Eleven-year cycle in solar rotation and meridional motions as derived from the positions of sunspot groups

Tuominen, Jaakko; Tuominen, I.; Kyröläinen, Juhani

doi:10.1093/mnras/205.3.691

Cited by 47 publications

(15 citation statements)

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“…The picture develops approximately in the same way in both hemispheres of the Sun. Tuominen, Tuominen, and Kyrol~inen (1983) analyzed Greenwich data on sunspot proper motions and confirmed these results for latitudes in which sunspot formation takes place. Also, in the same latitudes they detected meridional circulation cells (rolls).…”

Section: Introductionmentioning

confidence: 65%

“…

An approximate analytical solution for the zonal and meridional flows for a given magnetic wave is constructed.

…”

mentioning

confidence: 99%

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Large-scale flows excited by magnetic fields in the solar convective zone

Kleeorin

Ruzmaikin

1991

Sol Phys

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Observations demonstrate a nearly 22-year periodic zonal flow superimposed on general solar differential rotation (LaBonte and Howard, 1982) and some meridional motions (e.g., Tuominen, Tuominen, and Kyrol~inen, 1983). Such flows can be excited by the magnetic wave generated by the dynamo in the solar convective zone.An approximate analytical solution for the zonal and meridional flows for a given magnetic wave is constructed. This approach is justified by the fact that the magnetic field is generated by differential rotation and mean helicity, and the magnetic field in the time interval under consideration does not affect much this main flow; it can, however, strongly influence the perturbations of this flow.The density gradient in the convective zone is taken into account as an essential point in the solution construction. The solution agreed well with observational features and, in particular, it gives a phase shift between the rotatio/nal (zonal) wave and solar activity. A polar branch of the rotational wave can be described as an effect created by a poleward moving dynamo wave.Secular variatior~s in the symmetrical part of the differential rotation and in the asymmetry between the north and south hemispheres are predicted.The alternative approaches to the explanation of the origin of the observed large-scale flows are discussed.

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Section: Introductionmentioning

confidence: 65%

“…

An approximate analytical solution for the zonal and meridional flows for a given magnetic wave is constructed.

…”

mentioning

confidence: 99%

Large-scale flows excited by magnetic fields in the solar convective zone

Kleeorin

Ruzmaikin

1991

Sol Phys

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“…We vary s between two and six and n c between one and three. The higher degrees s represent more than one cell in each hemisphere; such multi-cell circulation occurs in numerical simulations (Brun and Toomre, 2002;Miesch, Brun, and Toomre, 2006) and has been observed by means of sunspot tracing on the solar surface (Tuominen, Tuominen, and Kyröläinen, 1983;Wöhl and Brajša, 2001). The models with odd s have an equator-crossing flow; we include these as such asymmetric flows have been found on the Sun as well (Haber et al, 2000;Zhao and Kosovichev, 2004).…”

Section: The Model Of the Meridional Circulationmentioning

confidence: 81%

Meridional Circulation and Global Solar Oscillations

Roth

Stix

2008

Sol Phys

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We investigate the influence of large-scale meridional circulation on solar p modes by quasi-degenerate perturbation theory, as proposed by Lavely and Ritzwoller (Roy. Soc. Lond. Phil. Trans. Ser. A 339, 431, 1992). As an input flow we use various models of stationary meridional circulation obeying the continuity equation. This flow perturbs the eigenmodes of an equilibrium model of the Sun. We derive the signatures of the meridional circulation in the frequency multiplets of solar p modes. In most cases the meridional circulation leads to negative average frequency shifts of the multiplets. Further possibly observable effects are briefly discussed.

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“…The torsional oscillations were also found later on by tracing the photospheric magnetic field patterns using the crosscorrelation technique (Snodgrass 1991;Komm et al 1993a) and by the time-distance helioseismology analysis of solar Dopplergrams (Beck et al 2002). Furthermore, Tuominen et al (1983) and Howard (1991b) have found some indications of torsional oscillations in the Greenwich Photoheliographic Results (GPR) and the Mt. Wilson sunspot data set, respectively.…”

Section: Introductionmentioning

confidence: 83%

Properties of the solar velocity field indicated by motions of coronal bright points

Vršnak

Brajša

Wöhl³

et al. 2003

A&A

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Abstract. Full-disc solar images obtained with the Extreme Ultraviolet Imaging Telescope (EIT) on board the Solar and Heliospheric Observatory (SOHO) are used to analyse properties of the solar velocity field by tracing coronal bright points from June 4, 1998 to May 22, 1999. Rotation velocity residuals, meridional motions and their relationship are investigated. Zones of slow and fast rotation found in motions of coronal bright points are consistent with the pattern of torsional oscillations, indicating that the statistical velocity pattern of bright point motions reflects the large-scale plasma flows. A complex pattern of meridional motion is deduced: The equatorward flows are found to dominate at low (B < 10• ) and high (B > 40 • ) latitudes, whereas at mid-latitudes (B ≈ 10• −40 • ) a poleward flow is inferred. The complete data set shows no significant correlation between rotation residuals and meridional motions. However, when a subsample of coronal bright points including only the "point-like structures" (predominantly young bright points) is considered, a statistically significant correlation is found. On average, faster tracers show equatorward motion and the slower ones show poleward motion. Such a segregation is reflected in a statistically significant covariance of the rotation residuals and meridional velocities in the order of −1000 m 2 s −2 , revealing an equatorward transport of angular momentum. The negative value of the covariance is provided by the high velocity tail in the velocity distribution of point-like structures, representing less than 15% of the population. The latitude dependence of the covariance can be expressed as Q = −62 B + 200 m 2 s −2 covering the range B = 0 • -60• .

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Eleven-year cycle in solar rotation and meridional motions as derived from the positions of sunspot groups

Cited by 47 publications

References 0 publications

Large-scale flows excited by magnetic fields in the solar convective zone

Large-scale flows excited by magnetic fields in the solar convective zone

Meridional Circulation and Global Solar Oscillations

Properties of the solar velocity field indicated by motions of coronal bright points

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