Jan, Cool. I have read many of Carl Wunsch's articles because he's an expert on ocean circulation and one of the few that believes lunar tidal forces may have a strong impact on climate via changes in that circulation. This is a Nature article of his from 2000

[Moon, tides and climate](https://www.nature.com/articles/35015639)

Much earlier than that he wrote about long period tides

> "The equilibrium hypothesis was tested by computing peridograms for the fortnightly and monthly tides on islands of the Pacific. Despite high noise levels, substantial deviations from equilibrium were found, with fluctuations over distances of about 3000 km. An approximate analytic solution to the Laplace tidal equations shows the measurements to be consistent with the hypothesis that the tides excite the Rossby wave modes of the ocean" [The Long-period Tides (1967)](https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/RG005i004p00447)

I essentially solved Laplace tidal equations along the equator and applied the tidal cycles to get where I'm at with the ENSO model. Alas, Prof Wunsch is at emeritus stage and is unlikely to be active in this area any longer.