K. Iskra

THEORETICAL AND EXPERIMENTAL STUDIES OF THE 11-YEAR AND 27-DAY VARIATIONS OF THE GALACTIC COSMIC RAYS INTENSITY AND ANISOTROPY

The changes of the structure in the energy range of the interplanetary magnetic field (IMF) turbulence versus solar activity can be considered as one of the important reasons of the long period (11-year) modulation of galactic cosmic ray (GCR) intensity; the amplitude of the 27-day variation of GCR anisotropy is greater in the qA > 0 periods than in the qA < 0 periods of the solar magnetic cycles in a good correlation with the similar changes of the 27-day variation of GCR intensity.

Rigidity spectrum of the long-period variations of the galactic cosmic ray intensity in different epochs of solar activity

We investigate character of correlations between the rigidity spectrum exponent γ of the 11-year variations of the Galactic Cosmic Ray (GCR) intensity and the exponent v of the Power Spectral Density (PSD) of the Interplanetary Magnetic Field (IMF) turbulence in period 1968-2012 using data of the IMF and carefully selected neutron monitors. We show that a clear inversely correlation between γ and v is observed when a resonance frequency range f1-f2 of the IMF turbulence (using for calculation of v), are determined taking into account changes of the solar wind velocity Vsw and strength B of the IMF versus solar activity. We assume that an essential contribution to the scattering of GCR particles in the heliosphere is setting up generally by the turbulence of By and Bz components of the IMF. Therefore, in this paper we use the exponents vy and vz of PSD of the By and Bz components of the IMF turbulence. Generally, both γ and v can be accepted as the essential proxies to study GCR propagation near earth orbit in heliosphere for the rigidity range of GCR particles to which neutron monitors and ground muon telescopes respond

2-D Modelling of Long Period Variations of Galactic Cosmic Ray Intensity

A new two-dimensional (2-D) time dependent model describing long-period variations of the Galactic Cosmic Ray (GCR) intensity has been developed. New approximations for the changes of the magnitude B of the Interplanetary Magnetic Field (IMF), the tilt angle δ of the Heliospheric Neutral Sheet (HNS) and drift effects of the GCR particles have been included into the model. Moreover, temporal changes of the exponent γ expressing the power law - rigidity dependence of the amplitudes of the 11-year variation of the GCR intensity have been added. We show that changes of the expected GCR particle density precedes changes of the GCR intensity measured by the Moscow Neutron (MN) monitor by about 18 months. So ~18 months can be taken as an effective delay time between the expected intensity caused by the combined influence of the changes of the parameters implemented in the time-dependent 2-D model and the GCR intensity measured by neutron monitors during the 21 cycle of solar activity.