Morphology of polar ionospheric O^＋ ion upflow： FAST observations during quiet time

• Published in: Chinese science bulletin 2007-12, Vol.52 (24), p.3403-3415
• Main Authors: Dang, Ge, Ma, ShuYing, Zhou, YunLiang
• Format: Article
• Language: English
• Subjects: 人造卫星观测; 双极电离层; 氧离子流; 磁气圈耦合
• ISSN: 1001-6538; 1861-9541
• DOI: 10.1007/s11434-007-0444-1

With energetic ion measurements on FAST satellite, the morphologic features of quiet-time ionospheric O^＋ ion upflowing at altitudes of 2000 to 4000 km are drawn out for the first time. The pre-noon cusp/cleft is the predominant region of upflowing occurrence for O^＋ with lower energy. Meanwhile the pre-dawn sector near the equatorward edge of the plasma convection dominates the occurrence for the higher energy O^＋ ions. No matter whether the energy is lower or higher, the upflows occur often over a wide MLT range of lower latitudes outside the auroral oval. The upflowing within the pre-midnight （21：00- 22：00 MLT） auroral oval carrys larger energy fluxes, with extremely large fluxes for higher energy O^＋appearing near the polar cap boundary. For altitudes of 2000--4200 km under observation, the ion conics occur much more frequently than ion beams. Ion beams are rarely found below 3000 km, while the conics occur uniformly over the observed altitudes.