PaulK: "Short period => long period, all done and substantiated"
TRUE; many observational proofs exist, like how sea ripples become sea waves. Geophysicists indeed had "figured this out already 50 to 100 years ago", and sailors long before.
An open problem is quantification of ratios of short period tidal forcing to short-period geostrophic Coriolis and Hadley Circulations, combining multi-chaotically to drive long period harmonic resonance of specific cases like ENSO and QBO. Where are those numbers?