Analysis of a long-term structure of the Southern Oscillation index and El Nino events

A multiscale temporal structure of El Nino-Southern Oscillation (ENSO) characteristics is studied. The ENSO is a global-scale process in the ocean-atmosphere system, which occurs in the tropical zone and affects the earth's climate. A number of El Nino events in the past 500 years and temporal variations of the Southern Oscillation index (average monthly values for 100 years and daily values for 10 years) are analyzed. In addition to conventional methods, a wavelet analysis well suited to the study of nonuniform processes involving periodic and nonperiodic components interacting over a wide range of scales and the time-delay embedding technique are used. The periodic components of the process, a number of local periodicities, and the time scales within which the data have a self-similar structure are revealed. As a whole, the process under study seems to exhibit a combined form of behavior, involving both a stochastic and a number of regular components.