The equatorward wall of the subauroral trough in the afternoon/evening sector

摘要: Abstract. Although ionospheric troughs are a very important feature of the subauroral ionosphere, many their properties remain incompletely documented and understood. Here Dynamics Explorer-2 satellite data used to investigate one specific part this complex phenomenon, namely its equatorward wall. We find that in afternoon/evening sector Northern Hemisphere location density drop depends primarily on level geomagnetic activity magnetic local time. Longitudinal variations only secondary importance. A formula is derived which summarizes these variations. The magnitude trough wall altitude longitude, lesser degree time activity. These also described quantitatively. Using superposed epoch type averaging procedure, mean latitudinal profile derived. No anomalous increase at edge observed. There is, however, significant electron temperature drop. Our results for empirical description numerical simulation troughs. They may be define boundary between middle latitudes.