Pivotal role of magnetic reconnection in the Earth's magnetosphere

Abstract

Magnetic reconnection plays a pivotal role in the physics of the Earth's magnetosphere. It determines the framework of the magnetosphere by defining the field-line topology where the field lines from the polar cap are open to the solar wind. The open field lines are produced by the reconnection on the dayside magnetopause, and the energy flow along these field lines is the predominant mode of the energy supply from the solar wind to the magnetosphere. The magnetotail is formed on the nightside of the Earth by the open field lines which are stretched by the solar wind. Then the reconnection occurs in the magnetotail and liberates the magnetic energy stored in the stretched field lines. The energy released by this reconnection accelerates the plasma in the magnetotail and produces the global disturbance called magnetospheric substorm. The above picture applies to a wide range of directions of the interplanetary magnetic field (IMF), but another mode of the reconnection occurs when the IMF direction is close to being northward.