An auroral electrojet index ( measured in nanotesla ) is regularly derived from ground data and serves as a general measure of auroral activity.
2.
In the high latitude ionosphere ( or auroral zones ), the Birkeland currents close through the region of the auroral electrojet, which flows perpendicular to the local magnetic field in the ionosphere.
3.
By a strange twist of physics, the magnetic disturbance on the ground due to the main current almost cancels out, so most of the observed effect of auroras is due to a secondary current, the auroral electrojet.
मोबाइल