Numerical simulation of the atmospheric ionization and the generation of cosmogenic nuclides for different topologies of the geomagnetic field

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Cosmics rays of solar and galactic origin partly are screened off from the Earth's surface by two filters, the magnetosphere and the atmosphere. The terrestrial magnetic field is known to be quite variable on different time scales. The field and its variability, which is most obvious in magnetic field reversals accompanied by dramatic decrease in the magnetic field strength, originates in a magnetohydrodynamic dynamo process inside Earth's core. Changes in the geomagnetic field modify the access of energetic particles to the lower atmosphere, altering the generation of cosmogenic nuclides such as 10Be and 14C as well as the ionization of the mid-atmosphere caused. In this study we will develop a model combining the particle propagation in a geomagnetic field of different strenghts and topologies and the particle interaction with the atmosphere to determine (a) the generation of cocmogenic nuclides and (b) the ionization caused by the energetic particles for different topologies/strengths of the geomagnetic field. The results of this study can be used as additional tests for dynamo models and as an input to determine atmospheric changes, such as the ozone content or the global circuit, for different states of the geomagnetic field.