Pattern of Shell Currents in the Ionosphere

A new method is developed for the determination of the global pattern of closure currents
in the ionosphere from data on field aligned currents (FACs) and modification
of the International Geomagnetic Reference Field (IGRF) due to compression
on the magnetopause. The study of ionospheric closure currents is important
because they contribute to Joule heating and the ionosphere-thermosphere
coupling. The problem is solved in several steps. First, the Euler potentials
for the magnetic field above the ionosphere are calculated. Next, the
Euler potentials for the current density of FACs are determined. The magnetic
field induced by FACs is calculated with these potentials. Finally, the
closure currents in the base of the ionosphere are derived from the condition
that FACs do not penetrate the base of the ionosphere.