Effects of the tilted and wavy current sheet on the solar modulation of galactic cosmic rays

TL;DR

This paper presents a numerical study of how the tilted and wavy heliospheric current sheet influences the solar modulation of galactic cosmic rays, using a time-dependent 3D stochastic differential equation approach.

Contribution

It introduces a fully time-dependent, three-dimensional code for modeling GCR transport considering the wavy heliospheric current sheet, capturing solar cycle variations.

Findings

Reproduced a 22-year solar cycle in GCR modulation.

Simulated proton energy spectra at 1 AU consistent with BESS observations.

Demonstrated the impact of the wavy current sheet on cosmic ray trajectories.

Abstract

Transport equation of the galactic cosmic ray (GCR) is numerically solved for qA>0 and qA<0 based on the stochastic differential equation (SDE) method. We have developed a fully time-dependent and three-dimensional code adapted for the wavy heliospheric current sheet (HCS). Results anticipated by the drift pattern are obtained for sample trajectories and distributions of arrival points at the heliospheric boundary for GCR protons. Our simulation reproduced a 22-year cycle of solar modulation which is qualitatively consistent with observations. Energy spectra of protons at 1 AU are calculated and compared with the observation by BESS.