  The ability to predict times of greater galactic cosmic ray (GCR) fluxes is
important for reducing the hazards caused by these particles to satellite
communications, aviation, or astronauts. The 11-year solar cycle variation in
cosmic rays is highly correlated with the strength of the heliospheric magnetic
field. Differences in GCR flux during alternate solar cycles yield a 22-year
cycle, known as the Hale Cycle, which is thought to be due to different
particle drift patterns when the northern solar pole has predominantly positive
(denoted a qA>0 cycle) or negative (qA<0) polarities. This results in the onset
of the peak cosmic ray flux at Earth occurring earlier during qA>0 cycles than
for qA<0 cycles and hence the peak being more domed for qA>0 and more sharply
peaked for qA<0. In this study, we demonstrate that properties of the
large-scale heliospheric magnetic field are different during the declining
phase of the qA<0 and qA>0 solar cycles, when the difference in GCR flux is
most apparent. This suggests that particle drifts may not be the sole mechanism
responsible for the Hale Cycle in GCR flux at Earth. However, it is also
demonstrated that these polarity-dependent heliospheric differences are evident
during the space-age but much less clear in earlier data: using geomagnetic
reconstructions, it is shown that for the period of 1905 - 1965, alternate
polarities do not give as significant a difference during the declining phase
of the solar cycle. Thus we suggest that the 22-year cycle in cosmic ray flux
is at least partly the result of direct modulation by the heliospheric magnetic
field and that this effect may be primarily limited to the grand solar maximum
of the space-age.
