[P-EM13] Dynamics of the Inner Magnetospheric System

[PEM13-P17] Numerical Modeling of Electron Dynamics during Dipolarization Substorm Events

*Kirolosse M. Girgis¹, Tohru Hada¹, Kaiti Wang³, Fumiko Otsuka², Akimasa Yoshikawa¹ (1.International Research Center for Space and Planetary Environmental Science (i-SPES), Kyushu University, 2.Department of Earth System Science and Technology (ESST), Interdisciplinary Graduate School of Engineering Sciences (IGSES), Kyushu University, 3.Aerospace Engineering Department, Tamkang University, Taiwan)

Keywords:Dipolarization, Substorm, Electron Dynamics, Test Particle Simulations, Tsyganenko Model, Inductive and Irrotational Electric Fields

We developed a test particle simulation code to examine the electron dynamics during multiple dipolarization substorm events detected by the THEMIS mission. We evaluated the trajectories of 0.1, 1, and 10 keV electrons with different initial pitch angles and L-shells by implementing the Tao-Chan-Brizard guiding center model and the full Lorentz particle motion. We applied the Tsyganenko model TS05 and the IGRF-12 to generate the time-varying magnetic field model with the corresponding inductive and polarized electric fields.
Our preliminary simulation results confirmed that the particle energies were enhanced in the nighttime magnetosphere during dipolarization events. We suggest that the increase in the magnetic field strength in the dipolarization event and the corresponding induced/polarized electric field energizes and transports the particles earthward, which may explain the mechanism of the particle flux enhancement in the inner magnetosphere.