Fig. 4: Quarter-precessional cycles in theoretical insolation curves and their comparison with geological proxy reconstruction.
From: Precession-induced millennial climate cycles in greenhouse Cretaceous
A The theoretically-proposed largest equatorial seasonal insolation amplitude (termed equatorial insolation). The insolation amplitude is estimated from the differences between the two insolation maxima at spring and fall equinoxes and the two insolation minima at summer and winter solstices, that is, max (SE, FE)-min (SS, WS), where SE, FE, SS, WS denote the spring equinox, fall equinox, summer solstice, winter solstice, respectively11. B The combined effect of equatorial and bi-hemisphere maximum insolation. C The log (Ca/Ti) in the SK2 of SLB. D The periodogram spectra of equatorial insolation. E The periodogram spectra of the combined effect of equatorial and bi-hemisphere maximum insolation at 8 °N/S.
