—Can capture vast majority of #ElNino and #LaNina events post-1950 by training only on pre-1950 data, with 1 lunar calibrating interval 🌛 pic.twitter.com/10PAirJAYD

— Paul Pukite (@WHUT) August 17, 2017

Applying the ENSO model to predict El Nino and La Nina events is automatic. There are no adjustable parameters apart from the calibrated tidal forcing amplitudes and phases used in the process of fitting over the training interval. Therefore the cross-validated interval from 1950 to present is untainted during the fitting process and so can be used as a completely independent and unbiased test.

Note that each of the El Nino peaks and La Nina valleys defined as “ENSO years” is predicted.

Fig 1: Strong ENSO events, from https://www.esrl.noaa.gov/psd/enso/past_events.html

That’s essentially two cycles — the Draconic and Anomalistic lunar month  — and a sharply modulated seasonal cycle which, when applied to the wave equation, recovers the ENSO behavior.

Fig 2: Model training interval is in yellow.  A short interval from 2000 to 2003 is used to calibrate the lunar forcing amplitudes and phases to the unrelated Earth’s length-of-day (LOD) measurement.

This is simply ocean tidal analysis applied on a different scale. Solving Laplace’s tidal equations is the first step, and determining the lunar forcing constituents at a monthly and fortnightly scale is the key.

I will present the ENSO model at this fall’s AGU meeting (should the abstract get accepted)