I was on-line talking to yet another academic trying to explain to them that the whole temperature signal is natural variation (at least in the null hypothesis) and they kept insisting that the PDO, ENSO, AMO were “things” and not “noise”.
I was saying they were a resonance in the system responding to natural variation. Afterwards I realised that whilst I could work out what it looked like (with experience you can just do things like this in your head). But I hadn’t actually done some simulations to see whether what I was saying was sensible. (It’s just what I expected)
So here is ENSO (El Nino) and the PDO
And here is the response of a simple damped oscillator to 1/f noise which I cobbled together in half an hour (note red is ~20sample average):
Yep – I’m reasonably happy the two look visually similar enough for me to say that PDO and ENSO are indistinguishable from the resonant response to 1/f type noise as seen in the global temperature.