Cross-correlation MSL v sunspots

Daily sunspot area is anti-alias filtered with a 732d low-pass and resampled at annual intervals to match the Jevrejava mean sea level reconstruction. Rate of change of MSL was taken as the annual difference.

The cross-correlation shows the main solar cycle of around 10.49 years being modulated over a longer period. Visual estimation of the nodes suggests a long period of 79.1 years.

The first peak, as well as can be attained from this annual resolution data is with sunspots leading sea level by about six months.

The two main peaks show a low but significant correlation.

10.49 and 71.9 are found from the power spectrum:

Though there are other variations this seems to be the main effect. This is a clear interference pattern between two close periodicities. The other frequency causing the modulation can be estimated by:

1/79.1+1/10.49 = 9.23 years.
1/71.9+1/10.49 = 9.15 years.

This is suggestive of a lunar cycle. Periods of 9.1 +/- 0.1 years have been reported by Nicola Scafetta [1] and Berkeley Earth project (9.1 ± 0.4 years)[2] .

 [1] Nicola Scafetta: “Empirical evidence for a celestial origin of the climate oscillations and its implications”

 [2] “Decadal Variations in the Global Atmospheric Land Temperatures”

Richard A. Muller1, Judith Curry, Donald Groom,
Robert Jacobsen, Saul Perlmutter, Robert Rohde,
Arthur Rosenfell, Charlotte Wickham, Jonathan