Cosmic-ray modulation by the heliospheric neutral sheet

The observed long-period variations in cosmic rays are subdivided into two types: those caused by the curvature of the neutral sheet of the interplane tary magnetic field and those due to the solar activity level. The McMurdo, Rome, and Tokyo neutron monitor data for the periods of negative (1982-198 8) and positive (1992-1998) polarities of the global solar magnetic Held ar e analyzed. The dependence of the cosmic-ray modulation on the neutral shee t tilt is explained and qualitatively estimated in terms of a theoretical m odel including their drift in the magnetic field.