field-aligned current system

The field-aligned current system is a crucial component of Earth's magnetosphere, influencing the geomagnetic field. This system consists of two main current sheets, known as Region 1 and Region 2, which encircle Earth. These currents are driven by the interaction between the solar wind and Earth's magnetic field.

Region 1 currents originate from the electrically charged interface where solar wind drags magnetic field lines. Region 2 currents arise from charge separation due to particle drift within the magnetosphere. These two current systems are interconnected through the ionosphere, forming a single electrical circuit. While these currents significantly alter the magnetic field in space, their effects are largely undetectable on Earth's surface because the oppositely directed currents largely cancel each other's magnetic fields. The system does, however, drive secondary ionospheric currents known as electrojets.1