Long-Term Modulation of Cosmic Rays in the Heliosphere and its Influence at Earth

Abstract

The temporal variation of the cosmic-ray flux at Earth directly influences the production rate of cosmogenic isotopes in the Earth’s atmosphere. Here we put the emphasis on problems of the modulation of cosmic rays in the heliosphere. The physics of the modulation region, e.g., the heliosphere, is described and also the transport theory of the cosmic rays through the heliosphere is presented. The discussion includes more recent ideas of the modulation in the heliosheath. In the light of these ideas the cosmic-ray fluxes during the Maunder minimum are discussed. It is also discussed, that the 22-year cycle observed in the cosmogenic isotopes is a modulation effect of the cosmic rays, and hence directly connected with the physics of the outer heliosphere.