The radiation environment in the lower atmosphere: a numerical approach
The radiation exposure in the lower atmosphere caused by extraterrestrial sources is increasing with altitude. This phenomenon is caused by particles penetrating the atmosphere and producing secondary particles in interactions with atoms in the air. The main sources of the primary radiation are galactic cosmic rays from outside the solar system. Additionally, during short time periods particles may be accelerated during solar events causing increases in the particle intensities on ground which are measurable by Neutron Monitors in so-called Ground Level Enhancements (GLE). Investigating such GLEs and the related increase of the radiation exposure in the atmosphere and especially at aircraft altitudes is the topic of the present work. Detailed calculations of the transport of relevant primary particles through the Earth's magnetosphere and the atmosphere based on a Monte-Carlo technique were performed, and the resulting secondary particle fluxes and radiation exposures were determined.