Comparison of Two Fitting Methods for Ring Diagram Analysis of Very High<i>l</i>Solar Oscillations

Patrón, J.; Hernández, I. Gonzälez; Chou, Dean‐Yi; Sun, Ming-Tsung; Mu, T.-M.; Loudagh, S.; Bala, B. K.; Chou, Y. C.; Lin, Chia-Hsien; Huang, I-Lun; Jiménez, A.; Rabello-Soares, M. C.; Ai, G. X.; Wang, G.-P.; Zirin, H.; Marquette, W.; Nenow, J.; Ehgamberdiev, S. A.; Khalikov, S.

doi:10.1086/304469

Cited by 28 publications

(20 citation statements)

References 6 publications

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“…These power spectra are referred to as ring diagrams because of the characteristic ringlike shape of regions where the power is concentrated in cuts of constant temporal frequency, reflecting the near-azimuthal symmetry of the power in k-space. A detailed description of the ring-diagram technique is given by Patrón et al (1997) and . Ring-diagram analysis has the advantage over globalmode analysis in that it can be used to study both the nonaxisymmetric component of the structure and dynamics of the Sun, as well as the antisymmetric component of these quantities between the solar northern and southern hemispheres.…”

Section: Discussionmentioning

confidence: 99%

Structure of the Near‐Surface Layers of the Sun: Asphericity and Time Variation

Basu

Antia

Bogart

2007

ApJ

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We present results on the structure of the near-surface layers of the Sun obtained by inverting frequencies of highdegree solar modes from ''ring diagrams.'' We have results for eight epochs between 1996 June and 2003 October. The frequencies for each epoch were obtained from ring diagrams constructed from Michelson Doppler Imager (MDI) Dopplergrams spanning complete Carrington rotations. We find that there is a substantial latitudinal variation of both sound speed and the adiabatic index À 1 in the outer 2% of the Sun. We find that both the sound-speed and À 1 profiles change with changes in the level of solar activity. In addition, we also study differences between the northern and southern hemispheres of the Sun and find a small asymmetry that appears to reflect the difference in magnetic activity between the two hemispheres.

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Section: Discussionmentioning

confidence: 99%

Structure of the Near‐Surface Layers of the Sun: Asphericity and Time Variation

Basu

Antia

Bogart

2007

ApJ

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“…The Doppler cubes are then Fourier transformed to obtain a three-dimensional power spectrum. A more detailed discussion of the construction of ring diagrams can be found in Patron et al (1997) and Basu et al (1999).…”

Section: Datamentioning

confidence: 99%

Evidence for Solar Frequency Dependence on Sunspot Type

Baldner¹,

Bogart²,

Basu³

2011

ApJ

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High-degree solar mode frequencies as measured by ring diagrams are known to change in the presence of the strong magnetic fields found in active regions. We examine these changes in frequency for a large sample of active regions analyzed with data from the Michelson Doppler Imager on board the Solar and Heliospheric Observatory spacecraft, spanning most of solar cycle 23. We confirm that the frequencies increase with increasing magnetic field strength, and that this dependence is generally linear. We find that the dependence is slightly but significantly different for active regions with different sunspot types.

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“…Analysis of ring diagrams begins by fitting a model to the 3D power spectrum to determine the frequencies and other parameters. Different techniques and models have been used for this purpose (Schou & Bogart 1998;Patrón et al 1997;). These techniques basically use a maximum likelihood method (Anderson et al 1990) to fit a model profile to the different rings in power spectra that correspond to different values of n. For example, use the model…”

Section: The Techniquementioning

confidence: 99%