Latitudinal Dependence of Cosmic Rays Modulation at 1 AU and Interplanetary-Magnetic-Field Polar Correction

Abstract

The cosmic rays differential intensity inside the heliosphere, for energy below 30 GeV/nuc, depends on solar activity and interplanetary magnetic field polarity. This variation, termed solar modulation, is described using a 2-D (radius and colatitude) Monte Carlo approach for solving the Parker transport equation that includes diffusion, convection, magnetic drift and adiabatic energy loss. Since the whole transport is strongly related to the interplanetary magnetic field (IMF) structure, a better understanding of his description is needed in order to reproduce the cosmic rays intensity at the Earth, as well as outside the ecliptic plane. In this work an interplanetary magnetic field model including the standard description on ecliptic region and a polar correction is presented. This treatment of the IMF, implemented in the HelMod Monte Carlo code (version 2.0), was used to determine the effects on the differential intensity of Proton at 1\,AU and allowed one to investigate how latitudinal gradients of proton intensities, observed in the inner heliosphere with the Ulysses spacecraft during 1995, can be affected by the modification of the IMF in the polar regions.

accepted for publication inAdvances in Astronomy

References in corpus (3)

• PAMELA Measurements of Cosmic-ray Proton and Helium Spectra
• Measurements of 0.2 to 20 GeV/n cosmic-ray proton and helium spectra from 1997 through 2002 with the BESS spectrometer
• Systematic Investigation of Solar Modulation of Galactic Protons for Solar Cycle 23 using a Monte Carlo Approach with Particle Drift Effects and Latitudinal Dependence

Cited by in corpus (9)

• Solution of heliospheric propagation: unveiling the local interstellar spectra of cosmic ray species
• Propagation of Cosmic Rays in Heliosphere: the HelMod Model
• HelMod in the works: from direct observations to the local interstellar spectrum of cosmic-ray electrons
• Modulation of Galactic Cosmic Rays in the Inner Heliosphere over Solar Cycles
• Modulation of Galactic Cosmic Rays in the Inner Heliosphere, Comparing with PAMELA Measurements
• Galactic Cosmic-Ray Propagation in the Inner Heliosphere: Improved Force-Field Model
• The HelMod Model in the Works for Inner and Outer Heliosphere: from AMS to Voyager Probes Observations
• The HelMod Monte Carlo Model for the Propagation of Cosmic Rays in Heliosphere
• Cosmic Rays Propagation with HelMod: Difference between forward-in-time and backward-in-time approaches