Features of cosmic ray modulation in October and November 2003

Abstract

Using data from the worldwide network of cosmic ray stations, Forbush decreases on October 29–31 and November 20–21, 2003 were studied using method of spectrographic global survey. The indices of the variation spectrum for the power representation of the particle magnetic rigidity over the range of 10–50 GV are given for different stages of the development of Forbush decreases, which proved to be greater for the event on November 20–21 than for the one on October 29–31, 2003. A high degree of anisotropy in the angular distribution of cosmic rays in the Forbush decrease periods and its phase variability indicate the dispersal of magnetic clouds and the high degree of regularity of the interplanetary magnetic field (IMF) in these structures; the presence of bidirectional anisotropy suggests a loop structure of the IMF during the events of October 29, 2003.