Hausdorf dimension of electromagnetic chorus emissions in their excitation region according to Van Allen probe data

Abstract

We study typical very low-frequency magnetospheric chorus electromagnetic emissions recorded by the Van Allen probe in their excitation region. The Hausdorf dimension of chorus is determined by means of a numerical calculation based on experimental data of the burst mode that provides high time resolution samples. Some cases of halving and jumping of the dimension value for appropriate time intervals are noted. This confirms the possibility of chorus excitation in different space eigenmodes, for example, in one side mode. The obtained results are important as confirmation for the beam pulse amplifier mechanisms of chorus excitation, for a quantitative comparison of the analytical results and numerical simulations with experimental data, and for automatic separation of different types of electromagnetic emissions.