Polarization characteristics of Pi 2 pulsations and implications for their source mechanisms: Influence of the westward travelling surge |
| |
| Authors: | JC Samson G Rostoker |
| |
| Institution: | Department of Physics and Institute of Earth and Planetary Physics, University of Alberta, Edmonton, Alberta, Canada T6G 2J1 |
| |
| Abstract: | This paper expands the earlier results of Rostoker and Samson (1981), who noted that there are two latitudinal areas of Pi 2 localization near the high latitude, substorm enhanced electrojets. The detailed study presented here outlines the morphology of the polarizations of the Pi 2's in and near the westward travelling surge. There are two latitudinal areas of Pi 2 localization. A poleward Pi 2 predominates within the surge and to the East, whereas an equatorward Pi 2 predominates equatorward and West of the surge. These Pi 2 localizations appear to correlate with the substorm enhanced westward and eastward electrojets respectively. However, the maximum in the Pi 2 power does not always coincide with the center of the electrojet. The poleward Pi 2 has largest amplitudes to the East of the head of the westward travelling surge. This Pi 2 shows a latitudinal polarization reversal from clockwise on the equatorside (viewed down on H-D plane) to counterclockwise on the poleside of a latitudinal demarcation line, which occurs just poleward of the initial breakup. This demarcation line is usually equatorward of the most poleward expansion of the surge. To the West of the surge front, where the equatorward Pi 2 predominates, there is again a latitudinal polarization reversal but in this case the polarization is counterclockwise equatorward and clockwise poleward of the demarcation line. This demarcation is equatorward of that for the poleward Pi 2, and appears to lie at the latitude of the initial breakup. Consequently, the westward travelling surge appears to mark the longitudinal transition from equatorward to poleward Pi 2. The elliptical polarization of the Pi 2's is most likely caused by azimuthai (longitudinal) expansion of the field-aligned currents in the surge, in association with reflection of the field-aligned current pulses from northern and southern high latitude ionospheres. |
| |
| Keywords: | |
| 本文献已被 ScienceDirect 等数据库收录！ |
|
