Model of the evolution of the plasmasphere during a geomagnetic storm

The morphology of the plasmasphere during a geomagnetic storm is simulated by considering the two dimensional E × B drift motion of plasmaspheric charged particles in the equatorial plane. Assuming a time-independent dipolar magnetic field and a corotation electric field plus, a spatially uniform dawn–dusk convection electric field varying with Kp index, the spatial distributions of charged particles at different time during a geomagnetic storm are obtained. Our results show that if Kp increases with time, some particles inside the original plasmapause will convect into the magnetopause, forming a long tail that stretches from the plasmasphere to the magnetopause in the afternoon region. The particle convection weakens as Kp decreases, and as Kp returns to its normal value, the plasmasphere develops a thin tail that wraps around the Earth.