Lunar Tides and the Long-Term Variation of the Peak Latitude Anomaly of the Summer Sub-Tropical High Pressure Ridge over Eastern Australia

Ian R.G. Wilson*
Queensland Department of Education and Training, Toowoomba State High, Mt. Lofty Campus, Stuart St., Toowoomba, QLD 4350, Australia.

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© 2012 Ian R.G. Wilson;

open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

* Address correspondence to this author at the Queensland Department of Education and Training, Toowoomba State High, Mt. Lofty Campus, Stuart St., Toowoomba, QLD 4350, Australia; Tel: +61746371363; Fax: +61746371310; E-mail:


This study looks for evidence of a correlation between long-term changes in the lunar tidal forces and the interannual to decadal variability of the peak latitude anomaly of the summer (DJF) subtropical high pressure ridge over Eastern Australia (L) between 1860 and 2010. A simple “resonance” model is proposed that assumes that if lunar tides play a role in influencing L, it is most likely one where the tidal forces act in “resonance” with the changes caused by the far more dominant solar-driven seasonal cycles. With this type of model, it is not so much in what years do the lunar tides reach their maximum strength, but whether or not there are peaks in the strength of the lunar tides that re-occur at the same time within the annual seasonal cycle. The “resonance” model predicts that if the seasonal peak lunar tides have a measurable effect upon L then there should be significant oscillatory signals in L that vary in-phase with the 9.31 year draconic spring tides, the 8.85 year perigean spring tides, and the 3.80 year peak spring tides. This study identifies significant peaks in the spectrum of L at 9.4 (+0.4/-0.3) and 3.78 (± 0.06) tropical years. In addition, it shows that the 9.4 year signal is in-phase with the draconic spring tidal cycle, while the phase of the 3.8 year signal is retarded by one year compared to the 3.8 year peak spring tidal cycle. Thus, this paper supports the conclusion that long-term changes in the lunar tides, in combination with the more dominant solar-driven seasonal cycles, play an important role in determining the observed inter-annual to decadal variations of L.

Keywords: Atmospheric Pressure, High Pressure Ridge, Lunar Tides.