Modulation of Galactic Cosmic Rays in the Inner Heliosphere over Solar Cycles

Abstract

The 11-year and 22-year modulation of galactic cosmic rays (GCRs) in the inner heliosphere are studied using a numerical model developed by Qin and Shen in 2017. Based on the numerical solutions of Parker's transport equations, the model incorporates a modified Parker heliospheric magnetic field, a locally static time delayed heliosphere, and a time-dependent diffusion coefficients model in which an analytical expression of the variation of magnetic turbulence magnitude throughout the inner heliosphere is applied. Furthermore, during solar maximum, the solar magnetic polarity is determined randomly with the possibility of $A>0$ decided by the percentage of the north solar polar magnetic field being outward and the south solar polar magnetic field being inward. The computed results are compared with several GCR observations, e.g., IMP 8, SOHO/EPHIN, Ulysses, Voyager 1 \& 2, at various energies and show good agreement. It is shown that our model has successfully reproduced the 11-year and 22-year modulation cycles.

Accepted for publication in The Astrophysical Journal

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Cited by in corpus (6)

• Variations of the Galactic Cosmic Rays in the Recent Solar Cycles
• Effects of shock and turbulence properties on electron acceleration
• Unfolding Drift Effects for Cosmic Rays over the Period of the Sun's Magnetic Field Reversal
• A Model of Sunspot Number with Modified Logistic Function
• Magnetic Cloud and Sheath in the Ground-Level Enhancement Event of 2000 July 14. II. Effects on the Forbush Decrease
• Solar modulation of cosmic proton and helium with AMS-02