The Curious Case of the El Niño That Never Happened

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The Curious Case of the El Niño That Never Happened: A perspective from 40 years of progress in climate research and forecasting

 

Capsule: The first ever El Niño forecast 40 years ago was, in retrospect, a failure. We turn back the clock to 1975, the forecast target year, to reconstruct what happened and why. The mystery is solved, but the quest for deeper understanding of El Niño dynamics and more skillful seasonal forecasts continues.

Forty years ago, Klaus Wyrtki of the University of Hawaii launched an "El Niño Watch" expedition to the eastern equatorial Pacific to document oceanographic changes that were expected to develop during the onset of an El Niño event in early 1975. He and his colleagues used a very simple atmospheric pressure index to predict the event and convinced the National Science Foundation and Office of Naval Research to support an expedition to the eastern Pacific on relatively short notice. An anomalous warming was detected during the first half of the expedition, but it quickly dissipated. Given the state of the art in El Niño research at the time, Wyrtki and colleagues could offer no explanation for why the initial warming failed to amplify, nor could they connect what they observed to what was happening in other parts of the basin prior to and during the expedition. With the benefit of hindsight, we provide a basin scale context for what the expedition observed, elucidate the dynamical processes that gave rise to the abbreviated warming that was detected, and present retrospective forecasts of the event using modern coupled ocean-atmosphere dynamical model prediction systems. In reviewing this history, we are reminded that early pioneers in El Niño research, despite the obstacles they faced, were able to make significant progress through bold initiatives that advanced the frontiers of our knowledge. We are also reminded that, even though we know much more, and have more advanced observational capabilities and sophisticated seasonal forecasting tools, skillful El Niño predictions remain a major challenge.

 

http://journals.ametsoc.org/doi/pdf/10.1175/BAMS-D-14-00089.1