EL NIÑO

A complex state of the equatorial ocean-atmosphere system associated with anomalously warm ocean temperatures in the central and eastern Pacific Ocean, anomalously cold ocean temperatures in the western Pacific Ocean, and a weakening of the southeasterly trade winds. Changes in the ocean temperatures result in increased convection over the warmer waters of the central and eastern Pacific and decreased convection over the western Pacific. Weather patterns are also affected in other regions of the world. [See teleconnection.] El Niño occurs every three or four years.