Characteristics of Magnetic Variations and Current Wedge in the Sawtooth Event on 30 September 2000

Abstract

AbstractThe purpose of this paper is to study the response of auroral electrojets during the sawtooth event observed by LANL satellites on 30 September 2000. Firstly, we establish a method to determine large‐scale 2‐dimensional ionospheric equivalent current systems in the high‐latitude ionosphere using the spherical elementary current system method. Then we apply this method and magnetic data of high‐latitude magnetometers in the Northern Hemisphere to study the variations of auroral electrojets during the sawtooth event. By comparing characteristics of enhancements of nightside ionospheric westward electrojets with those of positive magnetic bays of H components in the middle/low‐latitude ground magnetic field after each sawtooth injection, it is demonstrated that there are current wedges formed during this sawtooth event. The local time width of current wedges suggested by the two observations are both around 11 hours (MLT). In addition, time durations of middle/low‐latitude magnetic bays to reach maximum variations were generally longer than those for high‐latitude electrojets, implying that source currents for middle/low‐latitude magnetic bays are multiple.