  Monte Carlo simulations are performed to study the correlation between the
ground cosmic ray intensity and near-earth thunderstorms electric field at YBJ
(4300 m a.s.l., Tibet, China). The variations of the secondary cosmic ray
intensity are found to be highly dependent on the strength and polarity of the
electric field. In negative fields and in positive fields greater than 600
V/cm, the total number of ground comic ray positrons and electrons increases
with increasing electric field strength. And these values increase more
obviously when involving a shower with lower primary energy or a higher zenith
angle. While in positive fields ranging from 0 to 600 V/cm, the total number of
ground comic ray positrons and electrons declines and the amplitude is up to
3.1% for vertical showers. A decrease of intensity occurs for inclined showers
in positive fields less than 500 V/cm, which is accompanied by smaller
amplitudes. In this paper, the intensity changes are discussed, especially
concerning the decreases in positive electric fields. Our simulation results
are in good agreement with ground-based experimental results obtained from
ARGO-YBJ and the Carpet air shower array. These results could be helpful in
understanding the acceleration mechanisms of secondary charged particles caused
by an atmospheric electric field.
