El Niño on the Devil's Staircase: Annual Subharmonic Steps to Chaos

Science  01 Apr 1994:
Vol. 264, Issue 5155, pp. 70-72
DOI: 10.1126/science.264.5155.70


The source of irregularity in El Niño, the large interannual climate variation of the Pacific ocean-atmosphere system, has remained elusive. Results from an El Niño model exhibit transition to chaos through a series of frequency-locked steps created by nonlinear resonance with the Earth's annual cycle. The overlapping of these resonances leads to the chaotic behavior. This transition scenario explains a number of climate model results and produces spectral characteristics consistent with currently available data.