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Abstract
We investigate the spherical harmonic degree (l) dependence of the
'seismic' quasi-biennial oscillation (QBO) observed in low-degree solar
p-mode frequencies, using Sun-as-a-star Birmingham Solar Oscillations
Network data. The amplitude of the seismic QBO is modulated by the 11-yr
solar cycle, with the amplitude of the signal being largest at solar
maximum. The amplitude of the signal is noticeably larger for the l= 2
and 3 modes than for the l= 0 and 1 modes. The seismic QBO shows some
frequency dependence but this dependence is not as strong as observed in
the 11-yr solar cycle. These results are consistent with the seismic QBO
having its origins in shallow layers of the interior (one possibility
being the bottom of the shear layer extending 5 per cent below the solar
surface). Under this scenario the magnetic flux responsible for the
seismic QBO is brought to the surface (where its influence on the p
modes is stronger) by buoyant flux from the 11-yr cycle, the strong
component of which is observed at predominantly low latitudes. As the l=
2 and 3 modes are much more sensitive to equatorial latitudes than the
l= 0 and 1 modes the influence of the 11-yr cycle on the seismic QBO is
more visible in l= 2 and 3 mode frequencies. Our results imply that
close to solar maximum the main influence of the seismic QBO occurs at
low latitudes (
Original language | English |
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Pages (from-to) | no-no |
Journal | Royal Astronomical Society. Monthly Notices |
DOIs | |
Publication status | Published - 1 Dec 2011 |
Keywords
- Sun: oscillations
- Sun: helioseismology
- methods: data analysis
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Dive into the research topics of 'Quasi-biennial variations in helioseismic frequencies: can the source of the variation be localized?'. Together they form a unique fingerprint.Projects
- 1 Finished
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Sounding the Stars---The Birmingham and Queen Mary Seismology Programme
Elsworth, Y. (Principal Investigator), Chaplin, B. (Co-Investigator) & Miglio, A. (Co-Investigator)
SCIENCE & TECHNOLOGY FACILITIES COUNCIL
1/04/12 → 31/03/15
Project: Research Councils