Pi 2 pulsations and the auroral electrojet

Abstract

Measurements of the properties of Pi 2 pulsations along a magnetic meridian at high latitudes during a number of substorms have been analyzed for their relationship to the auroral electrojet. It is found that the maximum Pi 2 pulsation amplitudes are closely associated with the instantaneous position of the electrojet. That is, the average pulsation amplitude in the Pi 2 band as well as the amplitudes of pulsations at specific frequencies in the band have maximum amplitudes at latitudes close to the instantaneous electrojet location. Stations equatorward of the electrojet tend to observe a classical Pi 2 waveform concurrent with the onset of the substorm electrojet. Stations near the electrojet observe a broad spectrum of pulsations indicating a multiplicity of sources. Stations poleward of the initial electrojet position see little pulsation activity until the electrojet moves overhead. The appearance of large amplitude Pi 2 pulsations at a station which was poleward of the electrojet at the onset of a substorm appears to be coincident with the arrival of the poleward border of the electrojet.