Sources of Large-Scale Birkeland Currents

Abstract

Magnetic field observations conducted from satellites nearly 30 years ago confirmed the presence of field-aligned currents proposed by Birkeland. Such currents are one of the most important elements in the circuit between interplanetary space, the magnetosphere, and the polar ionosphere, and they also play an important role in the shape of the magnetosphere itself. Much work has been conducted on Birkeland currents in the past few years with ground-based and satellite observations, theory, and simulations. Significant advances have been made in developing improved geomagnetic field maps and particle precipitation patterns and in conducting near-simultaneous multisatellite measurements in critical regions near noon and midnight. The objective of this study is to use this knowledge to identify the many sources of large-scale Birkeland currents.