The Solar Cycle

Hathaway, David H.

doi:10.1007/lrsp-2015-4

Cited by 829 publications

(608 citation statements)

References 205 publications

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“…Since the original RGO series was terminated in 1976, its extension with SOON (Solar Observing Optical Network) data (Neidig et al 1998) may have a transition inhomogeneity related to the reported group areas (Lockwood et al 2014;Hathaway 2015). However, this transition does not affect the present analysis, where we only consider the number and position of spot groups, not their sizes.…”

Section: Datamentioning

confidence: 97%

“…The time-latitude evolution of sunspot occurrence, known as the Maunder butterfly diagram, is one of the most spectacular manifestations of the cyclic variability of solar activity, resulting from the action of the solar dynamo in the Sun's convection zone (Charbonneau 2010;Hathaway 2015). With the butterfly diagram, we can study the detailed evolution of the latitude distribution of sunspots and, thus, the dynamo wave propagation (e.g., Newton & Milsom 1955;Carbonell et al 1993;Pulkkinen et al 1999;Li et al 2002;Ballester et al 2005;Berdyugina et al 2006).…”

Section: Introductionmentioning

confidence: 99%

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Wings of the butterfly: Sunspot groups for 1826–2015

Leussu

Usoskin

Pavai

et al. 2017

A&A

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The spatio-temporal evolution of sunspot activity, the so-called Maunder butterfly diagram, has been continously available since 1874 using data from the Royal Greenwich Observatory, extended by SOON network data after 1976. Here we present a new extended butterfly diagram of sunspot group occurrence since 1826, using the recently digitized data from Schwabe (1826Schwabe ( -1867 and Spörer (1866Spörer ( -1880. The wings of the diagram are separated using a recently developed method based on an analysis of long gaps in sunspot group occurrence in different latitude bands. We define characteristic latitudes, corresponding to the start, end, and the largest extent of the wings (the F, L, and H latitudes). The H latitudes (30 • -45 • ) are highly significantly correlated with the strength of the wings (quantified by the total sum of the monthly numbers of sunspot groups). The F latitudes (20 • -30 • ) depict a weak tendency, especially in the southern hemisphere, to follow the wing strength. The L latitudes (2 • -10 • ) show no clear relation to the wing strength. Overall, stronger cycle wings tend to start at higher latitudes and have a greater wing extent. A strong (5-6)-cycle periodic oscillation is found in the start and end times of the wings and in the overlap and gaps between successive wings of one hemisphere. While the average wing overlap is zero in the southern hemisphere, it is two to three months in the north. A marginally significant oscillation of about ten solar cycles is found in the asymmetry of the L latitudes. The new long database of butterfly wings provides new observational constraints to solar dynamo models that discuss the spatio-temporal distribution of sunspot occurrence over the solar cycle and longer.

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Section: Datamentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Wings of the butterfly: Sunspot groups for 1826–2015

Leussu

Usoskin

Pavai

et al. 2017

A&A

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“…These processes are crucial for the evolution of the solar cycle. On the latter, we refer the reader to the Living Review by Hathaway (2010).…”

Section: Modelling the Evolution Of Ars From Emergence Through Decaymentioning

confidence: 99%

Evolution of Active Regions

Driel-Gesztelyi

Green

2015

Living Rev. Sol. Phys.

250

131

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The evolution of active regions (AR) from their emergence through their long decay process is of fundamental importance in solar physics. Since large-scale flux is generated by the deepseated dynamo, the observed characteristics of flux emergence and that of the subsequent decay provide vital clues as well as boundary conditions for dynamo models. Throughout their evolution, ARs are centres of magnetic activity, with the level and type of activity phenomena being dependent on the evolutionary stage of the AR. As new flux emerges into a pre-existing magnetic environment, its evolution leads to re-configuration of small-and large-scale magnetic connectivities. The decay process of ARs spreads the once-concentrated magnetic flux over an ever-increasing area. Though most of the flux disappears through small-scale cancellation processes, it is the remnant of large-scale AR fields that is able to reverse the polarity of the poles and build up new polar fields. In this Living Review the emphasis is put on what we have learned from observations, which is put in the context of modelling and simulation efforts when interpreting them. For another, modelling-focused Living Review on the sub-surface evolution and emergence of magnetic flux see Fan (2009). In this first version we focus on the evolution of dominantly bipolar ARs. Article RevisionsLiving Reviews supports two ways of keeping its articles up-to-date:Fast-track revision. A fast-track revision provides the author with the opportunity to add short notices of current research results, trends and developments, or important publications to the article. A fast-track revision is refereed by the responsible subject editor. If an article has undergone a fast-track revision, a summary of changes will be listed here.Major update. A major update will include substantial changes and additions and is subject to full external refereeing. It is published with a new publication number.For detailed documentation of an article's evolution, please refer to the history document of the article's online version at http://dx

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“…However, SN series cannot be internally verified, and no selfconsistency checks are available beyond some non-strict empirical relations between the length and the amplitude of solar cycle (Waldmeier 1935;Hathaway 2015) or between the number of sunspots and groups (Friedli 2017). Accordingly, it is hardly possible to assess the reliability of different series from the sunspot data alone.…”

Section: Introductionmentioning

confidence: 99%

Assessment of different sunspot number series using the cosmogenic isotope ⁴⁴ Ti in meteorites

Asvestari

Usoskin

Kovaltsov

et al. 2017

Mon. Not. R. Astron. Soc.

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Many sunspot number series exist suggesting different levels of solar activity during the past centuries. Their reliability can be assessed only by comparing them with alternative indirect proxies. We test different sunspot number series against the updated record of cosmogenic radionuclide 44 Ti measured in meteorites. Two bounding scenarios of solar activity changes have been considered: the HH-scenario (based on the series by Svalgaard and Schatten), in particular, predicting moderate activity during the Maunder minimum, and the LL-scenario (based on the R G series by Lockwood et al.) predicting moderate activity for the 18th-19th centuries and the very low activity level for the Maunder minimum. For each scenario, the magnetic open solar flux, the heliospheric modulation potential and the expected production of 44 Ti were computed. The calculated production rates were compared with the corresponding measurements of 44 Ti activity in stony meteorites fallen since 1766. The analysis reveals that the LL-scenario is fully consistent with the measured 44 Ti data, in particular, recovering the observed secular trend between the 17th century and the Modern grand maximum. On the contrary, the HH-scenario appears significantly inconsistent with the data, mostly due to the moderate level of activity during the Maunder minimum. It is concluded that the HHscenario sunspot number reconstruction significantly overestimates solar activity prior to the mid-18th century, especially during the Maunder minimum. The exact level of solar activity after 1750 cannot be distinguished with this method, since both H-and L-scenarios appear statistically consistent with the data.

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The Solar Cycle

Cited by 829 publications

References 205 publications

Wings of the butterfly: Sunspot groups for 1826–2015

Wings of the butterfly: Sunspot groups for 1826–2015

Evolution of Active Regions

Assessment of different sunspot number series using the cosmogenic isotope ⁴⁴ Ti in meteorites

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The Solar Cycle

Cited by 829 publications

References 205 publications

Wings of the butterfly: Sunspot groups for 1826–2015

Wings of the butterfly: Sunspot groups for 1826–2015

Evolution of Active Regions

Assessment of different sunspot number series using the cosmogenic isotope 44 Ti in meteorites

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Product

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Assessment of different sunspot number series using the cosmogenic isotope ⁴⁴ Ti in meteorites