Correlation studies of the inclinations of the heliospheric current sheet with: I. Cosmic ray intensity of different rigidities

This work investigates the observed dependence of neutron monitor intensities on the waviness of the heliospheric current sheet (HCS). The results indicate that the waviness of HCS plays an important role in the modulation of cosmic rays. The intensities of cosmic ray are directly sensitive to, and organized by, the interplanetary magnetic field (IMF) and its neutral sheet tilt angles. Intensities have shown a much stronger tilt-angle dependence during the qA<0 period (1981–1989) than in the qA>0 epoch (1971–1978). The rigidity dependence of sensitivities of cosmic-rays differ during the two IMF epochs, for the period qA<0 it was R−1.3±0.1, while for the qA>0 epoch it was R−0.80±0.05. The reversal of the IMF in 1979/1980 caused the computed spectra to be harder than before it. The observed correlations are consistent with the prediction of the gradient drift model.