THE QUASI-BIENNIAL PERIODICITY AS A WINDOW ON THE SOLAR MAGNETIC DYNAMO CONFIGURATION
- 21 February 2013
- journal article
- Published by American Astronomical Society in The Astrophysical Journal
- Vol. 765 (2), 100
- https://doi.org/10.1088/0004-637x/765/2/100
Abstract
Manifestations of the solar magnetic activity through periodicities of about 11 and 2 years are now clearly seen in all solar activity indices. In this paper, we add information about the mechanism driving the 2-year period by studying the time and latitudinal properties of acoustic modes that are sensitive probes of the subsurface layers. We use almost 17 years of high-quality resolved data provided by the Global Oscillation Network Group to investigate the solar cycle changes in p-mode frequencies for spherical degrees ℓ from 0 to 120 and 1600 μHz ≤ν ≤ 3500 μHz. For both periodic components of solar activity, we locate the origin of the frequency shift in the subsurface layers and find evidence that a sudden enhancement in amplitude occurs in just the last few hundred kilometers. We also show that, in both cases, the size of the shift increases toward equatorial latitudes and from minimum to maximum solar activity, but, in agreement with previous findings, the quasi-biennial periodicity (QBP) causes a weaker shift in mode frequencies and a slower enhancement than that caused by the 11-year cycle. We compare our observational findings with the features predicted by different models, that try to explain the origin of this QBP and conclude that the observed properties could result from the beating between a dipole and quadrupole magnetic configuration of the dynamo.This publication has 48 references indexed in Scilit:
- On the Origin of the Double Magnetic Cycle of the SunThe Astrophysical Journal, 2008
- Grand minima and maxima of solar activity: new observational constraintsAstronomy & Astrophysics, 2007
- Mode enslavement in a two-layer stellar dynamoMonthly Notices of the Royal Astronomical Society, 2007
- Modulation of solar and stellar activity cyclesPublished by Springer Science and Business Media LLC ,2007
- Hot Spots for Solar Flares Persisting for Decades: Longitude Distributions of Flares of Cycles 19–23The Astrophysical Journal, 2003
- Localizing the Solar Cycle Frequency Shifts in Globalp‐ModesThe Astrophysical Journal, 2002
- Width and Energy of Solarp‐Modes Observed by Global Oscillation Network GroupThe Astrophysical Journal, 2000
- Solar Cycle–induced Variations in GONGp‐Mode Frequencies and SplittingsThe Astrophysical Journal, 2000
- Temporal Variations of the Rotation Rate in the Solar InteriorThe Astrophysical Journal, 2000
- Dynamic Variations at the Base of the Solar Convection ZoneScience, 2000