Relationship between the dayside auroral electrojets and the DPY current

Three main electric current systems are known to flow in the high‐latitude ionosphere. These are the auroral electrojets, modulated by the interplanetary magnetic field (IMF) Bz; the DPY currents, modulated by the IMF By; and the Sq current system which is not modulated by the IMF. In the past several years, researchers have tried to establish whether or not there is a relationship between the DPY current and the auroral electrojets, with some researchers contending that the DPY is a separate current system while others believing that the DPY merely reflects a redistribution of the electrojet in a manner regulated by the IMF By. To further study this question, we inspect latitude profiles of the magnetic disturbance field recorded by the CANOPUS array in north central Canada and deal with subsets of these profiles during times of relative constant IMF Bz and positive and negative IMF By polarities. We find evidence for modulation of the auroral electrojets south of the cleft region by IMF By. Moreover, our results suggest that the DPY is part of a twin electrojet system consisting of two antiparallel Hall currents. Both these currents represent an extension across noon of the directly driven electrojets.