The Tendencies of Change of the Incoming Solar Radiation to the Upper Atmosphere Boundary and Their Spatial Localization

Satellite-based measurements of the total flow of incoming solar radiation arriving at the Earth (total solar irradiance (TSI)) have been carried out since 1977. By now, a continuous series of variations of the TSI is obtained. The 11-year cycle and its amplitude in multiyear variations of solar radiation are revealed. However, two mechanisms having different physical nature are defined in regulation of the incoming solar radiation to the Earth (with the atmosphere not accounted for), and in its distribution over the Earth surface (solar climate of the Earth). One mechanism is related to the variation in solar activity. Another mechanism is defined by celestial-mechanical processes, which alter the orbit elements of the Earth (Earth–Sun distance, duration of the tropical year, etc.), the Earth rotation axis tilt, and the relevant variations in the Earth’s insolation. The performed calculations of the insolation related to the celestial-mechanical processes were used as a basis for differentiating the satellite observational data on the changes of the TSI with respect to the mechanisms of different physical nature. It was made possible to estimate the contributions of the variation in solar activity and of the celestial-mechanical processes to the total incoming solar radiation.