Simulation study of near-Earth space disturbances: 1. magnetic storms

Yusuke Ebihara

doi:10.1186/s40645-019-0264-3

Abstract

A magnetic storm is the world-wide geomagnetic disturbance taking place in near-Earth space environment, lasting for a few days. Geomagnetic fields can be depressed by ~ 1% on the ground for large magnetic storms. The prime cause of the long-lasting, world-wide geomagnetic disturbance is the development of the ring current that surrounds the Earth. The ring current is an electric current carried by charged particles. Thus, the growth and decay of the ring current correspond to accumulation and loss of the ring current particles, respectively. The ring current is strong enough to modulate near-Earth space environment, and leads to many observable effects. In this sense, the ring current can be regarded as an important mediator in the near-Earth space environment. Here, the dynamics and structure of the ring current and its active role are briefly reviewed on the basis of numerical simulation results.

Highlights

Magnetic storms are characterized by irregular disturbance of the geomagnetic field
The H-component of the geomagnetic field returns to the pre-storm level, which is primarily caused by the decay of the ring current
The development and the decay of the magnetic storm are understood to accumulation and loss of the charged particles trapped by the Earth’s magnetic field, respectively

Summary

Introduction

Magnetic storms are characterized by irregular disturbance of the geomagnetic field. A magnetic storm starts with an initial phase, followed by a main phase and a recovery phase. This suggests that the intensification of the ring current is caused by the enhancement of the convection electric field and the enhancement of the plasma sheet density and/or temperature (Ebihara and Ejiri 1998; Kozyra et al 1998b; Ebihara and Ejiri 2000; Liemohn et al 2001).

Results

Conclusion