Advancing the yard-stick on that paper

https://www.researchgate.net/profile/Marta_Martin-Rey/publication/336306423_Ocean_dynamics_shapes_the_structure_and_timing_of_Atlantic_Equatorial_Modes/links/5d9b264ba6fdccfd0e7f4148/Ocean-dynamics-shapes-the-structure-and-timing-of-Atlantic-Equatorial-Modes.pdf
> "ocean dynamics is essential to explain the equatorial SST variations, while air‐sea fluxes control the off‐equatorial SST anomalies. "

Here is a chart supporting an annual impulse driving AMO. An example of [double-sideband carrier suppressed modulation](https://en.wikipedia.org/wiki/Double-sideband_suppressed-carrier_transmission). It's not quite as obvious as for ENSO or PNA, but the long-period sidebands are distinct.

![](https://imagizer.imageshack.com/img922/6499/Slw1rm.png)

The way to read the chart is to fold the frequency spectrum from 0 to 0.5/year onto the reversed spectrum from 1.0 down to 0.5 year. Across the range, the correlation coefficient is above 0.5 which is highly significant.