEY TERMS

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Coupled system

—A system with parts that are linked in such a way that they respond to changes in each other. The atmosphere and the ocean form a coupled system, so that changes in one will cause a response in the other, which will in turn cause another change in the first, etc.

El Niño

—The phase of the Southern Oscillation characterized by increased sea water temperatures and rainfall in the eastern Pacific, with weakening trade winds and decreased rain along the western Pacific.

ENSO

—Abbreviation for El Niño/Southern Oscillation.

Jet streams

—High velocity winds that blow at upper levels in the atmosphere and help to steer major storm systems.

La Niña

—The phase of the Southern Oscillation characterized by strong trade winds, colder sea water temperatures and dry weather in the eastern Pacific, with increased rainfall along the western Pacific.

Monsoon

—An annual shift in the direction of the prevailing wind that brings on a rainy season and affects large parts of Asia and Africa.

Southern oscillation

—A large scale variation in the winds, ocean temperatures and atmospheric pressure of the tropical Pacific Ocean which repeats about every three to four years.

Additional topics

Science EncyclopediaScience & Philosophy: Dysprosium to Electrophoresis - Electrophoretic TheoryEl Niño and La Niña - Discovery And Study Of The El Niño Southern Oscillation, Regional And Global Effects Of El Niño And La Niña