Changes in the Insolation

With the use of modern numerical methods of celestial mechanics, the incoming irradiance flux to the Earth from the Sun has been calculated under the assumption of the invariability of its luminosity through interval of 1700–2000 A.D. Harmonics of the annual period of the Earth as well as harmonics of the synodic period of Venus, Mars, Jupiter, Saturn and harmonics corresponded to combination frequencies, are clearly visible in the power spectrum of time series of the insolation. The periods of these harmonics are located in the range from 100 days to 15.7 years.

The power spectrum of time series of the incoming to the Earth irradiance flux of the Sun under the assumption of the invariability of its luminosity in the time interval from 1700 through 2000 is analyzed in the region of frequencies, connected with the motion of the Moon. In the power spectrum of insolation, together with the basic peak with the period of synodic month 29d .53, are manifested also the peaks corresponding to the combination frequencies of this month with the harmonics of the annual period of the Earth.