27-Day variations of galactic cosmic rays and changes of solar and geomagnetic activities

On the Relationship of the 27-day Variations of the Solar Wind Velocity and Galactic Cosmic Ray Intensity in Minimum Epoch of Solar Activity

“…We consider two types of 3-D models of the 27-day variation of GCR intensity: (1) with planar HNS, and (2) with the sector structure of the IMF. The theoretical calculation shows that the sector structure of the IMF does not influence significantly the 27-day variation of GCR intensity as it was also shown before based on the experimental data (Alania et al, 2001b;Alania et al, 2005;Gil et al, 2005). We show that the first harmonic waves of the theoretically expected 27-day variation of the GCR intensity (obtained as a solution of the 3 -D model) and Kiel neutron monitor data are in good agreement for BR period # 2379 of 23 November 2007 -19 December 2007.…”

“…The proposed 3-D model of the 27-day variation of the GCR intensity corresponds to the instant state of the heliosphere during one BR period (27-days) and it can be considered as a stationary and rigidity R. The Equation (10) was transformed to the algebraic system of equations using the implicit finite difference scheme method and then solved by the Gauss-Seidel method of iteration as in papers published elsewhere (e.g., Alania, 2002;Iskra et al, 2004;Modzelewska et al, 2006;Wawrzynczak and Alania, 2008 expressions of β and 1 β is acceptable for the scattering of the GCR particles to which neutron monitors and ground muon telescopes respond and it is in accord with the quasi linear theory (Jokipii, 1971;Shalchi, 2009). …”

“…Previously, Alania et al, (2001aAlania et al, ( , 2001b; Gil and Alania (2001); Vernova et al, (2003); Iskra et al, (2004) demonstrated that the amplitudes of the 27-day variation of the GCR intensity obtained from neutron monitors are greater in the minimum epochs of solar activity for A>0 than for A<0. Recently, we demonstrated Modzelewska 2008a, 2008b;Gil et al, 2005) that also the amplitudes of the 27-day variation of the GCR anisotropy at solar minimum are greater when A>0 than when A<0.…”

27‐day variations of solar indices and cosmic ray neutron monitor intensities

“…The modulations are 50% larger during the A > 0 epochs than during the A < 0 epochs in all the data sets". Alania et al (2001Alania et al ( , 2005 also found out that the amplitudes of the 27-day variation of CR are 1.5 times larger during the minima and near minima epochs for the qA > 0 solar magnetic cycle than those for the qA < 0 magnetic cycle. Moreover, they concluded that these variations also depend on the N-S asymmetry of the solar activity distribution and on a change of a global magnetic field (magnetic field reversal) that occurs in cycle maxima.…”

“…The main problem with the existence of the 27-day periodicity of the cosmic rays is, as claimed by a great majority of authors, e.g., Reames & Ng (2001), Richardson,Cane Corresponding author: vrusin@ta3.sk & Wibberenz (1999), Alania et al (2001) and references therein, a "peculiar" behaviour of its amplitude over a solar cycle; different values have been obtained for different signs of qA, as well as for the absolute magnitudes of this amplitude pertinent to different maxima and minima of solar activity, e.g., Meyer & Simpson (1954) and Gil et al (2005). This is obviously connected with the structure of the heliosphere, which is induced and governed by the Sun's magnetic field dragged and stretched-out by solar wind, flares, coronal mass ejections, etc.…”