Look at the top 3 tidal constituents (Mf, Mm, and 18.6 year) in the following chart (note its plotted on a log scale) and then compare to the table below it adapted from R.D.Ray.

![](https://imagizer.imageshack.com/img923/7461/Fj2DqK.png)

![](https://imagizer.imageshack.com/img922/4118/LDtvyM.png)

All the modelled ENSO time-series peaks align based on the assignment of tidal gravitational forcings in the last column $$V_0/g$$

The ranking matched the falloff in strength $$ Mf > Mm > 18.6y > Mt > Msm > Msq $$

Everything below this in strength are essentially secondary factors

![](https://imagizer.imageshack.com/img924/8088/u05MbM.png)

This doesn't happen by accident, it happens as a result of a solution to Laplace's Tidal Equations applied to an equatorial waveguide topology consisting of standing-wave modes. Alas, the consensus will point to ENSO as being a chaotically-driven behavior as that is a default rationale if they are not able to come up with an adequate physics-based model.