B.: Substorm behavior of the auroral electrojet indices, Ann

Abstract. The behavior of the auroral electrojet indices AU and AL during classical substorms is investigated by the use of global auroral images. A superposition of the 12 AE sta-tions onto global auroral images and identification of the AL and AU contributing stations enable an understanding of the temporal as well as spatial behavior of the indices with respect to the substorm coordinate system and time-frame. Based on this simple technique it was found that at substorm onset the AL contributing station makes a charac-teristic jump from a location near the dawn terminator to the onset region, typically bypassing one or more AE stations. During the expansion phase this station typically lies at the poleward edge of the surge region. This is the location of the intense substorm current wedge electrojet in the semiempir-ical self-consistent substorm model of the three-dimensiona