Investigating Remote-Sensing Techniques to Reveal Stealth Coronal Mass Ejections
Investigating Remote-Sensing Techniques to Reveal Stealth Coronal Mass Ejections
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DOI：
10.3389/fspas.2021.695966
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发表时间：
2021-06
期刊：
影响因子：
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通讯作者：
E. Palmerio;N. Nitta;T. Mulligan;M. Mierla;J. O’Kane;I. Richardson;Suvadip Sinha;N. Srivastava
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文献类型：
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作者：
E. Palmerio;N. Nitta;T. Mulligan;M. Mierla;J. O’Kane;I. Richardson;Suvadip Sinha;N. Srivastava
来自太阳的日冕物质抛射（CME）的爆发通常与一些可以在太阳盘图像中识别的特征有关。然而，也有一些情况下，日冕物质抛射数据中观察得很好的日冕物质抛射缺少一个清晰的低日冕对应物。这些事件在近年来受到关注，主要是由于多点观测的增加，现在被称为“隐形CME”。在这项工作中，我们分析了具有不同程度的模糊性隐形日冕物质抛射的例子。所有选定的案例研究都产生了由日冕仪检测到的大规模日冕物质抛射，并且从至少一个次要观点进行了观察，从而能够先验地了解其大致源区。对于每个事件，我们应用几种图像处理和几何技术，目的是评估这些方法是否可以提供额外的信息相比，“正常”的强度图像的研究。我们能够确定至少弱的喷发签名的所有事件后，仔细调查遥感数据，注意到不同的处理图像可能需要正确解释和分析难以捉摸的意见。我们还发现，几何技术的有效性强烈依赖于CME的传播方向相对于观察员和相对航天器的分离。能够观测并因此预报隐形日冕物质抛射在空间天气方面非常重要，因为这类事件有时是所谓的“问题地磁暴”的太阳对应物。
Eruptions of coronal mass ejections (CMEs) from the Sun are usually associated with a number of signatures that can be identified in solar disc imagery. However, there are cases in which a CME that is well observed in coronagraph data is missing a clear low-coronal counterpart. These events have received attention during recent years, mainly as a result of the increased availability of multi-point observations, and are now known as “stealth CMEs.” In this work, we analyze examples of stealth CMEs featuring various levels of ambiguity. All the selected case studies produced a large-scale CME detected by coronagraphs and were observed from at least one secondary viewpoint, enabling a priori knowledge of their approximate source region. To each event, we apply several image processing and geometric techniques with the aim to evaluate whether such methods can provide additional information compared to the study of “normal” intensity images. We are able to identify at least weak eruptive signatures for all events upon careful investigation of remote-sensing data, noting that differently processed images may be needed to properly interpret and analyze elusive observations. We also find that the effectiveness of geometric techniques strongly depends on the CME propagation direction with respect to the observers and the relative spacecraft separation. Being able to observe and therefore forecast stealth CMEs is of great importance in the context of space weather, since such events are occasionally the solar counterparts of so-called “problem geomagnetic storms.”