Patterns of long-term variations of cosmic ray intensities

Abstract

The recovery of cosmic ray intensity has been earlier reported to have followed two distinct patterns, slow recovery during odd solar activity cycles 17, 19,21, and fast recovery during even cycles 18,20, Further analysis shows that the recovery in cycle 22 was fast and fitted this pattern, However, it was noticed that the sunspot number pattern also was different in even cycles as compared to the odd cycles in cycles 17-22, with step functions almost similar for sunspots and cosmic rays in even cycles. Thus, the differential effects on cosmic rays in alternate cycles could be related to sunspot activity itself. In addition, it was noticed that the correlations improved still further if solar indices in the corona, like coronal green line intensity index, were considered instead of the sunspot numbers. Hence, the hypothesis that the cosmic ray patterns might have been caused by solar polar magnetic field reversals may not be necessary.