  A variety of events such as gamma-ray bursts and supernovae may expose the
Earth to an increased flux of high-energy cosmic rays, with potentially
important effects on the biosphere. Existing atmospheric chemistry software
does not have the capability of incorporating the effects of substantial cosmic
ray flux above 10 GeV . An atmospheric code, the NASA-Goddard Space Flight
Center two-dimensional (latitude, altitude) time-dependent atmospheric model
(NGSFC), is used to study atmospheric chemistry changes. Using CORSIKA, we have
created tables that can be used to compute high energy cosmic ray (10 GeV - 1
PeV) induced atmospheric ionization and also, with the use of the NGSFC code,
can be used to simulate the resulting atmospheric chemistry changes. We discuss
the tables, their uses, weaknesses, and strengths.
