![]() In particular, two prominent types, namely an eastern Pacific (EP) type El Nino and a Central Pacific (CP) type El Nino have been identified 18, 19, 20. Recognition that ENSO occurs in various ‘flavours’ or ‘types’ has replaced the earlier thinking of a ‘canonical’ El Nino 17. The event-to-event variability of the ENSO is now recognized to be a manifestation of the ‘diversity’ of the ENSO 15, 16. More importantly, the models fail to predict the observed event-to-event variability in evolution and amplitude of ENSO as highlighted by the failure of almost all models in predicting the 2014–15 event when almost all models predicted an ‘monster’ El Nino that failed to appear 12, 13, 14. However, the skill of even the latest models falls far short of the limit of potential predictability 9, 10, 11. Since the first failed attempt to predict the 1975 El Nino 5 and the first successful forecast 6, the ENSO predictions have made great strides 7, 8. As a consequence, ENSO prediction has remained on the top of agenda of the climate prediction community. Early warning of amplitude and evolutionary history of an impending ENSO event, therefore, is critical for disaster mitigation and planning for adaptation strategy. The largest signal of climate variability on inter-annual time scale arising from ocean-atmosphere interaction in the tropics 1, 2, the El Nino and Southern Oscillation (ENSO) has deep and wide ranging impacts across the globe 3, 4. Therefore, skillful prediction of all shades of ENSO depends critically on the coupled models’ ability to simulate the three modes with fidelity, providing basis for optimism for future of ENSO forecasts. We further demonstrate it to be a useful framework for understanding biases of climate models in simulating and predicting the ENSO. The modal description of ENSO provides a framework for understanding the predictability of and global teleconnections with the ENSO. ![]() The ENSO ‘slow manifold’ can be fully described by three leading predictable modes, a quasi-quadrennial mode (QQD), a quasi-biennial (QB) mode and a decadal modulation of the quasi-biennial (DQB). Here, we show that the ENSO diversity thought previously as ‘complex,’ arises largely as varied contributions from three leading modes of the ENSO to a given event. ![]() Improving climate models for ENSO forecasts relies on deeper understanding of the ENSO diversity but currently at a nascent stage. The El Nino and Southern Oscillation (ENSO) ‘diversity’ has been considered as a major factor limiting its predictability, a critical need for disaster mitigation associated with the trademark climatic swings of the ENSO.
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