A comparison of ground level cosmic ray enhancements of November 22, 1977 and February 25, 1969

Publisher Website
Google Scholar
Abstract
The anisotropic solar flare increases observed by neutron monitors on November 22, 1977 and February 25, 1969 are discussed. These events occurred at quite different modulation levels of galactic cosmic rays. The characteristics of the events such as anisotropy, rise and decay times are not significantly different from one event to the other. This implies that the interplanetary conditions for propagation of cosmic rays of a few GeV (109 eV) energy are comparable at the sunspot maximum and minimum of solar cycle 20. Therefore, the near‐earth environment does not play a major role in the modulation of galactic cosmic ray intensity and the cause of its 11‐year variation has to be sought in the regions off the ecliptic plane and/or farther out in the ecliptic plane.