Interplanetary Magnetic Field Turbulence and Rigidity Spectrum of the Galactic Cosmic Rays Intensity Variation (1969-2011)

The present study investigates the relation between the rigidity R spectrum exponent. of the galactic cosmic rays (GCR) flux changes (delta D(R)/D(R)proportional to R-gamma.)and the exponents nu(y) and nu(z) of the power spectral density of the By and B-z components of the heliospheric magnetic field (HMF) fluctuations. Two parameters have been introduced: (1) the exponent. demonstrating the rigidity dependence of long-term changes of GCR flux on solar activity (SA) and (2) the exponents nu(y) and nu(z) signifying the state of turbulence which is divided of the B-y and B-z components. This study considers the period of time between 1969 and 2011 divided into four subperiods, according to the solar global magnetic field polarities: (I) 1969-1979, (A > 0) (positive polarity magnetic field lines are directed away from the Sun's northern hemisphere); (II) 1980-1988, (A < 0) (negative polarity magnetic field lines are directed toward the Sun's northern hemisphere); (III) 1991-2001, (A > 0); and (IV) 2002-2011, (A < 0). The paper finds that temporal changes of the resonant frequency (f(res)) of GCR protons in heliospheric magnetic field turbulence in relation to SA are mainly caused by variations of the induction of B components from year to year, while the contribution of the solar wind speed remains insignificant. The analyses of the four subperiods show that gamma increases and nu(y) and nu(z) decrease in the periods of increased SA, and conversely, the. decreases and nu(y) and nu(z) increase in the periods of reduced SA. The study concludes that the exponents gamma, and nu(y) and nu(z) can be considered as important indices (proxies) for research on GCR transport in the heliosphere.