Using Galactic Cosmic Ray Observations for Determination of the Heliosphere Structure During Different Solar Cycles

Abstract

Our studies of the neutron and muon components data from many observatories with different cut‐off rigidities during solar cycles 19–22 have made it possible to investigate the hysteresis character of the relationships between the variations in solar activity and in galactic cosmic ray intensity. We use here a special model described the connection between solar activity and CR convection‐diffusion global modulation with taking into account time‐lag of plasma processes in the Heliosphere relative to the active processes on the Sun. We supposed different dimension of the modulation region and for each dimension was determined the correlation coefficient between variations of expected and observed CR intensities. We found that the maximum of correlation coefficient occurred for even cycles for about two‐three times in the shorter time than for odd cycles. We came to conclusion that this difference is caused by CR drift effects: during even cycle drift effect from minimum to maximum of SA produced the small increasing of CR global modulation additional to the caused by convection‐diffusion mechanism, and after maximum of SA ‐ about the same decreasing of CR modulation. This gives sufficient decreasing of observed time‐lag between CR and SA in even solar cycles. For odd solar cycles we have inverse situation: drift effect from minimum to maximum of SA produced the additional decreasing of CR global modulation caused mainly by convection‐diffusion mechanism, and after maximum of SA ‐ increasing of CR modulation. This gives sufficient increasing of observed time‐lag between CR and SA in odd solar cycles. By comparison of expected results with observed for particles of different energy we determine the relative role of convection‐diffusion and drift mechanisms in formation of CR global modulation in the Heliosphere.