General properties of charged particle diffusion in heliosphere inferred from Forbush decreases

Despite significant advancements in modeling solar modulation, the comprehension of the diffusion parameters remains challenging due to model parameter degeneracies and limited 3D in situ observations. Nevertheless, the study of Forbush decreases (FDs) still offers a natural probe for investigating particle transport properties. During FDs, coronal mass ejections and the associated magnetic disturbances propagating in the interplanetary medium enhance magnetic field turbulence, reducing diffusion of galactic cosmic rays (GCR). The result is a temporary reduction of GCR intensity, with recovery occurring over a few days. Previous studies linked FD observations to changes in diffusion parameters or turbulence levels, enabling insights into its rigidity dependence. In this work, we analyze five FDs observed by AMS-02 between 2011 and 2019 using a stochastic differential equation numerical code, based on the HELMOD-4/CUDA model, introducing localized changes to diffusion parameters in the inner heliosphere. Our results indicate that the rigidity dependence of the diffusion tensor remains consistent during both quiet and perturbed periods, suggesting that turbulences inducing FD do not fundamentally alter GCR propagation properties. These findings support the use of FDs to study particle transport in localized heliospheric environments, providing insights applicable to the broader heliosphere and improving diffusion modeling accuracy. These findings support the use of FDs to study particle transport in localized heliospheric environments, providing insights applicable to the broader heliosphere and improving diffusion modeling accuracy.