Dynamics of El Niño–Southern Oscillation

Abstract

In this chapter, the observed characteristics of the El Niño -- Southern Oscillation (ENSO) is described, followed by the discussion of the ENSO instability and oscillatory theories. Next, the mechanisms of its phase locking to the annual cycle are discussed. Through the oceanic mixed-layer budget analysis, physical mechanisms responsible for El Niño and La Niña amplitude asymmetry and El Niño and La Niña evolution asymmetry are investigated. How the interdecadal mean state modulates the El Niño behavior is further discussed. Finally, an air--sea interaction mode with a characterized zonal-dipole structure in the tropical Indian Ocean is described.