Solar and Interplanetary Determinants of Long-term Solar Modulation of Cosmic-Ray Intensity for Median Rigidities of 11–107 GV

Abstract We investigate the long-term modulation of cosmic-ray (CR) intensity across median rigidities from 11 to 107 GV using over four decades (1980–2023) of data from neutron monitors (NMs) and muon detectors (MDs). The analysis incorporates global NM stations and the Nagoya Multi-Directional Muon Telescope to evaluate the influence of key heliospheric parameters: interplanetary magnetic field (IMF) strength, heliospheric current sheet tilt angle (TA), and solar wind (SW) speed. Results reveal pronounced rigidity-dependent modulation patterns. Lower-rigidity NMs exhibit stronger sensitivity to heliospheric conditions, driven largely by IMF and TA, consistent with diffusion- and drift-dominated transport. In contrast, higher-rigidity MDs show reduced modulation amplitudes, with IMF remaining the dominant influence and SW gaining relative importance as drift effects diminish. These findings provide new insight into the energy-dependent roles of heliospheric drivers in CR modulation and offer a robust framework for advancing space weather prediction and heliospheric transport modeling.