Quiet-time mid-latitude trough : influence of convection, field-aligned currents and proton precipitation

摘要: Abstract. A combination of EISCAT CP-3 (latitude scans) and satellite (DMSP) data have been used to study the structure quiet-time evening-sector auroral subauroral ionosphere, in particular mid-latitude trough. The main mechanism behind trough formation evening sector ionosphere is believed be flow stagnation a region where convection corotation counteract each other. However, there also possibility that field-aligned currents (FAC) more directly modify ionospheric density if current carried by thermal electrons. quantitative test flow-stagnation scenario an estimate possible direct effects caused performed. We found electron densities observed can indeed explained scenario, but altitude profiles sometimes differ from what should expected stagnation. effect downward cannot identified data, simple shows it affect plasma density, causing decreased densities. In 2 current/trough typically significant ion production resulting proton precipitation which may this effect. Charge exchange precipitating protons causes lateral spread smooth associated conductance enhancement. Thus, whereas number flux insufficient carry current, practice produces necessary charge carriers. suggest do play crucial role electrodynamics dark small enhancement producing carriers trough-associated current.