Evolution of the Radial Size and Expansion of Coronal Mass Ejections Investigated by Combining Remote and In Situ Observations
Evolution of the Radial Size and Expansion of Coronal Mass Ejections Investigated by Combining Remote and In Situ Observations
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DOI：
10.3847/1538-4357/acd847
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发表时间：
2023-05
期刊：
影响因子：
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通讯作者：
B. Zhuang;N. Lugaz;N. Al-Haddad;R. Winslow;C. Scolini;C. Farrugia;A. Galvin
中科院分区：
文献类型：
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作者：
B. Zhuang;N. Lugaz;N. Al-Haddad;R. Winslow;C. Scolini;C. Farrugia;A. Galvin
日冕物质抛射 (CME) 的一个基本特性是其径向膨胀，这决定了日冕物质抛射 (CME) 传播时日冕物质抛射 (CME) 径向尺寸的增加和日冕物质抛射 (CME) 磁场强度的减小。日冕物质抛射径向膨胀可以通过远程观测或基于多个航天器径向结合的现场测量来研究。然而，结合远程观察和现场观察的案例研究很少。因此，尚不清楚远程估计的日冕径向膨胀是否与日光层本地估计的一致。为了解决这个问题，我们首先选择了2010年至2013年之间的22个日冕物质抛射事件，这些事件被日冕仪和两三个径向联合航天器很好地观测到。我们使用分级圆柱壳模型来估计日冕中日冕物质抛射的径向尺寸、径向膨胀速度和无量纲膨胀参数的测量。还计算了基于原位测量的相同参数和两个附加测量，即随着日冕物质抛射日心距离的增加，径向尺寸增加和磁场强度减少。对于大多数事件，通过远程观测估计的日冕物质抛射径向大小与现场估计不一致。我们进一步统计分析了使用远程和现场观测估计的这些膨胀参数的相关性，并讨论了不一致的潜在原因及其对 CME 空间天气预报的影响。
A fundamental property of coronal mass ejections (CMEs) is their radial expansion, which determines the increase in the CME radial size and the decrease in the CME magnetic field strength as the CME propagates. CME radial expansion can be investigated either by using remote observations or by in situ measurements based on multiple spacecraft in radial conjunction. However, there have been only few case studies combining both remote and in situ observations. It is therefore unknown if the radial expansion in the corona estimated remotely is consistent with that estimated locally in the heliosphere. To address this question, we first select 22 CME events between the years 2010 and 2013, which were well observed by coronagraphs and by two or three spacecraft in radial conjunction. We use the graduated cylindrical shell model to estimate the radial size, radial expansion speed, and a measure of the dimensionless expansion parameter of CMEs in the corona. The same parameters and two additional measures of the radial-size increase and magnetic-field-strength decrease with heliocentric distance of CMEs based on in situ measurements are also calculated. For most of the events, the CME radial size estimated by remote observations is inconsistent with the in situ estimates. We further statistically analyze the correlations of these expansion parameters estimated using remote and in situ observations, and discuss the potential reasons for the inconsistencies and their implications for the CME space weather forecasting.