Modeling and forecasting the southern oscillation: a time-domain approach.

Abstract

An index consisting of the difference of normalized sea level pressure departures between Tahiti and Darwin is used to represent the Southern Oscillation (SO) fluctuations. Using a time-domain approach, autoregressive-moving average (ARMA) processes are applied to model and predict this Southern Oscillation Index (SOI) on a monthly and seasonal basis. A purely autoregressive (AR) process is identified as representative of the seasonal SO fluctuations, with the SOI for the current season being derived from the index for the immediate past three seasons and a single random disturbance term for the current season. To allow for the phase locking of the SOI with the annual cycle, ARMA processes with seasonally varying coefficients are also considered.-Authors