Coupled <Emphasis Type="Italic">G</Emphasis>-Mode Intersections and Solar-Cycle Variability |
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| Authors: | David A Juckett |
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| Institution: | (1) W.W. Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA 94305, USA |
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| Abstract: | Wolff (Astrophys. J.
193, 721, 1974) introduced the concept of g-mode coupling within the solar interior. Subsequently, Wolff developed a more quantitative model invoking a reciprocal interaction
between coupled g modes and burning in the solar core. Coupling is proposed to occur for constant values of the spherical harmonic degree ℓ] creating rigidly rotating structures denoted as sets(ℓ). Power would be concentrated near the core and the top of radiative zone RZ] in narrow intervals of longitude on opposite
sides of the Sun. Sets(ℓ) would migrate retrograde in the RZ as function of ℓ and their intersections would deposit extra energy at the top of the RZ. It is proposed that this enhances sunspot eruptions
at particular longitudes and at regular time intervals. Juckett and Wolff (Solar Phys.
252, 247, 2008) detected this enhancement by viewing selected spherical harmonics of sunspot patterns within stackplots twisted into the
relative rotational frames of various sets(ℓ). In subsequent work, the timings of the set(ℓ) intersections were compared to the sub-decadal variability of the sunspot cycle. Seventeen sub-decadal intersection frequencies
(0.63 – 7.0 year) were synchronous with 17 frequencies in the sunspot time-series with a mean correlation of 0.96. Six additional
non-11-year frequencies (periods of 8.0 to 28.7 year) are now shown to be nearly synchronous between sunspot variability and
the model. Two additional intersections have the same frequency as the solar cycle itself and peak during the rising phase
of the solar cycle. This may be partly responsible for cycle asymmetry. These results are evidence that some of the solar-cycle
variability may be attributable to deterministic components that are intermixed with a broad-spectrum stochastic and long-term
chaotic background. |
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