The current‐voltage relationship in auroral current sheets

Abstract

The current‐voltage relation within narrow auroral current sheets is examined through the use of high‐resolution data from the high‐altitude Dynamics Explorer 1 satellite. The north‐south perpendicular electric field and the east‐west magnetic field are shown for three cases in which there are large amplitude, oppositely directed paired electric fields which are confined to a region less than 20 km wide. The magnetic field variations are found to be proportional to the second integral of the high‐altitude perpendicular electric field. It is shown that at the small‐scale limit, this relationship between Δ B and E is consistent with a linear “Ohm's law” relationship between the current density and the parallel potential drop along the magnetic field line. This linear relationship had previously been verified for large‐scale auroral formations greater than 20 km wide at the ionosphere. The evidence shown here extends our knowledge down to the scale size of discrete auroral arcs.