Schematic diagram illustrating the time variation of solar activity and its modulation effect on the GCR transport within the heliosphere. The information regarding solar activity is transmitted to Earth through electromagnetic waves and recorded via the observed SSN and solar radio flux (F10.7). The information regarding solar activity is also carried by the solar magnetic open flux (OF). The cyan arrows illustrate the propagation of the solar activity information within the heliosphere as the solar wind plasma travels away from the Sun. The azure arrows linking the LIS, considered constant in time beyond the heliopause, with the GCR flux, continuously recorded near Earth, indicate that the solar activity information is encoded in the GCR modulation.