Mostly unfiltered SOI ENSO time-series model. The high frequency cycling is likely not noise but high wavenumber standing-waves or traveling-waves that are solutions to LTE.

![](https://imagizer.imageshack.com/img923/5503/eWyosP.png)

The high-frequencies are filtered out with the averaged response of the NINO34 ENSO time-series.

![](https://imagizer.imageshack.com/img924/7915/l33Rsl.png)