Cosmic ray ionization effect in the atmosphere during the maximal GLE05 − on 23.02.1956

Abstract

The ground level enhancements (GLEs) due to solar cosmic rays (SCRs) are of significant astrophysical, cosmophysical and geophysical interest for a number of planetary processes on the Earth. In the present work the ionization rate profiles in the Earth’s atmosphere during the outstanding ground level enhancement GLE05 on 23 February 1956, the largest one in the entire history of observations of SCRs, are obtained. The contribution of the galactic cosmic rays (GCRs) is also taken into account. The ionization in the atmosphere is calculated using the energetic spectra of solar protons, GCRs and the corresponding atmospheric cascade simulation. The spectra of solar cosmic rays are derived on the basis of ground-based measurements with neutron monitors. This method is based on solving the inverse problem - reconstruction of SCR spectrum on the boundary of the magnetosphere. The contemporary magnetosphere model Tsyganenko 01 and 03 is used in this method. The calculation of asymptotic cones (AK) held with increments of 0.001 GV in the range of 1-20 GV. The aforementioned method is developed in the Polar Geophysical Institute (in Apatity) of the Russian Academy of Sciences. Recent simulations with RUSCOSMICS software package (based on GEANT4 program of CERN) are carried out. The energy deposit of solar protons and GCRs in the atmosphere is received. The ion production rate profiles in the stratosphere and troposphere (the region 0-40 km) are calculated for geomagnetic cut-off rigidities 1, 2, 3 and 5 GV (i.e. polar, subpolar, higher and middle latitudes, respectively). The so obtained ionization profiles are compared and thoroughly discussed. Implementations of these results are also debated. The obtained results are important for the improvement of the recent models of cosmic ray induced ionization in the whole atmosphere, for the determination of electron and ion density in the middle and lower atmosphere (troposphere), for the various atmospheric processes (as for instance in atmospheric chemistry and physics - ozone production, global electric circuit between the ground and ionosphere), for the studies of solar-terrestrial influences on space weather and space climate) and for many other applications.