Low-altitude ion upflow observed by EISCAT and its effects on supply of molecular ions in the ring current detected by Arase (ERG)
Low-altitude ion upflow observed by EISCAT and its effects on supply of molecular ions in the ring current detected by Arase (ERG)
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EISCAT观测到的低空离子上流及其对Arase（ERG）检测到的环流中分子离子供应的影响
DOI：
10.1029/2020ja028951
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发表时间：
2021
期刊：
影响因子：
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通讯作者：
et al.
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文献类型：
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作者：
Takada;M.;Seki;K.;Ogawa;Y.;Keika;K.;Kasahara;S.;Yokota;S.;et al.
在2017年9月7日开始的磁暴期间，ARASE(ERG)卫星上的MEP-I仪器观测到了环电流中的分子离子(O2+/NO+/N2+)。在这次磁暴期间，ARASE在四个轨道上观察到了分子离子。这表明存在来自电离层的连续分子离子供应。在2017年9月8日第二次DST极小值(∼−100nT)附近的风暴主相期间，欧洲非相干散射雷达观测到了低海拔(250-350公里)电离层中的离子上升流(∼50-150m和1)以及高达2,000K的强离子加热。欧洲非相干散射雷达观测到的约110公里高度电子加热产生的对流电场也增加了2倍。观测表明，低海拔额外的离子加热有助于引起快速上升流并将分子离子向上输送。由于解离重组，通量从280公里高度下降到350公里高度，估计约为两个数量级。这导致了显著的分子离子通量保持在350公里的高度。这些结果表明，由离子摩擦加热引起的低空离子上行使分子离子能够逃逸到空间，防止解离复合导致的快速损失。
During the magnetic storm starting on September 7, 2017, the MEP‐i instrument onboard the Arase (ERG) satellite observed molecular ions (O2+/NO+/N2+) in the ring current. The molecular ions were observed by Arase in four orbits during this magnetic storm. This indicates that there was a continuous molecular ion supply from the ionosphere. During the storm main phase around the second Dst minimum (∼−100 nT) on September 8, 2017, the European Incoherent Scatter (EISCAT) radar observed the ion upflow (∼50–150 m s−1) in the low‐altitude (250–350 km) ionosphere together with strong ion heating up to >2,000 K. The convective electric field derived from the electron heating observed by EISCAT at an altitude of approximately 110 km was also enhanced by a factor of 2. The observations suggest that the additional ion heating at low altitudes helps to cause the fast upflow and transport molecular ions upward. The flux decreases from 280 to 350 km altitudes due to the dissociative recombination was estimated to be approximately two orders of magnitude. This resulted in significant molecular ion flux remaining at 350 km altitude. These results suggest that the low‐altitude ion upflow caused by the ion frictional heating enables molecular ions to escape to space against rapid loss by the dissociative recombination.