Measurement of Kodaikanal White–Light Images: Relaxation of Tilts of Spot Groups as Indicator of Subsurface Dynamics of Parent Flux Loops

Sivaraman, K. R.; Gokhale, M. H.; Sivaraman, H.; Gupta, Siddharth; Howard, Robert F.

doi:10.1086/510546

Cited by 13 publications

(14 citation statements)

References 20 publications

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“…The first investigation of cycle-to-cycle variations in active region tilt was undertaken by Dasi-Espuig et al ( 2010 ). They used the Mount Wilson and Kodaikanal white-light sunspot data and found tilt angles as functions of latitude similar to those found from these data by Howard ( 1991b ) and by Sivaraman et al ( 2007 ). Although they were unable to find the Joy’s Law relation for each cycle, they did calculate a proxy — the average tilt angle divided by the average latitude — and found that it varied inversely with cycle amplitude.…”

Section: Individual Cycle Characteristicssupporting

confidence: 56%

“…In a later study, Sivaraman et al ( 2007 ) noted that the sunspot group tilts relax toward the average tilt at their emergent latitude after initial emergence. This behavior, relaxation to the average tilt rather than zero tilt, was also found by Kosovichev and Stenflo ( 2008 ) in their study of magnetograms from SOHO/MDI.…”

Section: Individual Cycle Characteristicsmentioning

confidence: 91%

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The Solar Cycle

Hathaway

2015

Living Rev. Sol. Phys.

779

505

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The solar cycle is reviewed. The 11-year cycle of solar activity is characterized by the rise and fall in the numbers and surface area of sunspots. A number of other solar activity indicators also vary in association with the sunspots including; the 10.7 cm radio flux, the total solar irradiance, the magnetic field, flares and coronal mass ejections, geomagnetic activity, galactic cosmic ray fluxes, and radioisotopes in tree rings and ice cores. Individual solar cycles are characterized by their maxima and minima, cycle periods and amplitudes, cycle shape, the equatorward drift of the active latitudes, hemispheric asymmetries, and active longitudes. Cycle-to-cycle variability includes the Maunder Minimum, the Gleissberg Cycle, and the Gnevyshev-Ohl (even-odd) Rule. Short-term variability includes the 154-day periodicity, quasi-biennial variations, and double-peaked maxima. We conclude with an examination of prediction techniques for the solar cycle and a closer look at cycles 23 and 24.Electronic Supplementary MaterialSupplementary material is available for this article at 10.1007/lrsp-2015-4.

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Section: Individual Cycle Characteristicssupporting

confidence: 56%

Section: Individual Cycle Characteristicsmentioning

confidence: 91%

The Solar Cycle

Hathaway

2015

Living Rev. Sol. Phys.

779

505

View full text Add to dashboard Cite

show abstract

“…The first investigation of cycle-to-cycle variations in active region tilt was undertaken by Dasi-Espuig et al (2010). They used the Mount Wilson and Kodaikanal white-light sunspot data and found tilt angles as functions of latitude similar to those found from these data by Howard (1991b) and by Sivaraman et al (2007). Although they were unable to find the Joy's Law relation for each cycle, they did calculate a proxy-the average tilt angle divided by the average latitude-and found that it varied inversely with cycle amplitude.…”

Section: Active Region Tilt -Joy's Lawmentioning

confidence: 84%

The Solar Cycle

Hathaway

2010

Living Rev. Sol. Phys.

460

345

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The Solar Cycle is reviewed. The 11-year cycle of solar activity is characterized by the rise and fall in the numbers and surface area of sunspots. We examine a number of other solar activity indicators including the 10.7 cm radio flux, the total solar irradiance, the magnetic field, flares and coronal mass ejections, geomagnetic activity, galactic cosmic ray fluxes, and radioisotopes in tree rings and ice cores that vary in association with the sunspots. We examine the characteristics of individual solar cycles including their maxima and minima, cycle periods and amplitudes, cycle shape, and the nature of active latitudes, hemispheres, and longitudes. We examine long-term variability including the Maunder Minimum, the Gleissberg Cycle, and the Gnevyshev-Ohl Rule. Short-term variability includes the 154-day periodicity, quasi-biennial variations, and double peaked maxima. We conclude with an examination of prediction techniques for the solar cycle.

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“…However, the relationship between the area and the life time of sunspot groups may be exponential rather than linear (Javaraiah, 2003a). Properties such as the rotation rate, meridional motion, tilt angle, etc., of sunspots and sunspot groups depend on their life time and size as well as their age (e.g., Ward, 1965Ward, , 1966Howard, Gilman, and Gilman, 1984;Balthasar, Vázquez, and Wöhl, 1986;Javaraiah and Gokhale, 1997;Javaraiah, 1999;Sivaraman et al, 2007). Studies on these properties of sunspot groups may provide information on the subsurface dynamics of the Sun (e.g., Howard, 1996;Javaraiah and Gokhale, 1997;Hiremath, 2002;Sivaraman et al, 2003Sivaraman et al, , 2007Sivaraman et al, , 2010.…”

Section: Introductionmentioning

confidence: 99%

“…Properties such as the rotation rate, meridional motion, tilt angle, etc., of sunspots and sunspot groups depend on their life time and size as well as their age (e.g., Ward, 1965Ward, , 1966Howard, Gilman, and Gilman, 1984;Balthasar, Vázquez, and Wöhl, 1986;Javaraiah and Gokhale, 1997;Javaraiah, 1999;Sivaraman et al, 2007). Studies on these properties of sunspot groups may provide information on the subsurface dynamics of the Sun (e.g., Howard, 1996;Javaraiah and Gokhale, 1997;Hiremath, 2002;Sivaraman et al, 2003Sivaraman et al, , 2007Sivaraman et al, , 2010. Therefore, the studies on the variations in the numbers (counts) of sunspots and sunspot groups in different sizes look to be important for understanding the basic mechanism of solar activity and solar cycle, and also the relationship between sunspots and other activity indices (e.g., Kilcik et al, 2011;Clette and Lefèvre, 2012).…”

Section: Introductionmentioning

confidence: 99%

The G–O Rule and Waldmeier Effect in the Variations of the Numbers of Large and Small Sunspot Groups

Javaraiah

2012

Sol Phys

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We have analysed the combined Greenwich and Solar Optical Observing Network (SOON) sunspot group data during the period of 1874 -2011 and determined variations in the annual numbers (counts) of the small (maximum area A M < 100 millionth of solar hemisphere, msh), large (100 ≤ A M < 300 msh), and big (A M ≥ 300 msh) spot groups. We found that the amplitude of an even-numbered cycle of the number of large groups is smaller than that of its immediately following odd-numbered cycle. This is consistent with the well known Gnevyshev and Ohl rule or G-O rule of solar cycles, generally described by using the Zürich sunspot number (R Z ). During cycles 12 -21 the G-O rule holds good for the variation in the number of small groups also, but it is violated by cycle pair (22, 23) as in the case of R Z . This behavior of the variations in the small groups is largely responsible for the anomalous behavior of R Z in cycle pair (22, 23). It is also found that the amplitude of an odd-numbered cycle of the number of small groups is larger than that of its immediately following even-numbered cycle. This can be called as 'reverse G-O rule'. In the case of the number of the big groups, both cycle pairs (12, 13) and (22, 23) violated the G-O rule. In many cycles the positions of the peaks of the small, large, and big groups are different and considerably differ with respect to the corresponding positions of the R Z peaks. In the case of cycle 23, the corresponding cycles of the small and large groups are largely symmetric/less asymmetric (Waldmeier effect is weak/absent) with their maxima taking place two years later than that of R Z . The corresponding cycle of the big groups is more asymmetric (strong Waldmeier effect) with its maximum epoch taking place at the same time as that of R Z .

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Measurement of Kodaikanal White–Light Images: Relaxation of Tilts of Spot Groups as Indicator of Subsurface Dynamics of Parent Flux Loops

Cited by 13 publications

References 20 publications

The Solar Cycle

The Solar Cycle

The Solar Cycle

The G–O Rule and Waldmeier Effect in the Variations of the Numbers of Large and Small Sunspot Groups

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