  The galactic cosmic rays are the main source of ionization in the Earth
stratosphere and troposphere. The induced by primary cosmic ray particles
ionization is important in various processes related to atmospheric physics and
chemistry, specifically the minor constituents. The ion production in the
atmosphere is enhanced compared to the average following major solar energetic
particles events, specifically over the polar caps. During the solar cycle 23
we observed several strong ground level enhancements, one of the strongest
among them been the Bastille day event on 14 July 2000. In the work presented
here we apply a full Monte Carlo 3-D model in order to compute the cosmic ray
induced ionization. The model is based on atmospheric shower simulation with
the PLANETOCOSMICS code and the ion production rate is considered as a
superposition of cosmic rays with galactic and solar origin. The ion production
rate is computed as a function of the altitude above the sea level and the
short, mid and long term ionization effect relative to the average due to
galactic cosmic rays is computed.
