Abstract Prior to its discovery, O+ from the Earth's high-latitude ionosphere was not expected to be present in any significant amount in the magnetosphere. It is now known that O+ can dominate ionospheric outflow and dominate magnetotail composition during geomagnetically active times. Observations from the Magnetospheric Multiscale (MMS) mission are used here to illustrate properties of O+ in the dayside outer magnetosphere and to identify gaps in the knowledge of this ionospheric ion. When the interplanetary magnetic field (IMF) is southward, O+ from the high-latitude ionosphere convects to the magnetotail then from the magnetotail to the dayside. The two primary O+ populations observed in the dayside magnetosphere are the ring current and warm plasma cloak. They are sometimes distinguishable by their energy, although velocity-space distribution functions are often needed to make a true distinction. There are several sinks for these populations in the dayside magnetosphere. One important sink is the dayside magnetopause. While much is understood about O+ in the dayside magnetosphere, there are several open questions detailed in the final section of the paper.

中文翻译：

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日侧磁层中的电离层氧离子

摘要 在发现之前，地球高纬度电离层中的 O+ 预计不会在磁层中大量存在。现在已经知道，在地磁活动期间，O+ 可以主导电离层流出并主导磁尾成分。这里使用磁层多尺度 (MMS) 任务的观测结果来说明日侧外磁层中 O+ 的特性，并确定对这种电离层离子的认识存在差距。当行星际磁场（IMF）向南时，来自高纬度电离层的O+对流到磁尾，然后从磁尾到日侧。在日侧磁层中观察到的两个主要 O+ 群是环流和暖等离子体斗篷。它们有时可以通过它们的能量来区分，尽管通常需要速度空间分布函数来进行真正的区分。这些种群在日侧磁层中有几个汇。一个重要的水槽是日侧磁层顶。虽然对日侧磁层中的 O+ 了解很多，但在论文的最后一部分中详细说明了几个悬而未决的问题。