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Khutsishvili, E. V.; Gigolashvili, M. Sh.; Kvernadze, Teimuraz

doi:10.1023/a:1015068629350

Cited by 9 publications

(8 citation statements)

References 13 publications

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“…This agrees with the high correlation between the rotation parameter A and various indices of solar activity. This result is consistent with many other observational findings, obtained by different tracers and methods, so a higher average rotation velocity in activity minima was found by many authors who analysed the solar rotation using various sunspot data series by different methods (Lustig 1983;Gilman & Howard 1984;Balthasar et al 1986;Hathaway & Wilson 1990;Gupta et al 1999;Khutsishvili et al 2002;Zuccarello & Zappalá 2003;Brajša et al 2006). Moreover, Chandra et al (2010) measured the differential rotation of the soft X-ray solar corona and investigated its variation with the solar activity.…”

Section: Discussion Interpretation and Conclusionsupporting

confidence: 90%

“…For the investigation of possible variations in the solar rotation, the Greenwich data set was used by Balthasar & Wöhl (1980), Arévalo et al (1982), and Balthasar et al (1986); the Kanzelhöhe data set by Lustig (1983); the Mt. Wilson data set by Gilman & Howard (1984) and by Hathaway & Wilson (1990); the Mitaka data set by Kambry & Nishikawa (1990); the Suzuka data set by Suzuki (1998); the extended Greenwich data set by Pulkkinen & Tuominen (1998), Javaraiah (2003), Zuccarello & Zappalá (2003), Javaraiah et al (2005), Javaraiah & Ulrich (2006), and Brajša et al (2006Brajša et al ( , 2007; the Kodaikanal data set by Gupta et al (1999); and the Abastumani data set by Khutsishvili et al (2002). Also, temporal variations in the solar rotation were studied using other Article published by EDP Sciences A17, page 1 of 6…”

Section: Introductionmentioning

confidence: 99%

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A relationship between the solar rotation and activity in the period 1998–2006 analysed by tracing small bright coronal structures in SOHO-EIT images

Jurdana-Šepić

Brajša

Wöhl

et al. 2011

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Section: Discussion Interpretation and Conclusionsupporting

confidence: 90%

Section: Introductionmentioning

confidence: 99%

A relationship between the solar rotation and activity in the period 1998–2006 analysed by tracing small bright coronal structures in SOHO-EIT images

Jurdana-Šepić

Brajša

Wöhl

et al. 2011

A&A

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“…Except for the already mentioned overlapping with Sudar et al (2014Sudar et al ( , 2017 rotation results (Table 3, rows 8 and 16), in most of the other studies listed in Table 3 the differential rotation parameters are in agreement with our results (Table 3, rows 20 and 21); the exceptions are the GPR result for reccurent sunspot groups (Brajša et al 2002a) (Table 3, row 4); the Mt. Wilson result concerning only sunspot groups as tracers (Table 3, row 15); the Abastumani result (Khutsishvili et al 2002) ( Table 3, row 13); and the KSO results (Lustig 1982(Lustig , 1983Balthasar & Fangmeier 1988) (Table 3, rows 17 -19).…”

Section: Comparison With Other Data Setssupporting

confidence: 91%

“…Wilson data for sunspot groups (Table 3, row 15), but it is not clear what could be the cause. A higher value of the equatorial velocity, as well as the lower value of the differential rotation gradient was obtained with the Abastumani data (Khutsishvili et al 2002) ( Table 2). Sidereal rotation velocity is denoted by ω and heliographic latitude by b. N -northern hemisphere, S -southern hemisphere.…”

Section: Comparison With Other Data Setsmentioning

confidence: 54%

“…The mean absolute differences between the KSO and DPD positions are lower in all cases -except for the longitude difference for complex sunspot groups -than the mean absolute difference between the KSO and GPR positions. As the KSO and GPR comparison was made for the year 1972, it may be possible that the KSO data is influenced by the er- , 1874, -1976, Table 3, row 1 GPR, 1879-1975, Javaraiah (2003, Table 3, row 3 GPR , 1940-1968, Balthasar & Wöhl (1980, Table 3, row 6 EGR, 1878 -2011, Sudar et al (2014), Table 3, row 8 EGR , 1976, -2002, , Javaraiah (2003, Table 3, row 9 EGR, 1874 -1996, Pulkkinen & Tuominen (1998), Table 3, row 10 Mt. Wilson, 1921-1982, Table 3, row 15 DPD , 1974, , Sudar et al (2017, Table 3, row 16 KSO, 1947-1981, Lustig (1983, Table 3, row 18 KSO, 1964 Table 3, row 20 KSO, 1964 Table 3).…”

Section: Comparison With Other Data Setsmentioning

confidence: 99%

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Solar differential rotation in the period 1964–2016 determined by the Kanzelhöhe data set

Beljan

Jurdana-Šepić

Brajša

et al. 2017

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Context. Kanzelhöhe Observatory for Solar and Environmental Research (KSO) provides daily multispectral synoptic observations of the Sun using several telescopes. In this work we made use of sunspot drawings and full disk white light CCD images. Aims. The main aim of this work is to determine the solar differential rotation by tracing sunspot groups during the period 1964 -2016, using the KSO sunspot drawings and white light images. We also compare the differential rotation parameters derived in this paper from the KSO with those collected fromf other data sets and present an investigation of the north -south rotational asymmetry. Methods. Two procedures for the determination of the heliographic positions were applied: an interactive procedure on the KSO sunspot drawings (1964 -2008, solar cycles nos. 20 -23) and an automatic procedure on the KSO white light images (2009 -2016, solar cycle no. 24). For the determination of the synodic angular rotation velocities two different methods have been used: a daily shift (DS) method and a robust linear least-squares fit (rLSQ) method. Afterwards, the rotation velocities had to be converted from synodic to sidereal, which were then used in the least-squares fitting for the solar differential rotation law. A comparison of the interactive and automatic procedures was performed for the year 2014. Results. The interactive procedure of position determination is fairly accurate but time consuming. In the case of the much faster automatic procedure for position determination, we found the rLSQ method for calculating rotational velocities to be more reliable than the DS method. For the test data from 2014, the rLSQ method gives a relative standard error for the differential rotation parameter B that is three times smaller than the corresponding relative standard error derived for the DS method. The best fit solar differential rotation profile for the whole time period is ω(b) = (14.47 ± 0.01) -(2.66 ± 0.10) sin 2 b (deg/day) for the DS method and ω(b) = (14.50 ± 0.01) -(2.87 ± 0.12) sin 2 b (deg/day) for the rLSQ method. A barely noticeable north -south asymmetry is observed for the whole time period 1964 -2016 in the present paper. Rotation profiles, using different data sets, presented by other authors for the same time periods and the same tracer types, are in good agreement with our results. Conclusions. The KSO data set used in this paper is in good agreement with the Debrecen Photoheliographic Data and Greenwich Photoheliographic Results and is suitable for the investigation of the long-term variabilities in the solar rotation profile. Also, the quality of the KSO sunspot drawings has gradually increased during the last 50 years.

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Temporal Variations of the Solar Rotation Determined by Sunspot Groups

2006

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The extended Greenwich data set consisting of positions of sunspot groups is used for the investigation of cycle-related variations of the solar rotation in the years 1874 -1981. Applying the residual method, which yields a single number for each year describing the average deviation from the mean value of the solar rotation, the dependence of the rotation velocity residual on the phase of the solar cycle is investigated. A secular deceleration of the solar rotation was found: the slope being statistically significant at the 3σ level. Periods of 33, 22, 11, 5.2, and 3.5 years can be identified in the power spectra. The rotation velocity residuals were averaged for all years with the same solar cycle phase relative to the nearest preceding sunspot minimum. The variation pattern reveals a higher than average rotation velocity in the minimum of activity and, to a lesser extent, also around the maximum of activity. The analysis was repeated with several changes in the reduction method, such as elimination of the secular trend, application of statistical weights, different cutoffs of the central meridian distance, division of the latitude into subregions and treating data from the years of activity minima separately. The results obtained are compared with those from the literature, and an interpretation of the observed phenomena is proposed.

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Cited by 9 publications

References 13 publications

A relationship between the solar rotation and activity in the period 1998–2006 analysed by tracing small bright coronal structures in SOHO-EIT images

A relationship between the solar rotation and activity in the period 1998–2006 analysed by tracing small bright coronal structures in SOHO-EIT images

Solar differential rotation in the period 1964–2016 determined by the Kanzelhöhe data set

Temporal Variations of the Solar Rotation Determined by Sunspot Groups

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