Field-Aligned Currents during Northward Interplanetary Magnetic Field
Yamada, Y., Takeda, M. & Araki, T.
Abstract
We propose a new method to estimate the horizontal distribution of field-aligned currents in the polar region using magnetic field perturbations observed by a polar-orbital satellite. The method is applied for data of MAGSAT on May 10－11, 1980 when the interplanetary magnetic field was successively northward. The result shows that a pair of field-aligned currents existed at the high latitude side of the Region 1 current pair and the flow direction was opposite to that of the Region 1. The current density of the additional current was about 21μA/㎡，which was more than twice of that of the Region 1, and its total current intensity was 600-800 kA. The ionospheric potential difference induced by the polar cap current was estimated at about 30 kV， which means that a characteristic size of the merging of magnetic field lines between geomagnetic and interplanetary magnetic fields is an earth radius.
