Predicting and Monitoring El Niño

The El Niño/Southern Oscillation (ENSO) phenomenon is the most prominent global climate signal on the seasonal-interannual time scale. It is associated with major fluctuations in the tropical Pacific Ocean and atmosphere, anomalies in monsoon rainfall, and wintertime climate anomalies in the higher latitudes of both hemispheres. It also results in major disruption of the marine ecosystem along the west coast of the Americas. The general nature of an ENSO episode is described. The 1982/83 ENSO was among the most intense of the past 100 years and differed in important respects from the typical pattern of events. Research and operational oceanic data acquired during this episode was far superior to that obtained during previous El Niño´s, and allowed limited real time monitoring of the anomalies. A ten year international research program to study the role of the tropical oceans in interannual climate variability begins in 1985. Plans for the ocean monitoring and prediction element of this program are reviewed.