Rigidity Dependence of the Long-Term Variations of Galactic Cosmic-Ray Intensity in Relation to the Interplanetary Magnetic-Field Turbulence: 1968 – 2002

• Published in: Solar physics 2014-11, Vol.289 (11), p.4297-4308
• Main Authors: Siluszyk, M., Iskra, K., Alania, M. V.
• Format: Article
• Language: English
• Subjects: Astrophysics and Astroparticles; Atmospheric Sciences; Cosmic rays; Exponents; Fluid dynamics; Fluid flow; In situ measurement; Magnetic fields; Monitors; Neutrons; Physics; Physics and Astronomy; Resonant frequencies; Rigidity; Solar physics; Space Exploration and Astronautics; Space Sciences (including Extraterrestrial Physics; Turbulence; Turbulent flow; Wind speed
• ISSN: 0038-0938; 1573-093X
• DOI: 10.1007/s11207-014-0573-z

We studied the relationship between the power-law exponent γ on the rigidity R of the spectrum of galactic cosmic-ray (GCR) intensity variation ( δD ( R )/ D ( R )∝ R − γ ) and the exponents ν y and ν z of the power spectral density (PSD) of the B y and B z components of the interplanetary magnetic field (IMF) turbulence (PSD∼ f − ν , where f is the frequency). We used the data from neutron monitors and IMF for the period of 1968 – 2002. The exponents ν y and ν z were calculated in the frequency interval Δ f = f 2 − f 1 =3×10 −6  Hz of the resonant frequencies ( f 1 =1×10 −6  Hz, f 2 =4×10 −6  Hz) that are responsible for the scattering of GCR particles with the rigidity range detected by neutron monitors. We found clear inverse correlations between γ and ν y or ν z when the time variations of the resonant frequencies were derived from in situ measurements of the solar wind velocity U sw and IMF strength B during 1968 – 2002. We argue that these inverse relations are a fundamental feature in the GCR modulation that is not restricted to the analyzed years of 1968 – 2002.