Observed solar cycle modulation of galactic cosmic rays over a range of rigidities

Abstract

We have studied the long-term, steady-state, solar cycle modulation of galactic cosmic ray intensity for seven cycles (17-23). Our analysis is based on the data obtained with a variety of detectors on earth (neutron monitors of the global network and muon detectors) as well as telescopes flown on high altitude balloons and on-board near-earth satellites. The median rigidity of response for these detectors to galactic cosmic ray spectrum lies in the range 1-70 GV. We correlate cosmic ray data to sunspot numbers, Ap, solar wind bulk speed (V), magnetic field (B), as well as to the cycle maximum (M), minimum (m), and the epochs of the solar polar field reversals. This enables us to derive the rigidity dependence of observations, and helps us to define the characteristics of the modulation function in the heliosphere. © 2004 Published by Elsevier Ltd. on behalf of COSPAR.