The project addresses three main questions: (1) What is the dependence of auroral precipitation on field-aligned current (Birkeland current) density, the ionospheric plasma properties and the EUV ionization; (2) what are the distributions of auroral precipitation associated with different distributions of Birkeland currents; and (3) how well does the Knight relationship actually compare to direct observations of the Birkeland currents? The tools to be used for this study will be the database of stable Birkeleand currents derived from the magnetometer data from the Iridium satellite constellation. The Birkeland current data will be used in combination with data from a variety of spacecraft, including TIMED, Polar, Cluster, and DMSP.
Field-aligned currents, also called Birkeland currents, provide the primary mechanism by which the magnetosphere is coupled to the ionosphere. Understanding how the current systems, both upward currents and downward currents, depend on the details of the charged particle precipitation and the accelerating voltage is critical to our ability to successfully model magnetosphere-ionosphere coupling and being able to generate realistic forecasts of the processes for space weather events.
