Abstract
We present a 2-dimensional time-dependent simulation based on Parker’s transport equation (PTE) describing the propagation of energetic astroparticles – cosmic rays (CR) in the heliosphere. PTE is a second order partial differential equation containing four major processes: diffusion, convection, drift, and adiabatic cooling responsible for modulation of the CR flux in the heliosphere. We implement in the numerical simulation, a few physical parameters as the tilt angle, delta , of the heliospheric current sheet (HCS), module, B, of the interplanetary magnetic field (IMF), and variations of drift effect of the CR particles with solar activity (SA). Our approach is the implementation of two independent parameters (proxies), gamma and nu . The parameters gamma and nu are calculated from various independent sources, gamma , from neutron monitors (NM) daily data, and nu , using the IMF hourly data. The solutions of PTE obtained from our numerical model are compared with the variations of the CR flux recorded by NMs. We prove the existence of a varying delay time (DT) between the changes of galactic cosmic ray (GCR) intensity and the parameters characterizing SA. Based on our investigation, we obtained different DTs in Solar Cycles 21 and 23. We conclude that the calculated DTs, after comparison with the observed DTs, are useful parameters for the study of GCR transport in the heliosphere.
Highlights
The problem of delay times between the intensity of galactic cosmic rays, I, and other parameters is relevant regarding different periods of solar activity (SA)
It is possible that some indices and parameters such as the solar sunspot number (SSN), the solar sunspot area (SSA), and the solar flare index (SFI) represent global effects, whereas others such as B and Ap represent local effects limited to the space near or at the Earth
Opposite to the above work on the delay time (DT) problem, in our last article Iskra et al (2019) we examined the whole period from 1959 to 2014 which includes two and a half 22-year solar magnetic cycle (SMC), and divided it into five periods corresponding to different signs of the polarity state of the solar magnetic field, A
Summary
The problem of delay times between the intensity of galactic cosmic rays, I , and other parameters is relevant regarding different periods of solar activity (SA). Mechanisms of GCR transport in the heliosphere are based on four major processes: diffusion, convection,
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