Intensity variations in the interplanetary magnetic field measured by Voyager 2 and the 11-year solar cycle modulation of galactic cosmic rays

1992 ◽  
Vol 97 (A4) ◽  
pp. 4305 ◽  
Author(s):  
J. S. Perko ◽  
L. F. Burlaga
Keyword(s):  
Magnetic Field ◽  
Solar Cycle ◽  
Cosmic Rays ◽  
Interplanetary Magnetic Field ◽  
Galactic Cosmic Rays ◽  
Voyager 2

scholarly journals Quasi-periodic changes in the 3D solar anisotropy of Galactic cosmic rays for 1965–2014

2017 ◽  
Vol 609 ◽  
pp. A32 ◽  
Author(s):  
R. Modzelewska ◽  
M. V. Alania
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Solar Activity ◽  
Solar Cycle ◽  
Cosmic Rays ◽  
Ecliptic Plane ◽  
Galactic Cosmic Rays ◽  
Magnetic Cycle ◽  
The North ◽  
Solar Magnetic Cycle

Aims. We study features of the 3D solar anisotropy of Galactic cosmic rays (GCR) for 1965−2014 (almost five solar cycles, cycles 20−24). We analyze the 27-day variations of the 2D GCR anisotropy in the ecliptic plane and the north-south anisotropy normal to the ecliptic plane. We study the dependence of the 27-day variation of the 3D GCR anisotropy on the solar cycle and solar magnetic cycle. We demonstrate that the 27-day variations of the GCR intensity and anisotropy can be used as an important tool to study solar wind, solar activity, and heliosphere. Methods. We used the components Ar, Aϕ and At of the 3D GCR anisotropy that were found based on hourly data of neutron monitors (NMs) and muon telescopes (MTs) using the harmonic analyses and spectrographic methods. We corrected the 2D diurnal (~24-h) variation of the GCR intensity for the influence of the Earth magnetic field. We derived the north-south component of the GCR anisotropy based on the GG index, which is calculated as the difference in GCR intensities of the Nagoya multidirectional MTs. Results. We show that the behavior of the 27-day variation of the 3D anisotropy verifies a stable long-lived active heliolongitude on the Sun. This illustrates the usefulness of the 27-day variation of the GCR anisotropy as a unique proxy to study solar wind, solar activity, and heliosphere. We distinguish a tendency of the 22-yr changes in amplitude of the 27-day variation of the 2D anisotropy that is connected with the solar magnetic cycle. We demonstrate that the amplitudes of the 27-day variation of the north-south component of the anisotropy vary with the 11-yr solar cycle, but a dependence of the solar magnetic polarity can hardly be recognized. We show that the 27-day recurrences of the GG index and the At component are highly positively correlated, and both are highly correlated with the By component of the heliospheric magnetic field.

Anisotropy of Galactic Cosmic Rays and the Interplanetary Magnetic Field

Nature ◽  
1965 ◽  
Vol 206 (4985) ◽  
pp. 703-704 ◽  
Author(s):  
V. SARABHAI ◽  
G. L. PAI ◽  
M. WADA
Keyword(s):  
Magnetic Field ◽  
Cosmic Rays ◽  
Interplanetary Magnetic Field ◽  
Galactic Cosmic Rays

scholarly journals Impact of solar magnetic field amplitude and geometry on cosmic rays diffusion coefficients in the inner heliosphere

2020 ◽  
Vol 10 ◽  
pp. 55
Author(s):  
Barbara Perri ◽  
Allan Sacha Brun ◽  
Antoine Strugarek ◽  
Victor Réville
Keyword(s):  
Magnetic Field ◽  
Solar Cycle ◽  
Cosmic Rays ◽  
Numerical Simulations ◽  
Transport Equation ◽  
Diffusion Coefficients ◽  
Galactic Cosmic Rays ◽  
Current Sheets ◽  
The Magnetic Field ◽  
Inner Heliosphere

Cosmic rays are remarkable tracers of solar events when they are associated with solar flares, but also galactic events such as supernova remnants when they come from outside our solar system. Solar Energetic Particles (SEPs) are correlated with the 11-year solar cycle while Galactic Cosmic Rays (GCRs) are anti-correlated due to their interaction with the heliospheric magnetic field and the solar wind. Our aim is to quantify separately the impact of the amplitude and the geometry of the magnetic field, both evolving during the solar cycle, on the propagation of cosmic rays of various energies in the inner heliosphere (within Earth orbit). We focus especially on the diffusion caused by the magnetic field along and across the field lines. To do so, we use the results of 3D magnetohydrodynamics (MHD) wind simulations running from the lower corona up to 1 AU. This gives us the structure of the wind and the corresponding magnetic field. The wind is modeled using a polytropic approximation, and fits and power laws are used to account for the turbulence. Using these results, we compute the parallel and perpendicular diffusion coefficients of the Parker cosmic ray transport equation, yielding 3D maps of the diffusion of cosmic rays in the inner heliosphere. By varying the amplitude of the magnetic field, we change the amplitude of the diffusion by the same factor, and the radial gradients by changing the spread of the current sheet. By varying the geometry of the magnetic field, we change the latitudinal gradients of diffusion by changing the position of the current sheets. By varying the energy, we show that the distribution of values for SEPs is more peaked than GCRs. For realistic solar configurations, we show that diffusion is highly non-axisymmetric due to the configuration of the current sheets, and that the distribution varies a lot with the distance to the Sun with a drift of the peak value. This study shows that numerical simulations, combined with theory, can help quantify better the influence of the various magnetic field parameters on the propagation of cosmic rays. This study is a first step towards the resolution of the complete Parker transport equation to generate synthetic cosmic rays rates from numerical simulations.

Streaming of galactic cosmic rays in the interplanetary magnetic field

Solar Physics ◽  
1972 ◽  
Vol 22 (1) ◽  
pp. 220-234 ◽  
Author(s):  
A. Hashim ◽  
M. Bercovitch ◽  
J. F. Steljes
Keyword(s):  
Magnetic Field ◽  
Cosmic Rays ◽  
Interplanetary Magnetic Field ◽  
Galactic Cosmic Rays
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