We present a study of wave processes occurring in solar active region NOAA 11131 on 10 December 2010, captured by the Solar Dynamics Observatory in the 1600 Å, 304 Å and 171 Å channels. For spectral analysis, we employed pixelized wavelet filtering together with a developed digital technique based on empirical mode decomposition. We studied the ∼3-minute wave dynamics to obtain relationships with the magnetic structuring of the underlying sunspot. We found that during development of wave trains the motion path occurred along a preferential direction, and that the broadband wavefronts can be represented as a set of separate narrowband oscillation sources. These sources become visible as the waves pass through the umbral inhomogeneities caused by the differing magnetic field inclination angles. We found the spatial and frequency fragmentation of wavefronts, and deduced that the combination of narrowband spherical and linear parts of the wavefronts provide the observed spirality. Maps of the magnetic field inclination angles confirm this assumption. We detect the activation of umbral structures as the increasing of oscillations in the sources along the front ridge. Their temporal dynamics are associated with the occurrence of umbral flashes. Spatial localization of the sources is stable over time and depends on the oscillation period. We propose that these sources are the result of wave paths along the loops extending outwards from the magnetic bundles of the umbra. This article is part of the Theo Murphy meeting issue 'High-resolution wave dynamics in the lower solar atmosphere.
|Number of pages||18|
|Journal||Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences|
|Early online date||21 Dec 2020|
|Publication status||Published - 08 Feb 2021|
Bibliographical noteFunding Information:
Data accessibility. Data are available from the referenced sources or from the authors on request, and are courtesy of NASA/SDO and the AIA, EVE and HMI science teams. Authors’ contributions. R.S. developed and tested the PWF and PMD spectral techniques. R.S. and D.B.J. calculated the peak period maps and derived the magnetic field inclination angles. D.B.J. calculated the three-dimensional extrapolation of the magnetic field. R.S., D.B.J. and J.S. created the figures and wrote the paper. Competing interests. We declare we have no competing interests. Funding. The study was performed within the basic funding from FR program II.16, RAS program KP19-270, and partially supported by the Russian Foundation for Basic Research (RFBR) (grant no. 17-52-80064 BRICS-a). R.S. research was funded by Chinese Academy of Sciences President’s International Fellowship
Initiative (grant no. 2020VMA0032). D.B.J. is funded by a Research & Development (grant no. 059RDEN-1) provided by Invest NI and Randox Laboratories Ltd. J.S. research was partly supported by National Natural Science Foundation of China (grant no. 11773038). Acknowledgements. The authors are grateful to the SDO/AIA/HMI teams for operating the instruments and performing the basic data reduction, and especially, for the open data policy. We are grateful to the referee for helpful and constructive comments and suggestions.
© 2020 The Author(s).
Copyright 2021 Elsevier B.V., All rights reserved.
- magnetic field
- solar atmosphere
ASJC Scopus subject areas
- Physics and Astronomy(all)