Speaker
Prof.
Michael Alania
(Siedlce University)
Description
Our attention is attracted by the temporal changes of an anomaly increase of the galactic cosmic, ray ( GCR) intensity ∆N(t) in the minimum phase of Forbush decrease (Fd) observed by neutron monitors on June 22, 2015. We make an ad hoc assumption for alternative explanations of the temporal changes of an anomaly increase of the GCR intensity: (1) that changes (denoted as ∆NR(t)) are caused by the variations of the Earth’s magnetic field in the minimum phase of Fd (due to decrease of magnetic cut-off rigidity), (2) the changes (denoted as ∆Nv(t)) are caused by the growth of diffusion coefficient related with the fluctuations of a structure of the interplanetary magnetic field (IMF) turbulence in the vicinity of the heliosphere, where Fd is settled, and (3) owing to superposition of the both ∆NR(t) and ∆Nv(t) effects (∆N(t) = ∆NR(t) + ∆Nv(t)). We have calculated a rigidity R spectrum exponent $\gamma$ of Fd ($ \delta D(R)/D(R)\propto R^{-\gamma} $ ) and the exponents $\nu_{y}$ and $\nu_{z}$ of the power spectral density (PSD) of the By and Bz components of the interplanetary magnetic field (IMF) turbulence before Fd, during minimum and in recovery phases of the GCR intensity. We have found that rigidity spectrum becomes softer in the minimum phase of Fd after correction of the intensity of GCR for changes of the magnetic cut off rigidity ∆R, caused by Dst variation of the Earth’s magnetic field. We show that a relationship between $\gamma$ and ν in the minimum phase of Fd ( $\gamma \approx 2-\nu$) is a little alternating after correction of the intensity of GCR for changes of the magnetic cut off rigidity ∆R, but generally remains in the range of values expected from the quasi linear theory of GCR propagation in the heliosphere.
We compose a 2D nonstationary model of the Parker’s transport equation for anisotropic diffusion case. Using this model we describe a dynamic of Fd 22 June 2015 taking into account an alternative nature of an anomaly increase of the GCR intensity in the minimum phase of Fd. We discuss the problem of compatibility of results obtained from theoretical modeling and observations by neutron monitors.
Primary author
Prof.
Michael Alania
(Siedlce University)
Co-authors
Dr
Anna Wawrzynczak
(Siedlce University, Poland)
Mr
I.I. Tuskia
(Nodia Institute of Geophysics, Ivane Dzavachishvili Tbilisi State University, Tbilisi, Georgia)
Mr
N. Glonti
(Nodia Institute of Geophysics, Ivane Dzavachishvili Tbilisi State University, Tbilisi, Georgia)
Mr
T.S. Bakradze
(Nodia Institute of Geophysics, Ivane Dzavachishvili Tbilisi State University, Tbilisi, Georgia)
