"coupled atmosphere/ocean climate phenomenon"

By atmosphere, do you mean lunar? It's becoming clear that ENSO is riven by a lunar forcing coupled to a strong annual signal, see

https://www.nature.com/articles/s41598-019-49678-w

Lin, J., Qian, T. "Switch Between El Nino and La Nina is Caused by Subsurface Ocean Waves Likely Driven by Lunar Tidal Forcing". Sci Rep 9, 13106 (2019).

Should be able to do better predictions with this knowledge.