A global model of thunderstorm electricity

Abstract

An axisymmetric numerical model in an Earth‐centered spherical coordinate system is created to calculate the electric field distribution and current distribution from a thunderstorm source in the global electrical circuit. The model includes a hemisphere in which the thunderstorm is located, an atmosphere and ionosphere with anisotropic height‐variable conductivities, and a passive magnetic conjugate hemisphere. Both single‐cell thunderstorms and symmetric multicell thunderstorm complexes can be modeled. The current output from the thunderstorm spreads out in the ionosphere and flows along the magnetic field lines into the conjugate hemisphere. Approximately half of the current that reaches the ionosphere flows into the conjugate hemisphere, and the rest is redirected to the fair‐weather portion of the storm hemisphere. Two examples of this general model are discussed, a single‐cell severe storm and a multicell severe storm. Results of this study show that it is important to include a realistic model of the ionosphere to evaluate the spread of current in the ionosphere and the mechanism of thunderstorm charging of the global electric circuit.