Electrodynamics of Auroral Forms

Abstract

This chapter provides a description of some major night side auroral forms and of the polar cap aurora, with particular emphasis on the ionospheric electrodynamics of these forms. By this we mean the local characteristics of the electric field, current, and conductivity patterns, and how these are interrelated. This relationship is governed by Ohm’s law, the requirement of current continuity, and use of field- aligned currents as the connecting agents between the ionosphere and the magnetosphere. This chapter provides a representative view of the characteristics and electrodynamics of the selected auroral forms for quasi-static conditions, leaving much of the discussion on the dynamical aspects and magnetospheric coupling to Chapter 8. The electrodynamic models presented in this chapter integrate ground- based observations, low-altitude satellite and rocket observations, and numerical modeling results into a synoptic picute of several major auroral forms.