Computation of complex ion production due to cosmic rays during the   Halloween sequence of GLEs on October-November 2003
  The possible effect of solar variability, accordingly cosmic rays variation on atmospheric physics and chemistry is highly debated over the last years. According to several recent models the induced by cosmic rays atmospheric ionization plays a key role in several different processes. At recent, an apparent effect on minor constituents and aerosols over polar regions during major solar proton events was observed. The ion production rate during ground level enhancements is a superposition of the contribution of cosmic rays with galactic and solar origin. The solar cycle 23 provided several strong ground level enhancements. The period of end October - beginning of November 2003 was characterized by a strong cosmic ray variability, namely a sequence of three GLEs was observed. In addition, there were several Forbush decreases, which led to a suppression of galactic cosmic ray flux. As a consequence the cosmic ray induced ion production in the atmosphere and the corresponding ionization effect were subject of dynamical changes. Here we compute the complex ion production due to cosmic rays during the Halloween sequence of ground level enhancements on October-November 2003 and we estimate the ionization effect. The spectral and angular characteristics of the solar protons are explicitly considered throughout the events as well their time evolution. The ionization effect during the period is computed at several altitudes above the sea level in a region with $R_{c}$ $\le$ 1 GV and $R_{c}$ $\le$ 2 GV. 
A. Mishev and P. Velinov
astro-ph.HE physics.space-ph