Features of Annual and Monthly Irradiation of the Earth in the Late Pleistocene

Based on the model of J. Laskar, which describes the smoothed (without short-period oscillations) orbital motion and rotation of the Earth, calculations of the annual and monthly insolation of the Earth and hemispheres have been carried out. It is determined that the annual irradiation of the Earth and the hemispheres is regulated by the dynamics of the eccentricity of the Earth’s orbit. Also, the dynamics of eccentricity determines the change in amplitude for the months of the tropical year corresponding to the position of the Earth at the points of the summer and winter solstices (July and January, according to modern chronology). The structure of the ~400 000-year cycle of annual irradiation intensity (I_an) of the Earth as a whole and by hemispheres, including the stages of low-amplitude and high-amplitude oscillations, has been studied. The range of fluctuations in the I_an in the stages of the high-amplitude oscillations is 5 times greater than the range of its fluctuations in the stages of the low-amplitude oscillations. The direct and inverse effect of dividing the monthly irradiation intensity (for July and January) into phases of increasing and decreasing I_an of the Earth as a whole and by Northern and Southern hemispheres was discovered, and its quantitative characteristics were calculated. On average, during the phase of increasing annual IR in July in the Northern Hemisphere, the radiation intensity is 3.687 W/m² (0.785%) greater than in the phase of its decreasing. During the phase of increasing I_an in January in the Northern Hemisphere, the opposite effect appears: the radiation intensity is on average 1.593 W/m² (0.752%) less than in the stage of decreasing I_an. In the Southern Hemisphere in July, during the stage of increasing I_an, the irradiation intensity exceeds the July IR in the stage of decreasing annual IR by an average of 1.614 W/m² (0.763%). In January, the opposite effect is observed in the Southern Hemisphere. In the phase of increasing I_an, the January irradiation intensity is inferior to the same parameter in the phase of decreasing I_an by an average of 3.527 W/m² (0.750%). Based on the division of monthly irradiation into phases of increasing and decreasing I_an in the Late Pleistocene, 9 warm and 7 cold epochs in the Earth’s solar climate are determined, which can be the basis of solar geochronology and climatostratigraphy of the Late Pleistocene.