THE PLASMA ENVIRONMENT OF THE EARTH

In this article we discuss the structure and dynamics of the Earth's plasma environment and how it is influenced by its interaction with the outer atmosphere of the Sun, as revealed by both space-based and ground-based observations over the past thirty years. We begin with a discussion of the basic physical principles involved, and then apply these principles to the solar wind and interplanetary magnetic field (IMF), and their interaction with the Earth's magnetic field. The structure and flow of magnetospheric plasma populations then follows, together with consequent magnetosphere-ionosphere interactions. The initial discussion applies to a steady-state magnetosphere driven by steady reconnection, which we then generalized to the time-dependent case resulting from variations in the direction of the IMF.