Coronal waves are an important aspect of the dynamics of the plasma in the corona. Wavefront dislocations are topological features of most waves in nature and also of magnetohydrodynamic waves. Are there dislocations in coronal waves? The finding and explanation of dislocations may shed light on the nature and characteristics of the propagating waves, their interaction in the corona and in general on the plasma dynamics. We positively identify dislocations in coronal waves observed by the Coronal Multi-channel Polarimeter (CoMP) as singularities in the Doppler shifts of emission coronal lines. We study the possible singularities that can be expected in coronal waves and try to reproduce the observed dislocations in terms of localization and frequency of appearance. The observed dislocations can only be explained by the interference of a kink and a sausage wave modes propagating with different frequencies along the coronal magnetic field. In the plane transverse to the propagation, the cross-section of the oscillating plasma must be smaller than the spatial resolution, and the two waves result in net longitudinal and transverse velocity components that are mixed through projection onto the line of sight. Alfvén waves can be responsible of the kink mode, but a magnetoacoustic sausage mode is necessary in all cases. Higher (flute) modes are excluded. The kink mode has a pressure amplitude that is smaller than the pressure amplitude of the sausage mode, though its observed velocity is larger. This concentrates dislocations on the top of the loop. To explain dislocations, any model of coronal waves must include the simultaneous propagation and interference of kink and sausage wave modes of comparable but different frequencies, with a sausage wave amplitude much smaller than the kink one.
Limb Observations of Global Solar Coronal Extreme-ultraviolet Wavefronts: The Inclination, Kinematics, Coupling with the Expanding Coronal Mass Ejections, and Connection with the Coronal Mass Ejection Driven Shocks
Exploring the Nature of EUV Waves in a Radiative Magnetohydrodynamic Simulation
日冕极紫外（EUV）波是在日冕中传播的大尺度扰动，其物理性质和起源已经讨论了几十年。我们首次报道了日冕极紫外波及其伴随的准周期波列的三维辐射磁流体动力学（RMHD）模拟。用MURaM程序进行了数值试验，模拟了太阳活动区是由对流层的磁通量出射到日冕而形成的。日冕极紫外波是由磁通量绳的喷发驱动的，这也会引起C级耀斑。它以半圆形的形状传播，初始速度范围从大约550到700 km s $^{-1}$，这对应于大约1.2的平均马赫数（相对于快磁声波）。此外，等离子体密度，压力和切向磁场在波前的突然增加证实了快模式激波的日冕EUV波的性质。准周期波列的周期约为30秒被发现作为多个二次波前传播的领先波前和前面的喷发磁通量绳。我们还注意到，3D空间中的真实波前可能非常不均匀，然而，EUV发射的视线积分显著地平滑了3D中的尖锐结构，并导致更漫射的波前。
Interaction of Fast Magnetoacoustic Wave with the Localized Coronal Null and Generation of the Energetic Alfvén Wave Packet
Indian Institute of Technology (BHU)（印度理工学院（贝拿勒斯印度教大学））；Institute of Physics University of Graz（格拉茨大学物理研究所）；Department of Astronomy and Astrophysics at Space Research Center, Ilia State University（伊利亚州立大学空间研究中心天文学与天体物理学系）；Evgeni Kharadze Georgian National Astrophysical Observatory（叶夫根尼·哈拉泽格鲁吉亚国家天文台）；Key Laboratory of Solar Activity and Space Weather, School of Aerospace, Harbin Institute of Technology, Shenzhen（哈尔滨工业大学深圳航天学院太阳活动与空间天气重点实验室）；Korea Astronomy and Space Science Institute（韩国天体与空间科学研究所）
Three-dimensional Propagation of the Global EUV Wave associated with a solar eruption on 2021 October 28
我们提出了一个案例研究的全球极紫外（EUV）波和色球对应的“莫顿-拉姆齐波”与第25太阳活动周的第二个X级耀斑和一个光环日冕物质抛射（CME）。在H $α$和EUV通带中观察到了具有不同特征温度的EUV波。在171毫米和193/195毫米的图像中，波以600-720 km s $^{-1}$的初速度和110-320 m s $^{-2}$的减速度循环传播。在波阵面通过期间，局部日冕等离子体从log（T/K）=5.9加热到log（T/K）=6.2。H $α$和304 INVESTIGATION图像还显示了速度为310-540 km s $^{-1}$的波传播特征。通过多波长双视角观测，我们发现波前可能以约53.2 $^{\circ}$的倾角向前倾斜地传播到太阳表面。我们的研究结果表明，这种EUV波是由相关CME的膨胀驱动的快模式磁流体动力学波或激波，其波前可能是一个圆顶状的结构，可能会影响上色球层，过渡区和日冕。
Signatures of localised particle acceleration at a global coronal shock wave
Dublin City University（都柏林城市大学）；Dublin Institute for Advanced Studies（都柏林高等研究院）；Observatoire de Paris（巴黎天文台）；PSL Research University（PSL研究大学）；CNRS（法国国家科学研究中心）；Sorbonne Université（索邦大学）；Université Paris Cité（巴黎西岱大学）
Quantifying the relationship between Moreton-Ramsey waves and "EIT waves" using observations of 4 homologous wave events
太阳大气中自由传播的全球波通常使用极紫外线通带（EUV或“EIT波”）观测，而在H-α（莫顿-拉姆齐波）中则不太规律。尽管经过数十年的研究，EUV和Moreton-Ramsey波的联合观测仍然很少见，这使得量化这些现象之间联系的努力变得复杂。我们提出了四个同源的全球波的观测，起源于同一个活动区域之间的2014年3月28日至30日，并使用EUV和H-α数据观察。太阳动力学天文台观测到了每一个全球极紫外波，并使用全球振荡网络组（GONG）网络确定了相关的莫顿-拉姆齐波。所有的全球波都表现出高的初始速度（例如，842-1388 km s $^{-1}$（在193 A通带中）和强减速（例如，-1437 - -782 m s $^{-2}$在193 A通带）在每个EUV通带的研究，EUV波运动学超过莫顿-拉姆齐波。使用差分发射测量和强度变化技术估计每个全球波的密度压缩比，两者都表明所观察到的波是弱冲击，快磁声马赫数略大于1。这表明，根据目前的模型，全球日冕波不足以产生莫顿-拉姆齐波，这表明这些观测结果的另一种解释。相反，我们的结论是，全球波的演变受到周围的日冕磁场的限制，在每一种情况下，产生一个向下的角度波前传播向北太阳极扰动色球层，并观察到作为莫顿-拉姆齐波。
