A1 Refereed original research article in a scientific journal
Artifacts of SDO/HMI data and long-period oscillations of sunspots
Authors: Smirnova V, Efremov VI, Parfinenko LD, Riehokainen A, Solov'ev AA
Publisher: EDP SCIENCES S A
Publication year: 2013
Journal: Astronomy and Astrophysics
Journal name in source: ASTRONOMY & ASTROPHYSICS
Journal acronym: ASTRON ASTROPHYS
Article number: ARTN A121
Volume: 554
Number of pages: 7
ISSN: 0004-6361
DOI: https://doi.org/10.1051/0004-6361/201220825
Abstract
Results. It was found that those artifacts with periods of 12 and 24 h, as revealed even in variations of weak background magnetic fields, are actually present in SDO/HMI magnetograms. However, the quantitative impact of artifacts remains quite weak and does not change the picture of sunspot oscillations dramatically for as long as the magnetic field in the spot is less than about of 2000 Gauss. When the magnetic field strength is greater than 2000 G, the influence of these artifacts increases sharply to become the dominant factor. One can suggest that the amplification of noise components of these artifacts has a highly nonlinear character with the growth of the magnetic field, and the field strength of about 2000 G then takes on meaning of a threshold value.
Results. It was found that those artifacts with periods of 12 and 24 h, as revealed even in variations of weak background magnetic fields, are actually present in SDO/HMI magnetograms. However, the quantitative impact of artifacts remains quite weak and does not change the picture of sunspot oscillations dramatically for as long as the magnetic field in the spot is less than about of 2000 Gauss. When the magnetic field strength is greater than 2000 G, the influence of these artifacts increases sharply to become the dominant factor. One can suggest that the amplification of noise components of these artifacts has a highly nonlinear character with the growth of the magnetic field, and the field strength of about 2000 G then takes on meaning of a threshold value.
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