Editing Solar cycle (section)

== Patterns ==
[[File:SpaceEnvironmentOverview From 19830101.jpg|thumb |upright=1.5|An overview of three solar cycles shows the relationship between the solar cycle, galactic cosmic rays, and the state of Earth's near-space environment.<ref>{{cite web |title=Extreme Space Weather Events |publisher=[[National Geophysical Data Center]] |url=http://sxi.ngdc.noaa.gov/sxi_greatest.html |archive-url=https://web.archive.org/web/20011010173025/http://sxi.ngdc.noaa.gov/sxi_greatest.html |url-status=dead |archive-date=10 October 2001 |access-date=2015-11-17}}</ref>]]

Along with the approximately 11-year sunspot cycle, a number of additional patterns and cycles have been hypothesized.<ref name="hathaway_review">David H. Hathaway, [http://solarphysics.livingreviews.org/Articles/lrsp-2010-1/download/lrsp-2010-1Color.pdf "The Solar Cycle"], ''Living Reviews in Solar Physics,'' March 2010, Max Planck Institute for Solar System Research, Katlenburg-Lindau, Germany. ISSN
1614-4961 (accessed 19 July 2015)</ref>

=== Waldmeier effect ===

The '''Waldmeier effect''' describes the observation that the maximum amplitudes of solar cycles are inversely proportional to the time between their solar minima and maxima. Therefore, cycles with larger maximum amplitudes tend to take less time to reach their maxima than cycles with smaller amplitudes.<ref>{{cite journal | last1 = Du | first1 = Zhan-Le | last2 = Wang | first2 = Hua-Ning | last3 = He | first3 = Xiang-Tao | date = 2006 | title = The Relation between the Amplitude and the Period of Solar Cycles | journal = Chinese Journal of Astronomy and Astrophysics | volume = 6 | issue = 4| pages = 489–494 | bibcode = 2006ChJAA...6..489D | doi = 10.1088/1009-9271/6/4/12| s2cid = 73563204 | doi-access = free }}</ref> This effect was named after [[Max Waldmeier]] who first described it.<ref>[[Max Waldmeier|Waldmeier M.]], 1939, Astron. Mitt. Zurich, 14, 439</ref>

=== Gnevyshev–Ohl rule ===
{{Main|Gnevyshev–Ohl rule}}
The Gnevyshev–Ohl rule, in its original formulation, states that for the summary index of solar activity over the 11-year cycle, there is a close connection in pairs of even and subsequent odd cycles, while opposite pairs exhibit no such connection.<ref>{{cite journal |last1=Nagovitsyn |first1=Y. A. |last2=Osipova |first2=A. A. |last3=Ivanov |first3=V.G. |title=Gnevyshev–Ohl Rule: Current Status |url=https://link.springer.com/article/10.1134/S1063772924700069 |journal=Astron. Rep. |volume=68 |issue= 1|pages=89–96 |year=2024|doi=10.1134/S1063772924700069 |bibcode=2024ARep...68...89N |access-date=2025-02-05}}</ref>

=== Gleissberg cycle ===

The '''Gleissberg cycle''' describes an amplitude modulation of solar cycles with a period of about 70–100 years, or seven or eight solar cycles. It was named after Wolfgang Gleißberg.<ref name="hathaway_review" /><ref>{{cite journal |first1 = C. P.|last1 = Sonett|first2 = S. A.|last2 = Finney|first3 = A.|last3 = Berger|title = The Spectrum of Radiocarbon|journal = [[Philosophical Transactions of the Royal Society A]]|volume = 330|issue = 1615|pages = 413–26|date = 24 April 1990|doi = 10.1098/rsta.1990.0022|bibcode = 1990RSPTA.330..413S|s2cid = 123641430}}</ref><ref name="Braun05">{{cite journal |title = Possible solar origin of the 1,470-year glacial climate cycle demonstrated in a coupled model|journal = Nature|volume = 438|pages = 208–11|date = 10 November 2005|doi = 10.1038/nature04121|pmid = 16281042|last1 = Braun|first1 = H|last2 = Christl|first2 = M|last3 = Rahmstorf|first3 = S|last4 = Ganopolski|first4 = A|last5 = Mangini|first5 = A|last6 = Kubatzki|first6 = C|last7 = Roth|first7 = K|last8 = Kromer|first8 = B|issue = 7065|bibcode = 2005Natur.438..208B|s2cid = 4346459|url = http://epic.awi.de/13582/1/Bra2005e.pdf}}</ref><ref name="Hathaway2005">{{Cite journal |first1 = David H.|last1 = Hathaway|first2 = Robert M.|last2 = Wilson|title = What the Sunspot Record Tells Us About Space Climate|journal = [[Solar Physics (journal)|Solar Physics]]|volume = 224|issue = 1–2|year = 2004|pages = 5–19|doi = 10.1007/s11207-005-3996-8|url = http://science.msfc.nasa.gov/ssl/pad/solar/papers/hathadh/HathawayWilson2004.pdf|access-date = 19 April 2007|archive-url = https://web.archive.org/web/20060104223339/http://science.msfc.nasa.gov/ssl/pad/solar/papers/hathadh/HathawayWilson2004.pdf|archive-date = 4 January 2006|bibcode = 2004SoPh..224....5H|s2cid = 55971262}}</ref>

As pioneered by [[Ilya G. Usoskin]] and [[Sami Solanki]], associated centennial variations in magnetic fields in the [[Solar corona|corona]] and [[heliosphere]] have been detected using [[carbon-14]] and [[beryllium-10]] cosmogenic isotopes stored in terrestrial reservoirs such as [[ice sheet]]s and [[tree ring]]s<ref>{{cite journal |author = Usoskin I.G.| author-link=Ilya G. Usoskin |title = A History of Solar Activity over Millennia|journal = Living Reviews in Solar Physics|volume = 14|issue = 3|page = 3|date = 2017|doi = 10.1007/s41116-017-0006-9|bibcode = 2017LRSP...14....3U |arxiv = 0810.3972|s2cid = 195340740}} [https://link.springer.com/content/pdf/10.1007%2Fs41116-017-0006-9.pdf PDF Copy]</ref> and by using historic observations of [[geomagnetic storm]] activity, which bridge the time gap between the end of the usable cosmogenic isotope data and the start of modern satellite data.<ref>{{cite journal |author = Lockwood M.|title = Reconstruction and Prediction of Variations in the Open Solar Magnetic Flux and Interplanetary Conditions|journal = Living Reviews in Solar Physics|volume = 10|issue = 4|page = 4|date = 2013|doi = 10.12942/lrsp-2013-4|url = http://solarphysics.livingreviews.org/Articles/lrsp-2013-4/|bibcode = 2013LRSP...10....4L|doi-access = free}} [http://solarphysics.livingreviews.org/Articles/lrsp-2013-4/download/lrsp-2013-4Color.pdf PDF Copy]</ref>

These variations have been successfully reproduced using models that employ magnetic flux continuity equations and observed sunspot numbers to quantify the emergence of magnetic flux from the top of the solar atmosphere and into the [[heliosphere]],<ref>{{cite journal |author = Owens M.J.|author2 = Forsyth R.J.|name-list-style = amp|title = The Heliospheric Magnetic Field|journal = Living Reviews in Solar Physics|volume = 10|issue = 5|page = 5|date = 2013|doi = 10.12942/lrsp-2013-5| doi-access=free |url = http://solarphysics.livingreviews.org/Articles/lrsp-2013-5/|bibcode = 2013LRSP...10....5O|arxiv = 1002.2934|s2cid = 122870891}}</ref> showing that sunspot observations, geomagnetic activity and cosmogenic isotopes offer a convergent understanding of solar activity variations.

=== Suess cycle ===

The '''Suess cycle''', or '''de Vries cycle''', is a cycle present in radiocarbon proxies of solar activity with a period of about 210 years.
It was named after [[Hans Eduard Suess]] and [[Hessel de Vries]].<ref name="Braun05" /> Despite calculated radioisotope production rates being well correlated with the 400-year sunspot record, there is little evidence of the Suess cycle in the 400-year sunspot record by itself.<ref name="hathaway_review" />

=== Other hypothesized cycles ===
[[File:Carbon-14-10kyr-Hallstadtzeit Cycles.png|thumb|upright=1.35|2,300 year Hallstatt solar variation cycles]]

Periodicity of solar activity with periods longer than the solar cycle of about 11 (22) years has been proposed, including:
* The Hallstatt cycle (named after a cool and wet [[Hallstatt culture|period in Europe when glaciers advanced]]) is hypothesized to extend for approximately 2,400 years.<ref>{{cite web |url=http://pubs.usgs.gov/fs/fs-0095-00/fs-0095-00.pdf |title=The Sun and Climate |work=U.S. Geological Survey |id=Fact Sheet 0095-00 |access-date=2015-11-17}}</ref><ref>{{cite journal |first1=S. S. |last1=Vasiliev |first2=V. A. |last2=Dergachev |title=The ~ 2400-year cycle in atmospheric radiocarbon concentration: bispectrum of <sup>14</sup>C data over the last 8000 years |journal=Annales Geophysicae |volume=20 |issue=1 |pages=115–20 |year=2002 |doi=10.5194/angeo-20-115-2002 |bibcode=2002AnGeo..20..115V |doi-access=free}}</ref><ref>{{cite journal|vauthors=Usoskin IG, Gallet Y, Lopes F, Kovaltsov GA, Hulot G |title=Solar activity during the Holocene: the Hallstatt cycle and its consequence for grand minima and maxima |journal=Astron. Astrophys. |volume=587 |at=A150 |doi=10.1051/0004-6361/201527295 |arxiv=1602.02483 |bibcode=2016A&A...587A.150U |year=2016 |s2cid=55007495}}</ref><ref>{{cite journal |author=Scafetta, Nicola |author-link=Nicola Scafetta|author2=Milani, Franco|author3=Bianchini, Antonio|author4=Ortolani, Sergio|title=On the astronomical origin of the Hallstatt oscillation found in radiocarbon and climate records throughout the Holocene|journal=Earth-Science Reviews |volume=162 |year=2016 |pages=24–43 |doi=10.1016/j.earscirev.2016.09.004 |arxiv=1610.03096 |bibcode=2016ESRv..162...24S |s2cid=119155024}}</ref>
* In studies of [[carbon-14]] ratios, cycles of 105, 131, 232, 385, 504, 805 and 2,241 years have been proposed, possibly matching cycles derived from other sources.<ref>{{Cite journal|title = The Sun as a low-frequency harmonic oscillator.|url = https://journals.uair.arizona.edu/index.php/radiocarbon/article/view/1450|journal = Radiocarbon|date = 2006-03-31|issn = 0033-8222|pages = 199–205|volume = 34|issue = 2|doi = 10.2458/azu_js_rc.34.1450|first1 = Paul E.|last1 = Damon|first2 = John L.|last2 = Jirikowic}}</ref> Damon and Sonett<ref>Damon, Paul E., and Sonett, Charles P., "Solar and terrestrial components of the atmospheric C-14 variation spectrum," ''In The Sun in Time, Vol. 1'', pp. 360–388, University of Arizona Press, Tucson AZ (1991). [http://adsabs.harvard.edu/abs/1991suti.conf..360D Abstract] (accessed 16 July 2015)</ref> proposed carbon 14-based medium- and short-term variations of periods 208 and 88 years; as well as suggesting a 2300-year radiocarbon period that modulates the 208-year period.<ref name="AZgeos462climsolar">see table in {{cite web|title = Solar Variability: climatic change resulting from changes in the amount of solar energy reaching the upper atmosphere.|work = Introduction to Quaternary Ecology|url = http://www.geo.arizona.edu/palynology/geos462/20climsolar.html|access-date = 2015-07-16|archive-url = https://web.archive.org/web/20050320225607/http://www.geo.arizona.edu/palynology/geos462/20climsolar.html|archive-date = 2005-03-20}}</ref>
* [[Brückner-Egeson-Lockyer cycle]] (30 to 40 year cycles).
* A 2021 study investigates the changes of the Pleistocene climate over the last 800 kyr from European Project for Ice Coring in Antarctica (EPICA) temperature ([[δD]]) and CO<sub>2</sub>-CH<sub>4</sub> records<ref>{{Cite journal |last=Past Interglacials Working Group of PAGES |date=2016 |title=Interglacials of the last 800,000 years |url=https://agupubs.onlinelibrary.wiley.com/doi/10.1002/2015RG000482 |journal=Reviews of Geophysics |language=en |volume=54 |issue=1 |pages=162–219 |doi=10.1002/2015RG000482 |bibcode=2016RvGeo..54..162P |issn=8755-1209|hdl=10261/168880 |hdl-access=free }}</ref> by using the benefits of the full-resolution methodology for time-series decomposition singular spectrum analysis, with a special focus on millennial-scale Sun-related signals.<ref>{{Cite journal |last=Viaggi |first=P. |date=2021 |title=Quantitative impact of astronomical and sun-related cycles on the Pleistocene climate system from Antarctica records |journal=Quaternary Science Advances |volume=4 |pages=100037 |doi=10.1016/j.qsa.2021.100037 |issn=2666-0334|doi-access=free |bibcode=2021QSAdv...400037V }}</ref> The quantitative impact of the three Sun-related cycles (unnamed ~9.7-kyr; proposed 'Heinrich-Bond' ~6.0-kyr; Hallstatt ~2.5-kyr), cumulatively explain ~4.0% (δD), 2.9% (CO<sub>2</sub>), and 6.6% (CH<sub>4</sub>) in variance. A cycle of ~3.6 kyr, which is little known in literature, results in a mean variance of 0.6% only, does not seem to be Sun-related, although a gravitational origin cannot be ruled out. These 800-kyr-long EPICA suborbital records, which include millennial-scale Sun-related signals, fill an important gap in the field of solar cycles demonstrating for the first time the minor role of solar activity in the regional budget of Earth's climate system during the Mid-Late Pleistocene.