Solar rotation results at Mount Wilson

Howard, Robert; Adkins, J. M.; Boyden, J. E.; Cragg, T. A.; Gregory, T. S.; Labonte, B. J.; Padilla, S. P.; Webster, Leslie T.

doi:10.1007/bf00148283

Cited by 67 publications

(49 citation statements)

References 10 publications

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“…Finally, the summation is divided by the total number of pixels (regardless of magnetic field strength) in the magnetogram. The MWSI values are also calculated in much the same manner as the MPSI, but summation is only done for pixels where the absolute value of the magnetic field strength is greater than 100 G (Howard et al 1980(Howard et al , 1983Ulrich 1991;Ulrich et al 1991;Li et al 2014;Xiang et al 2014). The MPSI and MWSI should represent the activity of weak magnetic field (with plage/ facular regions and outside of sunspots) on the solar full disk and the strong magnetic field activity (in sunspots) on the disk, respectively (Chapman & Boyden 1986;Parker et al 1998;Li et al 2014;Xiang et al 2014).…”

Section: Datamentioning

confidence: 99%

What Causes the Inter-Solar-Cycle Variation of Total Solar Irradiance?

Xiang

Kong

2015

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The Physikalisch Meteorologisches Observatorium Davos total solar irradiance (TSI), Active Cavity Radiometer Irradiance Monitoring TSI, and Royal Meteorological Institute of Belgium TSI are three typical TSI composites. Magnetic Plage Strength Index (MPSI) and Mount Wilson Sunspot Index (MWSI) should indicate the weak and strong magnetic field activity on the solar full disk, respectively. Cross-correlation (CC) analysis of MWSI with three TSI composites shows that TSI should be weakly correlated with MWSI, and not be in phase with MWSI at timescales of solar cycles. The wavelet coherence (WTC) and partial wavelet coherence (PWC) of TSI with MWSI indicate that the inter-solar-cycle variation of TSI is also not related to solar strong magnetic field activity, which is represented by MWSI. However, CC analysis of MPSI with three TSI composites indicates that TSI should be moderately correlated and accurately in phase with MPSI at timescales of solar cycles, and that the statisticalsignificancetest indicates that the correlation coefficient of three TSI composites with MPSI is statistically significantly higher than that of three TSI composites with MWSI. Furthermore, the cross wavelet transform (XWT) and WTC of TSI with MPSI show that the TSI is highly related and actually in phase with MPSI at a timescale of a solar cycle as well. Consequently, the CC analysis, XWT, and WTC indicate that the solar weak magnetic activity on the full disk, which is represented by MPSI, dominates the inter-solar-cycle variation of TSI.

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Section: Datamentioning

confidence: 99%

What Causes the Inter-Solar-Cycle Variation of Total Solar Irradiance?

Xiang

Kong

2015

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“…An extensive set of Doppler velocity measurements taken at Mount Wilson during a period of 14 years, from 1967 through 1982, was published by Howard et al (1982). The full-disk magnetograms in Fe i line 5250.2 Å were fitted with the model 1…”

Section: Mount Wilson Datamentioning

confidence: 99%

Variability of Surface Flows on the Sun and the Implications for Exoplanet Detection

Макаров

2010

ApJ

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The published Mount Wilson Doppler-shift measurements of the solar velocity field taken in 1967-1982 are revisited with a more accurate model, which includes two terms representing the meridional flow and three terms corresponding to the convective limb shift. Integration of the recomputed data over the visible hemisphere reveals significant variability of the net radial velocity at characteristic time scales of 0.1-10 years, with a standard deviation of 1.4 m s −1 . This result is supported by independent published observations. The implications for exoplanet detection include reduced sensitivity of the Doppler method to Earth-like planets in the habitable zone, and an elevated probability of false detections at periods of a few to several years.

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“…Spiegel & Zahn (1992) suggested an explanation of the problem by introducing a strong anisotropy of the turbulent viscosity produced by horizontal mixing of the radiative interior below the convection zone. This explanation is not fully satisfactory, however, because the anisotropic mixing is known to enhance rather than to suppress the radial differential rotation (Lebedinski 1941;Kippenhahn 1963).…”

Section: Motivationmentioning

confidence: 99%

“…1 2~0~~e -o . i 7~~~~e ) prad/s (11) (Howard et al 1983). The axisymmetric magnetic field is represented as where A is the poloidal field potential.…”

Section: The Spherical Geometry Modelmentioning

confidence: 99%

The slender solar tachocline: a magnetic model

1997

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A model for the sharp transition from differential rotation in the solar convection zone to rigid rotation in the radiative interior is presented. Differential rotation in the radiative zone is shown to be quenched efficiently by an internal magnetic field. The poloidal field amplitude, Bo, is the input parameter for our model which determines the transition layer thickness and the toroidal field strength. It is illustrated analytically and confirmed numerically that a rather small field, Bo = Gauss, suffices to satisfy the helioseismological restrictions on the depth of the differential rotation penetration below the convection zone. The transition layer thickness decreases further with increasing Bo. The toroidal field amplitude 5 N 200 Gauss is almost independent of Bo.

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Solar rotation results at Mount Wilson

Cited by 67 publications

References 10 publications

What Causes the Inter-Solar-Cycle Variation of Total Solar Irradiance?

What Causes the Inter-Solar-Cycle Variation of Total Solar Irradiance?

Variability of Surface Flows on the Sun and the Implications for Exoplanet Detection

The slender solar tachocline: a magnetic model

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