We present observations of the same magnetic cloud made near Earth by the Advance Composition Explorer (ACE), Wind, and the Acceleration, Reconnection, Turbulence and Electrodynamics of the Moon's Interaction with the Sun (ARTEMIS) mission comprising the Time History of Events and Macroscale Interactions during Substorms (THEMIS) B and THEMIS C spacecraft, and later by Juno at a distance of 1.2 AU. The spacecraft were close to radial alignment throughout the event, with a longitudinal separation of $3.6^{\circ}$ between Juno and the spacecraft near Earth. The magnetic cloud likely originated from a filament eruption on 22 October 2011 at 00:05 UT, and caused a strong geomagnetic storm at Earth commencing on 24 October. Observations of the magnetic cloud at each spacecraft have been analysed using Minimum Variance Analysis and two flux rope fitting models, Lundquist and Gold-Hoyle, to give the orientation of the flux rope axis. We explore the effect different trailing edge boundaries have on the results of each analysis method, and find a clear difference between the orientations of the flux rope axis at the near-Earth spacecraft and Juno, independent of the analysis method. The axial magnetic field strength and the radial width of the flux rope are calculated using both observations and fitting parameters and their relationship with heliocentric distance is investigated. Differences in results between the near-Earth spacecraft and Juno are attributed not only to the radial separation, but to the small longitudinal separation which resulted in a surprisingly large difference in the in situ observations between the spacecraft. This case study demonstrates the utility of Juno cruise data as a new opportunity to study magnetic clouds beyond 1 AU, and the need for caution in future radial alignment studies.

中文翻译：

---

关于磁云的径向和纵向变化：ACE、Wind、ARTEMIS 和 Juno 观测

我们展示了由高级成分探测器 (ACE)、风以及月球与太阳相互作用的加速、重新连接、湍流和电动力学 (ARTEMIS) 任务在地球附近产生的同一磁云的观测结果，包括事件的时间历史和宏观尺度亚暴 (THEMIS) B 和 THEMIS C 航天器期间的相互作用，以及后来在 1.2 天文单位距离的朱诺号。在整个事件中，航天器接近径向对齐，朱诺号和地球附近的航天器之间的纵向间隔为 3.6 美元 ^{\circ}$。磁云很可能源自 2011 年 10 月 22 日 00:05 UT 的细丝喷发，并在 10 月 24 日开始在地球上引起强烈的地磁风暴。已使用最小方差分析和两个磁链拟合模型 Lundquist 和 Gold-Hoyle 对每个航天器的磁云观测进行了分析，以给出磁链轴的方向。我们探索了不同的后缘边界对每种分析方法的结果的影响，并发现近地航天器和朱诺的磁链轴方向之间存在明显差异，与分析方法无关。使用观测值和拟合参数计算轴向磁场强度和磁通绳的径向宽度，并研究它们与日心距离的关系。近地航天器和朱诺号之间结果的差异不仅归因于径向分离，但是由于纵向间隔很小，这导致航天器之间的原位观测出现了惊人的大差异。本案例研究证明了朱诺号巡航数据作为研究 1 AU 以外磁云的新机会的实用性，以及在未来的径向对准研究中需要谨慎。