Hi All, 12-9-09 You may find the below interesting.
Jack Smith --------- Long lunar cycles, tides and climate Posted by: "Ray Tomes" [email protected] rjtomes Date: Mon Dec 7, 2009 4:38 pm ((PST)) I have studied the shorter tidal cycles due to the lunar 8.85 year and 18.6 year orbital variations. These interact to make a cycle of about 89.5 years. I just came across a page that looks at much longer lunar tidal cycles. Lunar cycles affect the tides which affect the sea circulation which is a significant climate factor. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC18099/figure/F3/ "Figure 3 Varying strength of the global tide raising forces (bottom plot), as in Figs. ... together with parameters (top and middle plots) that reveal the basis for the 1,800- and 5,000-year tidal cycles, as described in the text. The plots are for a hypothetical 110-kyr sequence of tidal events beginning with the moon, sun, and earth in perfect alignment and closest approach (zero separation-intervals), producing a maximum γ of 17.165° per day never again attained. Tidal events occurring near peaks in the 5,000-year cycle (near zero crossings of top plot) are connected by straight lines to reveal their pattern (which includes a 23-kyr cycle not discussed in the text). Proc Natl Acad Sci U S A. 2000 April 11; 97(8): 3814â3819. Published online 2000 March 21. © The National Academy of Sciences" A larger version of the figure is available at the web page by clicking on the figure there. Although the text refers to a 5000 year cycle, examining the top graph there can be seen to be seen to be 20 cycles in 93,000 years, so the cycle averages 4,650 years. This is rather close to an outer planetary alignment cycle period. The cycle referred to as 1800 yaers can be seen in the second graph down. It averages 1790 years and has a phase shift cycle of about 15 times that long or around 26,850 years. This is close to the precession of the equinoxes cycle. The third graph also shows periodicity at about 23,000 to 26,000 years in the envelope. The peaks there are very clsoe to 1800 years apart, perhaps 1797 years. ----------- Re: Long lunar cycles, tides and climate Posted by: "Ray Tomes" [email protected] rjtomes Date: Mon Dec 7, 2009 4:42 pm ((PST)) More from the same site: The main page is http://www.ncbi.nlm.nih.gov/pmc/articles/PMC18099/ <http://www.ncbi.nlm.nih.gov/pmc/articles/PMC18099/> and there are many graphs and tabvles off this. Another one is: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC18099/figure/F1/ "Varying strength in an estimate of the tide raising forces, derived from Wood (ref. 5 <http://www.ncbi.nlm.nih.gov/pmc/articles/PMC18099/#B5> , Table 16). Each event, shown by a vertical line, gives a measure of the forcing in terms of the angular velocity of the moon, γ, in arc degrees per day, at the time of the event. Arcs connect events of strong 18.03-year tidal sequences. Centennial maxima are labeled, with the final one, âDâ, occurring in A.D. 2151." I note that these maxima are at intervals of 177, 187 and 177 years respectively. ----------- Global Temperature compared to known cycles Posted by: "Ray Tomes" [email protected] rjtomes Date: Mon Dec 7, 2009 7:57 pm ((PST)) Comparing just the 3 established cycles in climate of 2300 years, 208 yeatrs and 54 years to the last century and a half of global temperatures shows that most of the fluctuations that last more more than a decade fit these cycles well. The 2300 year cycle troughed in about 1650 with a peak due around 2800, so it is firmly in an uptrend now. At this stage we cannot seperate any trend that exists from that cycle, so the straight line with an upward slope is labeled accordingly. The 208 year de Vries cycle was at a low around 1900 and a high around 2000. Its downward contribution will not be very noticeable for a decade or two, but its next trough should be around 2110. The cycle of around 54 years (reported by Chizhevsky as 53 years) shows troughs and peaks that fit well with the instrumental record of temperature. The next low is due around 2020 and high in 2047. The strength of this cycle explains why temperatures have stopped rising since that cycle peaked around 1998. The next job, and the most important one, is to try and split out human effects from the 2300 cycle rise. That can only be done by looking at the phase and amplitude of past 2300 year cycles. The result may be too uncertain to say.
