This was mentioned on a chat discussion, but should probably go here because it has wider visibility and is in Jim's original IOD topic. This is referring to finding linkage or synchronization between IOD and ENSO (specifically the SOI dipole).

In the first chart below, it shows SOI=s as a function of IOD=i and in the second it is IOD as a function of SOI. The base correlation coefficient is 0.462 with no delays (i.e. zero lag).

![soi as iod](

With delays the IOD as a predictor of SOI works marginally better than SOI as a predictor of IOD, but it will need some interpretation to see what this means. These are both dipoles so no doubt that they share the same global forcing factors. The question is whether these lags are real or are just phase relationships that occur from occupying different positions on a standing wave. Remember that a standing wave is really a collective phenomenon, and where the peaks and valleys are is really dependent on where the measurements are taken.

![iod as soi](

The delays shown are in months, so that IOD either lags SOI by 1 month with a sign reversal, or as a stronger condition, SOI lags IOD by 17 months with a sign reversal.

I am having problems with running an implicit comparison between the two with Eureqa, i.e. setting the goal as 0 = f(soi,iod).