Monitoring and Predicting El Niño Invasions

Southern Oscillation indices (differences in sea level atmospheric pressure between Easter Island and Darwin, Australia, and between Juan Fernandez Island and Darwin) were treated so as to emphasize interannual changes and considered for monitoring unusual equatorial Pacific ocean-atmosphere developments and certain of their consequences (e.g., El Niño invasions). It now appears that their trends can be used to predict activity of El Niño intensity several months in advance.