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.