SELF-ORGANIZED CRITICALITY IN THE EL-NINO SOUTHERN-OSCILLATION

The Fourier analysis has been applied to observational sea surface tem perature (SST) data from the Southern Pacific. The spectral response o f the daily temperature fluctuations indicates that the so-called El N ino Southern Oscillation (ENSO) belongs to the class of dynamical phen omena which are in a self-organized critical state. This has implicati ons on the predictability of the significant events in the ocean-atmos phere interaction process. A toy model is used to point out the simila rities of this system with other large scale phenomena, as earthquakes and volcanic eruptions, which are considered to be consistent with th e hypothesis of self-organized criticality. The qualitative agreement between observational data and results of numerical simulations demons trates the validity extent of the theoretical approach.