CoachThe El Niño–Southern Oscillation (ENSO) is the coupled ocean–atmosphere mode of the tropical Pacific: coherent year-to-year variations of the sea-surface temperature, the convective rainfall, the surface pressure and the circulation along the equatorial Pacific, with preferred time scales of two to about seven years. El Niño is its warm phase, a warming of the sea surface of the central and east-central equatorial Pacific; La Niña is its cold phase, a cooling of the same region. The Southern Oscillation is its atmospheric part, a see-saw of surface pressure between the western and the eastern tropical Pacific: during El Niño the pressure is higher than average over Indonesia and the western Pacific and lower over the eastern Pacific, and the reverse during La Niña.
