Prolonged minima and the 179-yr cycle of the solar inertial motion, Rhodes W. Fairbridge and James H. Shirley, January 1987
We employ the JPL long ephemeris DE-102 to study the inertial motion of the Sun for the period A.D. 760Ė2100. Defining solar orbits with reference to the Sun's successive close approaches to the solar system barycenter, occurring at mean intervals of 19.86 yr, we find simple relationships linking the inertial orientation of the solar orbit and the amplitude of the precessional rotation of the orbit with the occurrence of the principal prolonged solar activity minima of the current millenium (the Wolf, SpŲrer, and Maunder minima). The progression of the inertial orientation parameter is controlled by the 900-yr great inequality of the motion of Jupiter and Saturn, while the precessional rotation parameter is linked with the 179-yr cycle of the solar inertial motion previously identified by Jose (1965). A new prolonged minimum of solar activity may be imminent.
The 2400-year cycle in atmospheric radiocarbon concentration: bispectrum of 14C data over the last 8000 years
We have carried out power spectrum, time-spectrum and bispectrum analyses of the long-term series of the radiocarbon concentrations deduced from measurements of the radiocarbon content in tree rings for the last 8000 years. Classical harmonic analysis of this time series shows a number of periods: 2400, 940, 710, 570, 500, 420, 360, 230, 210 and 190 years. A principle feature of the time series is the long period of 2400 years, which is well known. The lines with periods of 710, 420 and 210 years are found to be the primary secular components of power spectrum. The complicated structure of the observed power spectrum is the result of 2400-year modulation of primary secular components. The modulation induces the appearance of two side lines for every primary one, namely lines with periods of 940 and 570 years, of 500 and 360 years, and 230 and 190 years. The bispectral analysis shows that the parameters of carbon exchange system varied with the _2400-year period during the last 8000 years. Variations of these parameters appear to be a climate effect on the rate of transfer of 14C between the atmosphere and the ocean.
Time comparison of the epochs of high and low solar activity with climate alteration led to the conclusion that the cause of the approx. 2400-year cycle, both in the 14C concentration and in climate of the Earth, appears to be of a solar nature (Dergachev and Chistyakov, 1995).