H. Mavromichalaki et al., ON REPRODUCTION OF LONG-TERM COSMIC-RAY MODULATION AS SEEN BY NEUTRONMONITOR STATIONS, Astrophysics and space science, 232(2), 1995, pp. 315-326
The dependence of cosmic-ray intensity on 21st solar cycle phenomena h
as been studied using monthly cosmic-ray values from nine world wide N
eutron Monitoring Stations. For this purpose the long-term cosmic-ray
modulation is modelled by treating the most appropriate source functio
ns among various solar, interplanetary and terrestrial activity indice
s as the input and the cosmic-ray intensity as the output of a linear
system taking into account the corresponding time-lag. In this way the
modulated galactic cosmic-ray intensity has been reproduced to a cert
ain degree as the cosmic-ray variations follow the observations with a
standard deviation of similar to 10%. Still remaining short-term vari
ations in all stations with periods of 2.7 and 3.7 months can possibly
be related to the galactic origin of cosmic-rays. The Simpson solar w
ind model improved by the spherically symmetric diffusion-convection t
heory can describe our proposed method.