Width of Sunspot Generating Zone and Reconstruction of Butterfly

Иванов, В. П.; Miletsky, E. V.

doi:10.1007/s11207-010-9665-6

Cited by 22 publications

(9 citation statements)

References 12 publications

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“…1705), it suggests a weak toroidal field, causing a narrower latitudinal range of sunspot formation during the MM. This conclusion agrees with the results of more sophisticated analysis by Ivanov & Miletsky (2011), who found that the latitudinal span of the butterfly diagram during the late part of the MM should be 15-20…”

Section: Butterfly Diagramsupporting

confidence: 92%

The Maunder minimum (1645–1715) was indeed a grand minimum: A reassessment of multiple datasets

Usoskin

Arlt

Asvestari

et al. 2015

A&A

176

172

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Aims. Although the time of the Maunder minimum (1645-1715) is widely known as a period of extremely low solar activity, it is still being debated whether solar activity during that period might have been moderate or even higher than the current solar cycle #24. We have revisited all existing evidence and datasets, both direct and indirect, to assess the level of solar activity during the Maunder minimum. Methods. We discuss the East Asian naked-eye sunspot observations, the telescopic solar observations, the fraction of sunspot active days, the latitudinal extent of sunspot positions, auroral sightings at high latitudes, cosmogenic radionuclide data as well as solar eclipse observations for that period. We also consider peculiar features of the Sun (very strong hemispheric asymmetry of the sunspot location, unusual differential rotation and the lack of the K-corona) that imply a special mode of solar activity during the Maunder minimum.Results. The level of solar activity during the Maunder minimum is reassessed on the basis of all available datasets. Conclusions. We conclude that solar activity was indeed at an exceptionally low level during the Maunder minimum. Although the exact level is still unclear, it was definitely lower than during the Dalton minimum of around 1800 and significantly below that of the current solar cycle #24. Claims of a moderate-to-high level of solar activity during the Maunder minimum are rejected with a high confidence level.

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Section: Butterfly Diagramsupporting

confidence: 92%

The Maunder minimum (1645–1715) was indeed a grand minimum: A reassessment of multiple datasets

Usoskin

Arlt

Asvestari

et al. 2015

A&A

176

172

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“…Larger cycles achieve greater widths than do smaller cycles. Ivanov and Miletsky (2011) found a linear relationship between the width (maximum latitude -minimum latitude, in their study) of the sunspot latitude bands and the number of sunspot groups with no dependence on cycle amplitude. Comparing the RMS width to the sunspot area confirms the lack of any relational dependence on cycle strength but indicates a distinctly nonlinear relationship with an asymptotic limit to the widths as the total sunspot area increases (bottom panel of Figure 32).…”

Section: Active Latitudes -Spörer's Lawmentioning

confidence: 83%

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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“…In the light of all the other available activity indicators (auroral sightings, cosmogenic radionuclide data, solar eclipse observations) analyzed by Usoskin et al (2015), this interpretation seems unlikely. Moreover, during the MM, the latitude range where sunspots appeared (i.e., the width of the butterfly wings) was narrower (e.g., Ribes & Nesme-Ribes 1993;Ivanov & Miletsky 2011;Usoskin et al 2015) and strong hemispherical asymmetry was present (e.g., Ribes & Nesme-Ribes 1993;Sokoloff & Nesme-Ribes 1994). Analysis of sunspot proper motion seems to indicate slower rotation and stronger latitudinal surface differential rotation during the MM than for more prominent activity states (Eddy et al 1976;Ribes & Nesme-Ribes 1993).…”

Section: Introductionmentioning

confidence: 91%

Multiple dynamo modes as a mechanism for long-term solar activity variations

Käpylä

Olspert

et al. 2016

A&A

104

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Context. Solar magnetic activity shows both smooth secular changes, such as the modern Grand Maximum, and quite abrupt drops that are denoted as grand minima, such as the Maunder Minimum. Direct numerical simulations (DNS) of convection-driven dynamos offer one way of examining the mechanisms behind these events. Aims.In this work, we analyze a solution of a solar-like DNS that was evolved for roughly 80 magnetic cycles of 4.9 years and where epochs of irregular behavior are detected. The emphasis of our analysis is to find physical causes for such behavior. Methods. The DNS employed is a semi-global (wedge-shaped) magnetoconvection model. For the data analysis tasks we use Ensemble Empirical Mode Decomposition and phase dispersion methods, as they are well suited for analyzing cyclic (non-periodic) signals. Results. A special property of the DNS is the existence of multiple dynamo modes at different depths and latitudes. The dominant mode is solar-like (equatorward migration at low latitudes and poleward at high latitudes). This mode is accompanied by a higher frequency mode near the surface and at low latitudes, showing poleward migration, and a low-frequency mode at the bottom of the convection zone. The low-frequency mode is almost purely antisymmetric with respect to the equator, while the dominant mode has strongly fluctuating mixed parity. The overall behavior of the dynamo solution is extremely complex, exhibiting variable cycle lengths, epochs of disturbed and even ceased surface activity, and strong short-term hemispherical asymmetries. Surprisingly, the most prominent suppressed surface activity epoch is actually a global magnetic energy maximum; during this epoch the bottom toroidal magnetic field obtains a maximum, demonstrating that the interpretation of grand minima-type events is non-trivial. The hemispherical asymmetries are seen only in the magnetic field, while the velocity field exhibits considerably weaker asymmetry. Conclusions. We interpret the overall irregular behavior as being due to the interplay of the different dynamo modes showing different equatorial symmetries, especially the smoother part of the irregular variations being related to the variations of the mode strengths, evolving with different and variable cycle lengths. The abrupt low-activity epoch in the dominant dynamo mode near the surface is related to a strong maximum of the bottom toroidal field strength, which causes abrupt disturbances especially in the differential rotation profile via the suppression of the Reynolds stresses.

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Width of Sunspot Generating Zone and Reconstruction of Butterfly

Cited by 22 publications

References 12 publications

The Maunder minimum (1645–1715) was indeed a grand minimum: A reassessment of multiple datasets

The Maunder minimum (1645–1715) was indeed a grand minimum: A reassessment of multiple datasets

The Solar Cycle

Multiple dynamo modes as a mechanism for long-term solar activity variations

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