The name "El Niño" refers to a warm ocean current that flows along the coast of Peru every year around Christmas time. In some years the warming persists into the spring and summer. This extended warming not only disrupts the lives of people in South America, but also influences weather patterns in the rest of the world. The name "El Niño" has now become attached to this anomalous event. When this occurs, some parts of the globe suffer from drought, while others experience too much rain. It is important that we better understand the mechanics of El Niño in order to predict the occurrence and effects of this event.

Before an El Niño, strong westerly trade winds in the equatorial Pacific push warm water toward Indonesia. This produces a large pool of 84 degree Fahrenheit water in the Western Pacific. During an El Niño, the trade winds weaken and a wave of warm water moves eastward along the equator toward South America. This warms the central and eastern equatorial Pacific.

As El Niño develops, heavy rains normally found near Indonesia move into the central Pacific, warming the atmosphere there and disrupting the atmospheric circulation throughout the Pacific. Effects have been felt as far north as Canada and as far south as central Chile. Scientists are only beginning to appreciate the far-reaching effects of this phenomenon.

TOPEX/POSEIDON is helping scientists better understand the mechanics of El Niño and assisting them with the development of models that will predict future events. This may become even more compelling since in the last four years, El Niño has occurred with more frequency and has lasted longer with greater impact.

For current images of sea level height and information about the current El Niño event, please visit the TOPEX/POSEIDON Equatorial Pacific Sea Level Analysis web page.

Global Ocean Circulation