Cosmogenic 7Be produced by extreme solar particle events in the atmosphere: a unique tracer for atmospheric dynamics

Full text: We present a new physical model to calculate production of cosmogenic isotope 7Be in the atmosphere. The model is based on a full Monte-Carlo simulation of an electromagnetic-muon-nucleonic cascade in the atmosphere, using CORSIKA and FLUKA packages. The present results are in broad agreement with earlier empirical and semi-empirical models, and a comparison to direct and indirect measurements of the 7Be production rate in the atmosphere confirms the validity of the model in the whole range of geographical latitudes and altitudes. Special emphasis is given to an effect of a severe solar energetic particle event of January 2005, which led to greatly enhanced production of the isotope in polar atmosphere. In a sense, the effect is similar to a bomb test with known isotope production parameters but without disturbing the atmosphere itself. Soon after production, 7Be becomes attached to atmospheric aerosols, making it possible to trace transport of air mass. Then, using a detailed atmospheric transport model and a dataset of real meteodata for those periods, the 7Be transport can be simulated and confronted with the measured values. Eventually, this will provide a unique opportunity to test the atmospheric transport models using a case study. Thus, a new tool for a detailed study of tracing mass transport is proposed using the method of test particle with nearly instant injection during extreme solar particle events. (author)