A1 Vertaisarvioitu alkuperäisartikkeli tieteellisessä lehdessä
Artifacts of SDO/HMI data and long-period oscillations of sunspots
Tekijät: Smirnova V, Efremov VI, Parfinenko LD, Riehokainen A, Solov'ev AA
Kustantaja: EDP SCIENCES S A
Julkaisuvuosi: 2013
Journal: Astronomy and Astrophysics
Tietokannassa oleva lehden nimi: ASTRONOMY & ASTROPHYSICS
Lehden akronyymi: ASTRON ASTROPHYS
Artikkelin numero: ARTN A121
Vuosikerta: 554
Sivujen määrä: 7
ISSN: 0004-6361
DOI: https://doi.org/10.1051/0004-6361/201220825
Tiivistelmä
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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